# Homeostasis Notes

Essay by   •  September 14, 2017  •  Course Note  •  932 Words (4 Pages)  •  400 Views

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## 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
 Epithelial For secreting/absorbing things (e.g. stomach lining), transporting things (e.g. sodium out of urine and into blood. Connective-tissue Stop us from falling apart Nerve Allow communication b/w organs and tissues Muscle Smooth, skeletal, and cardiac
• Body Systems are made up of multiple organs to perform a function
• E.g. Urinary system consists of:
• Kidney
• Ureter
• 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
 Reflex Response sequences Stimulus The detectable change in internal/external environment Receptors Detect the environmental change Afferent pathway Carry the signals from receptors to control (integrating) centre Integrating centre Interprets the signals from the receptors Efferent pathway To carry the output (response) signal from the integrating centre to the effectors Effectors Carry out the response needed to “correct” the situation

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