Nervous system

Question 1

Peripheral nervous system

Answer 1

All other nerves to extremities and organs

Question 2

Sensory neurones

Answer 2

carry messages from the peripheral sensory organs to the cns

Question 3

Motor neurones

Answer 3

convey instructions from the cns to the effector organs such as muscles or glands

Question 4

Reflex arc

Answer 4

Stimulus → Receptor → Sensory neurone → Relay neurone → Motor neurone → Effector → Response

Question 5

Synapse

Answer 5

1. Action potential arrives at the end of the presynaptic neurone
2. Calcium channels open, calcium ions enter the synaptic knob
3. Influx of calcium ions causes synaptic vessicles to fuse with the presynaptic membrane, releasing ACh into the synaptic cleft
4. ACh molecules bind with receptor sites on the sodium ion channel on membrane on postsynaptic membrane
5. Causes sodium channels to open allowing sodium ions to diffuse in rapidly
6. Influx of sodium ions generates a new action potential in the postsynaptic neurone