topic 8

Question 1

what does the nervous system split into?

Answer 1

the central nervous system (CNS) and peripheral nervous system

Question 2

what does the central nervous system consist of?

Answer 2

the brain and spinal chord

Question 3

what does the peripheral nervous system consist of?

Answer 3

sensory nerves (carries sensory information from receptors to CNS) and motor nerves (carries motor commands from the CNS to the effectors)

Question 4

what is the peripheral nervous system subdivided into?

Answer 4

the autonomic and somatic nervous systems

Question 5

what is the somatic nervous system?

Answer 5

voluntary responses which stimulate skeletal muscle

Question 6

what is the autonomic nervous system?

Answer 6

involuntary responses which stimulate smooth muscle, cardiac muscle, and glands

Question 7

what is the autonomic nervous system subdivided into?

Answer 7

the sympathetic and parasympathetic nervous system

Question 8

what is the sympathetic nervous system?

Answer 8

prepares body for a fight or flight response

Question 9

what is the parasympathetic nervous system?

Answer 9

prepares the body for rest and digest

Question 10

what is a nerve?

Answer 10

a complex structure containing a bundle of the axons of many neurones, surrounded by a protective covering

Question 11

what is the role of dendrites?

Answer 11

conduct impulses towards the cell body

Question 12

what is the role of the axon?

Answer 12

transmits impulses away from the cell body

Question 13

what are the three main types of neurone?

Answer 13

motor neurone, sensory neurone, and relay neurone

Question 14

where is the cell body located in motor neurones?

Answer 14

within the central nervous system (CNS), with the axon extending out

Question 15

were do motor neurones send impulses?

Answer 15

from the CNS to effectors (muscles or glands)

Question 16

where do sensory neurones carry impulses?

Answer 16

from sensory cells to CNS

Question 17

where are most relay neurones found?

Answer 17

within the CNS

Question 18

what is the role of relay neurones?

Answer 18

connect motor an sensory neurones.
also known as connector neurones or interneurones

Question 19

what is the fatty layer around the axon called?

Answer 19

myelin sheath

Question 20

what is the myelin sheath made up of?

Answer 20

schwann cells wrapped around the axon

Question 21

what is the role of the myelin sheath?

Answer 21

affects how quickly nerve impulses pass along the axon

Question 22

what is a reflex arc?

Answer 22

a simple nerve pathway responsible for reflexes

Question 23

what is a reflex?

Answer 23

a rapid, involuntary response to a stimuli

Question 24

what is the pathway of a simple reflex arc?

Answer 24

1. receptors detect a stimulus and generate a nerve impulse
2. sensory neurones conduct a nerve impulse to the CNS along a sensory pathway
3. sensory neurones enter the spinal chord/brain
4. sensory neurone forms a synapse with a relay neurone
5. relay neurone forms a synapse with a motor neurone, which leaves the spinal chord/brain
6. motor neurone carries impulses to an effector, which produces a response

Question 25

which nervous system controls the radial and circular muscles in the eye?

Answer 25

autonomic nervous system

Question 26

which reflex controls the radial muscles in the eye?

Answer 26

sympathetic reflex

Question 27

which reflex controls the circular muscles in the eye?

Answer 27

parasympathetic reflex

Question 28

when the pupil is constricted, which muscles are relaxed/contracted?

Answer 28

radial muscles relax (like spokes of a wheel, don’t have to contract to stretch the pupil so can relax), circular muscles contract

Question 29

when the pupil is dilated, which muscles are relaxed/contracted?

Answer 29

radial muscles contract (like the spokes of a wheel, contract/shorten to pull the pupil out/dilate it), circular muscles relax

Question 30

what causes the pupil to constrict?

Answer 30

high light levels strike the photoreceptors in the retina, causing nerve impulses to pass along the optic nerve to a number of different sits within the CNS, including coordinating cells in the midbrain. impulses from these cells are sent along parasympathetic motor neurones to the circular muscles of the iris, casing them to contract. at the same time, radial muscles relax, constricting the pupil to reduce the amount of light netting the eye

Question 31

what is the value of resting potential inside an axon?

Answer 31

-70mV (the inside of an axon is more negative than the outside, and the membrane is polarised)