neuromuscular system and muscle fibre types

Question 1

what is a motor neurone

Answer 1

nerve cells which transmit the brains instructions as electrical impulses to the muscles

Question 2

what is a motor unit

Answer 2

a motor neuron and all the muscle fibres its innovates

Question 3

what is the neuromuscular junction

Answer 3

where the motor neuron meets the muscle fibre

Question 4

what are the 3 muscle fibres

Answer 4

type 1/ slow twitch
type2a(fast)
type2b/x(fast)

Question 5

what does the CNS consist of

Answer 5

central nervous system:brain and spinal cord

Question 6

What is PNS (peripheral nervous system)

Answer 6

what connects the muscles to the CNS

Question 7

what are the 4 main components of a motor neuron and their functions

Answer 7

-dendrites receive electrical signals from other neurons
-cell body process the information received
-axon transmits the electrical impulse to the neuromuscular junction
-axon terminals release neurotransmitters to stimulate muscle action

Question 8

what does the muscle need to contract

Answer 8

enough action potential (ie nerve impulses) or reaching beyond action potential thresholds

Question 9

what is the main neurotransmitter in the body

Answer 9

acetylcholine

Question 10

what is a neurotransmitter

Answer 10

a chemical messenger

Question 11

how is acetylcholine used during muscle contraction

Answer 11

brain sends a signal through nerves to muscle, acetylcholine is released at the end of the nerve and crosses the synapse between the nerve and the muscle. when it reaches the muscle it binds to receptors causing the muscle to contract

Question 12

key differences between neurotransmitter and hormones

Answer 12

-hormones are chemical messengers in endocrine system whereas neurotransmitters are chemical messengers in the nervous system
-duration- neurotransmitter very short, hormones very long
-transport- hormones in blood, neurotransmitters over synapse
-production site- hormone secreted by endocrine glands, neurotransmitters released by neurone in brain and spinal cord

Question 13

what is motor unit size

Answer 13

refers to number of muscle fibres controlled by a single motor neuron

Question 14

describe the all or none law

Answer 14

states that when a motor unit is activated, all the muscle fibres within that unit will contract, but only if the stimulus is strong enough to reach the threshold

Question 15

how many motor units for strong contraction

Answer 15

impulses sent down all motor units for forceful movement

Question 16

how many motor units for weak contraction

Answer 16

impulses sent down few motor units for precise movement

Question 17

short term reponses of neuromuscular system

Answer 17

-increase in nerve transmissions: immediate increase in neural impulses to muscles
-immediate muscle activation: increase in nerve impulses = rapid recruitment of motor units
-muscle fibre type recruitment:slow twitch fibres are recruited for low intensity, fast twitch fibres are recruited for high intensity explosive movements
-motor unit recruitment: smaller motor units are recruited first for low intensity, larger motor units are recruited as exercise intensity increases
-reflex response:reflex arcs response rapidly to change in muscle length (muscle spindle) and muscle tension (Golgi tendon organ)

Question 18

what happens during neuromuscular fatigue?

Answer 18

reduced levels of acetylcholine which causes nerve impulses to be slower and inhibits muscle contraction.