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Biology GCSE Paper 2 > Topic 5- Homeostasis and Response > Flashcards

Topic 5- Homeostasis and Response Flashcards

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1
Q

Why do conditions in your body need to be kept steady?

A

Cells need the right conditions in order to function properly, including the right conditions for enzyme action.

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2
Q

What is homeostasis?

A

The regulation of the conditions inside your body (and cells) to maintain a stable internal environment, in response to changes in both internal and external conditions.

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3
Q

What is the purpose of automatic control systems and what are examples?

A

They regulate your internal environment including nervous and hormonal communication systems. There are control systems that maintain boody temperature, blood glucose and water content.

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4
Q

What three main components make up your automatic control systems?

A

Receptors, coordination centres (brain, spinal chord and pancreas) and effectors.

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5
Q

How do your automatic control systems keep your internal environment stable?

A

Using negative feedback - brings conditions back to normal when things are too high or low.

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6
Q

Describe negative feedback when levels are too high.

A

1) Receptor detects stimulus - level is too high.
2) The coordination centre recieves and processes the information, then organises a response.
3) Effectors produce a response, which counteracts the change and restores the optimum level - the level decreases.

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7
Q

Describe negative feedback when levels are too low.

A

1) Receptor detects a stimulus - level is too low.
2) The coordination centre recieves and processes the information, then organises a response.
3) Effectors produce a response, which counteracts the change and restores the optimum level - the level increases.

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8
Q

What does the nervous system do?

A

React to surroundings and coordinate behaviour.

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9
Q

What parts make up the nervous system?

A

Central nervous system (CNS), sensory neurone, motor neurone, effectors

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10
Q

What does the CNS consist of?

A

Consists of brain and spinal chord in vertebrates and in mammals, is connected to the sensory and motor neurones.

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11
Q

What are sensory neurones?

A

Neurones that carry information as electrical impulses from receptors to the CNS.

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12
Q

What are motor neurones?

A

Neurones that carry electrical impulses from the CNS to effectors.

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13
Q

What are effectors?

A

Muscles and glands - respond to nervous impulses bringing about a change.

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14
Q

What are receptors?

A

Cells that detect stimuli.

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15
Q

What do muscles do in response to a nervous impulse?

A

Contract.

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16
Q

What do glands do in response to a nervous impulse?

A

Secrete hormones.

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17
Q

What does the CNS do?

A

Coordination centre that recieves information from the receptors and then coordinates a response which is carried out by effectors.

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18
Q

List the order from stimulus to response.

A

Stimulus, receptor, sensory neurone, CNS, moror neurone, effector and response.

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19
Q

What is a synapse and how does it work?

A

The connection between two neurones. The nerve signal is transferred by chemicals which diffuse across the gap. The chemicals then set off a new electrical signl in the next neurone.

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20
Q

What are reflexes?

A

Rapid, automatic responses to certain stimuli that don’t involve the concious part of the brain reducing the chances of being injured.

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21
Q

What is a reflex arc?

A

The passage of information in a reflex from receptor to effector.

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22
Q

Describe the reflex arc.

A
  1. Bee sting
  2. Stimulation of pain receptor
  3. Impulses travels along the sensory neurone
  4. Impulses passed along relay neurone, via a synapse.
  5. Impulses travel along motor neurone, via synapse.
  6. When impulse reaches muscle, it contracts.
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23
Q

What is reaction time?

A

The amount of time it takes to respond to a stimulus.

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24
Q

What factors can effect reaction time?

A

Age, gender or drugs.

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25
Q

What drug can speed up reaction time?

A

Caffiene.

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26
Q

Describe how you can measure the effect of caffiene on reaction time.

A
  1. Person tested sits with arm on edge of table.
  2. Hold ruler vertically between their thumb and forefinger with 0 being level with the thumb. Let go with no warning.
  3. Person tested catch the ruler quickly.
  4. Reaction time measures by the number at the top of the thumb. The higher the number, the slower the reaction time.
  5. The person being tested should have caffiene and then do the experiment again after 10 minutes.
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27
Q

Reaction time experiment: What variables should you control?

A
  • Same person catching the ruler.
  • Same hand catching.
  • Ruler dropped from same height.
  • Person not had caffiene before.
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28
Q

What should the person avoid after the reaction time experiment?

A

Avoid having caffiene for the rest of the day as too much can cause unpleasant side effects.

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29
Q

What is another way of measuring reaction time?

A

Computer tests - person clicks on the mouse asa soon as they see a stimulus on the screen.

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30
Q

Why are computer reaction time tests more precise?

A
  • Remove the possibility of human error.
  • Record the reaction time in milliseconds is a more accurate measurment.
  • Remove the possiblity the person can predict when to respond - can’t anticipate the tester’s body language.
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31
Q

What is the brain?

A

Made up of billions of interconnected neurones - in charge of all our complex behaviours - controls and coordinates everything you do.

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32
Q

What are the three main regions in the brain?

A

Cerebal cortex, medulla and cerebellum.

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33
Q

What is the function of the cerebal cortex?

A

Outer wrinkly bit - responsible for conciousness, intelligence, memory and language.

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34
Q

What is the function of the medulla?

A

Controls unconscious activities like breathing and hearbeat.

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35
Q

What is the function of the cerebellum?

A

Responsibe for muscle coordination.

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36
Q

What methods do scientist use to study the brain?

A

Studying patients with brain damage, electrically stimuating the brain and MRI scans.

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37
Q

If a small part of the brain has been damaged, what can the effect this has tell you?

A

A function of the damaged part of the brain.

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38
Q

How can the brain be electrically stimulated - and what can you learn from this?

A

Pushing a tiny electrode into the tissue and giving it a zap of electricity. By observing what stimulating different parts doe, it gives you and idea of what those parts do.

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39
Q

What are MRI scans?

A

Magnetic resonance imaging scanner is a tube like machine that produces a detailed picture of the brains structure. Scientists can use this to find out what parts of the brain are active.

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40
Q

What treatment has electrical stimulation led to?

A

Reduces muscles tremors caused by nervous system disorders, eg. parkinson’s disease.

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41
Q

What are risks of brain function investigations?

A

Physical damage or increased problems with brain function (eg. speech diffuculties).

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42
Q

What is the sclera?

A

The tough supporting wall of the eye.

43
Q

What is the cornea?

A

The transparent outer layer found at the front of the eye. It refracts light into the eye.

44
Q

What is the iris?

A

Contains muscles that allow it to control the diameter of the pupil and therefore how much light enters the eye.

45
Q

What is the pupil?

A

The hole in the middle of the eye.

46
Q

What does the lens do?

A

Focus light onto the retina.

47
Q

What does the retina contain?

A

Receptor cells sensitive to light intensity and colour.

48
Q

What do the ciliary mucles and suspensory ligaments control?

A

The shape of the lens.

49
Q

What does the optic nerve do?

A

Carries electric impulses from the receptors on the retina to the brain.

50
Q

What happens when light receptors in the eye detect a very bright light?

A

A reflex is triggered which makes the pupil smaller. The circular muscles in the iris contract and the radial muscles relax, reducing the amount of light which can enter the eye.

51
Q

What happens when light receptors in the eye detect dim light?

A

Radial muscles contract and circular muscles relax making the pupil wider.

52
Q

What is accomodation?

A

When the eye focuses light on the retina by changing the shape of the lens.

53
Q

What does the eye do to look at near objects?

A

Ciliary muscles contract, slackening the suspensory ligaments. The lens becomes fat/ more curved. This increases the amound by which it refracts light.

54
Q

What does the eye do to look at distant objects?

A

Ciliary muscles relax, allowing the suspensory ligaments to pull tight. This makes the lens go thin (less curved), so it refracts a smaller amount.

55
Q

Why do older people often have to have reading glasses?

A

Your eyes lens loses flexibility as you get older so it can’t easily spring back to a round shape. Meaning light can’t be focused well for near viewing.

56
Q

What happens if the lens cannot refract the light by the right amount?

A

The person will be long or short sighted.

57
Q

What are long sighted people unable to focus on?

A

Near objects.

58
Q

Why does long sightedness occur?

A

The lens is the wrong shape and doesn’t refract the light enough or the eyeball is too short. The images of near objects are brought into focus behind the retina.

59
Q

How can you correct long sightedness?

A

Using glasses with convex lenses (lens which curves outwards). The lens refracts the light rays so they focus on the retina.

60
Q

What is the medical term for long-sightedness?

A

Hyperopia.

61
Q

What are short-sighted people unable to focus on?

A

Distant objects.

62
Q

Why does short sightedness occur?

A

The lens is the wrong shape and refracts the light too much or the eyeball is too long. The images of distant objects are brought into focus in front of the retina.

63
Q

How can you correct short-sightedness?

A

Using glasses with concave lenses (lens which curves inwards), so that light rays focus on the retina.

64
Q

What is the medical term for short sighteness?

A

Myopia.

65
Q

What are three alternative treatments to glasses, to treat vision defects?

A

Contact lenses, laser eye surgery and replacement lens surgery.

66
Q

What are contact lenses?

A

Thin lenses that sit on the surface of the eye and are shaped to compensate for the faulty in focusing.

67
Q

What are advantages of contact lenses?

A

They are invisible and lightweight.

More convenient than glasses for activitys light sport.

68
Q

What are the two main types of contact lenses?

A

Soft and hard lenses. Soft lenses are generally more comfortable but carry a higher risk of eye infections than hard lenses.

69
Q

What does laser eye sugery do?

A

Laser can vaporise tissue, changing the shape of the cornea (changing how strongly it refracts light into the eye).

70
Q

How does laser eye surgery improve short sight?

A

Slimming it down making it less powerful.

71
Q

How does laser eye surgery improve long sight?

A

Changing the shape so that it’s more powerful.

72
Q

How can laser eye surgery completely correct the vision?

A

The surgeon can precisely control how much tissue the laser takes off.

73
Q

What are disadvantages of laser eye surgery?

A

There is a risk of complications, like infection or the eye reacting in a way that makes your vision worse than before.

74
Q

What is replacement lens surgery?

A

The natural lens of the eye is removed and an artificial lens, made of clear plastic, is inserted in its place.

75
Q

Why does replacing a lens carry higher risks than laser eye surgery?

A

It involves working inside the eye - can cause possible damage to the retina which could lead to loss of sight.

76
Q

Why does the body balance the amount of energy gained and lost?

A

To keep the core body temperature constant.

77
Q

What does the thermoregulatory centre in the brain contain?

A

Receptors that are sensitive to the temperature of blood flowing through the brain. It also recieves impulses from temperature receptors in the skin, giving information about skin temperature.

78
Q

Describe how your body cools down.

A
  1. Temperature receptors detect that core body temperature is too high.
  2. The thermoregulatory centre acts as a coordination centre - it recieves information from the temperature receptors and triggers the effectors automatically.
  3. Effectors, eg. sweat glands, produce a response and counteract the change.
79
Q

Describe how your body warms up.

A
  1. Temperature receptors detect that core body temperature is too low.
  2. The thermoregulatory centre acts as a coordination centre - it recieves information from the temperature receptors and triggers the effectors automatically.
  3. Effectors, eg. muscles, produce a response and counteract the change.
80
Q

Why do some effectors work antagonistically?

A

They achieve a precise temperature - allows a more sensitive response.

81
Q

What does your body do when you’re too hot?

A
  1. Sweat is produced by sweat glands and evaportates from the skin transferring energy to the environment.
  2. Vasodilation
82
Q

What is vasodilation?

A

Blood vessels supplying the skin dilate so more blood flows close to the surface of the skin. This helps transfer more energy from the skin to the environment.

83
Q

What does your body do when you’re too cold?

A
  1. Hairs stand up
  2. No sweat produced
  3. Vasoconstriction
  4. Shiver
84
Q

Why do your hairs stand up when you’re cold?

A

Trap and insulating layer of air.

85
Q

What is vasoconstriction?

A

Blood vessels supplying skin capillaries constrict to close off the skin’s blood supply.

86
Q

Why do you shiver when cold?

A

Your muscles contract automatically - this needs respiration which transfers some energy to warm the body.

87
Q

What are hormones?

A

Chemical molecules released directly into the blood. Carried in the blood to other parts of the body, but only affect particular cells in particular organs (target organs). Hormones control things in organs and cells that need constant adjustment.

88
Q

Where are hormones produced?

A

Produced and secreted by various glands (endocrine glands).

89
Q

What do the various glands that produce hormones make up?

A

Endocrine system.

90
Q

List 6 glands.

A

Pituitary gland, thyroid, ovaries, adrenal gland, testes and pancreas.

91
Q

What is the pituitary gland?

A

Produces many hormones that regulate body conditions. Sometimes called the ‘master gland’, because these hormones act on other glands, directing them to release hormones that bring about change.

92
Q

What is the thyroid?

A

Gland which produces thryroxine - involved in regulating the rate of metabolism, heart rate and temperature.

93
Q

What do the ovaries produce?

A

Oestrogen - involved in the menstrual cycle.

94
Q

What do the testes produce?

A

Testosterone - controls puberty and sperm production in males.

95
Q

What does the adrenal gland produce?

A

Adrenaline - used to prepare the body for a ‘fight or flight’ response.

96
Q

What does the pancreas produce?

A

Insulin - regulates the blood glucose level.

97
Q

Compare nerves to hormones.

A

Nerves: Very fast action, act for a very short time, act on a very precise area.
Hormones: Slower action, act for a long time, act in a more general way.

98
Q

What happens when you eat foods containing carbohydrates?

A

It puts glucose into the blood from the gut.

99
Q

How is glucose removed from the blood?

A

By the normal metabolism of cells. Vigirous exercise removes much more.

100
Q

How is excess glucose stored?

A

As glycogen in the liver and muscles.

101
Q

What are changed in the level in glucose in the blood monitered by?

A

Monitored and controlled by the pancreas using the hormones insulin and glucagon in a negative feedback cycle.

102
Q

What happens why blood glucose levels are too high?

A

Insulin is secreted by the pancreas.
Glucose moves from the blood into the liver and muscle cells. Insulin makes the liver turn glucose into glycogen so blood glucose is reduced.

103
Q

What happens when the blood glucose level is too low?

A

Glucagon is secreted by the pancreas.
Glucose is released into the blood by the liver. Glucagon makes liver turm glycogen into glucose so the blood glucose level increases.

Biology GCSE Paper 2 (3 decks)

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