Human Human PhysiologyPhysiology

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lisa.harvey@vvc.edu 760-245-4271, ext. 2658760-245-4271, ext. 2658

Physiology isPhysiology is……

The study of the The study of the functionfunction of of all plants and animals in all plants and animals in their normal state.their normal state.

An integrative scienceAn integrative science

Function and ProcessFunction and Process::TeleologicalTeleological vs.vs. MechanisticMechanistic

Approach to ScienceApproach to Science

What is the purpose or function?What is the purpose or function? Why Why does something exist? does something exist? WhyWhy does it need to be done? does it need to be done?

What are the processes involved?What are the processes involved?

HowHow does something work? does something work?

Distinguish between Process & Function

Integrate both for complete picture!

How do we breathe?How do we breathe?

How does blood How does blood flow? flow?

How do RBCs How do RBCs transport Otransport O22??

Why do we breathe?Why do we breathe?

Why does blood Why does blood flow?flow?

Why do RBC Why do RBC transport Otransport O22??

Key Concept in Physiology: Key Concept in Physiology: HomeostasisHomeostasis

• Homeostasis Homeostasis refers to refers to maintaining maintaining relative relative constancy in a constancy in a system.system.

The ability of the body The ability of the body to survive in a to survive in a challenging and challenging and changing environment changing environment by keeping the internal by keeping the internal environment relatively environment relatively stablestable

• The change in the The change in the environment environment signals a response signals a response by the bodyby the body

• The response is to The response is to bring the body bring the body back to back to homeostasishomeostasis– If possible!If possible!

HomeostasisHomeostasis

A given system A given system tends to stay in tends to stay in equilibrium or equilibrium or balance despite balance despite influences that influences that cause cause disequilibrium.disequilibrium.

Negative FeedbackNegative Feedback

Negative Feedback Loops are Negative Feedback Loops are HomeostaticHomeostatic Negative feedback loops can restore the Negative feedback loops can restore the

normal state but cannormal state but can’’t prevent the initial t prevent the initial disturbance.disturbance.

Negative FeedbackNegative Feedback Refers to the corrective effect produced Refers to the corrective effect produced

by the feedback signal. The effect must by the feedback signal. The effect must be tobe to REDUCE the DIFFERENCE REDUCE the DIFFERENCE BETWEEN the SET POINT and the BETWEEN the SET POINT and the CONTROLLED VARIABLECONTROLLED VARIABLE

Negative FeedbackNegative Feedback

The body maintains a set point The body maintains a set point until there is a perturbation.until there is a perturbation.

The change in the environment The change in the environment signals a response by the bodysignals a response by the body

The response is to bring the body The response is to bring the body back to homeostasisback to homeostasis If possible!If possible!

• Positive Feedback is Positive Feedback is

NOT NOT homeostatichomeostatic• Positive Feedback Positive Feedback

reinforces the initial reinforces the initial stimulus rather than stimulus rather than decreasing or removing decreasing or removing it.it.

• The response sends the The response sends the variable being variable being regulated even farther regulated even farther from its normal valuefrom its normal value

Positive FeedbackPositive Feedback

Positive FeedbackPositive Feedback is NOT is NOT homeostatichomeostatic Positive Feedback reinforces the initial Positive Feedback reinforces the initial

stimulus rather than decreasing or stimulus rather than decreasing or removing it.removing it.

The response sends the variable being The response sends the variable being regulated even farther from its normal valueregulated even farther from its normal value

This triggers a vicious cycle of ever-This triggers a vicious cycle of ever-increasing response sending the system out increasing response sending the system out of control temporarilyof control temporarily

Must have a Must have a ““shut offshut off”” switch or it becomes switch or it becomes pathological.pathological.

http://www.youtube.com/watch?v=Vae5CcaPN_8&feature=related

The Science of PhysiologyThe Science of Physiologyisis

based on the based on the Scientific Scientific MethodMethod

ReviewReview

1.1. Basic steps of scientific Basic steps of scientific methodmethod

2.2. Parameters to considerParameters to consider

3.3. Experimental designExperimental design

Basic Steps of Scientific Basic Steps of Scientific Method:Method:

Observation (and/or study of prior Observation (and/or study of prior knowledge)/Questionknowledge)/Question

HypothesisHypothesis

ExperimentationExperimentation

Collection and analysis of data Collection and analysis of data (can you replicate results?)(can you replicate results?)

Conclusion: Conclusion: rejectreject or or acceptaccept hypothesishypothesis

theory

ExamplExample:e: Company has found new Company has found new

artificial artificial sweetener (S)sweetener (S)

Prior knowledge: Prior knowledge: Some food additives Some food additives

are not safe.are not safe.

Hypothesis: ?Hypothesis: ?

Experiments: ?Experiments: ?

Collect and analyze dataCollect and analyze data

Conclusion Conclusion

Animal vs. Human Experimentation

In Physiology most knowledge is derived In Physiology most knowledge is derived from _______ experimentation.from _______ experimentation.

Sometime human experimentation is Sometime human experimentation is necessary.necessary.

Difficulties of Human Experimentation:Difficulties of Human Experimentation: Very dissimilar test subjectsVery dissimilar test subjects Psychological aspects (placebo and nocebo Psychological aspects (placebo and nocebo

effects)effects) Ethical questions (is it o.k. to withhold Ethical questions (is it o.k. to withhold

potential drug from seriously ill?)potential drug from seriously ill?)

Focus on . . . . Focus on . . . . (Concept) Mapping(Concept) Mapping

1.1. Structure – function Structure – function mapsmaps

2.2. Process maps or Flow Process maps or Flow chartscharts

Follow process in sequenceFollow process in sequence