homeostasis Flashcards
what is homeostasis
prevent disturbance in the system
what is the life equation
Nutrients + O2 = Energy (ATP) + CO2 + wastes
what is negative feedback
There is oscillation around the set point.
2. Restore the regulated variable after its initial displacement, but cannot prevent it happening.
RESTORE CONDITIONS
what is a feed forward system
additional receptors permit system to anticipate change and therefore activate response earlier.
early warning - pre-emptive strike
positive feed back
greater disturbance
SELF AMPLIFICATION
how much body weight is water
60%
basic homeostasis concept
What we gain, we must lose
What we lose, we must replace
what are the 3 water compartments in the human body
Intracellular fluid
Interstitial fluid (fluid between cells) Plasma (fluid component of blood)
what is the water content breakdown between ICF and ECF
ICF 2/3 or 28 literes
ECF 1/3 or 14 litres
interstisal fluid is 11 litres
plasma is 3 litres
total body water content
42 litres (typical 70kg 21yo man)
how does water content between sex and age change
decrease with age as more fat
fat carries less water
by that logic females have less water content
what is the difference between plasma and ISF
plasma proteins which are too large
what is the dilution principle
c = m/v, v = m/c
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what is the only body fluid that can be measured to see water content
ONLY plasma can be sampled, only compartments of which plasma is a component can be measured directly (plasma, ECF, TBW).
how is plasma measured
Evans blue or I125albumin.
radioactive lables attached to plasma proteins
how is ECF measured
something that freely crosses capillaries
but to large for cell membrane
24Na+ , 36Cl-,
how is total body water measured
use a loading dose of water
how is the ICF and interstisial fluid measured
ISF = ECF-PV,
ICF = TBW-ECF
what do these terms mean hypo hyper Aemia uria glyc
less than normal more than normal in the blood urine glucose
what happens if there is an extreme homeostatic disturbance
may fall off the homeostatic plateau and lead to DEATH.