15- control+coordination

Question 1

How is the cell body of a neurone adapted for its function

Answer 1

• Many mitochondria to release energy as neurones are very active cells
• Contain lots RER to produce proteins+neurotransmitters
• Highly branched dendrites to receive nerve impulses from other axons

Question 2

Sensory neurone

Answer 2

long axon to carry info from cell body, long dendrites carrying info to cell body, cell body in middle of axon

Question 3

relay neurone

Answer 3

many short axons+dendrites(only intermediates)

Question 4

motor neurone

Answer 4

long axon, short dendrites, cell body at end of axon

Question 5

reflex arc: neural pathway- features

Answer 5

• involuntary (prevent brain being overloaded with stimulation)
• protect body from harm
• innate
• rapid

Question 6

Saltatory conduction

Answer 6

myelinated neurones
create local circuit in which
action potentials can ‘jump’ from node to nodes of ranvier

Question 7

benefits of saltatory conduction

Answer 7

+: more energy efficient, requires less ATP for NaK pump

Question 8

How wider axon affects speed

Answer 8

allows faster propagation speed of nerve impulse due to reduced resistance to flow of ions axon cytoplasm

Question 9

refractory period

Answer 9

time after action potential when no new action potential can be generated due to closed Na+ channels

Question 10

refractory period important bc:

Answer 10

• Ensures action potentials don’t overlap
• Limits frequency at which impulses are transmitted
• Guarantees that impulses only travel in 1 direction

Question 11

synapse function

Answer 11

• transmits impulses from 1 neurone to another, using neurotransmitters
• single impulse used to generate new ones in several diff neurones
• multiple impulses from diff sources combined into single response

Question 12

summation

Answer 12

process in synapses where low-frequency action potentials can trigger new action potential in postsynaptic neurone through rapid build up of neurotransmitter conc

Question 13

Why do ligand-gated ion channels close after neurotransmitters bind

Answer 13

prevent continuous depolarisation of postsynaptic neurone, ensuring response isn’t permanent

Question 14

What happens to neurotransmitters(Ach) after triggering action potential

Answer 14

enzyme acetylcholinesterase catalyses hydrolysis of Ach into
choline+ethanoic acid(acetate)
(products broken down reabsorbed into presynaptic knob for recycling)

Question 15

Why is it important to remove neurotransmitter from synaptic cleft:

Answer 15

allows the synapse to reset and respond to new stimuli
prevents continuous stimulation+neurotransmitter recycling