neurones

Question 1

effects of stimulation by the sympathetic neurone

Answer 1

• increase heart rate
• muscles in bronchioles relax and dilate
• blood vessels vasoconstrict
• pupils dilate
• ciliary muscles of the eye relax for distance vision
• inhibits secretion of saliva
• increases breathing rate
• inhibits peristalsis
  -increases sweat productivity

Question 2

effects of stimulation by the parasympathetic neurone

Answer 2

• decreases heart rate
• muscles in bronchioles contract and constrict
• blood vessels
• pupil constrict
• ciliary muscles contract for nearer vision
• stimulates secretion of saliva
• decreases breathing rate
• stimulates peristalsis

Question 3

which neurone doesn’t have myeline sheath

Answer 3

relay neurones

Question 4

function of sensory neurone

Answer 4

transmits impulses from receptor to CNS

Question 5

function of relay neurone

Answer 5

transmits impulse from sensory to motor neurone

Question 6

function of motor neurone

Answer 6

transmits impulse from CNS to effector

Question 7

which muscles respond to light in the iris

Answer 7

circular and radial muscles

Question 8

the response of the eye to bright light

Answer 8

1. the bright light stimulates photoreceptors in the retina
2. this causes more impulses to be sent along sensory neurones of the optic nerve to the brain
3. brain sends impulses along motor neurones of the parasympathetic nervous system to the iris muscles
4. this causes the circular muscles to contract and radial muscles to relax
5. pupil is now constricting
6. results in less light entering the eye

Question 9

the response of the eye to dim light (fight or flight response)

Answer 9

1. less photoreceptors are stimulated
2. fewer impulses pass along the sensory neurones of the optic nerve to the brain
3. brain sends impulses along the motor neurones of the sympathetic nervous system to the iris muscles
4. this causes circular muscles to relax and the radial muscles to contract
5. pupil now dilates
6. results in more light entering the eye

Question 10

the importance of Schwann cells

Answer 10

• Schwann cells make myelin which insulates the neurone
• ion exchange can only take place in the gaps between the Schwann cells called the node of Ranvier
• this makes the impulse travel faster as the impulse goes from node to node
• this is called saltatory conduction