nervous system

Question 1

lens meaning

Answer 1

transparent structure at front of eye, which changes shape to help refract light on retina

Question 2

cones meaning

Answer 2

photoreceptors in retina that detect colour of light

Question 3

rods meaning

Answer 3

photoreceptors in retina that detect light intensity

Question 4

CNS

Answer 4

brain + spinal cord, responsible for coordinating & controlling nervous system

Question 5

motor neurone meaning

Answer 5

carries electrical impulses from CNS to effector

Question 6

neurone meaning

Answer 6

nerve cell

Question 7

retina meaning

Answer 7

layer at back of eye, containing photoreceptors

Question 8

pupil meaning

Answer 8

hole in front of eye, that light enters through

Question 9

convex meaning

Answer 9

lens that causes parallel light to converge

Question 10

concave meaning

Answer 10

lens that causes light to diverge

Question 11

colour blindness meaning

Answer 11

inability to distinguish different colours

Question 12

receptor meaning

Answer 12

cell that detects stimulus

Question 13

coordinator meaning

Answer 13

role of brain/spinal cord in reflex arc

Question 14

suspensory ligaments meaning

Answer 14

connect ciliary muscles to lens

Question 15

accommodation meaning

Answer 15

ability of eye to change from focussing on distant to near object

Question 16

response meaning

Answer 16

action carried out by effector

Question 17

dendron meaning

Answer 17

long nerve fibre extension of neurone that carries electrical impulses towards cell body

Question 18

dendrite meaning

Answer 18

receiving/input portions of neuron, short, narrow, branched

Question 19

neurotransmitter meaning

Answer 19

chemical protein that diffuses across synapse

Question 20

nerve meaning

Answer 20

bundle of neurones surrounded by connective tissue

Question 21

relay neurone meaning

Answer 21

carries electrical impulses from sensory to motor, in CNS

Question 22

sensory neurone meaning

Answer 22

carries electrical impulses from receptor to CNS

Question 23

axon meaning

Answer 23

extension of neurone that carries electrical impulses away from cell body

Question 24

cataracts meaning

Answer 24

clouding of lens of eye, resulting in blurred vison

Question 25

synapse meaning

Answer 25

microscopic gap between neurones

Question 26

effector meaning

Answer 26

muscle/gland that carries out response to stimuli

Question 27

hyperopia meaning

Answer 27

long-sightedness

Question 28

myopia meaning

Answer 28

short-sightedness

Question 29

reflex arc meaning

Answer 29

pathway taken by electrical impulses in a reflex action

Question 30

stimulus meaning

Answer 30

change in organism's environment

Question 31

PNS meaning

Answer 31

peripheral nervous system, sensory + motor neurones

Question 32

sensory neurone structure

Answer 32

receptor cells -> dendron -> cell body -> axon -> CNS

Question 33

relay neurone structure

Answer 33

sensory -> dendrites -> cell body -> axon -> motor

Question 34

motor neurone structure

Answer 34

relay -> dendrites -> cell body -> axon -> effector cells

Question 35

myelin sheath meaning

Answer 35

fatty, insulating layer surrounding axon split into Schwann cells by nodes of Ranvier

Question 36

what happens to eye in dim light

Answer 36

-circular muscles relaxed -radial muscles contracted -pupil dilated

Question 37

what happens to eye in bright light

Answer 37

-circular muscles contracted -radial muscles relaxed -pupil constricted

Question 38

how does the eye focus on near objects

Answer 38

-ciliary muscles contract -suspensory ligaments relax -lens is thick & round for more refraction

Question 39

how does the eye focus on distant objects

Answer 39

-ciliary muscles relax -suspensory ligaments contract -lens is thin & less round for less refraction

Question 40

how is short-sightedness caused

Answer 40

-lens is too strong/thick -eye is too long -rays converge too early

Question 41

how is long-sightedness caused

Answer 41

-lens is too weak/thin -eye is too short -rays converge too late

Question 42

which lens is used to fix short-sightedness

Answer 42

concave

Question 43

which lens is used to fix long-sightedness

Answer 43

convex

Question 44

how's laser technology used to fix myopia

Answer 44

1.numbing drops & alcohol solution to soften cornea 2.surgeon smooths surface of cornea 3.excimer laser reshapes cornea curvature 4.soft contact lens is placed on to protect eye as it heals

Question 45

in what part of the eye do cataracts form

Answer 45

lens

Question 46

why do cataracts cause blurred vision

Answer 46

because the lens is cloudy the light is dispersed so when it reaches the retina there isn't a clear image.

Question 47

how are cataracts treated

Answer 47

tiny incision allows surgeon to remove clouded lens & replace it w/ a new artificial one

Question 48

advantages of using eye drops rather than surgery to treat cataracts

Answer 48

-cheaper -easier to use -less chance of infection -less chance of damage

Question 49

what do cells that produce neurotransmitters have lots of

Answer 49

mitochondria & ribosomes

Question 50

sequence of events at synapse

Answer 50

1.electrical impulse travels to end of 1st neurone 2.impulse triggers release of chemical neurotransmitters 3.neurotrasnmitters diffuse across synapse & bind to receptors on 2nd neurone 4.new electrical impulse travels down 2nd neurone

Question 51

the reflex arc steps

Answer 51

stimulus -> receptor -> coordinator -> effector -> response

Question 52

what happens when you grab a hot plate

Answer 52

1.temperature receptors in hand 2.electrical impulses travel along sensory neurones 3.spinal cord - relay neurones 4.electrical impulses travel along motor neurone 5. muscles in hand & bicep 6.contract muscles, drop plate

Question 53

what is the benefit of reflexes

Answer 53

allows body to respond rapidly that can prevent damage to tissue from potentially harmful stimuli