ingestive Behavior and Eating Disorders Physio EXAM 3

Regulatory Mechanism

System variable

set point

detector

correctional mechanism

System variable

this is what is regulated

ex: body temp

set point

the optimal point for the system variable

normal/homeostasis

EX: 98.6 being optimal human temp

Detector

recording variations from the set point

EX: being too cold or too hot → more or less away from 98.6

Correctional Mechanism

gets you back to that set point

Ex: sweating or shivering to regulate body temp

4 fluid compartments + 1

Intracellular

extracellular

Interstitial

Intravascular (Blood Plasma)

Cerebral Spinal Fluid (CSF)

Intracellular Fluid

found inside of cells

70% water, a lot of water is INSIDE of cells → 2/3

Isotonic

Extracellular Fluid

Interstitial Fluid

Intravascular Fluid

Cerebral Spinal Fluid

Interstitial Fluid

right outside of the cell

used as a cushion for the cell

isotonic, used intracellular & vice versa to maintain water/fluid levels

Intravascular (Blood Plasma)

Plasma is what makes blood movement easier → it acts as a lubricant

EX: new car oil versus old car oil → the new car oil works better

Less plasma means the heart works harder to pump blood throughout the body

Cerebral Spinal Fluid

Found in the brain & Spinal cord

Ventricles (holes in the brain) fill with __ to cushion/protect the brain

EX: having brain smack against skull → super dizzy after roller coaster rides this protects the brain from damage

Clear fluid should not leak if it does, there is potential for bacterial infection

Detectors/Correctional mechanisms

osmometric thirst

volumetric thirst

osmometric thirst

intracellular and interstitial

chemical and could go both ways

transfers from one compartment to another

high chemical level in the interstitial (outside the cell) use osmosis to pull water from the intracellular (inside the cell) to decrease salt level

Intracellular still needs water; if this process continues, cell death is possible

This process is used to dilute

Volumetric thirst (dehydration)

Blood plasma decreases (makes the heart work harder)
evaporation

blood loss/vomiting & Diarrhea

Evaporation

Lost water from all three compartments

1 intracellular 2 interstitial 3 blood plasma

When blood plasma is low, it pulls from the interstitial, which causes a ripple effect down the chain

intracellular → interstitial → blood plasma —> water movements → there is a limited amount of water, and when it is fully gone, cell death occurs

Could be sweating too much

Blood Loss/ Vomiting & Diarrhea

cut yourself → bleeding out → plasma goes too

food poisoning → both ends → you lose blood plasma as well

drops quickly compared to evaporation → keep a major eye on babies/toddlers

Sucralose = BAD → look for stevia

Kidney’s detect

^{blood loss → release an enzyme called Renin → create angiotensin}

Angiotensin

salt appitite and thirst (water)

works to tell kidney to conserve salt and water

Returning to Homeostasis

^{Once plasma returns to normal the H2O moves backwards and replenishes the cell}

^{maintaining blood plasma is the main component}