Neuromuscular responses to exercise

Question 1

Which neuromuscular unit is the functional unit of a skeletal muscle?

Answer 1

Motor Unit

Mainly responsbile for muscle contractions

motor neurons (part of the motor unit) carry electrical impulse from brain to muscle groups

Question 2

What makes up the motor unit?

Answer 2

motor neurons (and branches of motor neurons)
Muscle fibres and myofibrils

Question 3

What is the long thread like structure found in muscle cells/fibres?

Answer 3

myofibrils

Question 4

What are myofibrils made up of?

Answer 4

sarcomeres

repeating units of proteins

Question 5

What 2 proteins are found within sarcomeres of myofibrils?

Answer 5

actin
myosin

Question 6

What happens when actin and mysosin interact in myofibril?

Answer 6

enable muscle contraction

Question 7

Motor Neurons stimulate_______ to contract

Answer 7

muscle fibres

Question 8

What part of the motor neuron is made of a fatty substance that wraps around the axon?

Answer 8

myelin

Question 9

What are the 3 main roles of myelin?

Answer 9

speed up signals
protects the nerves through insulation
enabling **saltatory conduction ** (quicker communication)

Question 10

myelin, jumping

what is saltatory conduction?

Answer 10

where myelin allows signals to jump across nerves for quicker communication

Question 11

what is the main role of the neuromuscular junction?

Answer 11

transmit electrical impulses from motor neuron to skeletal muscle

Question 12

What is the name of the neuromuscular junctions main neurotransmitter

neurotransmitter=chemical messenger

Answer 12

Acetylcholine (ACh)

Ace-tyl-choline

Question 13

What are the three key regions of the neuromuscular junction?

Answer 13

pre-synaptic membrane
synaptic cleft
post-synaptic membrane

Question 14

Which region is located at the end of the nerve cell?

Answer 14

pre-synaptic membrane

Question 15

Which region releases the neurotransmitter acetylcholine (ACh) into synaptic cleft (the gap)

synaptic cleft=gap

Answer 15

pre-synaptic membrane

Question 16

What is the synaptic cleft and what chemical messenger travels across it?

Answer 16

space between nerve and muscle cell where Acetylcholine (ACh) travels across

Question 17

Which regions contains Acetylcholine (ACh) receptors?

Answer 17

post-synaptic membrane

Question 18

What happen when Acetylcholine (ACh) binds to its receptors in the post-synaptic region?

Answer 18

triggers muscle contraction

Question 19

7 steps

Explain how the neuromuscular junction functions

Answer 19

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1. Nerve Signal Arrival
2. Calcium Channel Activation
3. Fusion of Synaptic Vesicles
4. Release of Acetylcholine
   5.Binding to Receptors
   6.Generation of Action Potential
   7.Breakdown of Acetylcholine

Question 20

What is the approxomate ‘resting’ potential of the membrane?

Answer 20

-70mV

Question 21

What is the approxomate ‘threshold’ potential of the membrane?

Answer 21

-55mV

Question 22

What is the approxomate ‘peak’ potential of the membrane?

Answer 22

+40mV

Question 23

What is the approxomate ‘overshooting’ potential of the membrane?

Answer 23

-90mV

Question 24

5 steps

Explain the process of Skeletal Muscle Action Potential

Answer 24

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1.Starting potential of muscle fibre membrane -70mV. Inside of cell is negatively charged

2. Stimulus such as Acetylcholine binding to receptors during muscle contraction. Membrane potential increases to a possible threshold of -55mV. If this is reached then action potential is triggered.
3. Rapid depolarisation
4. Repolarisation
5. Return to resting potential

Question 25

What are the two types of refractory periods?

Answer 25

Absolute
Relative

Question 26

What is the type of refractory period where an Action potential may be activated, if the
stimulus is large enough?

Answer 26

relative

Question 27

What is an absolute refractory period?

Answer 27

Completely impossible or another action
potential to be activated, regardless of
the size of the stimulus.

Question 28

What is meant by the ‘all or nothing’ principle?

Answer 28

The all-or-none principle means that a muscle fiber (or a neuron) either fully responds to a stimulus or doesn’t respond at all.

Question 29

What is a muscle twitch?

Answer 29

A single action potential from a motor neuron produces one muscle fibre contraction

Question 30

frequency

What is a ‘treppe’ also known as the stair case effect.

Answer 30

repeated stimuli cause an increase in muscle contraction strength