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GCSE Triple Biology > Homoestasis > Flashcards

Homoestasis Flashcards

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1
Q

What is Homeostasis?

A

The regulation of the internal conditions of a cell or organism in to maintain optimum conditions for function in response to internal and external changes

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2
Q

What are the general features of an automatic control system?

A

Stimulus > Receptor Cells > Coordination centre > Effector > Response

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3
Q

What is a stimulus?

A

A change in the environment detected by receptor cells

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4
Q

Give one example of an internal and one external stimulus:

A

Internal:
- Blood Glucose Concentration

External:
- Temperature of Skin

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5
Q

What is the role of receptor cells?

A

To pass information on to the coordination centre

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6
Q

Give two examples of Coordination centres:

A

Brain
Spinal Cord
Pancreas

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7
Q

What is the role of the coordination centre

A

To recieve and process information from receptors and then send instructions to the effector

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8
Q

What is the role of the effector?

A

To carry out a response and restore optimum levels

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9
Q

What is a negative feedback loop?

A

A normal biological response in which the effects of a reaction slow or stop that reaction.

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10
Q

What are the 2 parts of the nervous system?

A
  • CNS which consists of the brain and spinal cord
  • Nerves that run to and from
    the CNS
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11
Q

A small bird is eating and it sees a cat walking towards it. Describe what happens between the bird spotting the cat and it flying away

A
  1. Receptors in the birds eye are stimulated
  2. Sensory Neurones carry info from the receptor to the CNS
  3. CNS recieves info and decides what to do then send info to the birds muscles via motor neurones
  4. The muscles contract and the bird flys away
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12
Q

Why are reflex actions faster than regular ones?

A

They bypass the concious part of the brain

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13
Q

What are the steps for a reflex action?

A
  1. Stimulus
  2. Sensory Neurone
  3. Relay Neurone
  4. Motor Neurone
  5. Effector
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14
Q

What happens at a synapse between a sensory and relay neurone

A

Nerve impulses trigger chemicals to be released which diffuse across the gap into the relay neurone

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15
Q

What are the chemical messengers released at synapses?

A

Neurotransmitters

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16
Q

What are the possible independent variables in the Reaction Times RP?

A

• The person having their RT tested
• Practise
• Which hand catches the ruler
• Effect of chemicals

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17
Q

What is the dependent variable in the Reaction Times RP?

A

• Reaction Time

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18
Q

What are the Control Variables in the Reaction Times RP?

A

• Distance between thumb and finger
• Take the measurement from the top of the thumb
• Conditions in the room

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19
Q

Describe an experiment that can be used to determine someone’s reaction time (RP)

A
  1. P1 sits on a stool and places their dominant hand across the table with their hand hanging over the edge
  2. P2 holds a ruler vertically with the 0cm mark between P1s thumb and first finger
  3. P2 tells P1 to prepare to catch the ruler, then drops the ruler at a random time
  4. P1 has to catch the ruler as quick as possible
  5. P2 records the measurement on the ruler that is level with the top of P1s thumb
  6. The results can be converted to a reaction time using a conversion table
  7. The experiment and a mean is calculated
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20
Q

Which is the Cerebellum?

A

3

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21
Q

Which is the Cerebral Cortex?

A

1

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22
Q

Which is the Medulla?

A

3

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23
Q

What is the function of the Brain?

A

Controls complex behaviour

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24
Q

True or False: The Brain is part of the Endocrine System

A

False, it’s part of the Central Nervous System

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25
Q

What is the job of the Cerebral Cortex?

A
  • Language
  • Memory
  • Conciousness
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26
Q

What is the job of the Cerebellum?

A
  • Balance
  • Coordinates movement
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27
Q

What is the job of the medulla?

A
  • Breathing
  • Heart rate
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28
Q

Give 3 reasons why the brain is difficult to treat/study

A
  1. It is encased in the skull so it’s hard to access
  2. The structures are complex, its hard to determine which bits carry out different functions
  3. It’s delicate and easily damaged
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29
Q

What are the three ways scientists study the brain?

A
  1. Look at patients who have study brain damage and link their impaired functions to the part of their brain that is damaged
  2. Electrically Stimulate parts of the brain and look at changes in the patient’s behaviour
  3. MRI Scanning can show what parts of the brain are active during certain activities
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30
Q

What is the Sclera?

A

The tough protective wall of the eye

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31
Q

What is role of the Cornea?

A

It refracts light into the eye

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32
Q

What is the Cornea?

A

Transparent outer layer at the front of the eye

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33
Q

What is the iris and its job?

A

The coloured part of the eye, it controls the diameter of the pupil

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34
Q

What does the lens do?

A

Focus light onto the retina

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35
Q

What does the Retina do?

A

Contains receptor cells sensitive to light intensity and color

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36
Q

What is the shape of the lens controlled by?

A

Ciliary muscles and suspensory ligaments

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37
Q

What is the job of the Optic Nerve?

A

Carries impulses from the retina to the brain

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38
Q

What is the pupil?

A

The space in the centre of the iris where light enters

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39
Q

What is the iris reflex?

A

A reflex action in response to very bright light that avoids damage to the eye

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40
Q

What happens to the radial muscles in bright light?

A

They relax and lenghten

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41
Q

What happens to the circular muscles in bright light?

A

They contract and shorten

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42
Q

What happens to the iris in bright light?

A

It gets smaller to stop lots of light getting in

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43
Q

What happens to the radial muscles in dim light?

A

They contract and shorten

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44
Q

What happens to the circular muscles in dim light?

A

They relax and lengthen

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45
Q

What happens to the iris in dim light

A

It gets bigger to let more light in

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46
Q

What happens in the eye when focusing on distant object?

A

The ciliary muscle relaxes, the suspensory ligaments tightened and the lens becomes thin

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47
Q

What happens in the eye when focusing on a near object?

A

The ciliary muscle contracts, the suspensory ligaments loosen and the lens becomes thick

48
Q

What is hyperopia?

A

Longsightedness

49
Q

What can’t long sighted people focus on?

A

nearby objects

50
Q

Why can’t hyperopic people focus on nearby objects?

A

The light focuses behind the retina

51
Q

Give two causes of hyperopia

A
  • The eyeball is too short
  • The lens is not elastic enough to focus
52
Q

What type of lenses treats hyperopia?

A

Convex

53
Q

What vision defect and what lens is this?

A

Hyperopia, Convex lens

54
Q

What is Myopia?

A

Shortsightenedness

55
Q

What can’t myopic people do?

A

Focus on far away objects

56
Q

Why can’t myopic people focus on far away objects?

A

Because the light focuses before the retina

57
Q

What causes myopia?

A
  • Eye is too long
  • Lens is too thick
58
Q

What lens treats myopia?

A

Concave

59
Q

What vision defect and what lens?

A

Myopia, Concave

60
Q

Name 2 pros and 2 cons of contact lenses:

A

PROS:
- Lightweight
- Invisible
- More convenient than glasses
- Comfortable
CONS
- Risk of eye infection
- Require more care than glasses

61
Q

2 Pros and 2 Cons of Laser eye surgery

A

Pros
- Easy, fast recovery
- Long lasting sight improvement
- Fast Results
- Painless
- No more glasses
Cons
- Risk of infection
- Risk of dry eye
- Risk of inflammation

62
Q

2 Pros and 2 Cons of Replacement Lens surgery:

A

PROS
- No more glasses
- Fast recovery
- Permanent improvement
CONS
- Possible damage to the retina
- Risk of infection

63
Q

What is the name of the centre that monitors and regulates body temperature?

A

Thermoregulatory centre

64
Q

Where is the thermoregulatory centre?

A

The brain

65
Q

Name two places that contain receptors sensitive to temperature

A

Thermoregulatory centre, Skin

66
Q

Name two responses to the body temperature being too high:

A
  • Sweating
  • Vasodilation
67
Q

How does sweating cool the body?

A

When the sweat evaporates off the body it takes energy from it, cooling it down

68
Q

What is vasodilation and how does it cool the body?

A

Capillaries at the surface of the skin dilate, allowing more blood to flow to the surface and therefore more heat escapes

69
Q

Name 2 responses to the body temperature being too low

A
  • Vasoconstriction
  • Shivering
  • Stop sweating
70
Q

What is vasoconstriction and how does it warm the body?

A

Capillaries at the surface of the skin constrict so less blood flows to the surface of the skin and less heat escapes

71
Q

How does shivering warm the body?

A

Skeletal muscles increase their rate of respiration to generate energy for contraction. This releases heat and warms the body

72
Q

What is a hormone?

A

A chemical messenger

73
Q

Which hormones does the pancreas produce and what are their roles?

A

Insulin and glucagon, control blood glucose levels

74
Q

Which hormones do the ovaries produce and what are their functions?

A

Oestrogen and Progesterone, important for reproductive development and puberty

75
Q

What hormones do the testes produce and what are their functions?

A

Testosterone, important for reproductive development and puberty

76
Q

Where is the thyroid?

A

In the neck

77
Q

What is the role of thyroxine?

A

Controls basal metabolic rate

78
Q

Where are the adrenal glands?

A

Above the kidneys

79
Q

When is adrenaline produced?

A

In times of fear or stress

80
Q

Where is the pituitary gland?

A

The brain

81
Q

What do the hormones secreted by the pituitary gland do?

A

stimulate other glands to produce hormones

82
Q

What is the endocrine system?

A

A network of glands and organs that use hormones to regulate the internal conditions of the body

83
Q

How do hormones get around the body?

A

In the bloodstream

84
Q

Name 2 differences between the endocrine and nervous systems

A
  • Endocrine system uses hormones, carried in the blood but Nervous system uses electrical impulses sent down neurones
  • Endocrine responses are slow and have a long lasting effect but nervous responses are fast and have short term effects
85
Q

Why is it important for the blood glucose concentration to remain constant?

A

Because all cells need glucose for respiration

86
Q

Which organ monitors blood glucose concentration?

A

Pancreas

87
Q

Name 3 ways that we lose water

A
  • Via the lungs when we exhale
  • When we sweat
  • Via the Kidneys in urine
88
Q

How does the kidney remove urea?

A

Blood passes through the capillaries where smaller molecules are filtered out. They pass into a tube via the Bowman’s Capsule, then all of the glucose, some of the ions and water are reabsorbed. Urea and excess ions leave as urine

89
Q

What waste products are reabsorbed by the kidneys?

A
  • Some water
  • Some ions
  • All glucose
90
Q

What is meant by deamination?

A

The liver breaks down excess amino acids into ammonia, then converts it to urea to
be excreted by the kidneys

91
Q

Why must ammonia be converted into urea?

A

Ammonia is toxic

92
Q

What happens when the becomes too concentrated? (lacks water)

A

The pituitary gland releases ADH

93
Q

How does ADH affect the kidneys?

A

Makes the tubules more permeable so more water can pass out

94
Q

What happens when the blood becomes too dilute?

A

The pituitary gland stops releasing ADH, more urine is produced and water levels return

95
Q

Why do dialysers have partially permeable membranes?

A

To mimic the function of the Bowman’s Capsule

96
Q

Why does dialysing solution contain the same glucose and mineral concentration as healthy blood and no urea?

A

So that only substances in excess will diffuse out and all the urea will leave

97
Q

Why do patients with kidney failure restrict their protein intake and take abti
clotting drugs?

A

Because excess protein will be deaminated and turned into urea which can’t be filtered in an unhealthy kidney. This can lead to clotting

98
Q

Explain briefly what happens during dialysis:

A
  1. Patients blood is run through the dialyser
  2. The dialyser has a selectively permeable which lets ions, water and urea
  3. Waste substances will diffuse across out of the blood
99
Q

Name two disadvantages of Dialysis:

A

• Risk of clotting
• Sessions are 3-4 hrs
• Sessions are frequent
• Expensive for NHS
• Immunosuppressants make you susceptible to illness

100
Q

Name two advantages of a kidney transplant

A

• No need for regular hospital visits
• One time payment
• Can lead a normal life
• Lasts around 8 years

101
Q

What is meant by a negative feedback loop?

A

a normal biological response in which the effects of a reaction slow or stop that reaction

102
Q

Which gland produces adrenaline and where is it?

A

Adrenal gland, kidneys

103
Q

When is adrenaline released?

A

In response to scary or stressful situations

104
Q

How does adrenaline affect the body?

A

Increases heart rate, breathing rate and oxygen and glucose levels to cells.

105
Q

Which gland secretes thyroxine and where is it?

A

Thyroid, the neck

106
Q

What does thyroxine regulate? Name 2 things

A
  • Basal Metabolic Rate
  • Protein Synthesis
  • Growth and development
  • Lipid Synthesis
  • Glycogen Synthesis
107
Q

What is hyperthyroidism caused by?

A

An overactive thyroid, too much thyroxine in the blood

108
Q

Name 2 symptoms of hyperthyroidism:

A

⬆️ Basal Metabolic Rate
⬆️ Rate of Respiration
⬆️ Lipid and Protein Synthesis
- Mood Swings
- Difficulty sleeping

109
Q

What is hypothyroidism caused by?

A

Underactive thyroid, not enough thyroxine in the blood.

110
Q

Name 2 symptoms of hypothyroidism:

A

⬇️ Basal Metabolic Rate
⬇️Rate of Respiration
⬇️Protein/Lipid/Glycogen Synthesis

111
Q

Where is Thyroid stimulating hormone released from?

A

The pituitary gland

112
Q

How are optimum thyroxine levels maintained?

A

Negative feedback loop

113
Q

What hormones do the ovaries produce?

A

Oestrogen and Progesterone

114
Q

What happens of Day 1 of the Menstrual cycle?

A

Lining sheds, blood flows out of uterus

115
Q

What happens of Day 4 of the Menstrual cycle?

A

Lining starts to thicken

116
Q

What happens of Day 14 of the Menstrual cycle?

A

Ovulation, Egg is released from an ovary

117
Q

What happens of Day 28 of the Menstrual cycle?

A

If egg isn’t fertilised, new period begins

GCSE Triple Biology (3 decks)

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