action potential and its properties

Question 1

what is ARP

Answer 1

absolute refractory period

where nearly all Na+ channels are in inactivated state so whatever stimulus is provided there will be no AP

Question 2

What is the RRP

Answer 2

relative refractory period
Na+ channels are recovering from inactivation and the excitability returns towards normal as the number of Na+ channels in the activated state decreases and the voltage-gated K+ channels close. in this periods a strong stimulus can generate an action potential.

Question 3

explain the basic structure of a voltage gated Na+ channel

Answer 3

a functional Na+ channel compromises only one alpha subunit.
contains a pore region and a voltage sensor (S4)
one alpha subunit consists of 4 similar sections or repeats.
contains an inactivation particle.

Question 4

explain the basic structure of a voltage gated K+ channel

Answer 4

one alpha subunit is 1/4 of a channel. so 4 individual alpha subunits comprises a functional k+ channel.
contains a pore region that contributes to selectivity and a voltage sensing s4 region.

Question 5

which form of anaesthetics is membrane permeable? use an example

Answer 5

unprotonated form is membrane permeable.
lidocaine is a widely used local anaesthetic that is used to treat certain cardiac arrhythmias. when it is unprotonated it can pass membranes but when its protonated its membrane impermeable so blocks sodium channels. this is how anaesthetics work.