y4.1 nervous system 🫣

Question 1

what structures are in the central nervous system?

Answer 1

brain and spinal cord

Question 2

what are the structures of a neurone? (in direction of receptors to effectors)

Answer 2

dendrites -> dendron -> cell body -> axon -> axon terminals

Question 3

what are Nodes of Ranvier?

Answer 3

regions on the neurone axon where myelin sheath is absent

Question 4

what substances transmit impulses over synapses?

Answer 4

neurotransmitters

Question 5

structure and function of sensory neurones

Answer 5

structure:
- circular body (in dorsal root ganglion)
- long dendron, short axon
function: transmit nerve impulses from receptors to CNS

Question 6

structure and function of relay neurones

Answer 6

structure:
- irregular or circular cell body
- dendrites, axon
function: transmit nerve impulses from sensory to motor neurones / other relay neurones

Question 7

structure and function of motor neurone

Answer 7

structure:
- irregular cell body
- dendrites, long axons (myelin sheath)
functions: transmit nerve impulses from CNS to effectors

Question 8

in what scenarios does the brain act as the central coordinator?

Answer 8

1) voluntary action: nerve impulses are produced in the brain, travel along relay neurones to spinal cord shenanigans
2) reflexes above the neck: usually eye-related sending nerve impulses to brain via sensory neurone, brain returns impulses along motor neurone

Question 9

what is a reflex?

Answer 9

a reflex is an immediate response to a specific stimulus that occurs without any conscious effort

Question 10

what does a reflex arc consist of?

Answer 10

1) a receptor (nerve tissue or sense organ)
2) sensory, relay, reflex centre, motor neurone
3) effector (muscle or gland)

Question 11

process of withdrawal reflex

Answer 11

1) receptors in the hand detect the stimulus and generates nerve impulses
2) nerve impulses travel along the sensory neurone to the spinal cord. neurotransmitters are released across the synapse between sensory and relay neurone
3) nerve impulses travel along the relay neurone. neurotransmitters are released across the synapse between relay and motor neurone
4) nerve impulses travel along motor neurone to the effector
5) the effector is the bicep muscles, which contracts to pull away and cause withdrawal action