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Biology revision > Homeostasis and response > Flashcards

Homeostasis and response Flashcards

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1
Q

What is a stimulus ?

A

A change in the environment

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2
Q

What stimuli do the nose receptors detect ?

A

odours ( chemicals in the air)

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3
Q

What stimuli do skin receptors detect ?

A

touch, temperature, pain

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4
Q

What stimuli do ear receptors detect ?

A

Sound

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5
Q

What stimuli do eye receptors detect ?

A

Light and movement

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6
Q

What stimuli do your tongue receptors detect ?

A

Chemicals in food and drink

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7
Q

What are the two sections of the nervous system ?

A

Central nervous system and peripheral nervous system

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8
Q

What is the central system made up of ?

A

Brain and spinal cord

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9
Q

What is the peripheral nervous system made up of ?

A

Neurons ( nerve cells) that carry information to or from the CNS

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10
Q

What does the nervous system enable us to do ?

A

Enables us to react to our surroundings and coordinate our behaviour

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11
Q

What is an effector ?

A

An organ that does something in response to a stimulus

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12
Q

What are the two types of effectors and what do they do ?

A

Muscles - contract and relax

Glands - release / produce hormones

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13
Q

How is information in the nervous system carried ?

A

Carried as electrical impulses

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14
Q

How are electrical impulses transmitted ?

A

Transmitted by nerve cells

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15
Q

What is the role of the sensory neuron ?

A

Carries nerve impulses from sense organs towards the central nervous system

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16
Q

What do relay neurons do ?

A

carry nerve impulses within the central nervous system

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17
Q

What does the motor neuron do ?

A

Carries nerve impulse away from CNS towards an effector organ ( muscle or gland )

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18
Q

What are receptors and what do they do ?

A

cells which are clustered together in sense organs such as your eyes

They detect stimuli and send information to CNS through sensory neurons

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19
Q

Describe the normal impulse route

A

A stimulus is detected by a receptor.

The receptor converts this information into a nerve impulse

This impulse is transmitted from the receptor to the CNS along sensory neurons

The CNS coordinates the information and sends another impulse in response.

This impulse passes along motor neurons to the relevant effector (normally a muscle or a gland) to bring about a response.

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20
Q

What is a reflex action ?

A

A rapid, automatic response of the nervous system which bypasses the brain

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21
Q

What is the impulse route for reflex actions called ?

A

The Reflex Arc

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22
Q

Why is the reflex Arc important ?

A
  • allows us to avoid danger or harm

- allows us to coordinate everyday bodily functions ie eating, seeing, walking, sleeping etc

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23
Q

Describe the reflex Arc

A

A stimulus is detected by a receptor

The receptor converts this information into a nerve impulse

The impulse is transmitted to the spinal cord along sensory neurons

Spinal cord will transfer the impulse to relay neurons

Relay neurons transfer impulse to a motor neurons

Motor neurons carries impulse to an effector which will bring about a response

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24
Q

What are the adaptations of a neuron ?

A
  • long fibre ( axon) so they can carry impulses up and down body over long distances
  • branched connections called dendrites which receive incoming nerve impulses from other neurons ( allows neurons to communicate)
  • axon is insulated by a fatty myelin sheath which increases the speed of the nerve impulses along the neuron
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25
Q

What is a synapse ?

A

The gap between two neurons

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26
Q

How do nerve impulses cross the gap between two neurons ?

A
  • when electrical impulse hits the end of a nerve, causes the release of chemical messengers called neurotransmitters
  • these diffuse across the synapse to the next nerve cell where they can trigger another electrical impulse
  • new impulse continues along the new nerve cell to the other end, where it will hit another synapse and process repeats
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27
Q

What are the two coordinators in the nervous system ?

A

brain and spinal cord

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28
Q

What is the role of brain and spinal cord

A

To receive and process information from receptors around the body

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29
Q

What is reaction time ?

A

The amount of time it takes to respond to a stimulus

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30
Q

what are some factors affecting reaction time ?

A

age, gender, physical fitness, fatigue, distraction, alcohol, personality type, and whether the stimulus is auditory or visual.

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31
Q

What are the steps for investigating human reaction times ? ( required practical 7)

A

Step 1: Person A sits on a stool with good upright posture and place the forearm of their dominant hand across the table with their hand overhanging the edge

Step 2: Person B holds the ruler vertically with the 0 cm mark between person A’s thumb and index finger

Step 3: Person B drops the ruler at a random time and person A has to catch the ruler with their thumb and index finger as quick as possible

Step 4: Person B records the measurement on the ruler which is level with the top of person A’s thumb

Step 5: Experiment is repeated and a mean reaction distance is calculated. Results can be converted into reaction times using a conversion table

Step 6: Person A and B switch places with person A now testing the reaction time of person B ( steps 1- 5 repeated )

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32
Q

What are some control variables for practical affecting reaction time ?

A

Starting distance between thumb and index finger should be kept constant

Measurement of reaction distance should always be measured from top of the thumb

Conditions in room should be kept the same ie lighting and background noise

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33
Q

What is the role of the cerebral cortex ?

A

Controls consciousness, intelligence, memory and language

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34
Q

What is the role of the cerebellum ?

A

Controls balance, coordination of movement and muscular activity

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35
Q

What is the role of the medula ?

A

controls unconscious activities such as heart beat and breathing rate

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36
Q

What is the role of the hypothalamus ?

A

It is the regulating centre for temperature and water balance in the body

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37
Q

What are the four main areas of the brain ?

A

Cerebral cortex, cerebellum, medula and hypothalamus

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38
Q

What are three methods used to map areas of the brain to their functions ?

A

CT scans , MRI and EEG scanner

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39
Q

What does MRI stand for ?

A

magnetic resonance imaging

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40
Q

How does an MRI scanner work ?

A
  • Magnets in the machine create a strong magnetic field
  • scanner then sends radio waves through your body
  • When radiowaves are turned off , the scanner picks up energy signals from your body
  • energy signals are then used to form pictures/ images of regions of your body
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41
Q

What are the advantages of MRI ?

A
  • non invasive ( ie doesn’t involve putting a camera inside of you )
  • Doesn’t use ionising radiation ( high dose of IR can cause cancer)
  • Safer than CT scans
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42
Q

What are some disadvantages of MRI ?

A
  • You can’t have MRI if you have any metal device or implant in your body ie a pacemaker
  • scanners can be very noisy
  • scanning speed is slow
  • patients have to be very still as any slight movement can cause distorted images
43
Q

What does CT stand for ?

A

Computed tomography scans

44
Q

How does a CT scanner work ?

A

CT scan combines a series of X-ray images taken from different angles around your body and uses computer processing to create cross-sectional images (slices) of the bones, blood vessels and soft tissues inside your body.

45
Q

What are the advantages of CT scans ?

A
  • fast scanning speed
  • Cheaper than MRI
  • less stringent about remaining motionless
  • non invasive
  • relatively quiet
46
Q

What are the disadvantages of CT scans ?

A
  • can cause harm to person due to exposure to ionising radiation
  • risk of allergic reaction to contrast material
47
Q

What is a contrast material ?

A

A Special dye used to highlight areas of the body being examined

48
Q

What does EEG stand for ?

A

Electroencepthalography

49
Q

How does an EEG scanner work ?

A
  • Works by attaching small sensors all over the scalp to detect electrical signals produced when brain’s cells communicate
  • highly trained specialists can read the signals to detect unusual activity
50
Q

What are the advantages of an EEG scanner ?

A
  • noiseless
  • non invasive technology
  • doesn’t aggravate claustrophobia
  • tolerant of movement
51
Q

What are the disadvantages of an EEG scanner ?

A
  • Poor spatial resolution
  • can’t be used to detect cancer
  • doesn’t specify where in the brain activity comes from
52
Q

What can an EEG scanner detect ?

A

epilepsy, fits and memory problems

53
Q

What is epilepsy ?

A

Sudden bursts of electrical activity in the brain which can cause seizures/ fits

54
Q

What can an MRI scanner detect ?

A

cancer cells, blood clots, abnormal blood flow and internal injuries

55
Q

What are three things a CT scanner can do ?

A
  • can be used to diagnose conditions ie damage to bones, strokes, cancer, and abnormal blood flow
  • can help determine the location, size and shape of a tumour before having radiotherapy/chemo
  • can be used to monitor conditions ie checking tumour size during and after cancer treatment
56
Q

What is a brain implant useful for ?

A

Helps diagnose and treat a range of brain pathologies ie Parkinson’s disease

57
Q

One advantage and disadvantage of brain implant

A
  • Your brain may get damaged in the process

- It can help your brain function properly again

58
Q

What is brain surgery used for ?

A

Used to remove as much of a brain tumour as possible

59
Q

What are the disadvantages of a brain surgery ?

A
  • May cause brain damage ie speech, memory loss

- may cause infection and the possibility of a stroke

60
Q

What is an advantage of brain surgery ?

A

Can save/prolong a person’s life

61
Q

What is the difference between radiotherapy and chemotherapy ?

A

Radiotherapy uses rays to destroy cancer cells

Chemotherapy uses drugs to destroy cancer cells

62
Q

What is an advantage and disadvantage of using radiotherapy/chemotherapy ?

A
  • Removal of tumour can save lives

- Risk of normal cells getting damaged in the process

63
Q

What are monoclonal antibodies ?

A

Identical copies of antibodies that have been made in labs, that are able to bind to cancerous cells and help immune system destroy them

64
Q

What is an advantage and disadvantage of monoclonal antibodies ?

A
  • offers hope in the treatment of cancer/ tumours

- can cause sore, red skin or an itchy rash

65
Q

What can stem cell therapy do ?

A

helps in repairing damaged nervous system and produces cancer killing molecules

66
Q

What is an advantage or disadvantage of stem cell therapies ?

A
  • repairs damage to nervous system tissue

- stem cells may be rejected by the immune system

67
Q

What is neurology ?

A

A branch of medicine that deals with disorders in the nervous system

68
Q

The eye is a _____ _____ containing ________ sensitive to ______ _______ and ______.

A

Sense organ
receptors
light intensity
colour

69
Q

What is the retina ?

A

A light sensitive tissue that lines the back of the eye

70
Q

What are the two light sensitive receptor cells that make up the retina ?

A

Cones and rods

71
Q

What are cones sensitive to…

A

Colour

72
Q

What are rods sensitive to…

A

Light

73
Q

What is the purpose of the retina ?

A
  • To receive light that the lens has focused

- Convert the light into neural signals and send the signals to brain via the optic nerve

74
Q

What does the iris do ?

A

It has sets of muscles that control the size of the pupil and regulate the light reaching the retina

75
Q

What happens to the muscles in the iris when there is dim lighting ?

A
  • radial muscles in iris contract
  • circular muscles in iris relax

This causes pupil to dilate ( become larger) to allow in more light

76
Q

What happens to the muscles in the iris when there is bright lighting ?

A
  • radial muscles in iris relax
  • circular muscles in iris contract

This causes pupil to contract ( become smaller) to allow in less light

77
Q

What is accomodation ?

A

Process of changing the shape of the lens to focus on near or distant objects

78
Q

What exactly is refraction ?

A

The bending of light rays as they travel from one medium to another

79
Q

How does the eye create an image ?

A

Light passes through the cornea and is refracted through pupil onto the lens

As light passes through the lens, it refracts again onto the retina where an image is formed

This double refraction causes the image to turn upside down

The inverted image travels as an impulse along the optic nerve to the brain’s occipital lobe. The brain turns the image right side up.

80
Q

What is the cornea ?

A

Transparent region of the sclera at the front of the eye

81
Q

What is the sclera ?

A

The tough outer layer of your eye ( the white of your eye)

82
Q

What does the lens do ?

A

Focuses light rays onto the retina

83
Q

What is the pupil ?

A

The hole in the centre of the iris that allows light to pass through

84
Q

What do the ciliary muscles and suspensory ligaments do ?

A

Change the shape of the lens to precisely focus light rays onto the retina

85
Q

What does the optic nerve do ?

A

Carries impulses from the retina to the brain

86
Q

How does the eye focus on near objects ?

A

Ciliary muscles contract which causes the suspensory ligaments to loosen

This makes the lens shape thick and round

This causes the light rays to be refracted more strongly, bringing them into perfect focus onto the retina

87
Q

Light from distant objects … (focus)

A

Only needs to be focused a small amount ( only a slight refraction of light needed)

88
Q

How does the eye focus on distant objects ?

A

Ciliary muscles relax which causes suspensory ligaments to be pulled tight

The lens is pulled thin and flat

Because the lens is thin, light rays are only slightly refracted, and light is focused to a point on the retina

89
Q

Light from near objects…

A

Needs be focused a large amount ( large refraction of light needed)

90
Q

What is myopia ?

A

Shortsightedness, when people can see objects at short distances but struggle to see objects at a distance

91
Q

Where is the image formed with normal vision ? Why ?

A

On the back of the retina

Light is correctly refracted by the cornea and lens in the eye

92
Q

Where is the image formed with myopia ? Why ?

A

In front of the retina

Eyeball is too long or cornea is too sharply curved or lens is too thick

93
Q

Where is the image formed with hyperopia ? Why ?

A

Behind the retina

Eyeball is too short or cornea isn’t curved enough or lens is less elastic ( can’t become thick enough to focus on near objects)

94
Q

What is hyperopia ?

A

When people can see objects at long distances away, but struggle to see near objects

95
Q

How can myopia be treated ?

A

Wearing glasses with a concave lens ( diverging lens )

This spreads out the light rays from distant objects before it enters the eye, so light can be bought into perfect focus onto the retina

96
Q

How can hyperopia be treated ?

A

Wearing glasses with a convex lens ( converging lens )

this brings the light rays together more before they reach the eye, so light can be bought to perfect focus on retina

97
Q

What does converging mean ?

A

Light rays move towards each other

98
Q

What does diverging mean ?

A

Light rays spread out

99
Q

What are the two techniques for replacing lenses ?

A

1- Permanent contact lens is implanted in the eye and natural lens is also left in

2- Faulty lens is removed ans artificial lens is implanted

100
Q

What do contact lenses do ?

A

Carry out the same job as glasses but cannot be seen

101
Q

what is the difference between hard and soft contacts ?

A

Hard contacts are more durable whereas soft contacts are more flexible and comfortable but not as durable

Both must be kept sterile to avoid infection

102
Q

How can laser eye surgery be used to treat myopia and hyperopia ?

A

For myopia, lens thickness reduced so cornea refracts light less strongly

For hyperopia, lasers change curve of the cornea so it refracts light from nearer objects more effectively

103
Q

why can laser surgery only be used for adults ?

A

It can cause damage to developing eyes of children

Biology revision (6 decks)

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