Types of ion channels in the cell membrane.

Question 1

list the types of ion channels

Answer 1

voltage gated
ligand gated
mechanical gated
temperature gated
_________________
leak channels
secondary messenger gated channels

Question 2

voltage-gated ion channels - structure

Answer 2

open or close depending on arrival of stimulus = change in voltage

made of protein complex embedded in phospholipid bilayer
- alpha subunits domain containing transmembrane segment
- voltage domain contains positively charged amino acids
- pore domain contains specific receptors to control entry/ exit from cell
- auxillary domain contains regulatory properties

Question 3

voltage-gated ion channels - function 1

Answer 3

voltage gated sodium channels
needed for rapid depolarisation during action potential

Question 4

voltage-gated ion channels - function 2

Answer 4

voltage gated potassium channels
needed for repolarisation of membrane after action potential

Question 5

voltage-gated ion channels - function 3

Answer 5

voltage gated calcium channels
needed for release neurotransmitters for muscle contraction

Question 6

ligand gated ion channel - structure

Answer 6

open or close depending on arrival of stimulus which is ligand

• ligand binding site = where ligand binds to
• intracellular domain
• pore domain containing specific receptors controlling what enters/ exits

Question 7

ligand gated ion channel - function 1

Answer 7

nicotinic Ach receptors awaiting for arrival of stimulus which is Ach to release Na+/Ca2+ for muscle contraction at site of neuromuscular junction

Question 8

ligand gated ion channel - function 2

Answer 8

GABA_A are ionotropic receptors that activated during influx of k+ for inhibitory neurotransmission to the brain

Question 9

ligand gated ion channel - function 3

Answer 9

glutamate - NMDA/AMPA receptors wait for arrival of glutamate needed for excitatory neurotransmission to the brain

Question 10

mechanical gated ion channels - structure

Answer 10

open or close upon arrival of stimulus which is change in mechanical pressure/ stress/ tension

• membrane spanning domain containing transmembrane segment for pore formation
• mechanosensitive domain containing specific receptors for detection of stimuli
• auxiliary domain for interaction with ECM components for transmitting mechanical forces

Question 11

mechanical gated ion channels - function 1

Answer 11

piezzo 1-2 channels needed for membrane stretching during touch/ sound/ bloodflow

Question 12

mechanical gated ion channels - function 2

Answer 12

TREK and TRAAK channels for membrane stretching during neuronal excitability/ ischemic damage

Question 13

mechanical gated ion channels - function 3

Answer 13

sensory cells on nerve cell membrane upon touch

Question 14

temperature gated ion channel - structure

Answer 14

open or close depending on arrival of stimulus which is change in temperature

• transmembrane domain needed for pore formation
• thermosensitive domain needed for conformational changes
• pore domain controling what enters/ exits due to specific receptors

Question 15

temperature gated ion channels - function 1

Answer 15

TRP-V1-V4 = high temps

Question 16

temperature gated ion channels - function 2

Answer 16

TRP-M8 = moderate temps

Question 17

temperature gated ion channels - function 3

Answer 17

TRP-A1 = low temps

Question 18

leak channels - structure

Answer 18

open or close depending on arrival of stimulus which is change in electrochemical gradient

Question 19

leak channels - function 1

Answer 19

sodium leak channels
maintain balance of na+ across membrane

Question 20

leak channels - function 2

Answer 20

potassium leak channels
restore resting membrane potential by leaking k+ out of cell

Question 21

secondary messenger gated channels - structure

Answer 21

open or close depending on the arrival of stimulus which is intracellular cascade event leading to activation of g-coupled protein