BIO 3520 Notes, 8/25/08
INTRODUCTION TO ANIMAL PHYSIOLOGY
I. Introduction. [Widmaiera, pg. 2]
A. Physiology = Science of the function of the living organism and its parts.
B. Mechanist vs. vitalist views of life.
a Widmaier, E.P., Raff, H., and Strang, K.T. Vander's, Human Physiology: The
Mechanisms of Body Function, 11th ed., McGraw-Hill, New York, 2008.
A. Definition -- Basic unit of structure and function of living organisms.
B. Diversity.
1. 200 different types of cells in human body.
2. Zygote
> undifferentiated stem cells> mature cells (figureb).
C. Basic cellular processes -- activities common to most cells.
1. Exchange of materials with their environment.
2. Energy utilization.
3. Synthesis of simple and complex molecules.
4. Response to external stimuli.
5. Reproduction.
D. Review cellular structures on your own (Widmaier, pp. 48-54; fig. 3-4).
b Copyright restrictions apply to all figures.
A. Cells must live in a stable environment.
1. Unicellular organisms are in direct contact with their external
environment.
a. Highly vulnerable to environmental stress.
b. Must be adaptable.
2. Multicellular organisms are able to sustain their own internal environment
> extracellular fluid.
B. Claude Bernard introduced the concept of the constancy of the internal
environment (1865).
1. Walter Cannon coined the term "homeostasis" (1929).
C. Homeostasis = Maintaining a constant internal environment in spite of
changes in the external environment.
D. Homeostasis is the central theme of physiology.
IV. Control Systems. [pp. 7-11]
A. Control systems are designed to maintain homeostasis.
B. Objective is to maintain a controlled variable within the range of a
set point.
C. Five elements of a control system.
1. Sensor (receptor).
a. Monitors the status of some controlled variable.
b. Example:
2. Afferent pathway.
a. Carries information from the receptor to the control center.
b. Example:
3. Control center (integrating center).
a. Compares the current status of the controlled variable to the set
point.
b. Makes a decision as to what action should be taken.
c. Example:
4. Efferent pathway.
a. Carries information from the integrating center to the effector.
b. Example:
5. Effector.
a. Produces changes in the controlled variable in response to the
commands of the control center.
b. Example:
6. Summary (fig. 1-6).
D. Physiological example.
1. Sensor
>
2. Afferent pathway
>
3. Control center
>
4. Efferent pathway
>
5. Effector
>
V. Control System Diagrams. [Widmaier, pg. 8]
A. Meaning of arrows.
1. A
> B If A increases then B increases.2. A -----> B If A increases then B decreases.
B. Example: Water bath.
1. When a change in the controlled variable triggers a response that
opposes the change (figure).
2. Maintains homeostasis.
3. Odd number of broken arrows.
4. Examples of negative feedback loops in physiology:
C. Positive feedback loops.
1. When a change in the controlled variable triggers a response that
sustains or accelerates the change.
2. Even number of broken arrows.
3. Brief or destructive.
4. Examples of positive feedback loops in physiology.
D. A more complex diagram: Regulation of blood calcium (figure).
VI. Discussion -- "How Are Control Systems Controlled?"
A. Salt deficiency in moose.
B. Phosphate deficiency in cattle.
C. Dehydration in camels.
D. Excess salt intake in marine birds.
E. Fever in desert iguanas.
VII. Tissues. [pp. 2-4]
A. Levels of organization:
Cells
> tissues> organs> organ systems
B. Tissue = Group of cells with similar functions.
C. Composed of:
1. Cells that are similar in structure and function.
2. Extracellular structures.
3. Interstitial fluid.
D. Primary tissues (fig. 1-1).
1. Muscle (figures: skeletal, cardiac, smoothc).
a. Function -- Contraction and generation of force.
b. Characteristics.
1. Elongated.
2. Composed of contractile filaments.
3. Sometimes organized into dark and light bands (striations).
2. Nerve (figurec).
a. Function -- Initiation and conduction of electrical signals.
b. Characteristics.
1. Large cell body.
2. Branching processes (called axons and dendrites).
3. Epithelium (figures: simple cuboidal, stratified squamousc).
a. Function -- Selective secretion and absorption of molecules.
b. Characteristics.
1. Cells lie close to one another.
2. Arranged in single or multiple layers.
3. Covers body surface and lines hollow organs.
4. Connective tissue (figures: elastic tissue, bonec).
a. Function -- Connecting and supporting body structures.
b. Characteristic -- Large amount of extracellular material.
c. Examples:
c Fox, S.I., Human Physiology, 7th ed., McGraw-Hill, New York, 2002.
Copyright restrictions apply.
VIII. Organs and Organ Systems. [pp. 4-5]
A. Organ = Two or more tissues joined in a structural unit to perform a
common function.
B. Organ system = Group of organs that work together to perform a
common function.
C. Survey of organ systems (table 1-1).
C. Summary (figured).
1. Homeostasis is essential for survival of cells.
2. Cells make up tissues, organs, and organ systems.
3. Organ systems maintain homeostasis.
dFigure is modified from Sherwood, L., Human Physiology: From Cells to Systems,
5th ed., Brooks/Cole, Belmont, CA, 2004. Copyright restrictions apply.
IX. Example of an Organ: Skin.
A. Functions.
1. Protection.
2. Thermoregulation.
3. Sensation (fig. 7-16).
B. Two layers (figurec).
1. Epidermis -- outer layer.
a. Composed of flattened epithelial cells.
b. Protects body against water loss and disease-causing organisms.
1. Epidermal cells of terrestrial animals produce a water-insoluble
protein called keratin.
a. Outermost cells are dead and keratinized.
b. Adaptation to dry environment.
c. Scales in reptiles.
d. Feathers in birds.
2. Epidermis of fish and amphibians has little or no keratin.
c. Dying cells are constantly being replaced by new cells.
d. Skin color is determined by a pigment, melanin, in epidermal cells.
1. Albino lacks melanin (figure).
2. Melanin protects skin against harmful effects of ultraviolet
radiation.
3. Sun exposure is responsible for 90% of skin cancers.
a. Basal cell carcinoma damages small areas, will spread
if not removed (figure).
b. Malignant melanoma (figure) can be fatal.
2. Dermis -- beneath epidermis.
a. Mosly connective tissue.
b. Structures.
1. Hair follicles in mammals.
2. Sweat glands and sebaceous glands for lubrication and
cooling.
3. Sensory nerve endings specialized for touch, pressure, pain, etc.
4. Blood vessels for nourishment.
C. Hypodermis.
1. Layer of fat just below the dermis -- not a part of the skin.
2. Storage of nutrients.
X. Introduction to PowerLab. [Lab Manual].
A. Components of the PowerLab recording system.
1. Transducer -- Transforms the energy of a physiological event into
electrical energy.
2. Amplifier -- Amplifies the electrical signals from the transducer.
3. Data acquisition unit -- Converts analog signals from the transducer
or amplifier into digital information.
4. Computer -- Records, displays, stores, and analyzes data.
a. Chart resembles a chart recording device.
b. Scope resembles an oscilloscope.
