W6 - Ion channels

Question 1

How many genes encode K channels

Answer 1

70

Question 2

what are the purpose of the K channels in the body

Answer 2

frequency and shape of action potentials

Secretion of hormones

Secretion of neurotransmitters

Membrane potential

Question 3

What is the standard amount of K+ in a cell

Answer 3

150 mMOL

Question 4

What is the extracellular amount of K+ at rest

Answer 4

2.5 mMOL

Question 5

At rest what happens in response to the concentration gradient K+

Answer 5

due to electrochemical gradient K+ moves out of the cell into the extracellular fluid

Question 6

What about Na+ and Ca2+ (electrochemical gradient

Answer 6

They have the opposite to K+ so move into the cell down the concentration gradient from the extra cellular fluid.

Question 7

Describe the structure of K+ channel

Answer 7

There is a N (NH2) terminus and C (COOH) terminus located intracellularly

There are 6 subunits S1 - S6 which are connected across the membrane (transmembrane)

There is a gap between S5 and S6 which is where the K+ ion is conducted through the membrane

S4 has a positive charge so is believed to be sensitive to voltage.

Question 8

What is an example of something that opens K+

Answer 8

Minoxidil opens the K+ channel and causes hyper polarization in smooth muscle cells, muscle relaxation and hence vasodilation.

Question 9

What can minoxidil be used to treat

Answer 9

can be used to treat hypertension in combination with a diuretic and beta adrenoreceptor blocker

Question 10

What type of channel is a sodium ion channel

Answer 10

voltage gated

Question 11

How many alpha subunits makes up a sodium channel

Answer 11

one pore forming alpha subunit (which can be associated with either one or two beta subunits)

Question 12

How many alpha subunits is a Potassium channel made up of

Answer 12

4 pore forming alpha subunits

Question 13

what is the minimum amount of genes coding a sodium channel

Answer 13

at least 10

Question 14

Describe the structure of a sodium channel

Answer 14

There is an amino terminus and a carboxyl terminus intracellularly

There are 6 Segments denoted s1 through to s6

S4 again is the voltage sensing subunit being positively charged

there is a gap between segment 5 and 6

While the transmembrane subunits they are connected to form the alphas subunit

Question 15

What are the two terminus’s of the sodium channel

Answer 15

carboxyl and amino terminus

Question 16

how many segments are there

Answer 16

6

Question 17

what is the voltage sensing segment

Answer 17

4

Question 18

why is s4 believed to be the voltage sensing segment

Answer 18

due to its positive charge

Question 19

where do the ions move through

Answer 19

there is a gap between s5 and s6

Question 20

What is an example of a drug that affect the sodium ion channel

Answer 20

lidocaine

Question 21

what does lidocaine do

Answer 21

blocks voltage gated sodium channels

Question 22

what is the primary target of lidocaine

Answer 22

Nav1.5 which is the main cardiac sodium channel

Question 23

what is the indication of lidocaine

Answer 23

ventricular arrhythmias, especially after myocardial infarction in addition to local anaesthesia

Question 24

what is myocardial infarction

Answer 24

heart attack

Question 25

What type of channel is Ca2+

Answer 25

voltage gated ion channel

Question 26

what do Ca2+ channels form

Answer 26

hetero oligomeric complexes

Question 27

What is an oligomer

Answer 27

a polymer whose molecules consist of relatively few repeating units.

Question 28

What is a hetero oligomer

Answer 28

Functional protein complexes formed by oligomerization of similar subunits.

Question 29

Describe the Ca2+ hetero oligomeric complex

Answer 29

The α1 subunit is pore-forming and provides the extracellular binding site(s) for practically all agonists and antagonists.

Question 30

What are the three families of Ca2+ channels

Answer 30

high voltage activated dihydropyridine sensitive channels The high voltage activated dihydropyridine insensitive channels low voltage activated channels

Question 31

What does L type refer to

Answer 31

high voltage activated dihydropyridine sensitive channels

Question 32

What does CaV1.x refer to

Answer 32

high voltage activated dihydropyridine sensitive channels

Question 33

What does CaV2.x refer to

Answer 33

The high voltage activated dihydropyridine insensitive channels

Question 34

What does T type refer to

Answer 34

low voltage activated channels

Question 35

What does CaV3.x refer to

Answer 35

low voltage activated channels

Question 36

what does alpha 2 delta 1 and 2 do

Answer 36

bind gabapentin and pregabalin

Question 37

Describe the structure of a high voltage activated calcium channel

Answer 37

N terminus C terminus intracellularly similar to K+ and Na+ Contains a gamma and a beta subunit (low voltage activated does not have either of these) Contains alpha 2 delta subunit Contains 4 domains which consist of 6 transmembrane sections as per the K+ and Na+ S4 is the voltage sensitive section there is a gap between s5 and s6 which Ca2+ travels through

Question 38

What two terminals does a Ca2+ channel have

Answer 38

NH2 | CooH

Question 39

What are the different subunits contained in a calcium channel

Answer 39

Alpha subunit Beta subunit Gamma Subunit

Question 40

How many sections does a domain of an alpha subunit have

Answer 40

6

Question 41

what is the voltage sensitive section of a domain of an alpha subunit

Answer 41

4

Question 42

where does the ca2+ travel through

Answer 42

there is a gap between s5 and s6

Question 43

what is a drug which effects the ca2+ channe

Answer 43

verapamil

Question 44

what does verapamil do

Answer 44

blocks voltage gated Ca"+ channels (L type)

Question 45

What effect does verapamil have

Answer 45

blocks calcium influx in myocardial and vascular smooth muscle cells. Lead to a reduction in cardiac and VSm contraction bringing about a dilation in coronary and systemic arteries

Question 46

what is the indication of verapamil

Answer 46

supraventricular arrhythmias, angina, hypertension (dose and preparation dependent)

Question 47

What channels effect epilepsy

Answer 47

K+ Ca2+ Na+

Question 48

What channels effect diabetes

Answer 48

K+ | Katp

Question 49

What channels effect ataxia

Answer 49

K+ | Ca2+

Question 50

what is ataxia

Answer 50

People with ataxia lose muscle control in their arms and legs. This may lead to a lack of balance, coordination, and trouble walking. Ataxia may affect the fingers, hands, arms, legs, body, speech, and even eye movements.

Question 51

What channels affect pain

Answer 51

Na+ | Ca2+

Question 52

What are ligand gated channels often known as

Answer 52

ionotropic receptors

Question 53

what do ligand gated channels do

Answer 53

they link ligand binding to an ionic flux

Question 54

How many subunits are ligand gated ion channels made up of

Answer 54

4-5

Question 55

How many ACh receptors are there

Answer 55

2

Question 56

What are the 6 receptor classes

Answer 56

``` nAChR Glutamate (ionotropic) 5HT3 Glycine GABAa ATP receptors (P2X) ```

Question 57

What gated Ion is nAChR

Answer 57

Na+

Question 58

What effect does Na+ have on the nAChR receptor

Answer 58

Excitatory

Question 59

What gated ion channel is Glutamate

Answer 59

Na+

Question 60

What effect does Na+ have on the Glutamate receptor

Answer 60

Excitatory

Question 61

What gated ion channel is 5HT3

Answer 61

Na+

Question 62

What effect does Na+ have on 5HT3

Answer 62

Excitatory

Question 63

What gated ion channel is Glycine

Answer 63

Cl-

Question 64

What effect does Cl - have on Glycine

Answer 64

inhibitory

Question 65

what gated ion channel is GABAa

Answer 65

Cl-

Question 66

what effect does Cl- have on GABAa

Answer 66

inhibitory

Question 67

What type of ion channels is P2X

Answer 67

Na+ K+ Ca2+ Exceptionally CL

Question 68

What are ligand gated ion channels

Answer 68

integral membrane proteins that contain a pore which allows the regulated flow of selected ions across the plasma membrane

Question 69

what type of process is ion flux

Answer 69

passive

Question 70

what is ion flux driven by

Answer 70

electrochemical gradient

Question 71

what are the channels opened by

Answer 71

ligand binding that triggers a conformational change that results in the conducting state

Question 72

What is the abbreviation of ligand gated ion channel

Answer 72

LGIC

Question 73

What scale do LGIC's mediate fast synaptic transmission

Answer 73

millisecond time scale

Question 74

Where do LGIC's mediate fast synaptic transmission

Answer 74

nervous system and somatic neuromuscular junction

Question 75

what suggests that LGIC's have additional functions

Answer 75

expression by non excitable cells

Question 76

Describe the structure of a typical ligand gated channel

Answer 76

There is a Nh2 terminus and a cooh terminus extra cellularly ACH binding site extracellularly near the Nh2 terminus there are 5 repeating subunits in each subunit there is TM2 which is the voltage sensitive

Question 77

What are exceptions to the standard structure

Answer 77

Ach, Gaba and Glycine receptor channels Glutamate receptor channels ATP receptor channels

Question 78

What drug can affect nAChR

Answer 78

Succinylcholine

Question 79

What does it do

Answer 79

its a full agonist of the nAChR receptor *activates the channel*

Question 80

what effect does Succinylcholine have

Answer 80

mimics the effects of ACh but is not subject to breakdown by AChE

Question 81

Indication of Succinylcholine

Answer 81

Neuromuscular blocade for surgery