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GCSE Biology > 7) Homeostasis > Flashcards

7) Homeostasis Flashcards

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1
Q

What does the endocrine system do?

A

Coordinate the body’s responses to changes in the environment

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2
Q

How does the endocrine system coordinate the body?

A

With chemical messengers

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3
Q

What is the process of chemical messengers reaching their targets?

A

1) Hormones released by glands
2) Hormones in bloodstream
3) Travel to target organs

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4
Q

What are the 6 endocrine glands?

A 
Pituitary 
Thyroid
Pancreas
Adrenal
Testes
Ovaries
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5
Q

What do the testes produce?

A

Testosterone

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6
Q

What is the pituitary gland linked with?

A

The hypothalamus

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7
Q

What do the ovaries produce?

A

Oestrogen

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8
Q

What does oestrogen control?

A

Puberty

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9
Q

What do the adrenal glands produce?

A

Adrenaline

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10
Q

What does the pancreas produce?

A

Insulin

Glucagon

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11
Q

What are insulin and glucagon used for?

A

Regulating blood glucose levels

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12
Q

What does the thyroid produce?

A

Thyroxine

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13
Q

What does thyroxine regulate?

A

Metabolism
Heart rate
Temperature

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14
Q

What are features of the CNS?

A

Rapid response
Electrical signals carried by neurones
Very short response
Acts on a precise part of the body

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15
Q

What are features of the endocrine system?

A

Slow response
Chemcial messengers carried by blood
Long-lasting response
Acts on large areas of the body`

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16
Q

What order does the CNS and endocrine system follow?

A

Receptor cells –> coordination centre –> effectors

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17
Q

What happens when the body has low thyroxine?

A

1) Hypothalamus produces TRH
2) Pituitary gland releases TSH
3) Thyroid secretes thyroxine

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18
Q

What happens when the body has high thyroxine?

A

1) TRH secretion reduced
2) TSH reduced
3) Thyroxine reduced

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19
Q

What effect does adrenaline have on bluud glucose?

A

Liver converts glycogen into glucose increasing blood sugar levels

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20
Q

What effect does adrenaline have on heart rate and blood pressure?

A

Vasoconstriction increases heart rate and blood pressure

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21
Q

What effect does adrenaline have on the lungs?

A

Enlarged air passages and metabolism changed to boost delivery of oxygen and glucose to brain and muscles

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22
Q

What does thyroxine increase?

A

Basal metabolic rate

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23
Q

What are features that appear during puberty called?

A

Secondary sex characteristics

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24
Q

What are male responses to puberty?

A

Testosterone rises, stimulating sperm production
Underarm, facial, pubic hair
Voice deepens

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25
Q

What are female responses to puberty?

A

Oestrogen rises and triggers menstrual cycle
Underarm and pubic hair
Breasts enlarge

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26
Q

What hormones control the menstrual cycle?

A

Follicle stimulating hormone (FSH)
Oestrogen
Luteinising hormone (LH)
Progesterone

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27
Q

When are all a females egg’s ready?

A

At birth

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28
Q

What produces FSH?

A

Pituitary gland

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29
Q

What does FSH do?

A

Causes an egg in the ovaries to mature

Stimuales oestrogen production

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30
Q

What does oestrogen do in the menstrual cycle?

A

Causes the development of the thick, spongy uterus lining
Stimulates LH
Inhibits FSH

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31
Q

What produces LH?

A

Pituitary gland

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32
Q

What does LH do?

A

Stimulates ovulation on day 14

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33
Q

What does progesterone do?

A

Maintains uterus lining during days 14-28

Inhibits FSH and LH

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34
Q

What causes the breakdown of the uterus lining?

A

A drop in progesterone levels

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35
Q

What is stage 1 of the menstrual cycle?

A

The uterus lining breaks down, resulting in a ‘period’

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36
Q

What is stage 2 of the menstrual cycle?

A

The uterus lining starts to build up again into a thick, spongy layer full of blood vessels

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37
Q

What is stage 3 of the menstrual cycle?

A

Ovulation happens. This is when an egg is released from one of the ovaries

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38
Q

What is stage 4 of the menstrual cycle?

A

The uterus lining is maintained, which means that it is now ready for the arrival of a fertilised egg (which will eventually grow into a baby). If no fertilised egg is attached to the uterus lining, the lining breaks down and the cycle begins again

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39
Q

What are the 2 main types of contraceptive pill?

A

Combined pill

Progesterone only pill

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40
Q

What does the combined pill contain and do?

A

Oestrogen and progesterone

Oestrogen builds up and inhibits production of FSH so no eggs mature

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41
Q

How does the progesterone only pill work?

A

Production of thick, sticky mucus prevents sperm penetration

Inhibits release of FSH

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42
Q

What are benefits of the progesterone only pill over the combined pill?

A

Just as effective but with fewer side effects

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43
Q

What does the contraceptive patch/ injection/ implant contain?

A

Progesterone

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44
Q

How long does the contraceptive implant last?

A

3 months

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45
Q

How long does the contraceptive implant last?

A

3 years

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46
Q

How long does the contraceptive patch last?

A

1 week

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47
Q

What do diaphragms do?

A

Prevent sperm from reaching the egg by beeing place inside the vagina at the entrance to the uterus (covered in spermicide)

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48
Q

How are intrauterine devices (IUDs) used?

A

inserted into uterus to prevent implantation of an embryo (some can release progesterone)

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49
Q

How often are contraceptive pills taken?

A

Daily

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50
Q

How are condoms used?

A

Worn on penis during sexual intercourse

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51
Q

What are benefits of condoms?

A

Contains spermicide
Prevents sperm from reaching an egg
Protects agaisnt STIs

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52
Q

What are the natural methods of contraception?

A

Abstinence

Timing

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53
Q

What is abstinence?

A

Not having sex until you are ready for a baby

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54
Q

What is the contraceptive method of timing?

A

Avoiding sex when females are ovulating

55
Q

What are drawbacks of timing?

A

Sperm can last up to 6 days inside a woman

56
Q

When does a female’s body temperature rise in the menstrual cycle?

A

During ovulation

57
Q

What is sterilisation?

A

Underoing a permanent procedure to remove any chance of getting pregnant

58
Q

What is sterilisation for females?

A

Cutting the fallopian tubes so an egg cannot reach the uterus

59
Q

What is sterilisation for men?

A

Cutting the sperm ducts so no sperm is released on ejaculation

60
Q

What causes a woman to be infertile?

A

Not having high enough levels of FSH to stimulate the maturation of eggs

61
Q

What are the 2 main reproductive technologies?

A

Clomifene (fertility drugs)

In Vitro Fertilisation

62
Q

What does clomifene do?

A

Trigger ovulation by increasing release of FSH

Increases LH concentration to cause ovulation

63
Q

What is the process of IVF?

A

1) Given fertility drugs to stimulate FSH and LH and grow large numbers of eggs
2) Eggs collected and fertilised in a dish in a lab using sperm from the father
3) Fertilised eggs grow into embyros and one is implanted into the woman’s uterus (sometimes two are implanted to increase the chance of pregnancy)

64
Q

What are disadvantages of fertiltiy treatments? (3)

A

High levels of stress
Chance of multiple pregnancies puts mother and children at risk
Expensive and not guranteed to work

65
Q

What does homeostasis describe?

A

All of the process that can happen in a cell or orgnaism to keep conditions optimal

66
Q

Why must we regulate our body’s internal conditions?

A

To make sure our enzymes and cells function well

67
Q

What happens to our enzymes if conditions are not optimal?

A

They can denature which reduces their ability to catalyse metabolic reactions

68
Q

What internal conditions need to be regulated? (5)

A 
Blood sugar levels
Carbon dioxide levels
Water levels
Urea concentration
Temperature
69
Q

What 3 parts make up control systems?

A

Effectors
Receptors
Coordination centres

70
Q

What do coordination centres do?

A

Receive and process information arriving from receptor cells

71
Q

What do receptor cells do?

A

Detect changes in the environment

72
Q

What do effectors do?

A

Carry out a response to a stimuli that helps to restore optimum levels

73
Q

What is the body’s optimal temperature?

A

37 degrees

74
Q

What receptors monitor temperature for the body?

A

Skin receptors monitor body surface temperature

Hypothalamus montiors interal body temperature

75
Q

What happens if your body is too cold?

A

Muscles contract- shivering
Hairs stand on end
Vasoconstriction

76
Q

What happens if your body is too hot?

A

Sweat is released from sweat glands under the skin
Hairs lie flat
Vasodilation

77
Q

How does shivering warm the body?

A

Muscles contract automatically when we are cold
This process needs energy from respiration
Respiration produces heat which warms us up

78
Q

How does sweating cool the body?

A

Sweat glands release sweat which covers epidermis
Heat energy is transsferred to water and evaporates
This takes heat with it and lowers body temperature

79
Q

What happens to body hairs when we are cold?

A

Hair erector muscles cotnract and causes the hair to stand on end and pull on the skin (goosebumps)
This traps an insulating layer of air around the body

80
Q

What happens to body hairs when we are hot?

A

Hair erector muscles relax

Hairs lie flat

81
Q

What happens to blood vessels when we are hot?

A

Muscular walls relax
Vasodilation
More blood flows through capillaries close to the skin surface which is transferred to the environment

82
Q

What happens to blood vessels when we are cold?

A

Muscular walls contract
Vasoconstriction
Reduced blood flow to skin surface keeps heat energy inside the body

83
Q

What is glucose important for?

A

Respiration

84
Q

What happens when we have too little glucose?

A

We cannot produce enough energy

85
Q

What happens if we have too much glucose?

A

Negative impact on osmosis as concentration gradients will be affected

86
Q

What detects blood glucose levels?

A

The pancreas

87
Q

What happens if blood glucose is too low?

A

1) Pancreas releases glucagon

2) Liver detects glucagon and converts glycogen into glucose and releases into bloodstream

88
Q

What happens if blood glucose is too high?

A

1) Pancrease releases insulin

2) Liver detects insulin and converts excess glucose into glycogen

89
Q

What is glycogen?

A

A form of glucose that is insoluble and stored for later use

90
Q

What does insulin do?

A

Converts excess glucose into glycogen

91
Q

What does glucagon do?

A

Converts glycogen into glucose

92
Q

What is type 1 diabetes?

A

When sufferers are unable to produce enough insulin

93
Q

What is type 2 diabetes?

A

When sufferers still produce insulin but their body no longer responds to it

94
Q

When does type 1 diabetes develop?

A

During childhood

95
Q

What is treatment for type 1 diabetes?

A

Injecting insulin when blood glucose levels rise too high

Managing diet and exercise keeps levels steady

96
Q

When does type 2 diabetes develop and why?

A

Later in life

Old age and being overweight

97
Q

What is treatment for type 2 diabetes?

A

Manging diet and exercising regularly

98
Q

Why must water levels be kept constant in the body?

A

To control the amount of water and ions diffusing in and out of cells

99
Q

What factors disrupt the body’s water balance? (4)

A

Sweating
Illness
Too much salt
Exhalation

100
Q

What is lost in sweat?

A

Water
Ions
Urea

101
Q

What does an isotonic solution mean?

A

Same water and ion concentration as cells

102
Q

What does a hypertonic solution mean?

A

Solution has lower water concentration and a higher ion concentration than cells

103
Q

What happens to cells if blood becomes hypertonic?

A

Cells lose water by osmosis and shrink

104
Q

What does a hypotonic cell mean?

A

Solution has a higher water concentration and a lower ion concentration than cells

105
Q

What happens to cells if blood becomes hypotonic?

A

Cells gain water by osmosis and burst

106
Q

What do kidneys control?

A

Water and ion levels in the blood

107
Q

What monitors the volume of water in the blood?

A

The hypothalamus

108
Q

Why must urea be removed from the bloodstream?

A

It is toxic and too much can harm cells and tissues

109
Q

What forms urea?

A

An excess of amino acids from digested proteins

110
Q

What happens to excess amino acids in the liver?

A

Deamination with the waste product ammonia

111
Q

Where does deamination happen?

A

The liver

112
Q

What is the waste product of deamination?

A

Ammonia

113
Q

What is converted into urea?

A

Ammonia

114
Q

What is the process of producing urea?

A

1) Digested proteins have excess amino acids
2) Amino acids unergo deamination in the liver and ammonia is a waste product
3) Ammonia is converted to urea

115
Q

What are the 2 stages of urine production?

A

Ultrafiltration

Selective reabsorption

116
Q

Where does urine production happen?

A

Nephrons in the kidneys

117
Q

What is the process of ultrafiltration?

A

1) Blood capillaries form a knotted cluster called a glomerulus in the Bowman’s capsule
2) Blood is filtered and water, urea and salts move into nephron tubule
3) Blood cells and proteins remain in the blood as they are too big to move across the capillary walls

118
Q

What is the process of selective reabsorption?

A

1) Useful substances such as glucose and some water are reabsorbed from the tubule back into the bloodstream
2) This leaves urea, excess salts and excess water in the nephron tubule
3) Thix mixture forms urine which is collected by the kidneys and travels to the bladder to be stored and excreted

119
Q

What is urine made up of?

A

Urea
Excess salts
Excess water

120
Q

How does the body respond to too little water?

A

1) Hypothalamus tells pituitary gland to release ADH
2) Increases permeability of kidney tubules so more water can be reabsorbed back into the bloodstream
3) Small volume of concentrated urine

121
Q

What does ADH do?

A

Increase permeability of kidney tubules

increase water levels

122
Q

How does the body respond to too much water?

A

1) Hypothalamus tells pituitary gland to stop the release of ADH
2) Reduces permeability of kidney tubules and less water is reabsorbed back into the bloodstream
3) Large volume of dilute urine

123
Q

What are possible treatments of kidney failure?

A

Transplants

Dialysis

124
Q

When is dialysis used?

A

When the kidneys cannot keep the concentrations of urea and salt at an optimum levels to ensure tissue damage does not occur

125
Q

What is the dialysis fluid designed to have?

A

Optimum concentrations of salts and glucose as a healthy person’s blood

126
Q

How does dialysis work?

A

1) Patient’s blood passes over a partially permeable membrane in the machine that is designed to replicate kidney tubules
2) Dialysis fluid on the other side establishes a concentration gradient and allows excess ions and urea to diffuse from an area of high concentration in the patient’s blood to an area of low concentration in the dialysis fluid

127
Q

What are disadvantages of dialysis? (3)

A

Lasts 3-4 hours and is needed 3 times a week
Increases risk of blood clots and infections
Expensive

128
Q

What are advantages of dialysis? (2)

A

Life-saving process

Gives a patient time to find a donor kidney

129
Q

Why are close relatives often organ donors?

A

They have a higher chance of being a tissue match

130
Q

When can organs be transplanted from people who have recently died?

A

When they are a tissue match and are registered on the organ donor register

131
Q

What do immunosuppressants do?

A

Suppress the immune system to prevent it from destroying the foreign cells of the transplanted organ

132
Q

What are advantages of kidney transplants? (2)

A

Time consuming dialysis treatment is not required

Transplants are cheaper than dialysis in the long run

133
Q

What are disadvantages of kidney transplants? (3)

A

Kidney may be rejected by the body
Can be a long waiting list for transplants
Immunosuppressant drugs can make a patient more prone to other infections

GCSE Biology (10 decks)

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