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Flashcards in Intro to CNS Deck (55)
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1

Biological membranes are essentially impermeable to ions

This is because the internal region of the bilayer is very hydrophobic and ions are hydrated by water

2

Protein families have evolved that function to allow ionic passage across the membrane

1. ATPase driven pumps
2. Transporters
3. Ion channels: some generalities

3

a) Integral membrane proteins
b) Multiple membrane-spanning domains
c) Form a hydrophobic channel in the center

ion channels

4

Selective for ions and regulated by :

changes in the cellular environment

5

Ion Channels have______gene products; multiple subunits and are Glycosylated on the

Multiple
extracellular side

6

Ion Channels have Consensus sequences for

kinases

7

non-gated, always open

Passive:

8

gated; the closed and open states of the channel are regulated

Active

9

Gating mechanisms

Membrane potential differences
small extracellular molecules (NT)
membrane proteins
intracellular molecules

10

this type of ion channel is open at RMP and can be either active or passive

leak chanel

11

all passive channels are

leak channels

12

intracellular proteins are predominately

anions

13

leak channels in the plasma membrane allow _____ and _____ movement across the membrane

K+ and Cl-

14

Conductance of _____ is 20 times greater then to Na

K+

15

Due to unequal conduction potentials, we see ______ distribution of Cl, K and Na across the membrane

unequal

16

____ is high inside and low outside

K+

17

____ and ____ are high inside and low outside

Na and Cl

18

We have both ____ and ______ for Na, Cl and K across the membrane

chemical and electrical potential

19

Ena =

+55mV

20

Ek =

-75 mV

21

Ecl=

-69mV

22

Some of the leak is opposed by the NaK ATPase pump that moves _____ions out of the cell and ____ions into the cel

Na
K

23

ion channels for a ______ channel in the center

hydrophyilic

24

is the membrane potential at which an ion is in electrochemical equilibrium across membrane

Nerst potential

25

As we increase conductance to Na we start to depolarize the membrane which leads to

voltage gate Na channels opening

26

These are more gradual opening and slower inactivation

Voltage gated K+ channels

27

Action potentials are

all or none; get to 100 mV in amplitude in 1-10 msec

28

Action potential is propagated down the axon through

cycles of depolarization and repolarization

29

Mechanisms by which initial change in membrane potential occurs to begin an action potential

Synaptic potential

30

Synaptic potential have what type of change in membrane potential

graded, short and small
the are LOCAL
and able to summate