Final Review Block 3

Question 1

which ion has the biggest difference in concentration between inside and out of cell?

Answer 1

Ca

Question 2

3 characteristics of simple diffusion

Answer 2

selectivity
passivity
competition
(no saturation)

Question 3

describe a simple diffusion channel

Answer 3

hole in the membrane that provides a hydrophilic path for molecules to move through down their concentration gradient

Question 4

what is Fick’s Law

Answer 4

j = DA (DC/Dx)

Question 5

what are the consequences of fick’s law?

Answer 5

larger concentration gradient, more molecules will move
larger molecules = slower movement
larger surface area = more molecules diffuse

Question 6

what is PTPC?

Answer 6

permeability transition pore complex in mito
closed = mito happy
open = apoptosis

Question 7

what are the 2 types of RyR receptors?

Answer 7

RyR1 skeletal mm

RyR2 other mm

Question 8

describe NMDA- type glutamine receptors

Answer 8

ligand gated Ca channels

antagonists: anesthetics, drugs (PCP)

Question 9

what is the reflection coefficient?

Answer 9

measure of how well a solute can cross a membrane
=1 (highest), solute cannot cross
0-1 = semi-permeable
=0 freely permeable

Question 10

what is required for a substance to be osmotically active?

Answer 10

cannot freely diffuse across the membrane

Question 11

what allows for the passage of water across a membrane?

Answer 11

aquaporins

Question 12

what characterizes facilitated diffusion?

Answer 12

competition, selectivity, saturability

Question 13

describe GLUT-2

Answer 13

facilitative glucose transporter that is found on pancreatic b-cells, acts as a glucose sensor for release of insulin, always present in the membrane (constitutive)

Question 14

describe GLUT-4

Answer 14

Facilitative glucose transporter that is found on skeletal and cardiac mm cells/fat cells, insulin binds to receptor yielding a signal for the cell to inset GLUT-4 into membrane (regulated)

Question 15

what are the Ca ATPases?

Answer 15

PMCA- plasma membrane, pumps Ca out
SERCA- pumps Ca into SER
SPCA- on golgi

Question 16

H/K ATPase on gastric parietal cells

Answer 16

1H out and 1K in per 1ATP

Question 17

vesicular ATPase

Answer 17

uses ATP to pump H into vesicles

Question 18

ABC transporter

Answer 18

uses APT to export xenobiotics, cholesterol and bile from liver

Question 19

which active transporter is importance re: diarrhea?

Answer 19

Na/glucose cotransporter, will help move water out of gut (target of oral rehydration therapy)

Question 20

K(ATP channel)

Answer 20

part of SUR, blocking k(ATP) leads to depol, which causes release of insulin

Question 21

consequence of severe hyponaturemia

Answer 21

brain swelling

Question 22

consequence of hypokalemia

Answer 22

constipation

Question 23

digoxin MOA

Answer 23

cardiac glycoside- inhibits Na/K ATPase, thereby decreasing extracellular Na and decreasing “fuel” to pump Ca out of cell (decreases contraction)

Question 24

CCB MOA

Answer 24

inhibit voltage gated Ca channels, decrease contraction strength - used for angina, arrhythmia and HTN, will decrease BP and decrease myocardial O2 consumption

Question 25

effect of ischemia on the heart

Answer 25

ischemia will decrease OXPHOS and thereby decreased ATP production, Na will reverse the Na/Ca exchanger and increased Ca will be inside of the cell, leading to arrhythmia, heart failure or CVA

Question 26

define equilibrium potential

Answer 26

the amount of charge needed to oppose the concentration gradient of the ion

Question 27

what are the equilibrium potentials for K, Na, Cl and Ca?

Answer 27

``` K= -92 mV Na = +64 mV Cl= -88 mV Ca = -150 mV ```

Question 28

what are the 2 things that govern membrane potential?

Answer 28

concentration gradient of ions | permeability of those ions

Question 29

what is the main determinant of equilibrium potential in most cells?

Answer 29

K+ because Na and Cl permeabilities are insignificant

Question 30

what is the consequence of increasing extracellular K?

Answer 30

depolarization

Question 31

when are channels refractory?

Answer 31

after they are inactivated and before the membrane is repolarized

Question 32

which type of cell has increased permeability to cl?

Answer 32

skeletal mm

Question 33

describe leak channels

Answer 33

channels for K, Na, Cl that are voltage gated and are OPEN when the membrane is at resting potential

Question 34

what is the cause of the "plateau" seen on myocardiocytes?

Answer 34

Ca influx

Question 35

3 special channels in pacemaker cells

Answer 35

Na-HCN K-KAch Ca-t type

Question 36

describe Na-HCN channels

Answer 36

in cardiac pacemaker cells, also called "funny", will open when cell is hyper polarized and allow Na in to bring cell back to resting potential

Question 37

describe K-KACh channes

Answer 37

ACh sensitive K channel- Ach opens channel and K flows out to repolarize, closing these will result in depol

Question 38

describe Ca T type Ca channels

Answer 38

transient, will open at the beginning of depol and allow cells to reach threshold

Question 39

sulfonylurea MOA

Answer 39

inhibits K(ATP) channel, leads to depol, depol opens Ca channels, increased Ca triggers release of insulin from b-cells

Question 40

what maintains resting membrane potential?

Answer 40

Na/K ATPase