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GCSE - Biology > 4. Nerves And Homeostasis > Flashcards

4. Nerves And Homeostasis Flashcards

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1
Q

What is a stimulus?

A

A change in your environment (which you may need to react to).

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2
Q

What are the five sense organs?

A

1) Eyes
2) Ears
3) Nose
4) Tongue
5) Skin

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3
Q

What are receptors?

A

Groups of cells which are sensitive to stimuli.

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4
Q

What do receptors do?

A

They convert the stimulus energy into electrical impulses.

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5
Q

Are sense organs the same as receptors?

A

No, sense organs usually contain the receptors (e.g. The eye contains light receptors)

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6
Q

What receptors do the eyes contain and what stimulus are they sensitive to?

A

Light receptors - sensitive to light

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7
Q

What receptors do the ears contain and what stimulus are they sensitive to?

A

Sound receptors - sensitive to sound

Balance receptors - sensitive to changes in position

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8
Q

What receptors does the nose contain and what stimulus are they sensitive to?

A

Smell receptors - sensitive to chemical stimuli

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9
Q

What receptors does the tongue contain and what stimulus are they sensitive to?

A

Taste receptors - sensitive to chemical stimuli

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10
Q

What receptors does the skin contain and what stimulus are they sensitive to?

A

Touch receptors - sensitive to touch, pressure, pain and temperature change.

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11
Q

What are some examples of stimuli?

A
  • Light
  • Sound
  • Touch
  • Pressure
  • Pain
  • Chemical
  • A change in position or temperature
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12
Q

Are light receptors cells the same as normal cells?

A

Yes, they have a nucleus, cytoplasm and cell membrane.

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13
Q

What does the CNS consist of?

A

The brain and spinal cord ONLY.

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14
Q

What does CNS stand for?

A

Central Nervous System

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15
Q

How is a stimulus processed?

A
  • Receptor cells detect a stimulus
  • Information as electrical impulses is sent to the coordination centres in the CNS via a neurone
  • A response is coordinated in the brain
  • A neurone transmits instructions to the effectors
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16
Q

What are neurones?

A

Nerve cells which carry signals around the body.

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17
Q

What is a sensory neurone?

A

Nerve cells that carry signals from the receptors to the CNS.

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18
Q

What is a relay neurone?

A

Nerve cells that carry signals from sensory neurones to motor neurones.

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19
Q

What is a motor neurone?

A

Nerve cells that carry signals from the CNS to the effector muscles or glands.

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20
Q

What is an effector?

A

Muscles and glands which respond to a stimulus.

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21
Q

How do muscles respond to a stimulus?

A

They contract.

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22
Q

How do glands respond to a stimulus?

A

They secrete chemicals (hormones).

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23
Q

What are control systems?

A

Automatic control systems help to keep conditions constant by responding to stimuli.

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24
Q

What are the parts of a control system?

A

Receptors -> Coordination centres -> Effectors

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25
Q

What is the fastest way for the body to respond to a stimulus?

A

Reflex reactions. They are quicker than normal responses, since you don’t have to think about the response.

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26
Q

What is the connection between two neurones called?

A

A synapse.

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27
Q

What is a synapse?

A

The connection between two neurones.

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28
Q

How is a nerve signal transmitted across a synapse?

A

Chemicals, which diffuse across the gap.

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29
Q

How fast is transmission across a synapse?

A

It is slower than in the neurones, because the diffusion takes time.

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30
Q

What are reflexes?

A

Automatic, rapid responses to certain stimuli.

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31
Q

What are reflex reactions used for?

A

To reduce the chance of injury.

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32
Q

Give an example of a reflex reaction.

A

If someone shines a bright light in your eye, your pupils automatically get smaller to stop the eye being damaged.

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33
Q

What is the path of a reflex reaction called?

A

A reflex arc.

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34
Q

Describe a reflex arc.

A

1) Stimulus is detected by the receptors
2) Impulse is sent along sensory neurone
3) Impulse passes across a synapse to relay neurone as chemical signal
4) Impulse travels along relay neurone
5) Impulse passes across a synapse to motor neurone as chemical signal
6) Impulse reaches effector and a response happens

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35
Q

Does a reflex arc go through the CNS?

A

Yes, the neurones gone through the spinal cord or an unconscious part of the brain.

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36
Q

Compare a reflex reaction and a normal response or behaviour.

A

Both pass through the CNS, except the reflex reaction doesn’t go to a conscious part of the brain.

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37
Q

What is the brain made of?

A

Billions of interconnected neurones.

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38
Q

What behaviours is the brain in charge of?

A

Complex behaviours.

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39
Q

What are the 3 parts of the brain?

A
  • Cerebral cortex
  • Medulla
  • Cerebellum
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40
Q

Where is the cerebral cortex?

A

Top, outer part of the brain. (Pg 45 diagram)

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41
Q

Where is the medulla?

A

Bottom, near the spinal cord. In front of the cerebellum. (Pg 45 diagram)

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42
Q

Where is the cerebellum?

A

Back, bottom, behind the spinal cord and medulla. (Pg 45 diagram)

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43
Q

What is the cerebral cortex responsible for?

A

Consciousness, intelligence, memory and language.

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44
Q

What is the medulla responsible for?

A

Unconscious activities - e.g. Breathing and heart rate

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45
Q

What is the cerebellum responsible for?

A

Muscle coordination (movement).

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46
Q

What 3 methods can be used to study the brain?

A

1) Studying patients with brain damage
2) Electrically stimulating the brain
3) MRI scans

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47
Q

How can studying patients with brain damage be used to study the brain?

A

If a small part of the brain is damaged, the effect on the patient can tell you what that part does.

48
Q

How can electrically stimulating the brain be used to study the brain?

A

When a part of the brain is stimulated, the effect can be observed and what that part does can be worked out.

49
Q

How can the brain be stimulated electrically?

A

By pushing a tiny electrode into the tissue and passing electricity through it.

50
Q

How can MRI scans be used to study the brain?

A

An MRI scanner can produce detailed images of the brain’s structures. It can be used to see which parts of the brain are active when a patient is doing a certain activity.

51
Q

What does an MRI scanner do?

A

Produces a detailed image of the brain’s structures.

52
Q

What does MRI stand for?

A

Magnetic Resonance Imaging

53
Q

What is homeostasis?

A

The process of maintaining a constant internal environment.

54
Q

What are some bodily levels that need to be controlled?

A
  • Ions content
  • Water content
  • Temperature
  • Sugar content
55
Q

What are bodily levels (e.g. water content) kept constant by?

A

Automatic control systems.

56
Q

What are the effectors in homeostasis usually?

A

Glands

57
Q

What are hormones and how do they work in homeostasis?

A
  • Chemicals substances secreted by glands

- Carried in blood to other parts of the body, but only affect particular cells (target cells)

58
Q

How are ions taken into the body?

A

In food.

59
Q

What happens when too much of an ion is taken into the body?

A

The excess needs to be removed.

60
Q

What are the ways in which ions can be removed from the body?

A
  • Sweat

* In the kidneys (as urine)

61
Q

What organ regulates ion content?

A

Kidneys

62
Q

How is water taken into the body?

A

Food and drink

63
Q

How is water lost from the body?

A
  • Sweat
  • Breath
  • Urine
  • Faeces
64
Q

How do the liver and kidneys work together to remove waste?

A
  • Liver breaks waste products into less harmful products

- Kidney then remove these in the urine

65
Q

What two main things is the liver responsible for?

A

Deamination and detoxification (see pg 47)

66
Q

What is deamination?

A

The liver breaking down amino acids into ammonia. This ammonia is then converted into urea which can be excreted.

67
Q

Why must deamination happen?

A

It gets rid of excess amino acids, which can be damaging if they stay in the body.

68
Q

What is detoxification?

A

The liver breaking harmful substances (e.g. alcohol, drugs and unwanted hormones) down into less harmful substances that are then excreted in the urine.

69
Q

Which substances does the liver break down?

A
  • Amino acids -> Ammonia ( -> Urea)
  • Alcohol, drugs and unwanted hormones
  • Old blood cells
70
Q

What does the liver do with old RBCs?

A

They are removed and the iron in them is stored.

71
Q

What do the kidneys do?

A

1) Filter the blood
2) Reabsorb needed products
3) Release urea, excess ions and excess water as urine

72
Q

What are nephrons?

A

Filtration units in the kidneys

73
Q

What are the filters in the kidneys called?

A

Nephrons

74
Q

In detail, how are substances absorbed and reabsorbed into the nephrons?

A
  • High pressure is built up
  • Small molecules fit through filter and are forced into the nephron
  • Larger molecules cannot fit and so stay in the blood
  • Useful substances are selectively reabsorbed into the blood (using active transport for sugar and ions)
  • Those which are not reabsorbed stay in the kidney and are stored in the bladder
75
Q

Which molecules are and are not absorbed in the kidneys?

A 
ABSORBED
• Water / Salt
• Urea
• Ions
• Amino acids
• Ammonia
• Sugar
NOT ABSORBED
• Cells
• Protein
76
Q

Which molecules are reabsorbed and not reabsorbed in the kidneys?

A 
REABSORBED
• Sugar
• Amino acids
• SOME Ions
• SOME Water / Salts
NOT REABSORBED
• Ammonia
• Urea
• SOME Ions
• SOME Water / Salts
77
Q

How is sugar reabsorbed into the blood from the kidneys?

A

Using active transport (since it is against the concentration gradient).

78
Q

How are ions reabsorbed into the blood from the kidneys?

A

Using active transport (since it is against the concentration gradient).

79
Q

What happens to molecules which are not reabsorbed from the kidneys?

A

They continue out of the nephron, into the ureter and down to the bladder as urine.

80
Q

Why must water concentration in the blood plasma be kept constant?

A
  • Prevents too much water moving into or out of the tissues by osmosis
  • Keeps blood pressure constant
81
Q

What controls the amount of water reabsorbed from the kidney nephrons?

A

ADH (Anti-diuretic hormone)

82
Q

What is ADH?

A

Anti-diuretic hormone

83
Q

How does ADH work?

A

It makes the nephrons more permeable so that more water is reabsorbed back into the blood.

84
Q

What is the coordination centre for water content in the blood?

A

The brain.

85
Q

How does the brain control blood water content?

A
  • The brain monitors the water content of the blood
  • The brain instructs the pituitary gland to release ADH
  • This regulates the blood water concentration
86
Q

What happens when water content of the blood get too low?

A
  • Brain detects lack of water
  • Brain instructs pituitary gland to release more ADH
  • Kidneys reabsorb more water
87
Q

What happens when the water content of the blood gets too high?

A
  • Brain detects excess water
  • Brain instructs pituitary gland to release less ADH
  • Kidneys reabsorb less water
88
Q

How does heat affect the urine produced and why?

A
  • Heat causes you to sweat, which loses water
  • This means more water needs to be reabsorbed into the blood
  • Therefore, less water is lost through urine, making the urine more concentrated
89
Q

How does exercise affect the urine produced and why?

A
  • Exercise causes you to sweat, which loses water
  • This means more water needs to be reabsorbed into the blood
  • Therefore, less water is lost through urine, making the urine more concentrated
90
Q

How does water intake affect the urine produced and why?

A
  • Not drinking enough will produce concentrated urine, since there is little excess water that needs to be lost
  • Drinking too much will produce dilute urine, since there is a lot of water that needs to be lost
91
Q

What happens if the kidneys stop working?

A

Waste substances build up in the blood and you can’t control ion and water levels in the blood. This can lead to death.

92
Q

What are the two methods of treating kidney failure?

A

1) Dialysis treatment

2) Kidney transplant

93
Q

What is dialysis treatment?

A

Filtering a patient’s blood using a machine instead of the kidneys.

94
Q

Why does dialysis have to be done regularly?

A

To keep concentrations of dissolved substances at normal levels and to remove waste.

95
Q

How does dialysis work?

A
  • Blood flows between partially permeable membranes, surrounded by dialysis fluid.
  • Dialysis fluid has the same concentration of ions and glucose as healthy blood.
  • This means only waste substances diffuse across the membrane.
  • The dialysis fluid is constantly pumped around to maintain a steady concentration gradient.
96
Q

How often is dialysis treatment required?

A

Most patients have it 3 times a week for 3-4 hours.

97
Q

What are the advantages and disadvantages of dialysis treatment?

A 
ADV.
• Can keep the patient alive until a donor organ is found
• No need for surgery
DIS.
• Not pleasant experience
• Takes a long time and is repetitive
• May cause blood clots or infections
• Expensive
98
Q

Where are donor kidneys taken from?

A
  • People who have recently died suddenly

* People who are still alive (since people have two kidneys)

99
Q

What are the advantages and disadvantages of kidney transplants?

A 
ADV.
• One time operation -> Permanent solution 
• Cheaper in the long term
DIS.
• Small risk to living donor
• Risk of operation
• Kidney may be rejected by patient
• Long waiting lists for kidneys
100
Q

Why is maintaining internal body temperature important?

A

Most enzymes work most efficiently at 37*C. If they cannot catalyse important reactions, it could even result in death.

101
Q

What part of the brain is responsible for controlling body temperature?

A

Thermoregulatory centre.

102
Q

How does the thermoregulatory centre control body temperature?

A
  • It contains receptors that are sensitive to the temperature of the blood flowing through the brain
  • It also receives impulses from receptors in the skin
  • It then controls the body’s responses
103
Q

How does the body respond to being too hot?

A

1) Hairs lie flat
2) Sweat is produced -> Evaporates, removing heat
3) Blood vessels supplying the skin capillaries dilate -> More blood flows close to surface

104
Q

How does the body respond to being too cold?

A

1) Hairs stand up on end -> Trap a layer of insulating air
2) No sweat produced
3) Blood vessels supplying skin capillaries constrict -> Less blood flows near surface
4) Shivering -> Heat released from respiration

105
Q

What are the two hormones involved in blood glucose control?

A

Insulin and glucagon

106
Q

How is glucose added and removed from the blood (not by hormones)?

A
  • Added by eating foods -> which are digested.

* Removed by cells -> where it is needed for respiration.

107
Q

How can excess glucose be stored?

A

1) As glycogen in the liver and muscles

2) When these stores are full -> As lipid (fat) in the tissues

108
Q

Which organ monitors blood glucose concentration?

A

Pancreas

109
Q

What is the response when blood glucose level gets too high?

A
  • Pancreas detects high level of glucose
  • Insulin is secreted into the blood by the pancreas
  • Insulin causes more glucose to be taken into liver and muscles, where it is stored as glycogen
  • This reduces blood glucose concentration
110
Q

What is the response when blood glucose level gets too low?

A
  • Pancreas detects low level of glucose
  • Glucagon is secreted into the blood by pancreas
  • Glucagon encourages glycogen to be converted to glucose and released into the blood
  • Blood glucose concentration increases
111
Q

What is diabetes?

A

A condition which affects your ability to control your blood sugar level.

112
Q

What is Type 1 diabetes?

A

Where the pancreas produces little or no insulin, meaning the blood glucose level can rise so high that it can kill the person.

113
Q

How can Type 1 diabetes be treated?

A
  • Having a carefully controlled diet and regularly exercising.
  • Injecting insulin -> This removes excess glucose
114
Q

What is Type 2 diabetes?

A

Where a person becomes resistant to their own insulin, which can cause blood glucose level to rise dangerously high.

115
Q

How can Type 2 diabetes be treated?

A
  • Having a carefully controlled diet -> Avoiding carbohydrate-rich foods
  • Exercise -> Keeps glucose levels low
  • Drugs -> Improve responsiveness to insulin
116
Q

Which type of diabetes is genetic and which can be developed?

A

Type 1 - Genetic

Type 2 - Can be developed (although partly genetic)

117
Q

What are some risk factors of developing Type 2 diabetes?

A
  • Obesity
  • Diet
  • Lack of exercise
  • Race
  • Genetics
  • Age

GCSE - Biology (11 decks)

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