B1O:TheHumanNervousSystem Flashcards
(85 cards)
1
Q
conditions inside the body
A
internal environment
2
Q
regulation of internal conditions of cells to maintain optimum conditions to function
A
homeostasis
3
Q
what are the controlled internal conditions?
A
body temperature, water content, blood glucose concentration
4
Q
receptors
A
cells that detect changes in the internal or external environment
5
Q
what are the changes known as?
A
a stimulus/stimuli
6
Q
coordination centres
A
areas that receive and process the receptors information, they send out signals to coordinate the response of the body
7
Q
examples of a coordination centre
A
the brain, the spinal cord, the pancreas
8
Q
what does the brain act as a coordination centre for
A
nervous system and parts of the hormonal system
9
Q
effectors
A
muscles or glands that bring about responses to the stimulus that has been received, these responses restore body conditions to optimum levels
10
Q
impulses
A
electrical signals
11
Q
how fast do impulses travel
A
1-120 metres per second
12
Q
cell structures in receptor cells
A
cell membrane, nucleus, cytoplasm
13
Q
what happens when a sensory receptor cell detects a change
A
the information is sent as an impulse along special cells called neurones
14
Q
hundreds or thousands of neurones
A
nerves
15
Q
where is the impulse carried to via the neurones?
A
central nervous system (CNS)
16
Q
what is the CNS made up of
A
the brain and the spinal cord
17
Q
what do sensory neurones do
A
carry impulses from your sense organs to your CNS
18
Q
what do motor neurones do
A
carry information from your CNS to the rest of your body
19
Q
what do muscles do as an effector
A
contract
20
Q
what do glands do as an effector
A
secrete chemical substances
21
Q
sum up the way the nervous system works with 4 words
A
stimulus, receptor, CNS, effector
22
Q
how can you measure reaction time
A
ruler drop test
23
Q
what is an automatic response called
A
reflex
24
Q
what are reflexes for
A
to avoid danger
25
why are reflexes automatic and rapid
as they don't involve the conscious part of your brain
26
what neurones are used in a reflex
sensory neurone, motor neurone, relay neurone
27
what are relay neurones
connect a sensory neurone and motor neurones, found in the CNS
28
sum up how the reflex works
stimulus, receptor, sensory, relay, motor, effector, response
29
what is this pathway called
reflex arc
30
what is a synapse
junctions which form physical gaps between neurones
31
how do synapses work
chemicals are released into the gaps between the neurones, chemicals attach to the surface of the next neurone and set up a new electrical impulse
32
examples of reflex actions
breathing, swallowing
33
texture of the brain
set yoghurt
34
what is the brain made up of
billions of interconnected neurones that form different regions
35
cerebral cortex function
consciousness, intelligence, memory and language
36
cerebellum function
coordinating muscular activity and balance
37
medulla function
unconscious activities, heartbeat, breathing
38
function of the hypothalamus
controlling body temperature
39
pituitary gland function
produces many chemicals such as hormones
40
name 5 regions of the brain
cerebral cortex, cerebellum, medulla, hypothalamus, pituitary gland
41
electrically stimulating the brain
scientists can remove the top of the skull and stimulate different areas to see what effect it may have eg hunger if that part of the brain is stimulated
42
why is brain surgery done on conscious patients
as there are no nerve endings in the brain
43
what does MRI stand for
magnetic resonance imaging
44
what do MRI scans help scientists look for
affected areas of the brain
45
why is it hard to fix brain disorders
as drugs don't often reach the brain, surgery is difficult as we have not yet discovered what each part of the brain does and we don't want to cause further damage
46
what is the eye
a sense organ containing many receptors
47
what are receptors in the eye sensitive to
light intensity and colour
48
where are all of the light-sensitive cells located in the eye
in a layer at the back of the eye called the retina
49
sclera
the white outer layer of the eye - tough and strong so the eyeball isn't easily damaged
50
cornea
a transparent area at the front of the eyeball that lets light into the eye
51
what is the cornea's curved surface useful for
changing the direction of the light rays entering the eye making sure they enter focused on the retina
52
iris
muscular and controls the size of the pupil
53
pupil
the hole in which light enters the eye
54
what happens to the size of the pupil in bright light
small so they light doesn't damage the delicate cells
55
what happens to the size of the pupil in dim light
enlarged fully so as much light as possible enters the ey
56
lens
a clear disc that light passes through
57
what holds the lens in place
suspensory ligaments and ciliary muscles
58
what is the eyeball filled with
thick transparent jelly that maintains the eye's spherical shape
59
what happens when light hits the retina
the light-sensitive cells are stimulated
60
what do the light-sensitive cells send to the brain
impulses along sensory neurones in the optic nerve
61
what happens when the brain receives the message from the sensory neurones
it interprets them as a visual image
62
where is the "blind spot"
where the optic nerve leaves the ye
63
why is the image we see blurry sometimes?
if the light is focused in front of or behind the retina
64
accommodation
process of changing the shape of the lens to see near and far
65
what is happening to the light we see from close objects
diverging very strongly
66
what is happening to the light we see from distant objects
travelling in almost parallel rays
67
what does the cornea do to the light entering our eye
refract it towards the retina
68
how to focus on a distant object
ciliary muscles relax so the suspensory ligaments are pulled tight and the lens is pulled flat and thin, slightly refracts light rays
69
how to focus on a near object
the ciliary muscles contract so the suspensory ligaments loosen, the lens is thicker and more curved, strongly refracts light rays
70
what happens to the lens as people get older
it hardens so accommodation gets more difficult
71
why do many old people need reading glasses
as accommodation getas harder so they can't focus on close up objects as easily
72
myopia
short-sightedness
73
hyperopia
long-sightedness
74
what happens in both myopia and hyperopia
the rays of the light aren't focused on the retina and the image is blurred
75
explain myopia
you can see close objects but distant objects look blurred, this is because the light is focused on the front of the retina so the image on the retina is out of focus and blurry
76
why may people be short-sighted
their lens may be too curved or they may have a long eyeball
77
ways to treat myopia
wear glasses with a concave lens that spread out the light from distant objects before it reaches the eye, this means the thicker lens can bring it into perfect focus on the retina
78
explain hyperopia
you can see distant objects but close objects seem to be blurry, this is because the lens can't refract the rays of light strongly enough. The light is focused behind the retina
79
why may people be long-sighted
their lens may be too flat and thin or they may have a short eyeball
80
ways to treat hyperopia
wear glasses with a convex lens, they bring the light rays together before reaching the eye itself. Now the thinner lens can bring the rays of light into perfect focus on the retina
81
name three new advances in technology to treat myopia and hyperopia
contact lenses, laser eye surgery, replacement lenses
82
explain contact lenses
lenses placed on the surface of the eye, good for playing sport and general activities. They have to be removed overnight to avoid infections. Most modern contacts are soft lenses which means they're flexible and comfortable
83
explain laser eye surgery
only available to adults when they're eyes have stopped growing and vision has become stable, used to treat myopia by reducing the thickness of the cornea so it refracts less strongly. They're used to treat hyperopia by changing the curve of the cornea so it refracts light from closer objects more effectively
84
explain replacement lenses
add another lens to the eye to correct vision permanently. Two ways to do it, one can keep the bad lens and also add a new one, the other removes the bad lens and changes it for a new one. Can be very dangerous and cause long term sight problems to the retina and the risk of cataracts developing
85
what happens if your internal environment keeps changing
your organs can't function properly
