Human Physiology Welcome to your first day of class!!
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Physiology is… • the study of the function of all plants and animals in their normal state. • an integrative science
Organ Systems • operate as integrated units • How many? Can you list them? Examples: Regulation of Plasma calcium concentration Blood pressure etc.
Function and Process:Teleologicalvs.MechanisticApproach to Science What is the purpose or function? Why does something exist? Why does it need to be done? What are the processes involved? How does something work?
Distinguish betweenProcess & Function Why do we breathe? Why does blood flow? Why do RBC transport O2? How do we breathe? How does blood flow? How do RBCs transport O2? Integrate both for complete picture!
Focus on . . . . (Concept) Mapping • Structure – function maps • Process maps or Flow charts Follow process in sequence
Key Themes in Physiology: • Homeostasis Body systems work together (Integration of function) Internal vs. external failure of homeostasis • Communication and movement across cell membranes Vital to integration & homeostasis Cells communicate with other cells, tissues & organs
Homeostasis • The Wisdom of the body • The ability of the body to survive in a challenging and changing environment by keeping the internal environment relatively stable • Negative Feedback • Positive Feedback
Negative Feedback • Negative Feedback Loops are Homeostatic • Negative feedback loops can restore the normal state but can’t prevent the initial disturbance. • Negative Feedback • Refers to the corrective effect produced by the feedback signal. The effect must be toREDUCE the DIFFERENCE BETWEEN the SET POINT and the CONTROLLED VARIABLE
Negative Feedback • The body maintains a set point until there is a perturbation. • The change in the environment signals a response by the body • The response is to bring the body back to homeostasis • If possible!
Positive Feedback • Positive Feedbackis NOT homeostatic • Positive Feedback reinforces the initial stimulus rather than decreasing or removing it. • The response sends the variable being regulated even farther from its normal value • This triggers a vicious cycle of ever-increasing response sending the system out of control temporarily • Must have a “shut off” switch or it becomes pathological.
The Science of Physiologyis based on the Scientific Method Review • Basic steps of scientific method • Parameters to consider • Experimental design
Basic Steps of Scientific Method: Observation (and/or study of prior knowledge)/Question Hypothesis Experimentation Collection and analysis of data (can you replicate results?) Conclusion: reject or accepthypothesis theory
Example: Company has found new artificial sweetener (S) Prior knowledge: Some food additives are not safe. Hypothesis: ? Experiments: ? Collect and analyze data Conclusion
Animal vs. Human Experimentation • In Physiology most knowledge is derived from _______ experimentation. • Sometime human experimentation is necessary. • Difficulties of Human Experimentation: • Very dissimilar test subjects • Psychological aspects (placebo and nocebo effects) • Ethical questions (is it o.k. to withhold potential drug from seriously ill?)