motor units

Question 1

what’s a motor unit?

Answer 1

a motor neuron and the muscle fibres that it stimulates

Question 2

what’s ach?

Answer 2

the neurotransmitter carrying the action potential across the synapse causing a muscle contraction

Question 3

what’s the cell body of a motor neuron?

Answer 3

includes the nucleus and is the control centre

Question 4

what are dendrites?

Answer 4

specialised to receive stimuli from sensory organs or from other neurons

Question 5

what’s the axon?

Answer 5

conducts nerve impulses to other cells

Question 6

whats the myelin sheath?

Answer 6

insulated nerve and covers ion gated channels for faster transmission of impulses

Question 7

what are the nodes of ranvier?

Answer 7

gaps where action potential jumps from node to node through ion gated channels

Question 8

what’s the synaptic end bulb?

Answer 8

enables action potential to be applied to adjacent cells

Question 9

what’s the all or none law?

Answer 9

if a motor unit recieves a stimulus to create an action potential that has reached threshold, all the muscle fibres within the motor unit will contract at the same time and with maximum force

Question 10

what’s the resting potential of transmission of neural messages?

Answer 10

negatively charged, -70mV

Question 11

what’s depolarisation?

Answer 11

adding positive charge so it becomes positively charged by flooding Na+ ions into the motor neuron

Question 12

what’s action potential?

Answer 12

impulse, +15mV

Question 13

what’s repolarisation?

Answer 13

negatively charged, flooding potassium ions out

Question 14

what’s hyper-polarisation?

Answer 14

Na+ floods out, K+ floods in. ions swap places

Question 15

describe the nervous stimulation of a motor unit

Answer 15

electrical impulse causes an action potential and travels down the axon
release of Na+ ions causes depolarisation
neurotransmitter ach travels across the synaptic cleft
if electrical charge is above threshold then muscles will contract
all of none law,