L1 - Intro to Ion Channels

Question 1

What do gated ion channels have?

Answer 1

a component that is able to block the pore to prevent flow

Question 2

Conductive channel =

Answer 2

ions/current flows

Question 3

Non-Conductive channel =

Answer 3

no flow/current

Question 4

Ion Channel Classification
Selectivity

Answer 4

whats the main ion that flows through

Question 5

Ion Channel Classification:
Gating

Answer 5

what makes them open or close

Question 6

Ion Channel Classification:
Regulation

Answer 6

What regulates the channel

Question 7

K.ir Potassium Channels

Answer 7

have 4 subunits of transmembrane channels with no receptor site

Question 8

K.v Potassium Channels

Answer 8

has 24 transmembrane domains and 2 beta subunits

Question 9

Na.v / Ca.v channels

Answer 9

have 24 transmembrane domains and 2 beta subunits

Question 10

CFTR Cl-

Answer 10

has 12 transmembrane domains

Question 11

Ach Channels

Answer 11

are ligand gated nicotinic ion channels

Question 12

What does the Patch Clamp technique do?

Answer 12

measures ion channel function

Question 13

How does the patch clamp technoque work?

Answer 13

1 - A glass pipette filled with salt solution and an electrode connected is touched onto the cell membrane.
2- The pipette is sucked and the membrane seals to the pipette
3 - ion channels can now be measured via the electrode

Question 14

What do whole cell recordings measure (patch clamp)

Answer 14

the current along the whole membrane of the cell

Question 15

What do single channel recordings measure (patch clamp)

Answer 15

the curent along a single section of the membrane

Question 16

What are the 3 things the patch clamp technique recordings allow for?

Answer 16

1 - Identification - what ion channels are present
2 - Regulation - the type of gating
3 - Physiological function - evaluation of the ion channels function

Question 17

What is the equation for current recordings?

Answer 17

I = N.Po.g (Vm -Ei)
total current carried by poulation channles on the membrane = number of channels x open probability x single channel conductance x (membrane potential - nerst potential)

Question 18

What is open probability?

Answer 18

A measure of how often the channels are open

Question 19

What is single channel conductance?

Answer 19

A measure of how many ions move through the pore

Question 20

Ion Channel Function …

Answer 20

When open, drive the membrane potential towards its nerst value

Question 21

What molecule is a potassium channel blocker?

Answer 21

Barium

Question 22

What molecule is a Sodium channel blocker?

Answer 22

Tetrodotoxin

Question 23

What are some syptoms of FHEIG?

Answer 23

Bi-temporal narrowing
Hypertrichosis (hairy)
Thin upper lip
Long bushy eyebrows
Delayed development of intellectual ability and motor skills.
Suseptibility to Seizures

Question 24

What are some syptoms of FHEIG?

Answer 24

Bi-temporal narrowing
Hypertrichosis (hairy)
Thin upper lip
Long bushy eyebrows
Delayed development of intellectual ability and motor skills.
Suseptibility to seizures
EEG anomalies

Question 25

What causes FHEIG?

Answer 25

Mutation in KCNK-4 (K+ channel)

Question 26

What kind of mutation is the KCNK-4?

Answer 26

Gain of function

Question 27

What areas are the KCNK-4 channels mainly expressed?

Answer 27

PNS & CNS

Question 28

The mutated KCNK-4 causes …

Answer 28

high extracellular K+ levels