Clinical Science

Overview

Mondays Slides

Up to Resp-

Structure of the Cell & Location of Organelles

Nucleus

• Contains genetic material – Necessary for cell reproduction – Regulates cellular production of proteins

• Each cell is “programmed” by the genes for the production of specific proteins – Allows the cell to carry out its function– Maintains cell homeostasis or stability– Promotes cell division

Cell Membrane• Structure

– Thin barrier that separates the intracellular fluid from the extracellular fluid

• Function– Essential for cellular integrity– Equipped with many mechanisms for

maintaining cell homeostasis

Structure of the Lipid Bilayer of the Cell Membrane

Features of the Cell Membrane• Specific receptor sites that allow interaction with

various chemicals

• Histocompatibility proteins that allow for self-identification

• Channels or pores that allow for the passage of substances into and out of the cell

Structures of the Cytoplasm• Mitochondria

• Endoplasmic reticulum

• Free ribosomes

• Golgi apparatus

• Lysosomes

Cell Properties

• Endocytosis – Involves incorporation of material into the cell– Pinocytosis and phagocytosis occur

• Exocytosis – Allows a cell to move a substance to the cell

membrane and secrete the substance outside the cell

– Hormones, neurotransmitters, and enzymes are excreted into the body by this process

Achieving Cell Homeostasis

• Passive transport – Happens without the expenditure of energy and

can occur across any semipermeable membrane– Occurs by diffusion, osmosis, and facilitated

diffusion• Active transport

– Energy-requiring process– Movement of particular substances against a

concentration gradient– Important in maintaining cell homeostasis

Diffusion vs. Osmosis• Diffusion

– Does not require energy

– The movement of solutes from a region of high concentration to a region of lower concentration across a concentration gradient

• Osmosis

– Does not require energy

– Movement of water from an area low in solutes to an area high in solutes

Phases of the Cell Cycle

• Interphase

• G0 phase: Resting phase

• G1 phase: Gathering phase

• S phase: Synthesizing phase

• G2 phase: Last substances needed for

division are collected and produced

• M phase: Actual cell division occurs, producing two identical daughter cells

The nucleus is called the control center for the cell because:

• A) It is the site of protein metabolism

• B) It contains the individual units of

inheritance, the genes

• C) The energy-rich ATP is made in the nucleus

• D) It participates in cell-to-cell recognition

Which of the following organelles contains powerful digestive enzymes that assist in

digesting intracellular materials?

• A) Golgi bodies

• B) Mitochondria

• C) Ribosomes

• D) Nucleoli

• E) Lysosomes

Immune Response and Inflammation

The Body’s Defenses• Barrier defenses

• Cellular defenses

• Inflammatory response

• Immune response

Types of Barrier Defenses

• Skin – Protects the internal tissues and organs of the

body

• Mucous membranes – Line the areas of the body that are exposed to

external influences but do not have skin protection

• Gastric acid– Secreted by the stomach in response to many

stimuli

• Major histocompatibility complex– Distinguishes between self-cells and foreign cells

Types of Cellular Defenses

• Mononuclear phagocyte system (MPS)– Composed of:

• Thymus gland• Lymphatic tissue• Leukocytes• Lymphocytes• Numerous chemical mediators

White Blood Cells

Description of a Typical Inflammatory Reaction

Heat– Caused by increased blood flow

Swelling– Caused by fluid that leaks into the tissues

Redness– Caused by the increase in blood flow due to

vasodilation

Pain– Caused by the activation of pain fibres

The Immune Response

• More specific responses to foreign agents stimulates a more specific immune response– Lymphocytes produced in the bone marrow can

develop into T lymphocytes or B lymphocytes

– Other identified lymphocytes include natural killer cells

• These cells are aggressive against cancer cells –– to promote rapid cellular death

Adaptive & Specific Immunity

Natural-PASSIVE maternal antibodies

Artificial- Passive, InjectedIMMUNOGLOBULINS

Natural -ACTIVE Infection

Artificial- ACTIVE VACCINATION

What are the self components that the immune system uses to distinguish

self from nonself?

• A. Antibodies

• B. Major histocompatibility molecules

• C. Cytokines

• D. Lymphocytes

Which one of the following is an example of Natural active

immunity?

• A) Protection against infections that is passed from mother to infant through the placenta

• B) Protection afforded after an infection

• C) Protection afforded against hepatitis by an injection of pooled gamma globulin

• D) Protection afforded to an infant from a mother’s breast milk

Nervous System

Autonomic Nervous System

• Definition– Involuntary or organ nervous system

• Function– Mostly with little conscious awareness of activity

– Regulates and integrates body internal functions

– Integrates parts of the CNS and PNS to react to changes in the internal and external environment

Main ANS Centers

• Hypothalamus

• Medulla

• Spinal cord

Functions Regulated by the ANS

• Blood pressure

• Heart rate

• Respiration

• Body temperature

• Water balance

• Urinary excretion

• Digestive functions

“Fight or Flight” Response to Stress

Composition of the Nervous System

• Central Nervous System (CNS)– Composed of the brain and spinal cord

• Peripheral Nervous System (PNS)– Sensory receptors bring information into the CNS– Motor nerves carry information away from the CNS

• Autonomic Nervous System (ANS)– Uses components of the CNS and PNS to regulate

automatic or unconscious responses to stimuli

Role of the Nervous System

• Controlling the functions of the human body

• Analyzing incoming stimuli

• Integrating internal and external responses

The Neuron—Functional Unit of the Nervous System

Types of Nerve Axons

• Afferent fibres – Nerve axons that run from peripheral receptors

into the CNS

• Efferent fibres– Nerve axons that carry nerve impulses from the

CNS to the periphery to stimulate muscles or glands

Formation of a Myelin Sheath in a Peripheral Axon

Examples of Neurotransmitters

• Acetylcholine– Communicates between nerves and muscles

• Norepinephrine and epinephrine – Catecholamines released by nerves in the

sympathetic branch of the ANS

Components of the Brain

• Hindbrain– Runs from the top of the spinal cord into the

midbrain; contains the brainstem– Controls basic, vital functions

• Midbrain – Contains the thalamus, the hypothalamus, and

the limbic system • The thalamus sends direct information into the

cerebrum to transfer sensations

Components of the Brain

• The hypothalamus acts as a major sensor for activities in the body

• The limbic system appears to be responsible for the expression of emotions

• Frontal Lobe – 2 cerebral hemispheres joined together by the

corpus callosum– Receives and sends nerve impulses,

coordinates speech and communication, and facilitates learning

Spinal Cord

• Made up of 31 pairs of spinal nerves– Each spinal nerve has two components or roots

• Sensory fibre (dorsal) – Brings information into the CNS from the periphery

• Motor fibre (ventral)– Causes movement or reaction

Functions of the Central Nervous System

• Sensory functions

• Motor functions

• Intellectual and emotional functions

Nodes of Ranvier are associated with nerve conduction in:

• A) unmyelinated axons

• B) astrocytes

• C) microglial cells

• D) ependymal cells

• E) myelinated axons

The brain region most closely associated with the control of

homeostasis is the

• A) diencephalon

• B) hypothalamus

• C) thalamus

• D) cerebral cortex

• E) basal ganglia

Nervous System & Endocrine System

• They work together to maintain internal homeostasis

• They integrate the body’s response to the external environment

Characteristics of All Hormones

• Produced in very small amounts

• Secreted directly into the bloodstream

• Travel through the blood to specific receptor sites

• Act to increase or decrease the normal metabolic processes of cells when they react with receptor sites

• Are immediately broken down

Hypothalamus

• Definition– “Master gland” of the neuro-endocrine system

• ActionConstantly monitors the body’s homeostasis by:

• Analyzing input from the periphery and the CNS• Coordinating responses through the autonomic,

endocrine, and nervous systems

The Endocrine System

Releasing Hormones Produced & Secreted by the Hypothalamus

• Growth hormone–releasing hormone (GHRH)

• Thyrotropin-releasing hormone (TRH)

• Gonadotropin-releasing hormone (GnRH)

• Corticotropin-releasing hormone (CRH)

• Prolactin-releasing hormone (PRH)

Hormones Produced by the Hypothalamus

• Antidiuretic hormone (ADH)

• Oxytocin– Stored in the posterior pituitary to be released

when stimulated by the hypothalamus

Connecting the Hypothalamus to the Pituitary Gland

• Vascular network carries the hypothalamic releasing factors directly into the anterior pituitary

• A neurological network delivers ADH and oxytocin to the posterior pituitary to be stored

Lobes of the Pituitary Gland• Anterior lobe

– Produces six major anterior pituitary hormones

• Posterior lobe– Stores two hormones

• Intermediate lobe– Produces endorphins and enkephalins

Major Anterior Pituitary Hormones

• Growth hormone (GH)

• Adrenocorticotropic hormone (ACTH)

• Follicle-stimulating hormone (FSH)

• Luteinizing hormone (LH)

• Prolactin (PRL)

• Thyroid-stimulating hormone (TSH, also called thyrotropin)

Negative Feedback System

Other Hormones Released in Response to Stimuli

• Insulin, glucagon, and somatostatin • Parathormone• Erythropoietin and renin • GI hormones• Calcitonin• Prostaglandins • ACTH and the adrenocorticoid hormones• Aldosterone

A characteristic common to all hormones is that they:

• A) exert their effects by altering the rate of a body reaction

• B) are secreted at a uniform rate

• C) must be produced in large quantities to exert their effects

• D) always exert their actions at the site of secretion

Which of the following is NOT considered a tropic hormone?

• A) Adrenocorticotropic hormone (ACTH)

• B) Thyroid-stimulating hormone (TSH)

• C) Aldosterone

• D) Luteinizing hormone (LH)

The Female Reproductive System

Role of the Female Ovary

• Store ova

• Produce the sex hormones estrogen and progesterone

Hormones Produced in the Ovaries

• Oestrogen– Oestradiol, Oestrone, and Oestriol– Enter cells and bind to receptors within the

cytoplasm – Promote protein synthesis

• Progesterone– Released into circulation after ovulation

Effects of Progesterone• Decreased uterine motility

• Development of secretory endometrium

• Thickened cervical mucus

• Breast growth

• Increased body temperature

• Increased appetite

Role of Female Sex Hormones

• Prepare the body for pregnancy

• Maintain pregnancy

Function of the Hypothalamus• Releases GnRH at puberty

• Stimulates the anterior pituitary release of FSH and LH

• Stimulates the production and release of the sex hormones

• Controls levels by a series of negative feedback systems

Pituitary and Ovarian Hormone Levels

Male Reproductive System

Components of the Testes• Seminiferous tubules

– Produce the sperm

• Interstitial (Leydig) cells– Produce the hormone testosterone

Production of Sperm in the Seminiferous Tubules

• In response to FSH stimulation, and testosterone in the interstitial cells

• In response to LH stimulation

Effects of Testosterone

• Growth of male and sexual accessory organs

• Growth of testes and scrotal sac

• Thickening of vocal cords

• Hair growth

• Increased protein anabolism and decreased protein catabolism

• Thickening of cartilage and skin

4 Phases of Human Sexual Response

• Period of stimulation with mild increases in sensitivity and beginning of stimulation of the SNS

• Plateau stage when stimulation levels off

• Climax resulting from massive sympathetic stimulation of the body

• Period of recovery or resolution

The function of the scrotum is to:

• A) produce sperm

• B) produce testosterone

• C) enclose and regulate the temperature of the testes

• D) transport sperm

All of the following are hormones related to the functioning of the male

reproductive system EXCEPT:

• A) luteinizing hormone

• B) follicle-stimulating hormone

• C) testosterone

• D) prolactin

The secretion of FSH and LH is under the direct control of:

• A) oestrogen

• B) thyroxin

• C) oxytocin

• D) gonadotropin-releasing factor

During the follicular stage of menstruation, increasing levels of what hormone exert a

negative feedback effect on FSH?

• A) Oestrogen

• B) Luteinizing hormone

• C) Progesterone

• D) Follicle-stimulating hormone

The Kidney and Organs of the Urinary Tract

Components of the Nephron• Bowman’s capsule

• Ascending loop of Henle

• Distal convoluted tubule

• Collecting ducts

• Renal pelvises

Processes Involved in the Functioning of the Nephrons

• Glomerular filtration– Straining fluid into the nephron

• Tubular secretion – Actively removing components from the capillary

system and depositing them into the tubule

• Tubular reabsorption – Removing components from the tubule to return

them to the capillary system and circulation

Factors Stimulating Release of ADH

• Falling blood volume

• Sympathetic stimulation

• Rising sodium levels

Role of the Kidneys• Influence blood pressure control

• Release renin to activate the renin–angiotensin system

• Leads to increased blood pressure and volume

• Increased blood flow to the kidney

• Can lead to water retention or excretion

Male Urethra

• Passes through the prostate gland– May enlarge or become infected

• Often associated with advancing age

The functional unit of the kidney is the:

• A) nephron

• B) glomerulus

• C) the proximal tubule

• D) the ascending and descending limb of the loop of Henle

• E) the collecting duct

“fine-tuning” of hydrogen & potassium secretion occurs in the:

• A) proximal tubule

• B) descending limb of the loop of Henle

• C) late distal tubule

• D) collecting tubule