Anatomy and Physiology – Midterm Review Anatomical terminology Definition of Anatomy vs. Physiology Anatomy – is the science of body structures and the relationships among them Physiology – is the science of body functions, how the body parts work Tissue Types (4)

1. EPITHELIUM Functions (jobs): 1) It protects us from the outside world – skin. 2) Absorbs – stomach and intestinal lining (gut) 3) Filters – the kidney 4) Secretes – forms glands Characteristics (Traits): 1) Closely attached to each other forming a protective barrier. 2) Always has one free (apical) surface open to outside the body or inside (cavity) an internal organ. 3) Always had one fixed (basal) section attached to underlying connective tissue. 4) Has no blood vessels but can soak up nutrients from blood vessels in connective tissue underneath. 5) Can have lots of nerves in it (innervated). 6) Very good at regenerating (fixing itself). i.e. sunburn, skinned knee. Classifications (types): 1) By shape a) squamous - flat and scale-like b) cuboidal - as tall as they are wide c) columnar - tall, column-shaped 2) By cell arrangement a) simple epithelium - single layer of cells (usually for absorption and filtration) b) stratified epithelium - stacked up call layers (protection from abrasion (rubbing) - mouth, skin.)

2. CONNECTIVE TISSUE Functions (jobs): 1) Wraps around and cushions and protects organs 2) Stores nutrients 3) Internal support for organs 4) As tendon and ligaments protects joints and attached muscles to bone and each other 5) Runs through organ capsules and in deep layers of skin giving strength The 3 Elements of Connective Tissue:

1) Ground substance – gel around cells and fibers 2) Fibers – provide strength, elasticity and support 3) Cells 2 Kinds of Connective Tissue: 1) Loose Connective Tissue: a) Areolar Connective Tissue – cushion around organs, loose arrangement of cells and fibers. b) Adipose Tissue – storehouse for nutrients, packed with cells and blood vessels c) Reticular Connective Tissue – internal supporting framework of some organs, delicate network of fibers and cells 2) Dense Connective Tissue: a) Dense Regular Connective Tissue – tendons and ligaments, regularly arranged bundles packed with fibers running same way for strength in one direction. b) Dense Irregular Connective Tissue – skin, organ capsules, irregularly arranged bundles packed with fibers for strength in all directions. 2(a)- SPECIAL CONNECTIVE TISSUES 1) CartilageFunctions (jobs): a) provides strength with flexibility while resisting wear, i.e. epiglottis, external ear, larynx b) cushions and shock absorbs where bones meet, i.e. intervertebral discs, joint capsules 2) BoneFunctions (jobs): a) provides framework and strength for body b) allows movement c) stores calcium d) contains blood-forming cells 3) BloodFunctions (jobs): a) transports oxygen, carbon dioxide, and nutrients around the body b) immune response

3. NERVOUS TISSUE Functions (jobs): 1) Conducts impulses to and from body organs via neurons The 3 Elements of Nervous Tissue 1) Brain 2) Spinal cord 3) Nerves

4. MUSCLE TISSUE Functions (jobs): 1) Responsible for body movement 2) Moves blood, food, waste through body’s organs 3) Responsible for mechanical digestion The 3 Types of Muscle Tissue

1) Smooth Muscle – organ walls and blood vessel walls, involuntary, spindle-shaped cells for pushing things through organs 2) Skeletal Muscle – large body muscles, voluntary, striated muscle packed in bundles and attached to bones for movement 3) Cardiac Muscle – heart wall, involuntary, striated muscle with intercalated discs connecting cells for synchronized contractions during heart beat. Origin of Anatomical Terms (Discoverer, Region, Shape, Function, Story Anatomical Position, Sectioning planes, Directions, Movements Anatomical Position –

Standard position of reference – anatomical position– directly facing observer with head level, feet flat on the floor, upper limbs are at the sides with palms facing toward forward

If the body is facing down – prone position If the body is lying face up – supine position

Sectioning Planes – Sagital Plane – vertical plane that divides the body or an organ into right and left sides. Midsagittal or Median Plane – when such a plane passes through the midline of the body or an organ and divides it into equal right and left sides Parasagittal Plane – if the sagittal plane does not pass through the midline but instead divides the body or an organ into unequal right and left sides Frontal or Coronal Plane – divides the body or an organ into anterior (front) and posterior (back) portions. Transverse or Cross-sectional or Horizontal Plane – divides the body or an organ inter superior (upper) and inferior (lower) portions Oblique Plane – passes through the body or an organ at an oblique angle (any angle other than a 90 degree angle) Directions – Directional Term Definition Example of Use Superior Toward the head, or the

upper part of a structure The heart is superior to the liver

Inferior Away from the head or the lower part of a structure

Stomach is inferior to the lungs

Anterior Nearer to or at the front of the body

The sternum is anterior to the heart

Posterior Nearer to or at the back of the body

The esophagus is posterior to the trachea

Medial Nearer to the midline The ulna is medial to the radius

Lateral Farther from the midline The lungs are lateral to the heart

Intermediate Between two structures The transverse colon is intermediate between ascending and descending colons

Ipsilateral On the same side of the body as another structure

The gallbladder and ascending colon are ipsilateral

Contralateral On the opposite side of the body from another structure

The ascending and descending colons are contralateral

Proximal Nearer to the attachment of a limb to the trunk; nearer to the origination of a structure

The humerus (arm bone) is proximal to the radius

Distal Farther from the attachment of a limb to the trunk; farther from the origination of a structure

The phalanges (finger bones) are distal to the carpals (wrist bones)

Superficial Toward or on the surface of the body

The ribs are superficial to the lungs

Deep Away from the surface of the body

The ribs are deep to the skin of the chest and back

Surface Anatomy (landmarks, regions)

Principle regions- head, neck, trunk, upper limbs, and lower limbs Head – skull (which encloses the brain) and face (eyes, nose, mouth,

forehead, cheeks, chin) Neck – supports the head and attaches to the trunk Trunk – chest, abdomen and pelvis Upper limb – attaches to the trunk… shoulder, armpit, arm (portion of the

limb from shoulder to the elbow), forearm (portion of the limb from the elbow to the wrist), wrist and hand

Lower limb – attaches to the trunk… buttock, thigh (portion from buttock to knee), leg (portion from knee to ankle), ankle and foot

Body Cavities & Potential Space

Cavity Comments Cranial Formed by cranial bones and contains

brain Vertebral canal Formed by vertebral column and

contains spinal cord and the beginnings of spinal nerves

Thoracic cavity Pleural Cavity Pericardial Cavity Mediastinum

Chest cavity; contains pleural and pericardial cavities and mediastinum Each surrounds a lung; the serous membrane of each pleural cavity is the pleura Surrounds the heart; the serous membrane of the pericardial cavity is the pericardium Central portion of the thoracic cavity between the lungs; extends from sternum to vertebral column and from first rib to diaphragm; contains heart, thymus, esophagus, trachea, and several large blood vessels

Abdominopelvic Cavity Abdominal Cavity Pelvic Cavity

Subdivided into abdominal and pelvic cavities Contains stomach, spleen, liver, gallbladder, small intestine, and most of large intestine; the serous membrane of the abdominal cavity is the peritoneum Contains urinary bladder, portions of large intestine, and internal organs of reproduction

Axial and Appendicular Skeleton

Homeostasis

Definition of Homeostasis Homeostasis – is the condition of equilibrium in the body’s internal environment due to the constant interaction of the body’s many regulatory processes Components of a Feedback Loop Variable – body temperature, blood pressure, blood glucose … all have controlled conditions Stimulus – disruption to the controlled condition of the variable Receptor – body structure that monitors changes in the controlled condition and sends input to a control center (afferent – towards control center) Control Center – sets the range of values that should be maintained, evaluates the input received from receptors and generates output commands when they are needed (nerve impulses, hormones) (efferent pathway – away from control center) Effector – body structure that receives output from control center and produces a response or effect that changes the controlled condition. Nearly every organ or tissue can behave as an effector Positive vs. Negative Feedback

Homeostasis and Disease Many diseases are the result of years of poor health behavior that interferes with the body’s natural drive to maintain homeostasis. An obvious example is smoking-related illness. Smoking tobacco ex- poses sensitive lung tissue to a multitude of chemicals that cause cancer and damage the lung’s ability to repair itself. Because dis- eases such as emphysema and lung cancer are difficult to treat and are very rarely cured, it is much wiser to quit smoking—or never start—than to hope a doctor can “fix” you once you are diagnosed with a lung disease. Developing a lifestyle that works with, rather than against, your body’s homeostatic processes helps you maximize your personal potential for optimal health and well-being. As long as all of the body’s controlled conditions remain within certain narrow limits, body cells function efficiently, homeostasis is maintained, and the body stays healthy. Should one or more components of the body lose their ability to contribute to homeostasis, however, the normal balance among all of the body’s processes may be disturbed. If the homeostatic imbalance is moderate, a dis- order or disease may occur; if it is severe, death may result. Signs vs. Symptoms A person with a disease may experience symptoms, subjective changes in body functions that are not apparent to an observer.

Examples of symptoms are headache, nausea, and anxiety.

Objective changes that a clinician can observe and measure are called signs. Signs of disease can be either anatomical, such as swelling or a rash, or physiological, such as fever, high blood pressure, or paralysis.

Tissues & Integument TISSUES Definition: Cell, Tissue, Organ, System Cell - Molecules combine to form cells, the basic structural and functional units of an organism that are composed of chemicals. Just as words are the smallest elements of language that make sense, cells are the smallest living units in the human body. Among the many kinds of cells in your body are muscle cells, nerve cells, and epithelial cells. Tissue - groups of cells and the materials surrounding them that work together to perform a particular function, similar to the way words are put together to form

sentences. There are just four basic types of tissues in your body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue. Epithelial tissue covers body surfaces, lines hollow organs and cavities, and forms glands. Connective tissue connects, supports, and protects body organs while distributing blood vessels to other tissues. Muscular tissue contracts to make body parts move and generates heat. Nervous tissue carries information from one part of the body to another through nerve impulses. Organ - At the organ level different types of tissues are joined together. Similar to the relationship between sentences and paragraphs, organs are structures that are composed of two or more different types of tissues; they have specific functions and usually have recognizable shapes. Examples of organs are the stomach, skin, bones, heart, liver, lungs, and brain. The stomach’s outer covering is a layer of epithelial tissue and connective tissue that reduces friction when the stomach moves and rubs against other organs. Underneath are three layers of a type of muscular tissue called smooth muscle tissue, which contracts to churn and mix food and then push it into the next digestive organ, the small intestine. The innermost lining is an epithelial tissue layer that produces fluid and chemicals responsible for digestion in the stomach. System - A system (or chapter in our language analogy) consists of related organs (paragraphs) with a common function. An example of the system level, also called the organ- system level, is the digestive system, which breaks down and absorbs food. Its organs include the mouth, salivary glands, pharynx (throat), esophagus (food tube), stomach, small intestine, large intestine, liver, gallbladder, and pancreas. Sometimes an organ is part of more than one system. The pancreas, for example, is part of both the digestive system and the hormone-producing endocrine system. Why are cells so small? (SA/Vol) 1. A cell is a metabolic compartment where a multitude of chemical reactions occur. 2. The number of reactions increases as the volume of metabolic volume within a cell increases. (The larger the volume the larger the number of reactions) 3.All raw materials necessary for metabolism can enter the cell only through its cell membrane. 4.The greater the surface area the larger the amount of raw materials that can enter at only one time. 5.Each unit of volume requires a specific amount of surface area to supply its metabolism with raw materials. The amount of surface area available to each unit of volume varies with the size of a cell. 6. As a cell grows its SA/V decreases. 7. At some point in its growth its SA/V becomes so small that its surface area is too small to supply its raw materials to its volume. At this point the cell cannot get larger PM Proteins

Ion Channels Pores or holes that specific ions can flow through to get into or out of cell Most ion channels are selective

Carriers/Transporters Selectively moving a polar substance or ion from one side of the membrane

to the other Receptors

Cellular recognition sites Each receptor recognizes and binds a specific type of molecule

Enzymes Catalyze specific reactions at the inside or outside surface of the cell

Linkers Anchor proteins in the plasma membranes of neighboring cells to one

another or to protein filaments inside and outside the cell Cell Identity Markers

Recognize other cells of the same kind during tissue formation Recognize and respond to potentially dangerous foreign cells

Cytoskeletal Elements Mircrofilaments

Thinnest elements of the cytoskeleton Composed of proteins: actin and myosin Prevalent at the edges of the cell Functions: help generate movement and provide mechanical support

(microvilli – increase surface area for absorption) Intermediate Filaments

Thicker than microfilaments but thinner than microtubules Several proteins compose intermediate filaments (strong) Found in parts of cell subject to mechanical stress – help stabilize

Microtubules Largest of the cytoskeleton components Long, unbranched hollow tubes Protein – tubulin Assembly begins in organelle – cystrosome – microtubules grow outward

towards the periphery of the cell Help determine shape, movement of organelles (chromosomes - cell division)

Cell Junctions Gap Junctions

Protein that spans plasma membrane of two adjacent cells Connexons connect neighboring cells Plasma membranes are not fused together, separated by a narrow

intercellular gap Through connexons ions can diffuse from the cytosol of one cell to the cytosol

of another Desosomes

Proteins span plasma membrane of two cells structurally (not providing pore)

Give it strength to adhere to each other Attach to intermediate filaments

Hemidesosomes ½ of desosome not connecting to another cell connecting to extracellular fluid

Tight Junctions zip lock bag seal water proof, water tight protein spans plasma membrane of two adjacent cells things don’t leak from gut into body without process

Adherens Junctions zipper (tightest hold) plaque of structural proteins to zip two cells together

ECM – Function, Composition Classification of Epithelium – layers, shapes, examples

1. Arrangement of cells in layers -The cells are arranged in one or more layers depending on function: Simple epithelium is a single layer of cells that functions in diffusion, osmosis, filtration, secretion, or absorption. Secretion is the production and release of substances such as mucus, sweat, or enzymes. Absorption is the intake of fluids or other substances such as digested food from the intestinal tract. Pseudostratified epithelium appears to have multiple layers of cells because the cell nuclei lie at different levels and not all cells reach the apical surface, but it is actually a simple epithelium because all its cells rest on the basement membrane. Cells that do extend to the apical surface may contain cilia; others (goblet cells) secrete mucus.

Stratified epithelium consists of two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear. 2. Cell shapes. Epithelial cells vary in shape de- pending on their function: Squamous cells are thin, which allows for the rapid passage of substances through them. Cuboidal cells are as tall as they are wide and are shaped like cubes or hexagons. They may have microvilli at their apical surface and function in either secretion or absorption. Columnar cells are much taller than they are wide, like columns, and protect underlying tissues. Their apical surfaces may have cilia or microvilli, and they often are specialized for secretion and absorption. Transitional cells change shape, from squamous to cuboidal and back, as organs such as the urinary bladder stretch (distend) to a larger size and then collapse to a smaller size. Basement Membrane

A thin extracellular layer that commonly consists of two layers, the basal lamina and reticular lamina.

The basal lamina (thin layer) is closer to—and secreted by—the epithelial cells. It contains proteins such as laminin and collagen (described shortly), as well as glycoproteins and proteoglycans (also described shortly).

The laminin molecules in the basal lamina adhere to integrins in hemidesmosomes and thus attach epithelial cells to the basement membrane.

The reticular lamina is closer to the underlying connective tissue and contains proteins such as collagen produced by connective tissue cells called fibroblasts.

In addition to attaching to and supporting the overlying epithelial tissue, basement membranes have other functions:

They form a surface along which epithelial cells migrate during growth or wound healing, restrict passage of larger molecules between epithelium and connective tissue, and participate in filtration of blood in the kidneys.

Connective Tissue

INTEGUMENT Structure (epidermis, dermis, hypodermis) Epidermis Structurally, the epidermis is a thick keratinued stratified squamous epithelium consisting of four distinct cell types and five distinct layers. Cells of the EpidermisCells populating the epidermis include: keratinocytes, melanocytes, Merkel cells, and Langerhans cells. Keratinocytes: The most numerous cells are the keratinocytes which produce keratin, a fibrous protein responsible for protective properties of the epidermis. They arise from the deepest part of the epidermis from cells undergoing almost continuous mitosis. The keratinocytes are organized into 4-5 cell layers depending on body location. By the time the cells reach the surface of the skin, they are dead, scale-like structures. Every 35-45 days a totally new epidermis occurs. In areas of highest friction ( hands, feet) both cell production and keratin formation is accelerated. Melanocytes: located at the base of the epidermis. Specialized cells that synthesize the pigment melanin. Melanin protects the cell nucleus from the destructive effects of UV radiation. Since all humans have the same relative number of these cells, individual and racial differences in skin coloring are probably due to differences in melanocyte activity. Langerhans cells: arise from the bone marrow and migrate to the epidermis and other areas of the body containing stratified squamous epithelial tissue. They are macrophages and cooperate with T helper cells to assist in the immune response. Merkel cells: present in small numbers at the epidermal-dermal junction. Associated with a disc-like ending of a sensory nerve fiber, called a Merkel disc, which functions as a sensory receptor. Layers of the Epidermis: In thick skin (palms, fingertips, soles of feet) the epidermis consists of five layers or strata: (from deep to superficial) stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum. Thin skin, which covers the rest of the body has only 4 layers, with the stratum lucidum absent. Stratum basale: single layer of cuboidal to columnar shaped cells. It is separated from the dermis by the basement membrane. Some cells move toward the surface while others migrate into the dermis and gives rise to sweat and oil glands. Many mitotic cells are seen. About 25% of the cells in this layer are melanocytes. Stratum spinosum: contains 5-10 rows of cells fitted closely together. The surface of the cells display minute spiney projections. Mitosis occurs here but not as frequently. Langerhans cells are scattered among the keratinocytes. Because cells superficial to this layer do not receive adequate nutrients, they become less viable and finally begin to die. Stratum granulosum: thin zone consisting of 3-5 layers of flattened cells. Keratinization begins in this third epidermal layer. The plasma membranes of these cells also thicken so that they become more resistant to destruction. Langerhans

cells are also found in this layer. At the upper border of this layer, the cells die and lysosomes begin to digest their organelles. Stratum lucidum (clear layer): translucent band just above the S. granulosum. Consists of a few rows of flattened dead keratinocytes with indistinct boundaries. Present only in thick skin. Stratum corneum: outermost layer; a broad zone 20-30 cell layers thick. Accounts for about 3/4 of the epidermal thickness. The shingle-like dead cells are remnants, completely filled with keratin fibrils, and are referred to as cornified or horny cells. Keratin provides a durable abrasion resistant and water-repellent "overcoat" protecting deeper cells from the environment. Dermis: The second major skin region, is a strong but flexible connective tissue layer. The cell types found in the dermis are fibroblasts (predominant cell type), macrophages, and occasional mast cells and white blood cells. Its gel-like matrix is heavily embedded with collagen, elastin, and reticular fibers. The dermis is your "hide" and is richly supplied with nerve fibers, blood vessels, and lymphatic vessels. The major portions of hair follicles, as well as oil and sweat glands, reside in the dermis, but are derived from epidermal tissue. The dermis varies in thickness and it has two major layers: papillary and reticular. Papillary: Thin superficial layer of loose connective tissue fibers. Forms a loosely woven mat that is heavily invested with blood vessels. Its superior surface is thrown into nipple-like projections called dermal papillae, that indent the epidermis above. Many dermal papillae contain capillary loops; others house free nerve endings and touch receptors (Meissner's corpuscles). On the ventral aspect of the hands and feet, the papillae are arranged in definite patterns that are reflected in the conspicuous looped and whorled ridges which enhance the gripping ability of the fingers and feet. Reticular: accounts for about 80% of the dermis and is a typical dense irregular connective tissue. It contains bundles of interlocking collagen fibers that run in various planes parallel to the skin surface. The fibers interlace in a netlike manner with the spaces between the fibers occupied by a small amount of adipose tissue, hair follicles, nerves, oil glands and ducts of sweat glands. The connective tissue fibers of the dermis give skin its strength and resiliency. Collagen binds water, thus helping to maintain the hydration of the skin. The reticular region is attached to underlying organs (bones, muscles) by the subcutaneous layer. GLANDS- REFER TO CHART Thick vs Thin Skin

How is skin an indicator of clinical conditions? 6 Functions of the Skin

1. Thermo-regulation – Maintenance of body temperature (37C) The skin contributes to thermoregulation in two ways: by liberating sweat at

its surface and by adjusting the flow of blood in the dermis High temp response – sweat production from eccrine glands increases,

evaporation on skin surface helps lower body temp, blood vessels in the dermis dilate (become wider) – more blood flow – more heat loss

Low temp response – production of sweat from eccrine glands decreases, dermis blood vessels constrict (narrow) – less blood flow – less heat loss

2. Blood reservoir – The dermis houses an extensive network of blood vessels that carry 8–10%

of the total blood flow in a resting adult. 3. Protection – PHYSICAL - Keratin protects underlying tissues from microbes, abrasion,

heat, and chemicals, and the tightly interlocked keratinocytes resist invasion by microbes.

CHEMICAL - Lipids released by lamellar granules inhibit evaporation of water from the skin surface, thus guarding against dehydration; they also retard entry of water across the skin surface during showers and swims. The oily sebum from the sebaceous glands keeps skin and hairs from drying out and contains bactercidal chemicals (substances that kill bacteria). The acidic pH of perspiration retards the growth of some microbes. The pigment melanin helps shield against the damaging effects of ultraviolet light

BIOLOGICAL - Epidermal Langerhans cells alert the immune system to the presence of potentially harmful microbial invaders by recognizing and processing them, and macrophages in the dermis phagocytize bacteria and viruses that manage to bypass the Langerhans cells of the epidermis.

4. Cutaneous sensations - Sensations that arise in the skin, including tactile sensations—touch,

pressure, vibration, and tickling—as well as thermal sensations such as warmth and cool- ness

Pain, usually is an indication of impending or actual tissue damage. There is a wide variety of nerve endings and receptors distributed throughout the skin, including the tactile discs of the epidermis, the corpuscles of touch in the dermis, and hair root plexuses around each hair follicle.

5. Metabolism - SYNTHESIS OF VITAMIN D- Synthesis of vitamin D requires activation of a

precursor molecule in the skin by ultraviolet (UV) rays in sunlight. Enzymes in the liver and kidneys then modify the activated molecule, finally producing calcitriol - is a hormone that aids in the absorption of calcium from foods in the gastrointestinal tract into the blood - the most active form of vitamin D.

6. Excretion/Absorption - EXCRETION - Besides removing water and heat from the body, sweat also is

the vehicle for excretion of small amounts of salts, carbon dioxide, and two

organic molecules that result from the breakdown of proteins—ammonia and urea

ABSORPTION – no water-soluble solutions through skin, fat-soluble vitamins (A, D, E, and K), certain drugs, and the gases oxygen and carbon dioxide. Toxic materials – acetone, chloride

Hypodermis (structure and function)

Attaches the skin to the underlying structures (fascia of muscles) Contains loose CT (adipose) – amount depends on age, sex, nutrition and

area of body Insulates and cushions the body

Membrane Potentials

What is potential? An electrical potential difference (voltage) across the membrane … in

excitable cells this voltage is termed the resting membrane potential

Ionic composition of Intracellular and Extracellular fluid Charge vs. Electrical Gradient

The electrochemical gradient is where the charge dictates where the ions should go. For example, if one side of the membrane is negative, then the electrochemical gradient would 'pull' positive ions to the negative side, as the positive ions are attracted to the negative environment. This will also work to depolarize the environment a bit.

The concentration gradient is the simpler one. Basically, the side of the

membrane with a higher concentration of a certain molecule/ion will lose them down the concentration gradient to the side with the lower concentration of those molecules.

Influx vs. Efflux Factors involved in maintaining RMP

1. Unequal distribution of ions in the ECF and cytosol Unequal distribution of various ions in extracellular fluid and

cytosol PM typically has more K+ leak channels than Na+ leak channels,

the number of potassium ions that diffuse down their concentration gradient out of the cell into the ECF is greater than the number of sodium ions that disuse down their concentration gradient from the ECF into the cell

2. Inability of most anions to leave the cell Most anions inside the cell are not free to leave They cant follow the K+ out of the cell because they are attached

to nondiffusible molecules such as ATP and large proteins

3. Sodium-Potassium Pumps Membrane permeability for Na+ is very low because of very few

channels – slowly diffuse inward Pumps maintain RMP by pumping out Na+ as fast as it leaks in Being in K+ - eventually leak out Na+ (3 out) K+ (2 in) Electrogenic – bring in more negative to the cell

Hyperpolarizing vs. Depolarizing Hyperpolarizing – more negative

Stimulus applied at this time (ex: opening of K+ channels which allows the exit of K+ from the cytoplasm to the extracellular fluid)

Depolarizing – more positive Stimulus applied at this time (ex: opening of Na+ channels which allows

entry of Na+ into the cytoplasm from the extracellular fluid or the opening of Ca+ channels which allows their entry)

Voltage Gated vs. Ligand Gated ion channels 1. Voltage Gated Channels – open and close in response to a change in

membrane potential (V)(. Participate in the generation and conduction of action potentials in the axons of all types of neurons

2. Ligand Gated Channel – open and close in response to the binding of a ligand (chemical) stimulus. Neurotransmitters, hormones, ions can open and close ligand gates. Located in some sensory neurons.

Graded Potential vs. Action Potential 1. Graded potentials – used for short distance communication only (small) 2. Action potentials – allow for communication over long distances within the

body (large)

Phases of the Action Potential Resting Stage – all voltage gated Na+ and K+ channels are closed. Axon plasma membrane is at RMPL small buildup of negative charges along inside surface of membrane and equal buildup of positive charges along outside surface membrane Depolarizing Phase – MP of axon reaches threshold, Na+ channel activation gates open. As Na+ ions move through these channels into neuron buildup of positive charges forms along inside surface of membrane and membrane becomes depolarized

Repolarizing phase begins – Na+ channel inactivation gates close and K+ channels open. Membrane starts to become repolarized as some K+ ions leave neuron and few negative charges begins to build up along inside surface of membrane Repolarization phase continues – K+ outflow continues. As more K+ ions leave neuron, more negative charges build up along inside surface of membrane. K+ outflow eventually restores resting membrane potential. Na+ channel inactivation gates open. Return to resting state occurs when K+ gates close. Importance of AP refractory periods

Must leave space in between messages in order for them to be delivered and for them to make sense – absolute refractory period

Stimulus needs to be very strong in order to surpass a – relative refractory period

Repeated stimuli can produce unfused (incomplete) tetanus, a sustained muscle contraction with partial relaxation between stimuli. More rapidly repeating stimuli produce fused (complete) tetanus, a sustained contraction without partial relaxation between stimuli.

Neurotransmission Spatial Summation of Postsynaptic Potentials

Summation of postsynaptic potentials in response to stimuli that occur at different locations in the membrane of a postsynaptic cell at the same time

Temporal Summation of Postsynaptic Potentials Summation of postsynaptic potentials in response to stimuli that occur a the

same location in the membrane of the postsynaptic cell but at different times Continuous vs. Saltatory Conduction Two types of propagation: Continuous Conduction

Involves step by step depolarization and repolarization of each adjacent segment of the plasma membrane

Ions flow through their voltage-gated channels in each adjacent segment of the membrane

AP propagates only a relatively short distance in a few milliseconds Unmyelinated axons and muscle fibres

Saltatory Conduction AP propagation that occurs along myelinated axons Occurs because of uneven distribution of voltage-gated channels Few voltage gated channels are present in regions where myelin sheath

covers the axolemma At not nodes of Ranvier (no myelin sheath) the axolemma has many voltage

gated channels Current carried by Na+ and K+ flow across the membrane mainly at the

nodes Electrical Synapses

AP (impulses) conduct directly between the PM of adjacent neurons through structures called gap junctions

Each GJ contains a hundred or so tubular connexons which act like tunnels to connect the cytosol of the two cells directly

GJ are common in visceral smooth muscle, cardiac muscle and the developing embryo Advantages:

1. Faster communication – AP conduct directly through gap junctions, ES are faster than CS. Directly from presynaptic to postsynaptic

2. Synchronization – coordinate the activity of a group of neurons or muscle fibres … produce action potentials in unison if they are connected by gap junctions (produce heart beat, move food through gastrointestinal tract)

Chemical Synapses PM of presynaptic and postsynaptic neurons in a chemical synapse are close ,

but DO NOT touch Separated by the synaptic cleft – space of 20-50 nm that is filled with

interstitial fluid Nerve impulses CANNOT conduct across the synaptic cleft In response to a nerve impulse the presynaptic neuron releases a

neurotransmitter that diffesis through te fluid in the synaptic cleft and binds to repectors in the PM of the postsynaptic neuron

Postsynaptic receives the chemical signal and produces postsynaptic potential (graded potential)

Synaptic Delay – time required at the chemical synapse (0.5 msec) – slow Excitatory Postsynacptic Potential

Neurotransmitter that causes depolarixation of postsynaptic membrane Brings membrane closer to threshold A single EPSP normally does not initiate a nerve impulse the postsynaptic cell

does become more excitable Inhibitory Postsynaptic Potential

Neurotransmitter that causes hyperpolarization of the postsynaptic membrane

During hyperpolarization generation of an AP is more difficult than usual because the membrane potential becomes inside more negative and thus even father from threshold than in its resting state

IPSP Classes of Neurotransmitters and their effects Removal of a Neurotransmitter

Removal of the neurotransmitter from the synaptic cleft is essential for normal synaptic function… 3 ways:

1. Diffusion – some of the released neurotransmitter molecules diffuse away from the synaptic cleft. Once out of reach of receptors, it can no longer exert an effect

2. Enzymatic degradation – certain neurotransmitters are inactivated through enzymatic degradation. For example, the enzyme acetylvholinrdterase breaks down acetylcholine in the synaptic cleft

3. Uptake by cells – many neurotransmitters are actively transported back into the neuron that released them (reuptake)

Muscle A&P Smooth vs. Cardiac vs. Skeletal

Skeletal Connective Tissue organization

Surrounds and protects muscular tissue Subcutaneous layer or hypodermis which separates muscle from skin is

composed of areolar connective tissue and adipose tissue. Provides a pathway for nerves, blood vessels and lymphatic vessels to enter

and exit muscles Adipose tissue – insulation and storage Fascia tissue that lines the body wall and limbs and supports and surrounds

muscles other organs of the body Perimysium – a layer of dense, irregular connective tissue, but it surrounds groups of 10 to 100 or more muscle fibres, separating them into bundles fascicles (bundle) Endomysium – penetrates the interior of each fascicle and separates individual muscles from one another. The endomysium is mostly reticular fibres (single fibre) Epimysium – outer most layer of sense irregular connective tissue that surrounds entire muscle

Skeletal Muscle Organization Sarcolemma

Multiple nuclei of the skeletal fiber are located just beneath Plasma membrane of the muscle cell

Transverse (T) tubules Thousands of ting invaginations of the sarcolemma Open to the outside of the muscle fiber – filled with interstitial fluid AP travel along sarcolemma and through T tubules throughout the muscle

fiber – excite entire muscle fiber in one instant Sarcoplasm

The cytoplasm of a muscle fiber Substantial amount of glycogen Used for synthesis of ATP

Myoglobin

Sarcoplasm contains red colored protein Found only in muscle Binds oxygen molecules that diffuse into muscle fibers from interstitial fluid Releases oxygen when it is needed by the mitochondria for ATP production

Myofibrils Sarcoplasm stuffed with little threads – myofibrils Contractile organelles of skeletal muscle Extend entire length of muscle fiber Appear stripped

Sarcoplasmic Reticulum Fluid filled system of membranous sacs encircles each myofibril Relaxed – stores calcium ions

Terminal Cisterns Dilated end sacs of the sarcoplasmic rectilium butt against the T tubule from

both sides Where Ca+ is released – triggers muscle contractions

Triad T tubule and two terminal cisterns on either side form this

Myofilaments/Filaments Within myofibrils these are smaller protein structures Thin filaments – composed mostly of the protein actin Thick filaments – composed mostly of the protein myosin 2 thin filaments for every 1 thick filaments directly involved in the contractile process

Sarcomeres basic functional units of myofibril

Striation Patterns (I vs A, M vs Z) Structural Proteins – titan, myomesin, z-disk Contractile Proteins – myosin & actin

The darker middle part of the sarcomere is the A band, which extends the entire length of the thick filaments. Toward each end of the A band is a zone of overlap, where the thick and thin filaments lie side by side.

The I band is a lighter, less dense area that contains the rest of the thin filaments but no thick filaments, and a Z disc passes through the center of each I band.

A narrow H zone in the center of each A band contains thick but not thin filaments. A mnemonic that will help you to remember the composition of the I and H bands is as follows: the letter I is thin (contains thin filaments), while the letter H is thick (contains thick filaments).

Supporting proteins that hold the thick filaments together at the center of the H zone form the M line, so named because it is at the middle of the sarcomere.

Factors affecting muscle size

Hypertrophy refers to an increase in the size of the cell while hyperplasia refers to an increase in the number of cells or fibers. A single muscle cell is usually called a fiber.

Neuromuscular Junction, Motor end plate, EC coupling

Role of Ca2+ in Contraction

Muscle contraction is regulated by calcium ions, which will change thin filament into an activated state by binding to troponin. The binding of calcium to the troponin changes it's shape so the myosin binding sites on the actin (thin filament) are exposed Sliding Filament Theory

Muscle contraction occurs because myosin heads attach to and “walk” along the thin filaments toward the M line

Thin filaments slide inward and meet at the center of a sarcomere Z discs come closer together and the sarcomere shortens The length of the individual thick and thin filaments do not change Shortening of the entire muscle

Actin, Myosin, Tropomyosin, Troponin Actin and Myosin - contractile proteins Troponin and Tropomyosin – regulatory proteins Sarcoplasmic reticulum releases calcium ions into the sarcoplasm They bind to troponin Troponin moves tropomyosin away from the myosin binding sites on actin Once binding sites are free the cycle that causes filaments to slide begins

Ca+, ATP and Contraction 1. ATP hydrolysis – myosis head includes an ATP binding site and an

ATPase (enzyme – hydrolyzes ATP into ADP). The hydrolysis reaction reorients and energizes the myosis head. Products are still attached to the myosin head

2. Attachment of myosin to actin to form cross bridges – energized myosin head attaches to the myosin binding site on the actin and releases the previously hydrolyzed phosphate group. When the myosin heads attach to actin during conreactin they are referred to as cross bridges

3. Power Stroke – the site on the cross bridge where ADP is still bound opens. As a result, the cross bridge roatates and releases the ADP. The cross bridge generates force as it rotates toward the center of the sarcomere, sliding the thin filament past the thick filament toward the M line

4. Detachment of myosin from actin – at the end of the power stroke the cross bridge remains firmly attached to actin until it binds another

molecule of ATP. As ATP binds to the ATP binding site on the myosin head, the myosin head detaches from actin

Factors Affecting Force (length, summation, diameter, # of fibres in motor unit) Muscle Length – too stretched or too compressed decreases force production, l not is resting length, force you can produce is very strong when at rest, when you stretch # of cross bridges decrease Action potential frequency – summation of stimulation (think Ca) # of fibres per motor unit – motor unit- one motor neuron and all the muscle fibres it innervates. 3 types of motor units exist based on the muscle fibre types (differ in size and ease of activation) – SIZE determines amount of force produced Types of Contraction Isotonic Muscle force does not equal load

Tension in muscle remains almost constant while the muscle changes its length

Moving objects Concentric Isotonic Contraction Force>Load – tension generated is great

enough to overcome the resistance of the object to be moved, the muscle shortens and pulls on another structure (tendon) to produce movement and to reduce the angle of a joint. (Picking book off table)

Eccentric Isotonic Contraction Force<Load– the length of the muscle increases during contraction (lowering book on table). The tension exerted by the myosin cross-bridges resists movement of a load and slows the lengthening process

Isometric Muscle force equals load

Tension generated is not enough to exceed the resistance of the object to be moved

The muscle does not change length Holding a book steady using an outstretched arm – contractions maintain

posture and supporting objects in a fixed position Most activities include both isotonic and isometric contractions

Skeletal Muscle Fiber Types Slow Oxidative Fibers

Smallest in diameter – least powerful type of muscle fiber Large amounts of myoglobin & many blood capillaries – appear dark red Large mitochondria – generate ATP by aerobic cellular resp. “Slow” – ATPase in the myosin head hydrolyzes ATP slow, and contractile

cycle is slow Slow speed of contraction Resistant to fatigue Examples: maintaining posture, endurance type activities

Fast Oxidative-Glycolytic Fibers Intermediate in diameter

Large amounts of myoglobin & many blood capillaries – appear dark red Generate ATP – cellular respiration – moderately high resistance to fatigue Intracellular glycogen level high – aerobic glycolysis (ATP) Generate ATP 3-5 times faster than SO Speed of contraction is faster Examples: walking and sprinting

Fast Glycolytic Fibers Largest in diameter and contain the most myofibrils Generate the most powerful contractions Low – myoglobin, low – blood capillaries, low – mitochondria – appear white Generate ATP – glycolysis Intense aerobic movements of short duration Examples – weight lifting, throwing a ball FG of weight lifter 50% larger than endurance athlete – increased synthesis

of muscle proteins Muscle enlargement – hypertrophy of FG fibers

Autonomic Nervous System Divisions of the NS (Central, Peripheral, Somatic, Autonomic, Motor, Sensory) Central Nervous system – brain and spinal cord (sensory in motor out) Peripheral Nervous System – messages towards brain and spinal cord

Somatic sensory division – walk, talk (involuntary) Autonomic sensory division – mostly interceptors – bladder is full, stomach is

full Motor division

Atonomic motor division – visceral motor o Sympathetic Division – flight, fight and fright (3Fs) o Parasympathetic Division – rest, relaxation, rumination (SLUDD*)

Somatic motor division – control of voluntary muscles (walk and talk) Motor: Somatic vs. Visceral (organization, NTs, target organs) Parasympathetic vs. Sympathetic

SLUDD (3 R’s and 3 F’s) Parasympathetic Rest Relaxation Rumination OR Salivation Lacrimation Urination Digestion Defecation Sympathetic Fight Flight Fright Vagus Nerve (targets and effects) Components –

Mixed

Sensory

Motor (branchial) Motor (autonomic)

Functions -

Taste from epiglottis. Proprioception from throat and voice box muscles. Monitors blood pressure and oxygen and carbon dioxide levels in blood. Touch, pain, and thermal sensations from skin of external ear. Sensations from thoracic and abdominal organs. Swallowing, vocalization, and coughing. Motility and secretion of gastrointestinal organs. Constriction of respiratory passageways Decreases heart rate.

Autonomic Receptors

Referred Pain Pain, apparently arising from the neck. left arm and forearm may well be due to heart damage. The autonomic sensory fibers (visceral afferents) travel with the sympathetic nerves and synapse in the dorsal route ganglia. In this dorsal route ganglia sensory nerves from the medial surface of arm and forearm also synapse. Your brain interprets the pain as originating from the somatic sensory nerves innervating the arm and forearm not he the visceral afferents nerves. Lung and diaphragm, heart, liver and gallbladder, kidney. There is also irritation of somatic nerves that leads to pain. C3 C4 C5 Central Nervous System CNS 1 – Meninges & Blood Supply PNS Organization Mixed spinal nerves carrying:

1) Sensory information from the body to CNS (afferents) 2) Motor information from CNS to body (efferent)

Cell Types 1) Neurons – signaling cells

2) Glial cells supporting cells surrounded by axons and cell bodies a. Sensory Neurons: afferents b. Neurons: signals c. Schwann Cells:

- encircle PNS axons, help with axon regeneration - each one myelinates a single axon

d. Motor Neurons – carry axon after carrying information through dendrites (efferent)

e. Blood - immune - T-cells - Macrophages

* 1 glial cell wraps around one axon PNS Regeneration

- occurs 1mm/day - neurons can sprout collaterals and regenerate - glia produce growth factors - macrophages remove debris

CNS Organization

1) Brain - lateralized 2) Spinal Cord – “interphase”

Cell Types 1) Neurons -

– signaling cells – possess ability to respond to a stimulus and convert it into an

action potential 2) Glial cells

– supporting cells – more in the brain

a. Astrocytes - Processes of astrocytes wrapped around blood capillaries isolate

neurons of the CNS from various potentially harmful substances in blood by secreting chemicals that maintain the unique selective permeability characteristics of the endothelial cells of the capillaries. In effect, the endothelial cells create a blood–brain barrier, which restricts the movement of substances between the blood and interstitial fluid of the CNS

- Can be found in both white and grey matter - Support neurons - Influence formation of neural synapses

b. Neurons - Send signals c. Microglia

– immune – function as phagocytes to remove cellular debris (ie. damaged

nervous tissue) d. Oligodendrocyes

– forming and maintaining the myelin sheath around CNS axons e. Grey matter f. White matter g. Ependyma

- Line the ventricles of the brain and central canal of the spinal cord - Produce, monitor and assist in the circulation of CSF - Form the blood-CSF barrier

*Many glial cells wrap around axon CNS Regeneration

- is extremely limited - neurons are postmitotic - Neurons cant regrow (glia prevents development of new axons for

connections) Parts of CNS Cerebral cortex

- voluntary motor movement - memory, thinking, - sensory perception

Diencephalon - gateway - sensory/motor relay center - autonomic functions - must go through here before rest of cerebral cortex - perched on top of brain stem

Brain stem - cranial nerves innervate muscles of the skin and neck - autonomic functions

Cerebellum - allows for coordination of movement (point, gestures)

Spinal Cord - motor and sensory input interface with PNS - reflexes Brain and spine surrounded by cerebral spinal fluid

Meninges (CNS)

- connective tissue coverings that protect the CNS, made up of: 1) Dura Matter - firmly attached to skull/periosteum - white - has to have own blood and nerve supply - Subdural space – contains interstitial fluid - Inward extensions of dura divide the cranium up into hemispheres

o Falx Cerebri: left and right cerebral hemispheres o Tentorium Cerebelli: cerebellar and cerebral hemispheres

o Tentorial Notch: an oval opening that is bounded by the anterior border of the tentorium cerebelli, that surrounds the midbrain, and that gives passage to the posterior cerebral arteries

- Dural extension separates hemispheres - contain meningeal arteries, veins and nerves

o cerebral veins lead to dural “sinuses” - Extreme movements of the CNS may be restricted by the dural extensions,

resulting in damage to the brain or nerves o Herniation: brain moving from different columns of skull

Can be caused by torn blood vessels o Coning: parts of the cerebellum moving downward through the

foramen magnum May cause compression of the lower brainstem and upper

spinal cord 2) Arachnoid Matter - Subarachnoid space contains cerebral spinal fluid (between arachnoid and

pia) - lines inner surface of dura - spider web like 3) Pia Matter - covers surface of brain and cerebral vessels - firmly attached to brain

Right brain – artistic Left-brain – logical, mathematical Foramen Magnum

- big hole Meningeal Nerves

- Headaches o Since blood vessels are plastered against the wall of the skull, they

begin to dilate o From trigeminal cranial nerve V

- Brain freeze o referred pain in meningeal nerves

Hematoma Mechanisms

1) Epidural Hematoma a. Rupture of meningeal blood vessels

2) Subdural Hematoma a. Rupture of cerebral vessels (veins)

3) Subarachnoid Hematoma a. Rupture of cerebral vessels (arteries)

Caused by:

- Blunt force to skull - Sudden movement of head causes brain to move inside skull

Meninges (Spinal Cord)

1) Dura - epidural fat space: between dura and periosteum: that allows for movements

of the spine because it is easily compressed - does not line spinal cord directly 2) Arachnoid - no cerebral spinal fluid - subarachnoid space filled with CSF 3) Pia

*Brain is formed as a tube during development

As an adult these tubes are called ventricles core of brain is filled with CSF ventricles lead to middle of spinal cord at top and bottom of cerebellum are little pores that allow CSF to get to

outside of brain

Cerebral Spinal Fluid Synthesis and Flow - CSF drains from the subarachnoid space into the superior sagittal sinus

(venous blood) - Leakage from ventricular system to subarachnoid space through foramina in

the thin room of the 4th ventricle - CSF is produced in the lateral, 3rd and 4th ventricles by the ependymal cells of

the choroid plexus** Choroid Plexus

- Allow plasma to leak out - Produced in the ventricles - Produce CSF - Located in the ventricles

Arachnoid Granulations

- transfer CSF from the subarachnoid space to the superior sagittal sinus - located in a parasagittal region along the superior sagittal sinus

Hydrocephalus

- caused by water on the brain - abnormal narrowing (stenosis) is located in 3rd ventricle

Arteries to the brain:

1) Subclavian 2) Aorta 3) Common Carotid 4) Vertebral – goes up through vertebrae, through foramen magnum into brain 5) Internal Carotid 6) External Carotid

Blood supply to brain

- 5 arteries going into brain o L & R Carotid o Basilar o L&R Vertebral

- 6 supplying to inside of brain - functional deficits due to strokes will depend on the area of brain supplied by

affected artery o anterior cerebral artery

– medial – passes forward toward frontal lobe of cerebrum

o middle cerebral artery – laterally between temporal and parietal lobes of cerebrum.

o posterior cerebral artery - passes behind to occipital lobe - Cell death due to ischemia

Circle of Willis

- blood can flow around and supply all arteries o Anterior Cerebral Artery o Middle Cerebral Artery o Posterior Cerebral Artery o Internal Carotid Artery – supplies eyes, ears, nose; frontal, temporal

and parietal lobes of cerebrum; pituitary glans and pia o Basilar Artery – passes along midline of anterior aspect o Vertebral Artery – through the neck, up foramen magnum to inferior

side of brain; supplies posterior portion of cerebrum, cerebellum, pons and inner ear

o Posterior Communicating Artery o Anterior Communicating Artery

- minimizes consequences of stroke because: o anastomosis – only works before the circle; no anastomosis among

cerebral arteries o provides alternate routes for blood flow to brain, should arteries

become damaged Arteries Supplying the Cortex

- functional deficits due to strokes will depend on the area of the brain supplied by the affected artery

- Anterior cerebral artery – frontal lobe - Middle cerebral artery – temporal and parietal lobes - Posterior cerebral artery- occipital lobe

Venous Drainage of Brain

- to superior vena cava and heart

Internal Jugular Veins

- Descend within carotid sheath lateral to internal and common carotid arteries

- Drain brain, meninges, bones of cranium, muscles and tissues of face and neck

- Major dural sinuses that contribute to internal jugular vein are:

1) Superior sagittal sinus

a. Drains nasal cavity; superior, lateral and medial cerebrum; skull bones;

meninges

2) Straight sinus

a. Drains medial and inferior cerebrum and the cerebellum

3) Sigmoid sinuses

a. Drains lateral and posterior aspect of cerebrum and cerebellum

External Jugular Vein - drains scalp and skin of head and neck, muscles of face and neck, and oral cavity and pharynx

Stroke Hemorrhagic Stroke – blood leaks into brain tissue Ischemic Stroke – clot stops blood supply to an area of the brain CNS 2 – Cortex and Diencephalon White Matter Vs. Grey Matter Brain

o Grey matter on outside

o White matter on inside

o Deep Grey Matter

o Thalamus

o Basal Ganglia

Spinal Cord o Grey matter on inside – core of spinal cord

o This is to allow axon tracks carrying action potentials to go down the

spinal cord

o White matter on outside

Superficial Features of Cerebrum - glued together by white matter tracks

- Fissures

o Longitudinal fissure – major groove separating two halves of the brain

o Lateral (Sylvian) Fissure

- Sulci

o Central Sulcus

- Gyri

o Precentral Gyrus – 1st motor cortex

Responsible for voluntary movements

o Postcentral Gyrus – 1st sensory cortex

Homunculus – There are more sensory and motor cortical neurons dedicated to the upper and lower limbs than the trunk Cellular Organization of Cortex

1) Superficial Grey Matter

– neurons

– organized into columns (cortical columns)

– uses graded potentials

2) Deep Nuclei

– neurons, formed around ventricles

– lateral to diencephalon

– contains limbic system & basal ganglia

3) White Matter Tracts – axons

Lobes of Cerebral Cortex Frontal Lobe

– association cortex

– intellect

– premotor cortex

Frontal Eye Field - Allows you to look in the right spot

Parietal Lobe - somatosensory association cortex

- touch

Occipital Lobe - visual cortex

- underside surface of brain detects smells

Temporal Lobe - auditory cortex (hearing)

Insular Cortex - motor control, language, and homeostatic regulation

- midbrain controls taste

Wernicke’s Area

- comprehending speech, put grammar together

Broca’s Area - physically make speech

Types of White Matter 1) Commissures – between hemispheres (corpus callosum

2) Association Fibres – within hemispheres between lobes

3) Projection Fibres – to different parts of CNS

Lateralization – left brain controls right hand, right brain controls left hand Deep Nuclei

1) Limbic System – emotions and memory

- around inside of ventricles

- consist of amygdala, hippocampus, fornix and mammillary bodies

Mammillary Bodies - olfactory relay nucleus – smell memories Hippocampus – long term memory formation, output to cortex via the fornix (who, what, where, when) Amygdala – analyses anger and fear expressions; assesses danger and elicits fear response; involved in forming emotional memories - output to hypothalamus of diencephalon

Memory

1) Episodic memory – random events

2) Semantic memory – concepts, school knowledge

3) Procedural memory – using a computer

Pathways Involved in Memory Formation Episodic

- Loop (Papez) circuits reinforce important memories

- Anterior thalamic nucleus: alertness

- Mammillary bodies: smell, emotion

- Entorhinal cortex: eye-ear, where

- Fornix

- Hippocampus

- Cingulate cortex: reality check, connects to cortex

Procedural - Primarily driven by vision

vision cerebellum basal nuclei thalamus premotor cortex Amnesia Alzheimer’s Disease

- neurofibrillary plaques and tangles

- inability to recall recent and past memories

- lack of attention, disorientation

- language problems, lack of problem solving

Hippocampal Atrophy - loss of dendrites

- inability to form new memories (anterograde amnesia)

- Inability to consolidate events

- Inability to recall past events (retrograde amnesia)

*if cerebral cortex is damaged, loss of memory occurs

2) Basal Nuclei (Corpus Striatum)

- initiate, coordinate and stops motor movements

- eliminates unnecessary movements

- skills memory (slow stereotypical movements ie. walking)

- inputs from cerebral cortex

- outputs to motor cortex via thalamus

Consists of: - Caudate (head & tail)

- Lenticular Nucleus (putamen and globus pallidus)

- Amygdala

- Substantia nigra

Feedback: Cortex caudate lenticular nuclei thalamus cortex Parkinson’s disease – can’t move Huntington’s parria – can’t stop moving Motor Planning

1) 1st Motor Cortex – Just do it

a. Reaches for drink

2) Cerebellum – How to do it

a. Where drink is in space/coordinate movement

3) Basal Ganglia – How fast to do it

a. Grab it quickly

How to Drink a Beer 1) See beer

2) Comes into brain thalamus

3) Visual cortex, puts it all together

4) Parietal cortex puts sensory information together

5) Frontal cortex initiates drinking/doesn't’t initiate drinking

6) Sends information to 3 parts of the brain

7) Motor cortex reaches for the beer

8) Cerebellum needs to know where drink is in space/allows for coordination of

motor movement

9) Basal ganglia allows you to grab it quickly

Diencephalon Consists of: Thalamus

- Relay nucleus for all sensations to cerebral cortex

o Inputs from cerebral cortex determine which sensations should be

conveyed to cortex

Selective attention: spotlight on important sensory information

Vision, hearing, touch, pressure, proprioception, pain &

temperature

- Gateway to cortex – from sense to perception

o Tells brain what’s important

- Context: memories, ethics, thought & emotion

Hypothalamus - control of autonomic nervous system: blood pressure, heart rate, digestive

motility, respiratory rate, pupil size

- pleasure, fear, rage

- temperature regulation

- appetite

- water intake and thirst

- sleep

- endocrine control

Pineal - clock

- circadian rhythms

o melatonin – secreted by pineal gland along with dopamine, tells you

when you’re sleepy

Stroke in the Thalamus

- Thalamic Syndrome

o May occlude thalamic arteries

o Loss of sensation on contralateral (opposite side of body)

o Contralateral paralysis (damage to descending motor fibers passing

nearby)

o Burning pain develops weeks later

o Sensory and motor problems

CNS 3- Brainstem, Cerebellum, Eye The Brain Stem brain stem located between spinal cord and the diencephalon. - nerves come from each part of the brainstem - Most of the cranial nerve nuclei are located in the brain stem - Consists of 3 structures:

o Medulla oblongata Nuclei- controls vital body functions Somatosensory tracts

o Pons Cerebellar peduncles

o Midbrain Superior Colliculus

Vision reflex relay Inferior Colliculus

Auditory reflex relay (Corpora Quadrigemina) Nuclei of brainstem

- Reticular formation: core of brain stem o Consciousness, sleep and arousal o control visual and auditory stimuli; mental activities; stimuli from

pain, touch and pressure receptors; receptors in our limbs and head that keep us aware of positions of body parts.

o Alertness o Release of endogenous opioids (endorphins and enkephalins) to

control pain o A net like region of interspersed gray and white matter o Neurons contain both sensory and motor functions o Cerebral aqueduct – inside of reticular formation

- Substantia Nigra o Releases dopamine o Connects with corpus striatum o Parkinson’s: loss of nerve cells in the substantia nigra

- Red nucleus o Motor pathways: flexion o Has good blood supply

Medulla Oblongata - called medulla - continuous with the superior part of the spinal cord - forms inferior part of brain stem - medulla’s white matter contains all sensory tracts and motor trats that extend between the spinal cord and other parts of the brain Pyramids: some of the white matter forming bulges on the anterior aspect of the medulla (a nerve tract) - cortico-spinal motor tracts control voluntary movements of the limbs and trunk

Decussation of pyramids: when axons in the left pyramid cross to the right side and axons in the right pyramid cross to the left side.

Explains why each side of the brain controls voluntary movements on the opposite side of the body

- contains nuclei and tracts - controls reflexes for sneezing, coughing and hiccupping

o Cardiovascular center: regulates rate and force of the heartbeat and the diameter of blood vessels

o Respiratory center: contains medullary rhythmicity area which adjusts the basic rhythm of breathing

o Vomiting center: causes vomiting o Deglutition center: promotes swallowing

- nuclei associated with touch, pressure, and vibration are located in the posterior part of the medulla called the gracile nucleus and cuneate nucleus. - also contains nuclei that are components of sensory pathways for taste (gustatory nucleus), hearing (cochlear nuclei) and balance (vestibular nuclei). Pons - bridge that connects parts of the brain with one another by axons - some axons of the pons connects the right and left sides of the cerebellum - relay nuclei from cortex to cerebellum - cerebellar peduncles: joins the pons to the cerebellum - lies directly superior to the medulla and anterior to the cerebellum - consist of both nuclei and tracts - ventral region: forms a large synaptic relay station consisting of gray centers called the pontine nuclei

nuclei contain white matter tracts, providing a connection between the cortex of one hemisphere and the opposite hemisphere of the cerebellum

o plays an essential role in coordinating and maximizing the efficiency of voluntary motor output throughout the body.

- dorsal region: contains ascending and descending tracts along with the nuclei of cranial nerves - pneumotaxic and apneustic areas control breathing Midbrain - Extends from the pons to the diencephalon - connects the third ventricle above with the fourth ventricle below - contains both nuclei and tracts - anterior part of the midbrain contains paired bundles of axons known as the cerebral peduncles

cerebral peduncles consist of axons of the corticospinal, corticobulbar and corticopontine tracts which conduct nerve impulses from motor areas in the cerebral cortex to the spinal cord, medulla and pons.

Cortico spinal motor tracts - posterior part of midbrain called tectum - superior colliculus: vision reflex relay - inferior colliculus: auditory reflex relay

- Cerebellum - occupies inferior and posterior aspects of the cranial cavity - highly folded surface that increases surface area, allowing for a greater number of neurons - transverse fissure separates the cerebellum from the cerebrum - central constricted area is the vermis - cerebral peduncles: input and output fibres - lobes are called cerebellar hemispheres - two functions: vision & vestibular - coordinates skilled movements are regulates posture and balance - evaluate how well movements initiated by motor areas in the cerebrum are actually being carried out. - Nonmotor functions such as acquisition of knowledge and language processing

Left and Right Cerebellums: Movement 1) frontal cortex notifies cerebellum of intentions to make a movement 2) proprioreceptors in muscles and tendons, visual input, and vestibular input

inform cerebellum about position of body and limbs 3) Cerebellar cortex calculates the best way to coordinate movement 4) Deep cerebellar nuclei send “blueprint” to cortex to initiate a coordinated

movement, to spinal cord to maintain posture Cerebellar Control Ipsilateral Cerebullum – vision, balance (vestibular) and proprioception

- Appendicular o Spinocerebellum

Regulation of muscle tone, coordination and planning of skilled voluntary movement

o Outer Cerebellum Movement of legs and arms

o Cerebrocerebellum Learned & planned actions, voluntary activity, storage of

procedural memory - Axial

o Vestibulocerebellum Maintenance of balance, control of eye movements

Diseases of the Cerebellum Ataxia

- damage from exposure to organic solvents - dissolve neurons of cerebellum - alcohol has similar effect (cant walk straight)

Intention Tremors - tremor when you intentionally touch your nose - problem with left cerebellum

Romberg Test – measures input to cerebellum from vision, proprioceptors and vestibular

- gets patient to close eyes, one input is removed

- usually if there is a problem with the cerebellum, 2 of the 3 inputs will be taken away - causes swaying

Cranial Nerves

- emerge from brainstem, below cerebral cortex - vision has 3 sensory & 3 motor - Special Sense Sensory & Motor Autonomic 1) Olfactory Tract (I) – smell 2) Optic Nerve (II) – vision 3) Oculomotor (III) – muscles of the eye, vision 4) Trochlear (IV) – muscles of the eye, vision 5) Trigeminal Nerve (V) – sensory: face, vision, chewing muscles 6) Abducens (VI) – muscles of the eye, vision 7) Facial (VII) – muscles of facial expressions, taste, vision 8) Vestibuocochlear (VIII) – hearing and balance 9) Glossopharyngeal(IX) – muscles of swallowing, taste

10) Vagus (X) – autonomic to internal organs 11) Spinal Accessory (XI) – muscles moving head 12) Hypoglossal (XII) – muscles of tounge

The Eye Cranial Nerves Involved in Vision

1) Optic Nerve (II) 2) Oculomotor (III) 3) Trochlear (IV) 4) Trigeminal Nerve (V) 5) Abducens (VI) 6) Facial (VII)

Motor Aspects of Vision - Extra ocular eye muscles - Coordinated eye movements - Accommodation - Pupil responses

Opening and Closing the Eyes - Cranial Nerve III opens eyelid

o Muscle: levator palpebrae – located at top of eyelid - Cranial nerve VII closes eyelid

o Muscle: orbicularis oculi – circles around outside of eyelid *Saccadic eye movements are necessary to expose the fovea to the entire scene you are looking at

- Retina is involved in motion detection - Only a small part of the retina is responsible for visual images

Extraocular Eye Muscles

- muscles that move the eyeballs because they originate outside the eyeballs and insert on the outer surface of the sclera (white of eye) - fast contacting and controlled skeletal muscles - 3 pairs:

o superior (CN III) and inferior (CN III) recti o lateral (CN VI) and medial (CN III) recti o superior (CN IV) and inferior (CN III) obliques

superior oblique moves eye ball inferiorly and laterally inferior oblique moves eye ball superiorly and laterally

- levator palpebrae superiorus is the muscle that raises the upper eyelid and opens the eye Seeing Far Objects

- Conjugate eye movements: moving both eyes together, looking at far objects o Lens is stretched and flat

- brainstem circuits tying the two eyes together for saccades - Medial Longitudinal Fasciculus: system that ties in the 3rd and 6th cranial nerve together in order to give saccadic eye movements

o Allows for coordinated movements from both eyes Problems

- Diplopia: double vision - Oculomotor Palsy: problem with CN III, eye is abducted

- Trochlear Palsy: problem with CN IV - Abducens Palsy: CN VI, eye cant abduct

o To move a specific eye, the CN III needs to be able to contract that eye’s medial rectus muscle

Seeing Near Objects

- Convergent gaze: both eyes focus on an object o Lens is relaxed and round

- both medial rectus muscles (control of CN III) have to be able to contract at the same time - three things happen when you look at something close: 1) Contraction of both medial rectus muscle 2) Since vision is now fuzzy, contraction of the ciliary body muscles must occur

to focus lens, pull lens towards the front to magnify 3) Constriction of pupil to increase depth of field

Pupillary Constriction - increase depth of field of optic system by closing the iris - controlled by pupillary constrictor (ties everything together) & radial muscle (pulls it out)

Function of the Iris - double layer of pigmented cells in the iris blocks all light except what the pupillary sphincter allows to get through the pupil - Pupillary Sphinter: bright light conditions constrict pupil

o under control of 3rd cranial nerve and parasympathetic nervous system

only found in the brain stem Accompanied by convergence and accommodation

o preganglionic parasympathetic fiber runs along the 3rd cranial nerve to cilliary ganglion in eye then postganglionic nerves run into the sclera of the eye to the front where it will then cause contraction of the pupillary sphincter as well as the cilliary body muscles, letting the eye round up

o miosis – excessively constricted - Pupillary Dialator: dim light conditions dilate pupil

o Control of sympathetic nervous system From thoracic region of spinal cord Accompanied by reduced blink and sweating

o Preganglionic sympathetic fibers in the lateral part of the spinal cord will send up to the collateral nervous system then postganglionic nerves will jump onto the carotid artery that leads to the back of the eye. Then, postganglionic nerves innervate pupillary dilation

o Mydriasis – excessive dilation o Injury to the superior cervical ganglion causes permanent constriction

of pupil because its no longer affected by the dilator

Lens - located behind the pupil and iris, within the cavity of the eyeball - contains proteins called crystallins that make up the refractive media of the lens - helps focuses images on the retina to facilitate clear vision

Problems - Presbyopia: diminution of accommodation of the lens of the eye, begins after age 40

Vision Health Care Professionals

- Optician o Fills optical prescriptions, fits eyeglasses

- Optometrist (BSc, OD) o Diagnosis refractive errors, prescribes glasses, prescribes topical

drugs - Ophthalmologist (BSc, MD, residency)

o Diagnosis diseases of the eye & orbit, prescribes systemic drugs, eye & orbit surgery

CNS 4 – Vision Elements in Vision

1) Refractive Media – bends the light and shines on to the retina – consists of cornea, aqueous humor, lens and vitreous humor

2) Neural Detection and Transmission to Brain - occurs through the detection of the light by the retina and sending that information out to the lateral geniculant of the thalamus for conscious perceptual vision and to the superior colliculus for unconscious use of vision

3 Coats of the Eye 1) Schlera/Cornea – fibrous coat 2) Choroid/Cillary Body/ Iris – vascular coat 3) Retina – neural coat

Sensory Aspects of Vision

- Sclera - Cornea - Lens - Retina & visual pathway - Glaucoma

Normal vision depends on the shape of the cornea and sclera

- Refractive power: air/water interface (80%) o Most of light is bent by the cornea

- Accommodation: lens (20% refraction) o Capable of adjusting the focus of the eye

- Hyperopia (farsightedness) o Image is elongated o Eyeball is flattened

o Need a lens with positive diopters (convex) o 60% of population

- Myopia (nearsightedness) o Eye is elongated, visual pathway is short o Need lens with negative diopters (concave) o 20-30% of population

Cornea

- responsible for bending the light - made up of collagen bundles - cornea is clear - epithelial layers get rid of water - cant have water in the stroma

To keep cornea clear: - make sure all bundles of collagen fibers are running in the same direction - ion pumps in the epithelium that pump salt out of the stroma of the cornea

into the tear film water follows concentration gradient dehydrated crystal

Crystalline structure disturbances: - scratch surface of epithelium no more pumps water then seeps into the

cornea and gives rise to an opacity - change shape of cornea after surgery, top layer (cornea epithelia) must be

put back on and healed properly o if not, opacity can be formed in the cornea

Conjunctiva

- mucus membrane on inside of eyelid and surface of sclera - responsible for keeping the eye moist - Cornea is kept moist by constantly keeping debris and bacteria away from

the cornea that would cause it to fail and get an opacity in it - Conjunctiva can get infected chemicals (chlorine) etc

o Leads to inflammation o Pink eye/conjunctivitis – inflammation of the conjunctiva

- Amygdala: overly sensitive to the appearance of blood on the face o Sends information to the hypothalamus gets feeling of empathy

Lacrimal Apparatus - found in the upper part of the eyelid - contains immunoglobulin in them

o salt, immune secretions & proteins that can attack invading bacteria - antimicrobial: Immunoglobulin A, NaCl - tears also keep conjunctiva clean - little bump in corner of eye is lacrimal caruncle which allows tears to drain

into your nose Eyelid Glands

- Tarsal glands: glands on inside surface of eyelids o Secretes an oil that floats to the top to prevent eyes from drying out

- Sebaceous glands help with this

Lens

- dehydrated crystal - no organelles - transparent and flexible - has an epithelium on the surface that pumps ions, making sure the ionic

movements result in the lens being dehydrated - fibres contain no mitochondria or nucleus - needs to be flexible; kill anaerobic metabolism and lens becomes opaque Problems - no renewal mechanisms for proteins - crystalline inside protein ages - Presbyopia: lens gets stuck in far sighted position

o Aging in lens fibers, blindness occurs Neural Retina

- lines inside of eye o rods and cones o neurons o ganglion cell axons project axon that goes out brain

Ophthalmoscope – used to view fundus Retinal Detachment

- retina detaches from the inside of eye Optic nerve is a blind spot

- all axons of the retinal ganglion cells go out through the optic nerve to reach the brain; no photoreceptors located there

- covered in dura, also contains CSF - Glaucoma: causes death of retinal cells - Supplied by the internal carotid artery

Fulvus - no arterioles supply to fovea - vasculature can go up to but not cross fovea - in diseases like diabetes, central vision loss because of degeneration of fovea

when the blood vessels become compromised Visual Pathway

1) Primary - CN II a. Information from eyes (things you see) come together at optic chiasm

where there is a 50% crossing b. Retinal ganglial cells that see the same thing in both eyes are paired

(nasal to temporal) when they go back to the lateral geniculate nucleus of the thalamus which is responsible for filtering your vision goes to visual cortex

c. Visual cortex is predominately driven by the fovea d. Ocular dominance columns

i. Presence of stain in the cortex that’s driven by one eye and a lack of stain in the neurons that are driven by the other eye

ii. When object is far way, the projection in the visual cortex will be in adjacent ocular dominance columns

iii. The closer the object, there is a bigger discrepancy between the two eyes so the ocular dominance columns have a different representation, object gets further and further apart

1. Ability to see in 3D (stereopsis) – comparing the visual input that comes from the two eyes in the visual cortex

Visual Field Defects - because of the crossing over, easier to detect where lesion is - when there is a problem with visual field, it is other part of the retina

that is being affected - Ex. Nasal problem means you have an issue with the temporal retina because

of the way the light shines into the eye - Ex. Patient with a lesion before the chiasm of the optic nerve – monocular

blindness (one eye) - Ex. Patient with lesion at the optic nerve chiasm – loss of vision in the two

temporal fields because it is the nasal retina that’s crossing over in the optic chiasm (bitemporal hemianopia)

- Homonymous hemianopia – same part of visual field that is affected 2) Secondary - CN II

a. Suprachiasmatic nucleus (in thalamus) – entrains circadian rhythms (how you know if its light or dark out)

b. Superior colliculus projects to different parts of the brain stem for: i. Perception

ii. Object location iii. Pupil constriction iv. Alertness v. Head position

Projection and drainage of Aqueous Humour

- produced by cilliary bodies that goes out over the surface of lens and out through the pupil and then resides in the anterior chamber of your eye right behind the cornea

- drained by the circular canal of Schlemm to join venous circulation system - drainage system called trabecular meshwork - constant aqueous humour production without drainage means raised

intraocular pressure Glaucoma

- pressure formed at the front of the eye has inadequate drainage - strangulates nerve - may cause blindness - Monitoring eye pressure: tonography

o Air pressure measures corneal deflection - Treatment: topical drugs

o Dilate veins that are draining aqueous humor to lower intraocular pressure

o Increase aqueous drainage