Homeostasis Notes

Statistics in Research

Deduction – go from general theory to a specific prediction/observation

• allows the application of a general rule to specific case to form a hypothesis

Induction – specific observation leads to general theory

• allows us to test a hypothesis deriving from specific observations

Hypothesis – a suggested explanation for a group of facts, accepted as the basis for further verification or accepted as likely to be true.

• Frame a hypothesis to deduct its consequences (specific case)

• must be falsifiable, refutable, or testable

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Null hypothesis – the effect you’re looking for in the experiment does not exist

P-value – the prob. That certain observations would be made if the null hypothesis were true

        Low P: likely that your hypothesis is true

        High P: unlikely that your hypothesis is true

False positive inference (type 1) – reject the null hypothesis when its true

• If we do everything right, the probability that we have made this error is equal to the P value we come up with

False negative inference (type 2) – accept the null hypothesis when it is really false

• If we do everything right, the probability that we have made this error is equal to (1‐ the ‘power’) of the test

Homeostasis

• Negative feedback loop

• Response reduces initial stimulus that caused the reaction
• Increase or decrease in whatever’s being regulated = response that changes it in the opposite direction to the original change

• Gas exchange

• Require surface area for exchange of gases b/w the body and environment

• In lungs – alveoli sacs increase SA

• Require transport system to get gas from lungs to other parts of the body: Vascular system

• Capillaries wrap around alveoli sacs which allows for gas exchange

• Cells

• During development, cells differentiate – so can perform different functions
• 4 basic types of cells

• Body Systems are made up of multiple organs to perform a function

• E.g. Urinary system consists of:

• Kidney
• Ureter
• Bladder
• Urethra

• Homeostasis

• The maintenance of relatively stable internal fluid environments in which the body’s cells reside (the extracellular fluid)

• Volume of fluid
• Composition

• State of dynamic consistency
• Detect and respond to deviations in physiological variables from their “set point”

• Effector responses are initiated that restore the variables towards optimal physiological range
• Set point can change

• E.g. Barrow receptors (control short term blood pressure) reset after exercise

• Body water

• Intracellular fluid: inside cells

• 2/3 of body
• Direct connection through cell membrane to interstitial fluid

• Interstitial fluid: environment where cells live in

• Direct connection through cell membrane to intracellular and plasma

• Plasma: environment blood cells live in

• Direction connection through cell membrane to intracellular fluid
• Plasma + Interstitial fluid = extracellular fluid

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• Reflex responses and homeostatic control

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