the nervous system and the eye Flashcards
what does the CNS and PNS consist of?
-CNS: brain, spinal cord
-PNS: cranial nerves, spinal nerves, sense organs
function of a sensory neurone?
transmit nerve impulses from receptors to CNS
function of a relay neurone?
transmit nerve impulses from sensory neurone to motor neurone
functions of a motor neurone?
transmit nerve impulses from CNS to effectors
structure of a neurone?
1) dendron: transmit nervous impulses towards cell body
2) axon: transmit nervous impulses away from cell bodu
differences between sensory neurone and motor neurones?
1) function:
- transmit impulses from receptors to CNS
- transmit impulses from CNS to effectors
2) cell body:
- circular in shape
- irregular in shape
3) axon:
- short
- long
4) dendron:
- long
- short
5) cell body location:
- outside CNS
- inside CNS
what is a synapse?
1) junction between two neurones
or
2) junction between neurone and transmitter
3) neurones release chemicals that help transmit nerve impulses to the next neurone across the synapse
what are nerves?
1) bundle of nerve fibres enclosed in a sheath of connective tissue
2) from the brain —> cranial nerves
3) from the spine —> spinal nerves
voluntary action?
1) brain
2) a relay neurone
3) a motor neurone
4) an effector
- brain is involved
brme
sensation?
1) receptor
2) a sensory neurone
3) a relay neurone
4) brain
- brain is directly involved
rsrb
reflex action?
1) receptor
2) a sensory neurone
3) a relay neurone in the brain/ spinal cord
4) a motor neurone
5) an effector
- brain only receives the nerve impulses from the relay neurone after the effector has received them
- brain is not directly involved in the action, but is involved in the responses that take place afterward
rsrme
example of a voluntary action?
raising your hand
1) nerve impulses produced in brain
2) nerve impulses transmitted to relay neurone in spinal cord
3) and transmitted to the motor neurone
4) effector muscles in rm recive nerve impulses from motor neurone
5) muscle in arm contracts
6) hand is raised
example of a sensation?
touching cold ice
1) temperature receptors in the skin are stimulated
2) nerve impulses produced and trnasmitted by sensory neurone
3) to relay neurone in spinal cord
4) brain interprets impulses
5) coldness felt
example of a reflex action?
touching a hot object; pulling hand away
1) temperature receptors in the skin are stimulated
2) nerve impulses are produced and transmitted by a sensory neurone
3) to relay neurone in spinal cord
4) and to a motor neurone
5) effector muscles in arm receive te nerve impulses from motor neurone
6) hand is pulled away
pupil reflex in response to bright light?
1) more light enters the eye
2) photoreceptors on the retina are stimulated
3) nerve impulses transmitted to the brain through the optic nerve
4) brain transmits impulses to the iris - circular muscles contract, radial muscles relax
5) pupil constricts
6) less light enters the eye
pupil reflex in response to dim light?
1) less light enters the eye
2) photoreceptors on the retina are stimulated
3) nerve impulses transmitted to the brain through the optic nerve
4) brain transmits impulses
to the iris -circular muscles relax, radial muscles contract.
5) pupils dilate
6) more light enters the eye
looking at nearby/ distant object
1) light rays from a near/ far object are divergent/ almost parallel
2) greater/smaller angle of refraction needed to focus on the object
3) ciliary muscles contract/relax
4) suspensory ligaments slacken/become taut
5) lens become thicker and more convex/ thinner and less convex
6) focal length decreases: increases
7) light rays sharply focused on retina
8) photoreceptors are stimulated
9) nerve impulses transmitted to brain via optic nerve
10) brain interprets impulses
11) person sees near/ distant object
