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Biology > 4.5 Homeostatis And Response > Flashcards

4.5 Homeostatis And Response Flashcards

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1
Q

What is homeostasis?

A

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

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2
Q

What for homeostasis do?

A

Maintains optimum conditions for enzyme action and all cell functions

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3
Q

What is controlled by homeostasis in the human body?

A

Blood glucose concentration
Body temperature
Water levels

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4
Q

What could automatic systems involve?

A

Nervous responses

Chemical responses

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5
Q

What do all control systems include?

A 
Stimulus
Cells called receptors
Coordination centres
Effectors
Response
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6
Q

Why must the water content of the body be controlled?

A

High water concentration in the body leads to high blood pressure

We need water for transport between cells and within cells

Too little water means solutions will be too concentrated

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7
Q

How is the water content of the body controlled?

A

Kidneys filter excess water, and you store in the bladder and then you excrete it, through urine

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8
Q

Why must the ion content of the body be controlled?

A

Ions such as Na+, K+ and Cl- are in the blood

Too many ions make high blood pressure due to water in the blood through osmosis

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9
Q

How is the ion content of the body controlled?

A

Kidneys filter excess ions through urine

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10
Q

Why must the temperature of the body be controlled?

A

Enzymes in the human body only work well when at optimum temperature, 37 degrees

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11
Q

How is temperature controlled?

A

If you are too cold you shiver and also vasoconstriction occurs which keeps blood in core so you go pale

If you are too hot vasodilation occurs which lets blood into skin layers and you go red also you sweat

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12
Q

Why must blood sugar levels be controlled?

A

Affects osmotic relations of cells

When there is too little sugar, more water will enter cells via osmosis

When there is too much sugar more water will leave cells via osmosis

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13
Q

How are blood sugar levels controlled?

A

Insulin

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14
Q

Why must carbon dioxide concentration of the blood?

A

When CO2 is added to water it makes weak carbonic acid

pH will drop and enzymes work best at optimum pH

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15
Q

How is carbon dioxide concentration of the blood controlled?

A

Increase breathing rate and depth to get all the co2 out of the lungs.

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16
Q

What does the nervous system allow humans to do

A

React to their surroundings and to coordinate their behaviour

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17
Q

What wakes up the CNS

A

The brain

Spinal chord

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18
Q

What does the CNS do?

A

Coordinates the response of effectors which may be muscles contracting or glands secreting hormones

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19
Q

Complete this flow chart

Stimulus —>______—>_______—> ______ —> _____—>response

A 
Stimulus
Receptor
Coordination centre
Effector 
Response
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20
Q

What happens to the effector in the case of negative feedback?

A

In negative feedback the effector opposes the change and pushes the variable back to set point value

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21
Q

What does the peripheral nervous include?

A

All other nerves that radiate from the brain and spinal chord.

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22
Q

What are nerve fibres?

A

A bundle of nerve cells called neurones

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23
Q

How are nerve cells adapted?

A

Axon is long, allows electrical impulses to pass through the body

Dendrites allow them to connect with other nerve cells

Myelin sheath insulates cells. It’s made of fatty material so is a good insulator

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24
Q

What is a reflex action?

A

Quick automatic responses to stimuli, often designed to protect the body from harm

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25
Q

Name the three types of neurone in the reflex arc

A

Sensory
Motor
Relay

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26
Q

What does the sensory neurone do?

A

Transmits impulses from the receptor to the coordinator

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27
Q

What does the relay neurone do?

A

Found in CNS it transmits impulses from the sensory to the motor neurone

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28
Q

What does the motor neurone do?

A

Transmits impulses from the relay to the effector

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29
Q

What does the thermoregulatory centre in the brain do?

A

Monitors and controls body temperature

Has receptors that monitor the temperature of the blood flowing through the brain

Received information from temperature receptors inn the skin

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30
Q

What happens if the body temperature is too high?

A

Blood vessels widen, directing more blood to the surface of the skin this is called vasodilation

More sweat is produced from the sweat glands and evaporates

Both these machinists cause a transfer of energy form the skin to the environment

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31
Q

What happens if the body temperature is too low?

A

Blood vessels narrow, directing blood away from the surface of the skin this is called vasoconstriction

Sweating stops

Skeletal muscles uncontrollably contract and relax quickly causing you to shiver, which transfers more heat to the blood

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32
Q

What does the brain control?

A

Complex behaviour

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33
Q

What does the brain include?

A

Cerebral cortex, cerebellum and medulla

It is made up of billions of interconnected neurone and has different regions that carry out different functions

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34
Q

How have neuroscientists been able to map the regions of the brain to particular functions?

A

Studying patients with brain damage
Electrically stimulation get different parts of the brain
Using MRI scanning techniques

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35
Q

Why is studying the brain so hard?

A

Complexity and delicacy of the brain

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36
Q

What is the eye?

A

Sense organ

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37
Q

What is the retina?

A

Contains receptor cells that are sensitive to the brightness and colour of light

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38
Q

What is the optic nerve?

A

Carries impulses from the retina to the brain

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39
Q

What is the sclera?

A

forms a tough outer layer, with a transparent region at he front called the cornea

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40
Q

What is the iris?

A

Controls the size of the pupil and the amount of light reaching the retina

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41
Q

What are the ciliary muscles and suspension ligaments?

A

Change the shape of the lens to focus light onto retina

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42
Q

What is accommodation?

A

The process of changing the shape of the lens to focus on near or distant objects

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43
Q

What is myopia?

A

Short sightedness

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44
Q

What is hyperopia?

A

Long sightedness

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45
Q

How are eye defects treated?

A

Spectacle lenses which refract the light rays so that they focus on the retina

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46
Q

Name new technologies that treat eye defects

A

Contact lenses
Laser surgery to change shape of cornea
Replacement eye lenses

47
Q

What is the endocrine system made up of?

A

Glands that secrete hormones directly into the bloodstream

48
Q

What are hormones?

A

Chemical messengers that are carried in the blood to target organ where they produce an effect

49
Q

What is the pituitary gland?

A

In the brain is a ‘master gland’

50
Q

What does the pituitary gland do?

A

Secrets several hormones in response to body conditions

51
Q

What is adrenaline?

A

Produced by the adrenal glands in times of fear or stress
Increase the heart rate, boosting the delivery of oxygen and glucose to the brain and muscles
Prepares the body for ‘flight or fight’

52
Q

What is thyroxine?

A

Produced by the thyroid gland
Increase metabolic rate
Controls growth and development in young animals
Is controlled by negative feedback

53
Q

What controls and monitors blood glucose concentration?

A

Pancreas

54
Q

What happens if blood glucose is too high?

A

The pancreas releases more of the hormone insulin

Insulin causes glucose to move from the blood into cells

In liver and muscle cells, excess glucose is converted to glycogen for storage

55
Q

What happens if blood glucose concentration is too low?

A

The pancreas releases glucagon

Glucagon stimulates glycogen to be converted into glucose and released into the blood

56
Q

What is type 1 diabetes?

A

Caused by the pancreas failing to produce sufficient insulin
Results in uncontrolled high blood glucose levels
Normally treated with insulin injection

57
Q

What is type 2 diabetes?

A

Caused by the body cells no longer responding to insulin

Has obesity as a risk factor
Treated with a carbohydrate controlled diet and regular exercise

58
Q

How does water leave the body?

A

From the lungs during breathing, from the skin in sweat and in urine

59
Q

What happens if the concentration of he blood changes?

A

Body cells will lose or gain too much water by osmosis

60
Q

What regulates balance of water and ions in the body?

A

The kidneys

61
Q

What is urea?

A

A waste product that is produced by the liver from the breakdown of proteins and contains nitrogen

62
Q

What did the kidneys excrete?

A

Urea

63
Q

What does the digestion of proteins from food result in?

A

Excess amino acids

64
Q

What does the liver convert amino acids into?

A

Ammonia

65
Q

What is the process called in which excess amino acids are converted into ammonia?

A

Deamination

66
Q

Why is ammonia immediately converted to urea and sent to the kidneys for safe excretion?

A

It is toxic

67
Q

How do the kidneys produce urine?

A

Filter the blood
Selective reabsorption of useful substances, such as glucose, some ions and water
This leaves unread and excess water and ions to form urine

68
Q

Where does the process of selective reabsorption take place?

A

Millions of small tubes in the kidneys called tubules

69
Q

What hormone controls the water level in the body?

A

ADH

70
Q

When is ADH released by the pituitary gland?

A

When the blood is too concentrated

71
Q

What does ADH do to the body?

A

It passes,in the blood, to the kidney tubules where it causes more water to be reabsorbed back into the blood

72
Q

How can people with kidney failure be treated?

A

Organ transplant or dialysis

73
Q

What is dialysis?

A

A dialysis machine gage over the role of the kidneys, it is used to remove waste products from the blood, three times a week

74
Q

Where is the thyroid gland?

A

In the neck

75
Q

Where is insulin made?

A

In the pancreas

76
Q

What is urea?

A

A ware product from the breakdown of proteins containing nitrogen

77
Q

If a person drinks a litre of water what effect will this have in ADH release?

A

It will reduce the release of ADH

78
Q

What is the female sex hormone?

A

Oestrogen from the ovaries

79
Q

What is ovulation?

A

When eggs begin to mature and be released

80
Q

What is the main male sex hormone?

A

Testosterone

81
Q

Where is testosterone produced?

A

Testes

82
Q

What does testosterone do?

A

Stimulates sperm production

83
Q

What does FSH stand for?

A

Follicle stimulating hormone

84
Q

What is FSH secreted by?

A

Pituitary gland

85
Q

What is the function of FSH in the menstrual cycle?

A

Causes eggs to mature in the ovaries

Stimulates ovaries to produce oestrogen

86
Q

What is oestrogen secreted by?

A

Ovaries

87
Q

What is the function of oestrogen in the menstrual cycle?

A

Inhibits FSH release
Stimulates LH release
Make lining of uterus grow again after menstruation

88
Q

What does LH?

A

Luteinising hormone

89
Q

What is LH secreted by?

A

Pituitary gland

90
Q

What is the function of LH in the menstrual cycle?

A

Stimulates the release of the egg from the ovary (ovulation)

91
Q

What is progesterone secreted by?

A

Empty follicle in the ovaries

92
Q

What is the function of progesterone in the menstrual cycle

A

Maintains lining of uterus during second half of cycle

Inhibits both FSH and LH release

93
Q

How can fertility be reduced?

A

Contraception

94
Q

LH is does the combined pull reduce fertility?

A

Contains oestrogen and progesterone which inhibit FSH so no eggs are released

95
Q

How does an injection, implant or skin patch reduce fertility?

A

Slow release of progesterone to stop release of eggs

96
Q

How do condoms and diaphragms (barrier methods) reduce fertility?

A

Prevent spent from reaching the egg

97
Q

How do intrauterine devices reduce fertility?

A

Prevent embryos form implanting in the uterus

98
Q

What do spermicidal creams do to sperm?

A

Kill or disable sperm

99
Q

What surgical methods are available to reduce fertility?

A

Cutting sperm ducts or tying Fallopian tubes

100
Q

What can doctors give to a woman if her own level of FSH is too low?

A

FSH and LH in a fertility drug

101
Q

What does In vitro fertilisation involve?

A
  • giving a woman FSH and LH to stimulate the growth of many eggs
  • collecting the eggs from the woman
  • fertilising the eggs with sperm from the father in the laboratory
  • inserting one or two embryos into the woman’s uterus
102
Q

What are the disadvantages of fertility treatment?

A
  • It is emotionally and physically stressful
  • the success rates are not high
  • it can lead to multiple births, which are a risk to both the babies and the mother
103
Q

What is a tropism?

A

When part of a plant responds by growing in a particular direction

104
Q

How do shoots react to the stimulus gravity?

A

Away= negatively geotropic/ gravitropic

105
Q

How do roots respond to the stimulus gravity?

A

Towards = positively gravitropic/ geotropic

106
Q

How do shoots respond to the stimulus light?

A

Towards= positively phototropic

107
Q

How does the growth of roots respond to the stimulus light?

A

Away = negatively phototropic

108
Q

What are tropisms controlled by?

A

A group of plant hormones called auxins

109
Q

Describe a plants response to light compared to roots through auxins

A

More light reaches one side of the shoot
More auxin is sent down the shaded side of the shoot
This results in cells on the shaded side elongating more
The shoot therefore, grows towards the light

In roots auxin moves to the bottom of the root and causes less elongation so the roots grow downwards

110
Q

What are gibberellins?

A

A group of plant hormones and are important in initiating seed germination

111
Q

What is ethane in plants?

A

A plant hormone. It controls cell division and ripening of fruits

112
Q

How are auxins used by farmers and gardeners?

A

As weed killers , auxins make the weeds grow so rapidly that they use up their food reserves and die

As rooting powders

Promoting growth in tissue culture

113
Q

How is ethene used in industry?

A

Control the ripening of fruits

114
Q

How are gibberellins used by farmers and gardeners?

A

End seed dormancy and make seeds germinate

Promote flowering, so that plants flower when there is most demand e.g. Mother’s Day

Increase fruit size

Biology (6 decks)

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