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Biology GCSE Paper 2 > Topic 5a- The Nervous System > Flashcards

Topic 5a- The Nervous System Flashcards

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1
Q

Why is it essential that the conditions in the body e.g. temperature and pH are kept constant?

A

The conditions inside your body need to be kept STEADY, even when the EXTERNAL ENVIRONMENT CHANGES.

This is really important because your CELLS need the RIGHT CONDITIONS in order to FUNCTION PROPERLY , including the right conditions for ENZYME ACTION.

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2
Q

How are the conditions inside the body kept constant?

A

HOMEOSTASIS is the way in which everything is kept at the right level.

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3
Q

Define homeostasis.

A

Homeostasis is 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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4
Q

What does homeostasis do for the body?

A

Cells in the body can only survive within narrow physical and chemical limits.

Homeostasis maintains optimal conditions for enzyme action and all cell functions.

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5
Q

Give some examples of conditions in your internal environment that need regulating and maintaining.

A
  • Body temperature (37℃)
  • Water levels
  • Ion levels
  • Glucose levels
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6
Q

What controls these conditions?

A

These conditions are controlled automatically (without any thought) so are called AUTOMATIC CONTROL SYSTEMS.

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7
Q

What are automatic control systems?

A

You have loads of automatic control systems in your body that regulate your internal environment- these include both NERVOUS and HORMONAL (chemical) communication systems.

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8
Q

What do control systems maintain/control?

A

There are control systems that maintain your:

1) Body temperature
2) Blood glucose concentration
3) Water levels

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9
Q

What do control systems consist of?

A

All your automatic control systems are made up of THREE MAIN COMPONENTS which work together to maintain a steady condition-cells called RECEPTORS, COORDINATION CENTRES (including the brain, spinal chord and pancreas) and EFFECTORS.

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10
Q

What mechanism is used by the automatic control system?

A

Your automatic control systems keep your internal environment stable using a mechanism called NEGATIVE FEEDBACK.

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11
Q

What is the function of negative feedback?

A

When the level of something (e.g. water or temperature) gets TOO HIGH or TOO LOW your body uses negative feedback to bring it back to NORMAL.

So negative feedback COUNTERACTS CHANGE.

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12
Q

What is a stimulus?

A

A change in your environment that you might need to respond to is a STIMULUS.

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13
Q

What are the 6 different types of stimuli?

A
  • Light
  • Sound and balance
  • Pressure
  • Pain
  • Chemicals
  • Change in temperature
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14
Q

What are the role of receptors in negative feedback?

A

The receptors of an automatic control system DETECT a STIMULUS when the level of something (e.g. water or temperature) is too high or too low.

They then SEND this INFORMATION the the COORDINATION CENTRE.

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15
Q

What is the role of the coordination centre in negative feedback?

A

The coordination centre PROCESSES the INFORMATION and ORGANISES a RESPONSE from the EFFECTORS.

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16
Q

What is the role of effectors in negative feedback?

A

The effectors respond to COUNTERACT the CHANGE- bringing the level back to its OPTIMUM.

(The mechanism that restores the optimum level is called a negative feedback mechanism).

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17
Q

How long do the effectors produce responses?

A

The EFFECTORS will just carry on producing the responses for as long as they’re STIMULATED by the COORDINATION CENTRE. This might cause the OPPOSITE PROBLEM-making the level change TOO MUCH (away from the ideal). Luckily the RECEPTOR detects if the level becomes TOO DIFFERENT and negative feedback starts again.

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18
Q

What type of process is negative feedback?

A

This process happens without you thinking about it- it’s all AUTOMATIC.

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19
Q

What is the purpose of the nervous system?

A

Organisms need to respond to STIMULI (changes in the environment) in order to survive. A SINGLE-CELLED organism can just RESPOND to its environment, but the cells of MULTICELLULAR organisms need to COMMUNICATE with each other first.

So as multicellular organisms evolved, they developed NERVOUS and HORMONAL COMMUNICATION SYSTEMS.

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20
Q

What does your nervous system do?

A

Your nervous system is what allows you to REACT to your SURROUNDINGS.

It also allows you to COORDINATE you BEHAVIOUR.

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21
Q

What is the nervous system made up of?

A

The nervous system is made up of all the NEURONES (nerve cells) in your body.

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22
Q

What is stimuli?

A

Stimuli are changes in environment.

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23
Q

What are receptors?

A

Receptors are the cells that DETECT STIMULI.

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24
Q

Name some receptors found in humans.

A
  • Light/photoreceptors in the eyes.
  • Chemoreceptors in the nose and tongue
  • Sound receptors in the ears
  • Thermoreceptors in the skin detect temp.

Receptors can form part of larger, complex organs, e.g. the retina in the eye is covered in light receptor cells.

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25
Q

What is the purpose of the brain, spinal chord and pancreas?

A

-Coordination centres (such as the brain, spinal cord and pancreas) that receive and process information from receptors.

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26
Q

What is the central nervous system?

A

The central nervous system (CNS) receives all the information sent from the RECEPTORS, and is where reflexes and actions are coordinated. The response is carried out by EFFECTORS.

So it’s a COORDINATION CENTRE.

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27
Q

What does the CNS consist of in vertebrates and mammals?

A

In vertebrates (animals with backbones) this consists of the BRAIN and the SPINAL CHORD only.

In mammals, the CNS is connected to the body by SENSORY NEURONES and MOTOR NEURONES. Neurones transmit information as ELECTRICAL IMPULSES to and from the CNS.

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28
Q

Where are the instructions from the CNS sent to?

A

‘Instructions’ from the CNS are sent along neurones to EFFECTORS.

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29
Q

What is the role of effectors in coordinating a response to the stimuli?

A

Effectors are MUSCLES or GLANDS which respond to nervous impulses and bring about a response to a stimulus.

Muscles and glands respond to nervous impulses in different ways:

  • MUSCLES CONTRACT
  • Glands SECRETE chemical substances called HORMONES.
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30
Q

Name the 3 types of neurone involved in the transfer of information to and from the CNS.

A
  1. Sensory neurone
  2. Relay neurone
  3. Motor neurone
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31
Q

What is the function of the sensory neurone?

A

The neurones that carry information as electrical impulses from the RECEPTORS in the sense organs to the central nervous system.

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32
Q

What is the function of the relay neurone?

A

The NEURONES that carry electrical impulses from the sensory neurones to motor neurones. They are found in the central nervous system.

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33
Q

What is the function of the motor neurone?

A

The neurones that carry electrical impulses from the central nervous system to the effectors.

The effectors are all your MUSCLES and GLANDS, which respond to nervous impulses.

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34
Q

Summarise the transmission of information to and from the CNS.

A

Sensory Relay Motor
neurone neurone neurone
stimulus ͢ receptor ͢ coordinator ͢ effector
͢ response

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35
Q

What are synapses?

A

The CONNECTION (gap) between TWO NEURONES is called a SYNAPSE.

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36
Q

How do nerve impulses travel between two neurones?

A

The nerve signal is transferred by CHEMICALS called a NEUROTRANSMITTER which DIFFUSES (move) across the gap.

These chemicals then set off a NEW ELECTRICAL SIGNAL in the NEXT neurone.

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37
Q

What are reflexes?

A

Reflexes are RAPID, AUTOMATIC responses to certain stimuli that DON’T INVOLVE the CONSCIOUS part of the brain-they can reduce the chances of being injured.

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38
Q

Explain the reflex action in the eye when a bright light is shone into them.

A

If someone shines a bright light in your eyes, your pupils automatically get smaller. This means that less light gets into your eyes, which stops them getting damaged.

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39
Q

What is a reflex arc?

A

The passage of information in a reflex (from receptor to effector) is called a REFLEX ARC.

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40
Q

Do reflex arc travel through the conscious part of the brain?

A

No- reflex actions are rapid, so you don’t have to think about them, so it doesn’t go through the conscious part of the brain.

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41
Q

What do neurones in a reflex arc go through?

A

The neurones in reflex arcs go through the spinal cord or through an unconscious part of the brain.

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42
Q

Describe the main stages in a reflex arc.

A
  1. When a STIMULUS (e.g. a painful bee sting) is detected by receptors, IMPULSES are sent along a SENSORY NEURONE to a RELAY NEURONE in the CNS.
  2. When the impulses reach a SYNAPSE between the sensory neurone and the relay neurone, they trigger chemicals to be released.

These chemicals cause impulses to be sent along the RELAY NEURONE.

  1. When the impulses reach a SYNAPSE between the relay neurone and a motor neurone, the same thing happens. Chemicals are released and cause impulses to be sent along the MOTOR NEURONE.
  2. The impulses then travel along the motor neurone to the EFFECTOR (which is usually a MUSCLE, like in this example).
  3. The MUSCLE then CONTRACTS and moves your hand away from the bee.
  4. Because you don’t have to think about the response (which takes time) it’s QUICKER than normal responses.
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43
Q

If a bee sting a person’s finger, the reflex response is that the hand moves away from the source of pain.

Describe the pathway taken by this reflex arc.

A
  1. Bee stings finger.
  2. Stimulation of the pain receptor.
  3. Impulses travel along the sensory neurone.
  4. Impulses are passed along a relay neurone, via a synapse.
  5. Impulses travel along a motor neurone, via a synapse.
  6. When impulses reach the muscle, it contracts.
  7. The hand moves away from the source of pain.
44
Q

why are reflex actions important?

A

Reflexes are AUTOMATIC (you don’t have to think about them) and RAPID so they’re often able to PREVENT or REDUCE the chance of INJURY.

45
Q

What is reaction time?

A

Reaction time is the time it takes to RESPOND to a STIMULUS- it’s often LESS than a SECOND.

46
Q

What is reaction time affected by?

A

It can be AFFECTED by factors such as AGE, GENDER or DRUGS.

The type of stimulus (e.g. whether you see, hear or touch it) can also affect the reaction time.

47
Q

Caffeine is a drug that can SPEED UP a person’s reaction time.
How can the effect of caffeine on reaction time be measured?

A

1) The person being tested should sit with their arm resting on the edge of a table (this should stop them moving their arm up or down during the test).

2) Hold a RULER vertically between their thumb and forefinger. Make sure that the ZERO END of the ruler is level with their thumbs and finger.
Then LET GO without giving any warning.

3) The person being tested should try to CATCH THE RULER as quickly as they can-as soon as they see it fall.
4) Reaction time is measured by the NUMBER on the ruler where it’s caught. The number should be read from the TOP of the THUMB. The further down the ruler it’s caught (i.e. the higher the number), the slower the reaction time.
5) Repeat the test several times, then calculate the MEAN DISTANCE that the ruler fell.
6) The person being tested should then have a CAFFEINATED DRINK (e.g. 300ml of cola). After TEN MINUTES, repeat steps 1-5.

48
Q

How can you ensure that the investigation of reaction time is a fair test?

A

You need to CONTROL ANY VARIABLES to make sure the test is fair.

49
Q

What are the control variables for reaction time investigation?

A
  • You should use the same person to catch the ruler each time.
  • That person should always use the same hand to catch the ruler.
  • The ruler should always be dropped from the same height.
  • You should make sure that the person being tested has not had any caffeine (or anything else that may affect their reaction time) before the start of the experiment.
50
Q

What’s the risk assessment for the reaction time experiment?

A

1) Any drinks need to be consumed outside the lab, away from any chemicals or other hazards.
2) Also, too much caffeine can cause UN-PLEASANT SIDE-EFFECTS, so the person being tested should avoid drinking any MORE CAFFEINE for the rest of the day after the experiment.

51
Q

How can you measure reaction time using a computer?

A

1) Simple COMPUTER TESTS can also be used to measure reaction time.

For example, the person being tested ha to CLICK THE MOUSE (or PRESS a KEY) as soon as they see a stimulus on the screen, e.g. a box CHANGE COLOUR.

52
Q

What are the advantages of using a computer to measure reaction time?

A

Computers can give a MORE PRECISE reaction time- because they remove the possibility of HUMAN ERROR from the measurement.

The computer can record the time in MILLISECONDS, it can also give a more ACCURATE measurement.

Using a computer removes the possibility that the person can PREDICT when to respond- using the ruler test, the catcher may learn to ANTICIPATE the drop by reading the tester’s BODY LANGUAGE.

53
Q

What is the function of the brain?

A

The brain controls complex behaviour. It controls and coordinates everything you do.

Along with the spinal cord, the brain is part of the CENTRAL NERVOUS SYSTEM.

54
Q

What is the structure of the brain?

A

It is made of BILLIONS of INTERCONNECTED NEURONES and has different regions that carry out different functions.

55
Q

What are the three regions of the brain you need to know called?

A

1) Cerebral cortex
2) Medulla
3) Cerebellum

56
Q

What is the function of the cerebral cortex and where is it located on the brain?

A

Cerebral cortex:

  • This is the outer wrinkly bit. It’s responsible for things like CONSCIOUSNESS, INTELLIGENCE, MEMORY and LANGUAGE.
  • It’s located towards the front of the brain.
57
Q

What is the function of the medulla and where is it located on the brain?

A

Medulla:

  • Controls UNCONSCIOUS ACTIVITIES (things you don’t have to think about doing) like BREATHING and your HEARTBEAT.
  • Found opposite, next to the spinal cord.
58
Q

What is the function of the cerebellum and where is it located on the brain?

A

Cerebellum:

  • It’s responsible for MUSCLE COORDINATION.
  • The cerebellum is found at the BACK of the brain.
59
Q

How have neuroscientists been able to map the regions of the brain to particular functions by studying patients with brain damage?

A

If a SMALL part of the brain has been DAMAGED, the EFFECT this has on the patient can tell you a lot about what the damaged part of the brain does.

E.g. if an area at the back of the brain was damaged by a stroke and the patient went BLIND, you know that, that area has something to do with VISION.

60
Q

How have neuroscientists been able to map the regions of the brain to particular functions by electrically stimulating different parts of the brain?

A

The brain can be STIMULATED ELECTRICALLY by pushing a tiny ELECTRODE into the tissue and giving it a small zap of electricity. By observing what stimulating DIFFERENT PARTS of the brain does, it’s possible to get an idea of what those parts do.

E.g. when a certain part of the brain (known as the MOTOR AREA) is stimulated, it causes MUSCLE CONTRACTION and MOVEMENT.

61
Q

How have neuroscientists been able to map the regions of the brain to particular functions by using MRI scanning techniques?

A

A magnetic resonance imaging (MRI) scanner is a big fancy tube-like machine that can produce a very DETAILED PICTURE of the brain’s structures.

Scientists use it to find out what areas of the brain are ACTIVE when people are doing things like listening to music or trying to recall a memory.

62
Q

Explain some of the difficulties of investigating brain function and treating brain damage and disease.

A

1) Knowledge of how the brain works has led to the development of TREATMENTS for DISORDERS of the nervous system.

For example, ELECTRICAL STIMULATION of the brain can help reduce MUSCLE TREMORS caused by nervous system disorders such as Parkinson’s disease.

2) However, the brain is incredibly COMPLEX and DELICATE- the investigation of brain function and any treatment of rain damage or disease is difficult.

It also carries RISKS, such as PHYSICAL DAMAGE to the brain or INCREASED PROBLEMS with brain function (e.g. difficulties with speech).

63
Q

What is the structure of the eye?

A

The eye has the following parts:

1) SCLERA- the TOUGH, SUPPORTING WALL of the eye.
2) CORNEA- the TRANSPARENT outer layer found at the FRONT of the eye. It REFRACTS (bends) light into the eye.
3) PUPIL- the HOLE in the centre of the eye, through which light enters.
4) IRIS- contains MUSCLES that allow it to control the DIAMETER of the PUPIL (the HOLE in the MIDDLE) and therefore HOW MUCH LIGHT enters the eye.
5) LENS- FOCUSES the LIGHT onto the RETINA (which contains receptor cells sensitive to LIGHT INTENSITY and COLOUR).
6) CILIARY MUSCLES and SUSPENSORY LIGAMENTS- control the shape of the lens.
7) OPTIC NERVE- carries impulses from the receptor on the retina to the brain.

64
Q

What are the two functions of the eye?

A
  • accommodation to focus on near or distant objects

* adaptation to dim light.

65
Q

What is the iris reflex?

A

VERY BRIGHT light can DAMAGE the retina- so you have a reflex to protect it.

66
Q

How does the iris reflex protect the eye from damage from bright light?

A

1) When LIGHT RECEPTORS in the eye detect very bright light, a REFLEX is triggered that makes the pupil SMALLER. The CIRCULAR MUSCLES in the iris CONTRACT and the RADIAL MUSCLES RELAX. This reduces the amount of light that can enter the eye.
2) The opposite process happens in dim light. This time, the RADIAL MUSCLES contract and the CIRCULAR MUSCLES relax, which makes the pupil WIDER.

67
Q

Explain the iris reflex in terms of a reflex reaction.

A

In terms of a reflex reaction, the light receptors in the retina detect the bright light and send a message along a sensory neurone to the CNS. The message then travels along a relay neurone in the CNS to a motor neurone cut which tells circular muscles in the iris to contract, making the pupil smaller.

68
Q

How does the eye focus on near and distant objects?

What is this called?

A

The eye focuses light on the retina by CHANGING the SHAPE of the LENS- this is known as ACCOMMODATION.

This is a REFLEX as it’s an automatic reaction, not controlled by the conscious brain.

69
Q

How do you look at near objects?

A

1) The CILIARY MUSCLES RELAX, which allows the SUSPENSORY LIGAMENTS to PULL TIGHT.
2) This makes the lens go THIN (less curved).
3) So it REFRACTS light by a SMALLER amount.

70
Q

How do you look at distant objects?

A

1) The CILIARY MUSCLES RELAX, which allows the SUSPENSORY LIGAMENTS to PULL TIGHT.
2) This makes the lens go THIN (less curved).
3) So it REFRACTS light by a SMALLER amount.

71
Q

What is the eye?

A

The eye is a sense organ containing receptors sensitive to light intensity and colour.

72
Q

Why do people have problems with their vision?

A

If the lens cannot refract the light by the RIGHT AMOUNT (so that it focuses on the RETINA), the person will be SHORT or LONG-SIGHTED.

73
Q

What does long-sighted mean?

A

Long-sighted people are UNABLE TO FOCUS on NEAR objects.

74
Q

What causes people to be long-sighted?

A

1) This occurs when the LENS is the wrong shape and doesn’t REFRACT (bend) the light enough or the EYEBALL is too SHORT.
2) The images of near object are brought into focus BEHIND the RETINA.

75
Q

What is the medical term for long-sightedness?

A

The medical term for long-sightedness is HYPEROPIA.

76
Q

How can you correct long-sightedness?

A

You can use glasses with a CONVEX LENS (a lens which CURVES INWARDS) to correct it. The lens REFRACTS the light rays so they focus on the RETINA.

77
Q

What does short-sighted mean?

A

Short-sited people are UNABLE TO FOCUS on DISTANT objects.

78
Q

What causes people to be short-sighted?

A

1) This occurs when the LENS is the wrong shape and refracts the light TOO MUCH or the EYEBALL is too LONG.
2) The images of distant objects are brought into focus IN FRONT of the RETINA.

79
Q

How can you correct short-sightedness?

A

You can use glasses with a CONCAVE LENS (a lens which CURVES INWARDS) to correct it, so that the light rays focus on the RETINA.

80
Q

What is the medical term for short-sightedness?

A

The medical term for short-sightedness is MYOPIA.

81
Q

Where is the image of a near object brought into focus in a long-sighted eye?

A

Images are brought into focus behind the retina.

82
Q

Other than glasses, how else can vision be corrected?

A
  • Contact lenses
  • Laser eye surgery
  • Replacement lens surgery
83
Q

What are contact lenses?

A

Contact lenses are thin lenses that sit on the SURFACE of the eye and are shaped to COMPENSATE for the fault in focusing.

84
Q

Why are contact lenses popular?

A

They’re popular because they are LIGHTWEIGHT and almost INVISIBLE.

They’re also more CONVENIENT than glasses for activities like SORTS.

85
Q

What are the 2 main types of contact lenses?

A

The two main types of contact lenses are HARD LENSES and SOFT LENSES.

Soft lenses are generally more COMFORTABLE, but carry a higher risk of EYE INFECTION than hard lenses.

86
Q

What is involved in laser eye surgery?

A

Bad eyesight can sometimes be corrected with LASER EYE SURGERY.

A laser can be used to VAPORISE TISSUE, changing the SHAPE of the cornea (and so changing how strongly it refracts light into the eye).

The surgeon can PRECISELY control how much tissue the laser takes off, completely correcting the vision.

87
Q

How is laser eye surgery performed on a person who’s short-sighted?

A

SLIMMING IT DOWN makes it LESS POWERFUL and can improve SHORT SIGHT.

88
Q

How is laser eye surgery performed on a person who’s long-sighted?

A

Changing the shape so that it’s MORE POWERFUL will improve LONG SIGHT.

89
Q

What are the risks of laser eye surgery?

A

However, like all SURGICAL PROCEDURES, there is a risk of COMPLICATIONS, such as an eye infection or the eye reacting in a way that makes your vision worse than before.

90
Q

Name one surgical technique that can permanently correct long or short-sightedness.

A

Replacement lens surgery

91
Q

What does replacement lens surgery treat?

A

Sometimes LONG-sightedness may be more effectively treated by REPLACING the lens of the eye (rather than altering the shape of the cornea with laser eye surgery).

92
Q

What does replacement lens surgery involve?

A

The natural lens of the eye is REMOVED and an ARTIFICIAL LENS, made of CLEAR PLASTIC, is inserted in its place.

93
Q

What are the risks involved in replacement lens surgery?

A

As it involves working INSIDE the eye, replacing a lens carries HIGHER RISKS than laser eye surgery, including possible damage to the RETINA (which could lead to loss of sight).

94
Q

Why is it important that the body temperature is kept constant?

A

Body temp needs to be kept at around 37℃ (because this is the temperature at which enzymes in the human body work best).

95
Q

What must be kept balanced to maintain a constant body temp?

A

The body temp must be carefully monitored and controlled- the body has to constantly BALANCE the amount of ENERGY GAINED (e.g. through respiration) and LOST to keep the CORE BODY TEMPERATURE CONSTANT.

96
Q

What monitors and controls body temperature in the human body?

A

There is a THERMOREGULATORY CENTRE in the HYPOTHALAMUS of the BRAIN. This acts as a thermostat.

97
Q

How does the thermoregulatory centre in the brain control body temp?

A

In order to control body temp it receives information about body temp from receptors-groups of cells which are sensitive to stimuli. These include:

  1. RECEPTORS in the THERMOREGULATORY CENTRE that are sensitive to the temperature of the BLOOD flowing through the brain.
  2. The thermoregulatory centre also receives impulses from TEMPERATURE RECEPTORS in the SKIN, giving info about SKIN TEMPERATURE.
98
Q

Describe the pathway response from receptors to effectors when core body temp is too high.

A
  1. TEMPERATURE RECEPTORS detect that core body temperature is TOO HIGH.
  2. The THERMOREGULATORY CENTRE acts as a COORDINATION CENTRE- it receives information from the temperature receptors and TRIGGERS the EFFECTORS automatically.
  3. EFFECTORS e.g. sweat glands, produce a RESPONSE and COUNTERACT the change.
99
Q

Describe the pathway response from receptors to effectors when core body temp falls.

A
  1. TEMPERATURE RECEPTORS detect that core body temperature is TOO LOW.
  2. The THERMOREGULATORY CENTRE acts as a COORDINATION CENTRE- it receives information from the temperature receptors and TRIGGERS the EFFECTORS automatically.
  3. EFFECTORS e.g. muscles, produce a RESPONSE and COUNTERACT the change.
100
Q

How do some effectors work to produce a very precise temperature?

A

Some effectors work ANTAGONISTICALLY, e.g. one effector heats and another cools- they’ll work at the same time to achieve a very precise temperature.

This mechanism allows a MORE SENSITIVE RESPONSE.

101
Q

How is body temp controlled?

A

The body temp is kept at a constant level due to a NEGATIVE FEEDBACK SYSTEM- if it gets too high or too low, the body responds to bring the temp back to optimum.

102
Q

Explain the response of effectors when the body temp is too hot?

(OFTEN EXAM QUESTION)

A
  1. Hairs on the skin lie FLAT. This means LESS AIR is trapped near the surface of the skin, so there isn’t a layer of INSULATING air surrounding the skin. This allows heat to be transferred to the environment more easily.
  2. SWEAT is produced by sweat glands and EVAPORATES from the skin. This transfers energy to the ENVIRONMENT.
103
Q

What do the effectors cause the blood vessels supplying the skin capillaries to do when you get too hot?

(OFTEN EXAM QUESTION)

A

The BLOOD VESSELS supplying the skin DILATE (get wider) so more blood flows close t the surface of the skin. This is called VASODILATION.

This helps TRANSFER ENERGY from the skin to the environment.

104
Q

Explain the response of effectors when the body temp is too cold.

A
  1. Hairs on skin stand up. This traps an INSULATING LAYER of AIR next to the skin, reducing the amount of energy transferred to the environment.
  2. NO SWEAT is produced.
  3. When you’re COLD you SHIVER (your muscles contract automatically). This needs RESPIRATION, which transfers some ENERGY to WARM the body.
105
Q

What do the effectors cause the blood vessels supplying the skin capillaries to do when you get too cold?

How does this help increase body temp?

(OFTEN EXAM QUESTION)

A
  • Blood vessels supplying skin capillaries CONSTRICT (get narrower) to REDUCE the skin’s blood supply. This is called VASOCONSTRICTION.
  • It reduces the amount of blood that flows close to the surface of the skin and so less energy is transferred from the skin to the environment.

Biology GCSE Paper 2 (3 decks)

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