Inhibitory Synapses and Neuromuscular Junctions

Question 1

What do inhibitory synapses do?

Answer 1

cause K+ ions to move out and Cl- ions to move in to the post-synaptic neurone

Question 2

What does the movement of Cl- and K+ ions result in?

Answer 2

the hyperpolarisation, combined effect lowers voltage to around -80mV, so action potentials unlikely to occur

Question 3

Why are inhibitory synapses important?

Answer 3

Will not overwhelm sense as not all stimuli will lead to a response

Question 4

What is a neuromuscular junction?

Answer 4

the gap between a motor neurone and a muscle

Question 5

What do neurotransmitters stimulate in a muscle?

Answer 5

contraction

Question 6

What is a similarity between neuromuscular junctions and synapses?

Answer 6

unidirectional

Question 7

What are 3 differences between neuromuscular junctions and synapses?

Answer 7

• neuromuscular junctions only connect motor neurones to muscle, whereas synapses join 2 neurones of any type
• NMJ are end point of the action potential, synapses trigger new action potentials
• Receptors bind to muscle membrane vs. receptors binding to membrane on post-synaptic neurone
• NMJ are only excitatory whereas synapses can be inhibitory as well

Question 8

Why would an inhibitor weaken muscle contraction?

Answer 8

no neurotransmitters bind to receptors, so no depolarisation/action potential

Question 9

Why would a reduction in acetylcholinesterase reduce the effects of an inhibitor at a neuromuscular junction?

Answer 9

less acetylcholine broken down, so more bind to receptors, therefore depolarisation can occur