NEUROPHYSIO

Question 1

What is action potential?

Answer 1

all or nothing reaction due to influx of positively charged ions, size of ap is constant

1. resting potential
2. depolarisation
3. repolarisation
4. hyperpolarisation
5. refactory period

Question 2

Na-K pump

Answer 2

pumps 3 Na+ ions out of cell
pumps 2 K+ ions into the cell
AGAINST concentration gradient
needs energy in the form of ATP ( ATP hydrolysed to ADP and energy is released)

Question 3

Resting potential

Answer 3

[Na+]i < [Na+]o
[K+]i > [K+]o

Question 4

What is Equilibrium Potential?

Answer 4

balance between concentration gradient and electrical gradient

Question 5

Depolarisation

Answer 5

• Na+ permeability increased
• Na+ channels open
• influx of Na+
• threshold reached, AP fired

Question 6

Repolarisation

Answer 6

• electrochemical driving force of Na+ decrease
• Na+ channels close
• K+ channels open
• K+ flows out of the cell
  (becomes less positive again, repolarise to initial negative)

Question 7

Hyperpolarisation (undershoot)

Answer 7

• K+ channels too slow to close
• conductance is temporarily higher than at resting condi ( undershoot)

Question 8

Refactory period

Answer 8

K+ conductance turned off, Na-K pump pumps K+ back into the cell again, resting potential reached again

Question 9

How does synaptic transmission work?

Answer 9

1. AP
2. voltage gated Ca2+ channels open
3. Ca2+ influx causes neurotransmitter-filled vesicles to fuse with cell membrane
4. neurotransmitter released into synaptic cleft and binds to receptor, causing ion channels to open
5. ion influx into postsynaptic neuron