92. nerve effector endings, neural plasticity

Question 1

What are efferent nerves

Answer 1

motor neurones

carry nerve impulses away from CNS to effectors eg muscles or glands

Question 2

what part of the neuron forms the neuromuscular junction with effectors
where are motor neurones found

Answer 2

axon

found in the gray matter of spinal cord and medulla oblongata

Question 3

what type of synapse is a neuromuscular junction

Answer 3

chemical synapse

Question 4

describe the synaptic transmission at neuromuscular junction

Answer 4

• action potential reaches presynaptic terminal of motor neuron. The activates calcium channels to open
• influx of Ca2+ and these bind to synaptic vesicles, triggering vesicle fusion with cell membrane
• neurotransmitter- acetylcholine diffuses across synaptic cleft. Binds to nicotinic acetylcholine receptors on cell membrane of muscle fibers
• depolarizes muscle fibers causing cascade that ends with muscle contraction

Question 5

what is acetylcholine synthesized from

Answer 5

dietry choline and acetyl CoA
involved in stimulation of muscle tissue in vertebrates

Question 6

what happens to the neurones that do not establish synapses with other neurones

Answer 6

eliminated by apoptosis

Question 7

Give an example of neural plasticity

Answer 7

after an injury, the neuronal circuits may be reorganized by the growth of neuronal processes, forming new synapses to replace ones lost by injury

Question 8

neural plasticity is controlled by growth factors produced by which cells
what are the proteins called

Answer 8

neurones and glial cells

in a family of proteins called neurotrophins

Question 9

The neural stem cells are in CNS what cells can they differentiate into

Answer 9

neurones, astrocytes, oligodendrocytes

Question 10

What is the process of chromatolysis (regeneration)

Answer 10

cell body sweels a bit, Nissl substance initially diminished, nucleus moves to periphery

bit of axon near wound degenerates slightly then grows again
schwann cells also align

Question 11

Which bit of nerve can regenerate/ degenerate

Answer 11

if cell body intact, severed/damaged axon can regenerate

distal part of axon deggenerate- isolated from new proteins myelin sheath shed