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
what aspen to the extra cellular fluid if we drink lots of water?
ECF volume increases
ECF osmolarity decreases
what is osmolarity?
conc of certain substance
what happens to the ECF in comparison to the ICF when we drink los of water?
ECF becomes more diluted than ICF so water moves into the ICF
this happens until osmolarities are equal
then the extra water is dispersed between them both
how does water movement in the extra and intra cellular fluid occur?
osmosis
what is osmosis?
diffusion of water along its conc gradient
describe the 3 conc scenarios in osmosis?
isotonic - same cons inside and out of cell
hypertonic - higher conc than blood
hypotonic -lower conc than blood
can homeostasis keep all variables at constant level all the time?
no as there is some delay in operating the control system
also each particular variable is not maintained at same value in different humans
can homeostasis keep all variables at constant level all the time?
no as there is some delay in operating the control system
also each particular variable is not maintained at same value in different humans
do all variables change in a person?
no eg. height
there is a normal range of values that are considering ‘normal’
