T1 L6: Physiology of neurones

Question 1

What is spatial summation?

Answer 1

A neurone decides whether to fire depending on the ‘add together’ coming from many different neurones

Question 2

What is temporal summation?

Answer 2

A neurone decides whether to fire depending on how fast it is receiving signals from other neurones

Question 3

Describe the 4 steps of action potentials

Answer 3

1. At rest, K+ is going out of the cell causing a negative membrane potential.
2. An external stimulus comes and depolarises the membrane
3. Na+ conductance then shoots up so the the membrane becomes more positive
4. With a time-delay, Na+ conductance diminishes and K+ conductance increases so K+ leaves the cell. Voltage returns to resting potential

Question 4

What happens at the initial depolarisation stage of an action potential?

Answer 4

Inward rectifier K+ channels open and K+ flows out

Question 5

At what voltage does the average cell rest?

Answer 5

-70mV

Question 6

When are inward rectifier channels open?

Answer 6

When the cell is negative