Module B-02 Flashcards Preview

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Flashcards in Module B-02 Deck (32):
1

Current flows passively in direction denoted by _________ in electrical field

movement of cations

2

cations move towards _______

cathode (negative terminal) by electrodiffusion

3

Anions move towards _______

anode (positive terminal)

4

What causes the resting membrane potential in cells?

the charge storing ability or capacitance of membranes

5

electric potentials vary based on _______

permeability of membranes to particular ions

6

Mean resting membrane potential of neurons

-65mV and -40mV

7

What channels are open at rest

- Potassium
- Chlorine
- few Sodium channels ( more in Photoreceptors)

8

Define membrane potential (Vm)

electrical potential of the interior of the cell relative to the exterior

9

net loss of positive charge by Na-K ATPase is offset by

passive leak channels

10

___ moles of influx of sodium ions can lead to depolarization of 100mV

10^-12 moles

11

Hyperkalemia - high extracellular K+ causes_______

depolarization

12

how are solutes and water transported across membrance

simple diffusion
active and passive transport

13

describe ion channels

- members of superfamily of membrane proteins
- has subunits surround a central aqueous pore
- ion selective filter
- non gated channels are leak channels

14

ionic movement through channels is influenced by

electric and ion concentration gradients

15

Transport of molecule in the same direction

Symport

16

Transport of molecule in the opposite direction

Antiport

17

Open probability

Proportion of time an ion channel remains in the open state

18

Open probability of voltage gated ion channels is dependant on __________

membrane potential

19

Open probability of Transmitter gated ion channels is dependant on __________

Transmitter concentration

20

Flow of charged ions is called__________ and its units are in _________

Conductance; Siemens (S)

21

Ohm's law

V=IR

22

conductance formula

g=I/V

23

total membrane conductance formula for an ion (x)

gx= (Nx) (yx)
Nx- number of ion channels for x
yx- single channel conductance

24

two types of gates in voltage gated ion channel

1) Activation gate
2) Inactivation gate

25

Nernst equation

E = (61.5 / z) log { [X]o / [X]i } mV

26

Equation for electrochemical gradient for an ion

Electrochemical Gradient for ion X = (Vm - Ex ) mV

27

Equation for total ionic current

Im = INa + IK + ICl. (Ca is negligible)

28

At rest Im=

0

29

Eg of channelopathy that is due autoimmune attack

Myasthenia Gravis

30

damage due to cellular swelling

cytotoxic edema

31

how does cytotoxic edema arise in ischemia?

failure of Na-K pumps due to lack of ATP causes accumulation of NaCl inside the cell which drives water in and the cell swells

32

What are 2 effects of Ischemic Cerebral edema

-Cytotoxic edema
-Secondary Vasogenic edema (damaged blood vessels allow leakage of blood)