nervous system and eye Flashcards

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1
Q

what are the conditions inside your body known as

A

internal environment

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2
Q

what is homeostasis

A

homeostasis is the regulation of the conditions inside your body to maintain a stable internal environment in response to internal or external changes

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3
Q

why does your body regulate the internal conditions in your cells

A

your body regulates the internal conditions in your cells to maintain an optimum temperature for your cells to work properly in response to changes externally or internally

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4
Q

why is it important for your body to respond to changes from the internal or external environment

A

so your body can maintain an optimum temperature for your cellular enzymes

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5
Q

what conditions are kept controlled in your body

A

body temperature
water content
blood glucose levels

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6
Q

what does your body use to detect and respond

A

automatic control system (nervous system)

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7
Q

what does your receptors do

A

They detect changes from the internal or external environment

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8
Q

what are the changes to your internal and external environment known as

A

stimuli

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9
Q

what does your coordination centre do and example of it

A

Your coordination centre receive and process information from your receptors and then sends out signal and coordinates these responses of the body
examples brain and spinal cord

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10
Q

what does your effectors do

A

these carry out the responses of the stimulus and restore the condition of your body back to its optimum temperature

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11
Q

what sub cellular cells do receptors have and where are they found

A

receptors have a nucleus, cell membrane and cytoplasm
they are found in clusters in sensory organs e.g eyes

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12
Q

how does your nervous system works

A

1) your receptors detect a change of stimulus then sends out signals along the sensory neuron to the CNS (central nervous system)
2) your CNS then coordinates the responses of the instruction and sends out signals along your motor neuron to effector organs
3) your effector organs then carry out these responses restoring back the conditions of your body

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13
Q

what are neurons

A

neurons are clusters of nerves

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14
Q

what is the independent (I) dependent (D) and control (V) variable of the reaction time experiment REQUIRED PRACTICAL

A

I- person having their reaction time tested
D- reaction time
C - starting distance between ruler and finger, conditions of the room and what we measure the ruler to get our recording

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15
Q

steps of reaction time experiment REQUIRED PRACTICAL

A

1) student 1 sits with a good posture and places their dominant hand over the edge of the table
2) student 2 then places the ruler vertically above students 1 thumb and first finger
3) student 2 then drops the ruler at a random time and student 1 catches it
4) student 2 then records the measurement of the ruler from the level of the thumb
5) the test is repeated several times then a mean is calculated

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16
Q

what are reflexes

A

automatic responses

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17
Q

what are reflexes used for

A
  • to avoid danger
  • help with your basic body functions e.g breathing
  • they help do unconscious act which do not require the conscious part of the brain
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18
Q

how are reflexes so fast

A
  • they do not use the conscious part of the brain so the result time between the stimulus and the effector organ is as short as possible
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19
Q

how does your reflex arc work

A

1) skin receptors detect a stimulus and send electrical impulses along the sensory neuron
2) the sensory neuros then releases chemicals which diffuses along the synapse to the relay neuron ad this starts a new electrical impulse
3) the electrical impulse continues to travel along the relay neuron until it meets another synapse, which then the relay neuron release chemicals which diffuses across the synapse to the motor neuron starting another new electrical impulse
4) the electrical impulse travels along the motor neuron until it reaches the last synapse which it then releases chemical which diffuse across the synapse to the effector

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20
Q

where is the relay neuron found

A

spinal cord

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21
Q

what are synapses

A

their gaps between neurons

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22
Q

what are the disadvantages of synapses

A
  • they slow down electrical impulses, delaying the reflex arc
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23
Q

how do synapses work

A

1) an electrical impulse is sent to the pre synaptic neuron
2) this cause the neuron vesicle to move towards the membrane of the pre synaptic neuron
3) neuron transmitters (chemicals) then diffuse across the synapse and attach onto the receptors of the post synaptic neuron
4) if enough neuron transmitters attaches onto the receptors it generates a new electrical impulse into the post synaptic neuron
5) some neuron transmitters are recycled back to the post synaptic neuron

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24
Q

where is the brain found and what is it surrounded by

A
  • it is found inside a skull and is surrounded by a protective membrane called meninges
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25
Q

what does the cerebral cortex do

A
  • it is the conscious part of the brain and controls memory language and intelligence
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26
Q

what does the cerebellum do

A

it controls the muscle activity and balance

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27
Q

what does the medulla do

A

this is the unconscious part of the brain and controls things like breathing

28
Q

what does your hypothalamus do

A

it control your body temperture

29
Q

what does your pituitary gland do

A

produces many chemicals

30
Q

what do MRI scans do and what does it stand for

A

Magnetic Resonance Imagery
they doctors see the part of the brain that is affective and help scientist link the affected area to the function of the body that is not working

31
Q

why is it hard to treat the brain

A
  • drugs do not always reach the brain due to the membrane surrounding it
  • it hard to perform surgery on the brain as we don’t fully understand it and surgeons do not want to cause any unintended damage to the brain
32
Q

except MRI scans how else can we see what part of the brain is affective

A
  • by electrically stimulating the brain by zapping it with an electrode at different parts of the brain and seeing what it does
33
Q

characteristics of the sclera

A

its the white outer layer of the eye
relatively strong and tough so it cannot be easily damage
has a transparent layer at the front of the eye called the cornea

34
Q

characteristics of the cornea

A
  • it has a curved surface so it can change the change direction of the light rays entering the eye so it focuses on the retina
35
Q

what is the pupil

A
  • its a hole that lets light in
36
Q

what is the iris

A
  • a muscle that contracts or relaxes so the pupil can control the amount of light entering the eye and determines your eye colour
37
Q

what happens to your pupils in dark and bright light

A
  • in a dim light your pupils get larger so as much light as possible can enter
  • in bright light your pupils get smaller as too much light can damage your light sensitive cells
38
Q

what does the lens do and what is it

A
  • your lens is a clear disc held by your ciliary muscles and your suspensory ligaments
  • changes the direction of light to produce a clear image on the retina
  • changes shape so you can focus on far and distant
39
Q

what does your optic nerve do

A
  • sends impulses generated by the light sensitive cells to the brain so you can produce an image
40
Q

what is the fovea

A
  • its the part of the eye where light focuses on
41
Q

what is the aqueous humour and what does it

A
  • transparent thick jelly which refracts light
42
Q

what does your ciliary muscles do

A
  • determines how much light your lens refract as it changes the shape of your lens
43
Q

how does light pass through your eye

A
  • by refraction
44
Q

what happens if light focuses behind or infront of the retina

A

the image would be blurred

45
Q

what do your circular muscles and radial muscles do if its bright

A

circular muscles
contract to squeeze the pupil smaller
radial muscles
relax to stretch the pupil larger

46
Q

what do your circular muscles and radial muscles do if its dark

A

circular muscles
relax
radial muscles contract to make pupil shorter and pulling it open

47
Q

what happens to the light when your looking at an object that is close

A
  • the light diverges strongly when it reaches your eye
48
Q

what happens to the light when your looking at an object that is far away

A
  • the light travels parallel to your eye
49
Q

what happens to your ciliary muscles, suspensory ligaments and your lens when you focus on distant objects

A
  • your ciliary muscles relax making your suspensory ligaments get pulled tightly making your lens thinner so the light entering your eye refracts slightly
50
Q

what happens to your ciliary muscles, suspensory ligaments and your lens when you focus on close objects

A
  • your ciliary muscles contract and the suspensory ligaments loosen, this causes the lens get thicker and fatter so the light entering your eye refracts strongly
51
Q

what is myopia

A

short sightedness ( so long distance appears blurry)

52
Q

what is hyperopia

A

long sightedness ( so short distance appears blurry)

53
Q

how can myopia be treated

A

with glasses with concave lens so it can spread out the light before it enters the eye

54
Q

how can hyperopia be treated

A

with glasses with convex lens so it can bring the light rays closer together before it enters the eye

55
Q

what causes myopia

A

the eye being too long or the cornea being to curved so images on the retina appear blurry

56
Q

what causes hyperopia

A

they eye being too short or the cornea being to flat so the cornea cant refract

57
Q

where does the light focus in myopia

A

in front the retina

58
Q

where does the light focus in hyperopia

A

behind the retina

59
Q

what is accomodation

A

the process where your lens change shape so that you can focus on objects that are far or close

60
Q

advantages of contact lenses

A
  • less visible - this makes it easier for people who play sport and complete general activities
  • hard contact lenses made from strong rigid material last long
  • modern contact lenses are comfortable
61
Q

disadvantages of contact lenses

A
  • hard contact lenses are uncomfortable
  • modern contact lenses don’t last long
  • contact lenses have to be removed before bed and sterilised
62
Q

advantages of laser surgery

A
  • can help with hyperopia and myopia
63
Q

disadvantages of laser surgery

A
  • requires surgery
64
Q

how can laser surgery help with myopia

A
  • reduces the thickness of the cornea so the light can refract less
65
Q

how can laser surgery help with hyperopia

A
  • can curve the cornea more so the light is refracted more efficiently
66
Q

advantages of replacement lens

A
  • your lens can be replaced to stop visual defects permanently by adding a new lens and leaving your natural lens in place or replacing your natural lens with artificial lens
67
Q

disadvantages of replacement lens

A
  • can cause cataracts (where your vison gets blurry) ,infections or damage to the retina