Chapter 4 Organization and Regulation of Body Systems

Chapter 4

Organization and Regulation of Body Systems

Points to Ponder

• What is a tissue? Organ? Organ system?

• What are the 4 main types of tissue?

• What do these tissues look like, how do they function and where are they found?

• What is the integumentary system?

• How can you prevent skin cancer?

• What is homeostasis and how is it maintained?

What is a tissue?

• A collection of cells of the same type that perform a common function

• There are 4 major tissue types in the body:

1. Connective

2. Muscular

3. Nervous

4. Epithelial

4.1 Types of tissues

The four tissues of the Body

• Epithelial Tissue: “covering”– Covers exposed surfaces– Lines internal passageways – Forms glands

• Connective Tissue: “support” – Fills internal spaces– Provides structure and strength to support

other tissues– Transports materials– Stores energy

The four tissues of the Body

• Muscle Tissue: “movement”– Specialized for contraction – Skeletal muscle, heart muscle, and walls of

hollow organs

• Neural Tissue: “control”– Carries electrical signals from 1 part of the

body to another

1. Connective tissue• Binds and supports parts of the body• All have specialized cells, ground substance

and protein fibers • Ground substance is noncellular and ranges

from solid to fluid• prevents microbe penetration

• The ground substance and proteins fibers together make up the matrix of the tissue

• There are three main types of connective tissue: A. fibrous , B. supportive and C. fluid

4.2 Connective tissue connects and supports

1. Connective Tissue

Protein Fiber types: 1. Collagen fibers: collagen protein -resists force 2. Reticular fibers: collagen protein -branchy, forms framework -framework of an organ

3. Elastic fibers: elastin protein -wavy, flexible- Designed to stretch

Figure 4–8

3 main types of connective tissue

A. Fibrous

B. Supportive

C. Fluid


Categories of Connective Tissue Proper

• Loose connective tissue:– more ground substance, less fibers – e.g., fat (adipose tissue)

• Dense connective tissue:– more fibers, less ground substance– e.g., tendons

Loose Connective Tissue

• Highly vascularized• Functions:

– Fill space– Cushion & support tissues– Store fat– Feed epithelial layers

• Three types:1. Areolar CT

2. Adipose Tissue

3. Reticular Tissue

Loose fibrous connective tissue

Loose Connective Tissue:

Areolar CT

Dense Connective Tissue

• Poorly vascularized• Mostly fibers, little ground substance• Only fibroblasts• Location:

– tendons (muscle to bone) – ligaments (bone to bone)– muscle coverings

• Function:- high strength attachment- stabilize positions

Dense Connective TissueDense Regular CT

B. Supportive Connective Tissues

• Strong framework and few cells• Function: support and shape• Mature cells in lacunae• Two types:

1. Cartilage: • gel-type ground substance• for shock absorption and protection

2. Bone: • calcified (made rigid by calcium salts, minerals)• for weight support

B. Supportive connective tissue: Cartilage

• Cells are in chambers called lacunae

• Matrix is solid but flexible

• 3 types are distinguished by types of fibers1. Hyaline cartilage – fine collagen fibers

Location: Nose, ends of long bones and fetal skeleton

2. Elastic cartilage – more elastic fibers than cartilage fibers Location: Outer ear

3. Fibrocartilage – strong collagen fibers Location: Disks between vertebrae


Hyaline Cartilage

Fibro Cartilage

Elastic Cartilage

B. Supportive connective tissue: Bone

• Highly vascularized• Little ground substance• Matrix

– solid and rigid that is made of collagen and calcium salts

• Cells: Osteocytes– Located in chambers called lacunae arranged around

central canals within matrix– Connected by cytoplasmic extensions that extend

through canaliculi• Canaliculi: excess blood supply

– Canaliculi necessary for nutrient and waste exchange, no diffusion through calcium

B. Structures of Bone

• Osteocytes– Connected by cytoplasmic extensions that extend

through canaliculi (small channels through matrix)– Canaliculi necessary for nutrient and waste exchange

Figure 4–15

LM X 362

Canaliculi

Osteocytesin lacunae

Matrix

Bloodvessels

Central canal

PERIOSTEUM

Fibrouslayer

Cellularlayer

B. Supportive connective tissue:Bone

• Function:– Support & Protection– Levers for movement– Storage of minerals1. Compact – made of repeating circular units

called osteons which contain the hard matrix and living cells and blood vessels Location: Shafts of long bone

2. Spongy – an open, latticework with irregular spaces

Location: Ends of long bones


What do bone and cartilage look like?4.2 Connective tissue connects and supports

C. Fluid connective tissue: Blood• Made of a fluid matrix

called plasma and cellular componentsthat are called formed elements

Function: - transport nutrients, wastes and defense cells throughout the body

• 3 formed elements:1. Red blood cells – cells

that carry oxygen2. White blood cells – cells

that fight infection3. Platelets – pieces of

cells that clot blood


Formed Elements of Blood

• Erythrocytes (RBCs): carry oxygen• Leukocytes (WBCs): defense

– Neutrophils, Eosinophils, Basophils, Lymphocytes (B and T cells), Monocytes (Macrophages)

• Platelets: carry clotting factors

Figure 4–12

C. Fluid connective tissue: Lymph

• Matrix is a fluid called lymph

• White blood cells congregate in this tissue

• Location: – contained in lymphatic vessels

• Function: – purify and return fluid to blood


2. Muscle tissue• Allows for movement in the body

• Made of muscle fibers/cells and protein fibers called actin and myosin

• There are 3 types of muscle tissue in humans:

A. Skeletal

B. Smooth

C. Cardiac

4.3 Muscle tissue moves the body

A. Muscle tissue - Skeletal• Appearance:

• long, cylindrical cells, multiple nuclei, striated fibers

• Location: • attached to bone for

movement

• Nature: • voluntary movement


B. Muscle tissue – Cardiac

• Appearance: • branched cells with

a single nucleus, striations with darker striations called intercalated disks between cells

• Location: heart• Nature:

• involuntary movement


C. Muscle tissue - Smooth• Appearance:

• spindle-shaped cell with one nucleus, lack striations

• Location: • walls of hollow

organs and vessels

• Nature: • involuntary

movement


3. Nervous tissue

• Function– Allows for communication between cells through

sensory input, integration of data and motor output

• Location:– Most in brain and spinal cord: Central Nervous System– 2% in Peripheral Nervous System

• Made of 2 major cell types: A. Neurons

B. Neuroglia

4.4 Nervous tissue communicates

A. Nervous tissue - neurons

• Made of dendrites, a cell body and an axon

• Dendrites carry information toward the cell body

• Axons carry information towards a cell body


Cell Parts of a Neuron

• Cell body:– contains the nucleus and nucleolus

• Dendrites:– short branches extending from the cell body– receive incoming signals

• Axon (nerve fiber):– long, thin extension of the cell body– carries outgoing electrical signals to their destination

A. Nervous tissue - neuroglia

• A collection of cells that support and nourish neurons

• Outnumber neurons 9:1

• Examples are

oligodendrocytes, astrocytes and microglia


4. Epithelial tissue

• A groups of cells that form a tight, continuous network

• Lines body cavities, covers body surfaces and found in glands

• Cells are anchored by a basement membrane on one side and free on the other side• Named after the appearance of cell layers and

the shape of the cells• There is transitional epithelium that changes in

appearance in response to tension

4.5 Epithelial tissue protects

Figure 4–1

Free Surface and Attached Surface

1. Apical Surface: exposed to environment, may have:

• Microvilli: absorption or secretion • Cilla: fluid movement

2. Basolateral Surface: attachment to neighboring cells via intercellular connections

Classes of Epithelia• Based on shape and layers• Shape: (all are hexagonal from the top)

1. Squamous: flat, disc shaped nucleus2. Cuboidal: cube or square, center round nucleus3. Columnar: tall, basal oval nucleus

Table 4–1

Layers

• Simple epithelium: – single layer of cells– Function:

• absorption, secretion, filtration

• Stratified epithelium:– 2 or more layers of cells– Function:

• Protection

**In stratified, name for apical cell shape**

How do we name epithelial tissue?

• Number of cell layers:• Simple: one layer of cells• Stratified: more than one layer of cells• Pseudostratified: appears to have layers but

only has one layer

• Shape of cell:• Cuboidal: cube-shaped• Columnar: column-shaped• Squamous: flattened

4.5 Epithelial tissue protects

Epithelial tissue

Epithelial tissue4.5 Epithelial tissue protects

How are cells connected within a tissue?

• Tight junctions – proteins join and form an impermeable barrier between plasma membranes in a zipper-like fashion

• Prevents passage of water and solutes

• Adhesion junctions – cytoskeletal fibers join between cells and have flexibility

• Gap junctions – a fusion of adjacent plasma membranes with small channels between them that allow small molecules to diffuse

– Allow ions to pass

– Coordinated contractions in heart muscle

4.6 Cell junction types

Cell junctions4.6 Cell junction types

Glandular EpitheliaFor secretion, makes up glands

1. Endocrine glands: “internally secreting”-secrete into interstital fluid blood

-secretions = hormones -regulate and coordinate activities e.g. pancreas andthyroid

2. Exocrine glands: “externally secreting” -secrete into duct epithelial surface e.g. digestive enzymes, perspiration, tears, milk, and mucus

Exocrine: Types of Secretion

1. Serous Glands: water + enzymes

- e.g. parotid salivary gland

2. Mucus Glands: mucin

(+water = mucus)

- e.g. goblet cell

3. Mixed exocrine glands:

(serous + mucus secretion)

-e.g. submandibular salivary gland

Structure of Multicellular Exocrine Glands

• Structural classes of exocrine glands

Figure 4–7 (1 of 2)

Simple Glands = undivided

tube shape blind pockets chamberlike

Structure of Multicellular Exocrine Glands

Figure 4–7 (2 of 2)

Compound Glands = Divided

tube shaped blind pockets chamberlike

Moving from tissue to organs and organ systems

• An organ is 2 or more tissue types working towards a particular function

• An organ system is a combination of organs that work together to carry out a particular function

4.7 Integumentary system

Body Cavities4.8 Organ systems

Body Cavities

• Function: – protect organs– permit changes in size and shape of internal

organs

• Two Cavities:1. Dorsal body cavity:

• Cranial and Spinal Cavity

2. Ventral body cavity: • Thoracic Cavity (heart and lungs)• Abdominopelvic Cavity (“guts”- viscera)

– Organs enclosed in a cavity are called viscera

The Ventral Body Cavity

• Includes organs of the– Respiratory,

cardiovascular, digestive, urinary, and reproductive system

• Divided by the diaphragm into the thoracic cavity and the abdominopelvic cavity

Figure 1–10a

Ventral Body Cavity: Abdominal Cavity

• Also the peritoneal cavity

1. Abdominal Cavity- liver, stomach, spleen, small intestine, and large

intestine- Kidneys and pancreas

2. Pelvic Cavity- Inferior large intestine, inferior urinary bladder, and

some reproductive organs- Superior urinary bladder, ovaries, and uterus

The Body Membranes lining Cavities• Mucous membranes

– lining of the digestive, respiratory, urinary and reproductive systems

• Serous membranes – line lungs, heart, abdominal cavity and covers the

internal organs; named after their location• Pleura: lungs• Peritoneum: abdominal cavity and organs• Pericardium: heart

• Synovial membranes – lines the cavities of freely movable joints

• Meninges – cover the brain and spinal cord

4.8 Organ systems

Organ Systems

• The body is divided into 11 organ systems

• All organ systems work together

• Many organs work in more than 1 organ system

What are the organ systems of the human body?

4.8 Organ systems

What are the organ systems of the human body?

4.8 Organ systems

Homeostasis

• The ability to maintain a relatively constant internal environment in the body

• The nervous and endocrine systems are key in maintaining homeostasis

• Changes from the normal tolerance limits results in illness or even death

• All systems important in maintaining homeostasis

4.9 Homeostasis

4.9 Homeostasis

What are the mechanisms for maintaining homeostasis?

• Negative feedback

• Positive feedback

4.9 Homeostasis

Negative feedback

• The primary mechanism for maintaining homeostasis

• Has two components: • sensor • control center

• The output of the system dampens the original stimulus

4.9 Homeostasis

Example of negative

feedback: Body Temperature

Positive feedback

• A mechanism for increasing the change of the internal environment in one direction

• An example is the secretion of oxytocin during birth to continually increase uterine contractions

• Can be harmful such as when a fever is too high and continues to rise

4.9 Homeostasis

Homeostasis

• Requires coordinated efforts of multiple organ systems. Any adjustment made by one physiological system has direct and indirect effects on a variety of other systems. Therefore, the use of homeostasis integrates the human body to allow for the support of life.

Structure of the Integument• 16% of body mass

• Composed of:1. Cutaneous Membrane:

1. Epidermis– Superficial epithelium

2. Dermis – underlying CT with blood supply

2. Accessory Structures: originate in dermis1. Hair

2. Nails

3. Exocrine Glands

• Subcutaneous layer – under the skin between the dermis and internal

structures where fat is stored

Parts of the Integumentary System

Figure 5–1

Functions of the Integument• Protects underlying tissues from infection,

exposure and dehydration• Excretes salts, water, and organic waste• Maintains normal body temp:

– conserve and radiate heat

• Synthesizes Vitamin D3 for calcium metabolism• Stores Nutrients and Fat• Sensory detection:

– Allowing awareness of surroundings – touch, pressure, pain, and temp.

Is important for maintaining homeostasis

Connections

• Circulatory system:– blood vessels in the dermis

• Nervous system:– sensory receptors for pain, touch, and

temperature

There are two regions of the skin

• Epidermis

• Dermis


The epidermis:

• The thin, outermost layer of the skin• Made of epithelial tissue• Cells in the uppermost cells are dead and become

filled with keratin thus acting as a waterproof barrier

• Langerhans cells – a type of white blood cell that help fight pathogens

• Melanocytes – produce melanin that lend to skin color and protection

for UV light

• Some cells convert cholesterol to vitamin D


Skin Color

• Pigment based: epidermal pigments and blood pigments contribute to the color

1. Epidermal Pigmentation

2. Dermal Circulation

Skin Color

1. Epidermal Pigmentation A. Carotene: yellow-orange, from diet

- converted into Vitamin A

- localized to epithelium

- functions in normal maintenance

of epithelia and photoreceptors

- excess accumulates

B. Melanin: Brown, from melanocytes

- for UV protection

1. Epidermal Pigmentation• Melanocytes: in stratum

basale– Packaged in melanosomes– Transferred to cytoplasm of

keratinocytes– Cluster around top side of

nucleus– Eventually digested by

lysosomes• Everyone has ~1000

melanocytes/mm2

– Pale People: small melansomes– Dark People: larger, greater

number of melansomes

1. Epidermal Pigmentation

• Freckles:– Overproduction of melanin form single

melanocytes

• UV exposure:– Some needed for Vitamin D3 production– Excess = damage (DNA mutation)

• Fibroblasts altered CT structures– Wrinkles

• Epidermal cells, melanocytes cancer– Squamous cell carcinoma– Melanoma

What you need to know about skin cancer?

• 2 of the 3 types that arise in the epidermis:• Basal cell carcinoma is the most common yet least

deadly form of skin cancer• Melanoma is the most deadly form of skin cancer but is

the least common

• What can you do to help prevent this?• Stay out of the sun between 10am-3pm• Wear protective clothing (tight weave, treated

sunglasses, wide-brimmed hat)• Use sunscreen with an SPF of at least 15 and protects

from UV-A and UV-B rays• Don’t use tanning beds


What might skin cancer look like?


Skin

2. Dermal Circulation: hemoglobin pigment

- Oxygenated blood:

- red color, hemoglobin in RBCs,

through skin looks pink

A) Vasodilation skin looks more red

B) Vasoconstriction skin looks more pale

The Dermis

• Is located between epidermis and subcutaneous layer

• Anchors epidermal accessory structures – hair follicles, sweat glands

• Contains:– All cells of CT proper, accessory organs of

integument, blood vessels, lymphatic vessels, nerves, and sensory receptors

• Has 2 components:– outer papillary layer – deep reticular layer

Dermis• Papillary layer:

– Thin (20%)

– Consists:• Areolar CT• Comprise dermal papillae• Capillaries, lymphatics, and

sensory neurons

– Function: feed epidermis

• Reticular Layer:– Thick (80%)– Consists:

• Dense irregular CT• Elastic and Collagen fibers

– Function: provide strength and flexibility

The Hypodermis

• The subcutaneous layer or hypodermis: – lies below the integument– Not part of cutaneous membrane– Stabilizes position of skin while permitting

independent movement of skin and muscles

Integumentary Accessory Structures

1. Hair and hair follicles2. Sebaceous glands3. Sweat glands4. Nails:• Accessory Structures:

– are derived from embryonic epidermis – are located in dermis– project through the skin surface

Functions of Hair• Function:

– Protects and insulates– Guards openings against

particles and insects– Is sensitive to very light

touch

Hair Color

• red: iron added• Range yellow to black due to melanin from

melanocytes in hair matrix– Melanin stored in cortex and medulla

With age, melanin declines, air pockets in medulla increase = gray or white hair

Nails

• Function: – protect tips from

mechanical stress, assist in gripping

• Consists of dead cells containing hard keratin

• New nail formed at nail root

What are the accessory organs of the skin and why are they important?

• Includes nails, hair and glands

• Nails are derived from the epidermis that offer a protective covering

• Hair follicles are derived from the dermis but hair grows from epidermal cells

• Oil glands are associated with hair and produce sebum that lubricates hair and skin as well as retards bacterial growth

• Sweat glands are derived from the dermis and helps to regulate body temperature


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Chapter 4 Organization and Regulation of Body Systems