Homeostasis Flashcards
what 4 things are part of the ‘internal environment’?
nutrients
oxygen
waste
carbon dioxide
what is homeostasis?
various physiological arrangements that serve to restore the normal state once it has bee disturbed
give an example of a body system that interacts with the external environment and expends energy?
nervous system
locomotor system
reproductive system
give an example of body systems that interact with the internal environment and help to achieve homeostasis?
cardiovascular
respiratory
excretory
alimentary
give an example of body systems that control other systems?
nervous system
endocrine system
why is homeostasis important?
- cells function most effectively under ‘optimal’ environmental conditions
- basic cellular functions tend to alter their immediate environment
- homeostasis operates to correct any changes in the cellular environment
where is the enzyme pepsin found?
stomach
where is the enzyme trypsin found?
intestines
what conditions are important for optimal enzymes activity?
pH
hormone secretion
temp
O2 concentration
glucose
name the 2 mechanisms of homeostasis control.
feed back control
feed forward control
describe negative feedback control?
change in variable activates mechanisms that alter the level of that variable to counteract the change
used in many physiological control systems
describe feedforward control?
involves Alterung behaviour before their is any obvious “error signal”
- anticipatory action
eg. stop eating before full
what is positive feedback control?
change in a variable activates mechanisms that alter the level of that variable so increases change
same change is amplified and converted to larger one
- not used in homeostatic control
- potentially disruptive
- used in blood clotting, child birth, action potentials
describe intra and extracellular fluids.
-extracellular fluids
= interstitial fluids 11 litres
= plasma 3 litres
-intracellular fluids
=28 litres
what can move between extracellular fluid and intracellular fluid?
water
some ions
