Physiology Lec 7 - Homeostasis

Front 1

what is the composition of water in the intracellular & extracellular compartments?

Back 1

- 60% intracellular

- 40% ECF

Front 2

75% of extracellular water is _____. What is this space?

Back 2

- interstitial

- this is the space between cells

Front 3

intracellular fluid doesn't communicate directly with blood plasma (except RBCs), how does it communicate then?

Back 3

- communicates via interstitial fluid (part of ECF)

Front 4

steady state: _______ acting on a substance are ____ over time & the rate of net movement is also constant

Back 4

- driving forces

- constant

Front 5

equilibrium: ______ is acting on a substance to force it across a membrane & no net transport of substance occurs

Back 5

- no net driving force

Front 6

difference between steady state & equilibrium?

Back 6

- in steady state there is a net constant driving force & a constant net rate transport of substance

- in equilibrium there is no driving force & no net movement of substance

Front 7

what is the difference between a passive & active driving force?

Back 7

- passive: [ ] gradients, electrical gradients (differences in voltage)

- active: ATP consuming acting against [ ] & electrical gradients

Front 8

how does lipid affect the interstitial ion concentration?

Back 8

- ions are only present in the aq phase - so when taken over total volume with lipid makes it look like total ion [ ] is lower

- therefore when high plasma lipid, plasma sample is not good estimate of interstitial ion concentration

Front 9

how do proteins affect the interstitial ion concentration?

Back 9

- same effect as high lipid, but also neg. charge on protein has effect on ion distribution

- makes it look like the total ion [ ] is lower

Front 10

what happens to cations with the effect of proteins & lipids in the plasma vs. interstitium?

Back 10

- for cations the neg. protein & lipid effect nearly cancel each other out

- proteins pulling cations out & lipids are diluting them

Front 11

what happens to anions with the effect of proteins & lipids in the plasma vs. interstitium?

Back 11

- for anions both neg. protein & lipid reduce the anion [ ] in the plasma

- makes insterstitium look higher in anions

Front 12

what is the anion gap?

Back 12

- in plasma there is a difference between major cations & major anions

- this is due to difference between cations & ignored anions

Front 13

what is the formula for the anion gap?

Back 13

- anion gap plasma = [Na]p - ([Cl-] + [HCO3-])

Front 14

why does the anion gap increase in diseases such as type I diabetes?

Back 14

- because increased amount of neg. charged metabolites such as acetoacetate & hydroxybutyrate

- this causes more sodium to go into the plasma but we're not measuring those anions so the anion gap increases

Front 15

what do disorders of extracellular K do?

Back 15

Any disorder in extracellular [K+] is likely to cause cardiac arrythmias and neuromuscular problems b/c it messes up electrical excitability

Front 16

what do disorders of Na+ do?

Back 16

- disturbances in extracellular Na+ can lead to water shifting in or out of neurons

- can lead to seizures, coma or death

Front 17

what does passive transport require?

Back 17

1) driving force - [ ] or electrical gradient
2) pathway through membrane

Front 18

what is unique about Co2, steroids & gaseous anesthetics in terms of their membrane transport?

Back 18

- because they are lipid soluble they can pass through membranes by simple diffusion

Front 19

secondary vs. primary active transport?

Back 19

- primary: driving force comes from hydrolysis of ATP

- secondary: driving force comes by coupling uphill movement to downhill movement of favorable [ ] gradient

Front 20

what does the alpha subunit of the Na-K pump do?

Back 20

- alpha subunit lines the pores & hydrolyzes ATP

- 3 Na out for 2 K in

Front 21

what does osmosis refer to the movement of?

Back 21

- only water

Front 22

osmolality: what is it? what are the osmoles of NaCl? glucose?

Back 22

- total concentration of particles in solution

- NaCl = 2 osmoles

- glucose = 1 osmole

Front 23

gibbs donnan?

Back 23

- effect of neg. charged trapped proteins on ion distribution

- neg ions move in them sodium moves in then water follows - generate osmotic gradient