week 1 Flashcards
define homeostasis + give 3 examples of variables under homeostatic control
maintenance of stable internal environment.
examples: plasma glucose, body temp, blood pressure
describe components needed to maintain homeostasis (5)
1 regulated variable
2 sensor
3 control center 4 set-point
5 effector
what is negative feedback loop? why is it called negative?
- turning back to normal set-point.
- called negative bc response of system is opposite direction of change that set it in motion.
what is positive feedback loop? why is it called positive?
- turning back to normal set-point.
- called positive bc response of system is same direction of change that set it in motion.
define moving DOWN a concentration gradient vs moving UP
- down: high to low concentration
- up: low to high concentration.
diff between chemical vs electrical driving force
chemical: higher concentration of molecules moves to lower.
electrical: movement of charged molecules (opposites attract and likes repel).
resting membrane potential is what charge?
negative (~70mV)
intracellular fluid is what charge? extracellular?
iNtra = Negative
extra = positive
if equilibrium potential is larger than membrane potential, the electrochemical force acts in same direction as the ___ force.
if membrane potential is larger than equilibrium potential, the electrochemical force acts in same direction as the ___ force.
chemical
electric
diff between hydrophobic and hydrophilic?
hydrophobic: not water-loving. cross phospholipid bilayer. ex lipids.
hydrophilic: water-loving. use membrane proteins for transport. ex ions, glucose.
which category does water fall into?
both
2 types of passive transport
simple diffusion
facilitated diffusion
diff between simple and facilitated diffusion
simple = thru phospholipid bilayer
facilitated = carriers or channels
which membrane would have higher net flux: high permeability or low permeability?
high! low perm = resistance
diff between carriers and channels for facilitated diffusion?
carriers: binds molecules on one side of a membrane and transports them to the other side.
channels: transports molecules via a passageway or pore in membrane.
why does facilitated diffusion reach a maximum/level off?
because the carrier proteins become 100% saturated at high concentrations.
most water diffuses across cell membranes through what membrane transport protein?
aquaporins
diff between active and passive transport re: electrochemical gradients
active: up
passive: down
diff between primary and secondary active transport regarding mechanisms
primary: pumps use ATP
secondary: carriers
ions/molecules inside (5) vs outside (4) cell
inside: potassium (+), amino acids, protein, phosphate, HCO3
outside: sodium (+), calcium (+), chlorine, HCO3