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Lecture 1: Introduction to Animal Physiology

Reading: Chapter 1Lecture Outline:

I. What is Physiology?

II. The Unifying Themes in Animal Physiology

III. What is Homeostasis?

IV. Regulatory Mechanisms

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What is this course?

Animal Physiology!Physiology:

Physis: Nature

Logos: study of

Study of the functions that make up living

things.

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Questions to be Answered in

Animal Physiology 225

What does it do? FUNCTION

How does it do it? MECHANISM

How is it controlled? REGULATION

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Structure - Function Relationship

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Multiple Levels of Biological Organization

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What makes up Physiology?

Animal

Genetics, Anatomy and Cell Biology

Physics and Chemistry

Environment

Temperature, Nutrients, Water, Oxygen,Protection / Exposure, Social interactions

Physics and Chemistry

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Phenotype

Genotype

Environment

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Laws of Physics and Chemistry influencePhysiological processes.

Physiological processes are regulated.

The phenotype is a product of the genotype

and the environment.

A genotype is the product of evolution,

acting through natural selection and other

evolutionary processes.

Four Unifying Themes in Animal Physiology

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Phenotype:Morphologyappearanceincludes physiology and behavior.

Phenotypic plasticity: is the ability of aphenotype to change in response to

environmental conditions.

Adaptation:Changes in population overevolutionary time as a result of natural

selection that improve the survivability orreproductive fitness of the species.

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Phenotypic Plasticity

The same genotype may result in multiplephenotypes.

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Factors Influencing Phenotype

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Homeostasis

Maintenance of a constant internal

environment despite changes in

external environment.

Not an equilibrium. Equilibrium = death!

Claude Bernard

(1871-1945)

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Any change in the env ironment el ic i ts

a physio log ical response which

func t ions to maintain homeos tas is .

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Homeostasis of the body is a composite of the

specialized functioning of individual cells, tissues,

organs and organ systems.

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The Regulatory Systems

Endocrine System

Nervous System

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The Regulatory Mechanisms

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Regulatory Mechanisms

Feedback

- Positive

- Negative

Feed Forward Action

Acclimatization

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Negative

feedback in

the controlof body

temperature

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Postive feedbackparturition (birth)

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Positive Feedback: Stimulus triggersmechanisms that amplify the responseand reinforces the stimulus.

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Positive feedback

uterine contractionsduring parturition

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What terminates the postive feedback?

Birth!

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Feed-Forward Action

Anticipatory Action

You put your jacket on before leavingthe building.

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Acclimatization

Adjustment in physiological function/s inresponse to changes in the environment

(multiple factors).

- Typically reversible.

- Example: Recovering from jetlag.

Acclimation

A laboratory phenomenonAdjustment in

response to only one factor.