Communication between excitable cells

Question 1

what is a synapse?

Answer 1

gap between two nerve cells

Question 2

what is the process of communication between excitable cells - 10 steps

Answer 2

1. presynaptic action potential at synaptic knob
2. depolarisation of synaptic terminal
3. Ca2+ ions diffuse into knob (via voltage gated channels)
4. causes exocytosis of transmitter vesicles
5. Ach diffuses across synaptic cleft and binds to complementary specific receptors
6. Ach receptor-activated channels open
7. Na+ diffuse into the post synaptic cell while K+ also diffuses out through the same channel
8. if excitatory post synaptic potential reaches threshold an impulse is set up
9. breakdown of Ach by AchE in the cleft
10. broken down products are taken up by active transport for the re-synthesis of transmitter

Question 3

what are the two types of synapse?

Answer 3

EPSP- excitatory post synaptic potential

IPSP - inhibitory post synaptic potential

Question 4

what does EPSP do

Answer 4

stimulate an AP in the post synaptic neurone

Question 5

what does IPSP do

Answer 5

inhibit action potential

e.g. glycine and GABA which open Cl channelled that hyperpolarise the cell so it does not reach the potential

Question 6

how is there communication in the cardiac muscle

Answer 6

gap junctions - spreads depolarisation to adjacent cells located on the intercalated discs