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Biology - Topic 5 Homeostasis Flashcards

1
Q

What is homeostasis

A

Maintaining a stable internal environment despite changing conditions

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2
Q

Why does the body need to maintain optimal conditions

A

For optimal enzyme action and cell function

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3
Q

What internal conditions need to be maintained

A

Body Temperature
Blood glucose levels
Water content

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4
Q

Describe the order of the control system

A

receptors ; coordination centre ; effector

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5
Q

What is the role of a receptor

A

detects changes in internal or external environment

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6
Q

What is the role of coordination centre

A

Interprets changes and organises a responce

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7
Q

Where are the coordination centres located in the body

A

Brain, spinal cord, pancreas

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8
Q

Name 2 type of effectors and state what they do

A

muscles contract when stimulated and glands release hormones

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9
Q

What system does homeostasis rely on and what does it mean

A

Homeostasis relies on a system of negative feedback, meaning whenever levels of something get too high they’re brought back down, and whenever the levels of something get to low, they’re brought back up.

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10
Q

what does an electrical impulse do

A

passes along nerve cells

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11
Q

what is a synapse

A

the gap between two neurones

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12
Q

What is released across a synapse

A

chemicals - the nerve signals are transferred by chemicals which diffuse across the gap

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13
Q

What is the CNS

A

Part of nervous system - in vertebrates this consist of the brain and spinal cord only. In mammals the CNS is connected to the body by sensory neurones and motor neurones

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14
Q

What is the role of a sensory neurone

A

transfer a signal from a receptor to the CNS

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15
Q

What is the role of a motor neurone

A

transfer a signal from the CNS to an effector

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16
Q

What is the role of a relay neurone

A

transfer a signal from a sensory neurone to a motor neurone

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17
Q

What is a reflex

A

Automatic response to a stimulus that don’t involve the conscious part of your brain

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18
Q

What is the pathway of a reflex arc

A

stimulus; receptor; sensory neurone; relay neurone; motor neurone; effector; responce

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19
Q

Why are reflexes important

A

they prevent injury

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20
Q

What is the brain made up of

A

billions of interconnected neurones

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21
Q

What is the role of the cerebral cortex

A

Responsible for things like consciousness intelligence, memory and language

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22
Q

What is the role of the cerebellum

A

Responsible for muscle coordination and balance

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23
Q

What is the role of the medulla

A

Controls unconscious activities such as breathing and heart rate

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24
Q

What is the role of the hypothalamus

A

regulates our body temperature

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25
Q

Where is the medulla found

A

in the brain stem

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26
Q

How do scientists study the brain

A
  • Studying patients with brain damage - seeing what part was damaged and relaying this back to the effect it has on the patient
  • Electrically stimulating the brain - by pushing a tiny electrode into the tissue and giving it a small zap of electricity scientists can see what specific parts do
  • MRI scans - provides a very detailed picture of the brains structure
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27
Q

Why is treating the brain so difficult

A

there is a huge range of things that can go wrong
it is had to access as it is encased within the skull
it is very complicated so hard to target with medication

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28
Q

What is the cornea

A

transparent layer at front of the eye which refracts light

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29
Q

What is the optic nerve

A

carries impulses from the receptors on the retina to the brain

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30
Q

What is the pupil

A

the gap through the eye which light passes to reach the lens

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31
Q

what is the lens

A

focuses the light onto the retina

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32
Q

What are the two types of receptors called in the retina

A

Rod cells and Cone cells

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33
Q

what is the point where light focuses on the retina called

A

the fovea - this region contains the highest concentration of cone cells and gives the sharpest image

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34
Q

What is the purpose of the iris reflex

A

to ensure the optimum amount of light enters the eye

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35
Q

Which two muscles make up the iris

A

Circular and Radial muscles

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36
Q

When does the pupil constrict

A

When it is exposed to bright light the circular muscles in the iris contract and the radial muscles relax

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37
Q

What does FSH do

A

Stimulates ovaries to produce oestrogen and causes the eggs to mature

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38
Q

What does LH do

A

it stimulates the egg to be released

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39
Q

outline the process in which the nerve impulses are transmitted across the synapse

A
  • The relay neurone releases a neurotransmitter
  • The neurotransmitter diffuses across the synapse
  • the neurotransmitter binds to second neurone
  • the binding of the neurotransmitter causes an electrical impulse
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40
Q

What structures of the eye bend light that enters the eye

A

the lens and cornea

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41
Q

When light enters the eye where should the light be focused

A

the fovea on the retina

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42
Q

When looking at a nearby object what shape should the lens be

A

When looking at a nearby object the light from the object will hit the eye at a very wide angle so the lens must be short and fat to successfully refract the light

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43
Q

For the lens to become short and wide what must happen

A

the ciliary muscle contracts and the suspensory ligaments slacken

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44
Q

What happens to the ciliary muscle, suspensory ligaments, and the lens, when the eye focuses on a distant object?

A

The suspensory ligaments are pulled taut
Lens is pulled tall and thin
The ciliary muscle relaxes

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45
Q

What does long sighted mean

A

The eye is unable to focus on nearby objects

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46
Q

What is a solution to long-sightedness

A

To wear glasses that contain a convex lens

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47
Q

Where do the glands release the hormone

A

glands release hormones into the bloodstream. The hormones bind to specific cells that have the correct receptors
This will bring about some change within the cells

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48
Q

Describe the thyroid gland

A

Thyroid releases thyroxine. Thyroxine regulates metabolism such as heart rate. If the level of thyroxine in the blood is too low, the pituitary gland will release more thyroid stimulating hormone.

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49
Q

Describe the adrenal gland

A

Adrenal gland releases adrenaline. Adrenaline stimulates fight or flight response

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50
Q

Describe the pancreas in terms of insulin

A

The pancreas releases insulin. Insulin decreases blood sugar levels if they are too high.

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51
Q

What organ is testosterone released from

A

testes

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52
Q

What organ is oestrogen released from

A

ovaries

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53
Q

What does oestrogen and testosterone do

A

stimulates puberty and growth in female and males.

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54
Q

What happens if blood glucose concentrations fall too low

A

There won’t be enough glucose for blood tissue cells to respire

55
Q

What does the pancreas detect a change in

A

the pancreas detects changes in blood glucose concentration

56
Q

Which hormone decreases blood sugar levels

A

insulin

57
Q

What are the two main organs that insulin stimulates to absorb glucose from the blood?

A

Muscle and liver

58
Q

When glucose is absorbed by the liver for long term storage, what molecule is it converted to?

A

Glycogen

59
Q

How does glucagon work

A

When blood glucose levels fall too low, it’s detected by the pancreas. This causes the pancreas to release the hormone glucagon into the bloodstream. The glucagon then travels around the body and binds mainly to cells in the liver. This stimulates those liver cells to break down their stored glycogen into glucose and release it into the bloodstream. This extra glucose increases blood glucose levels back up to normal.

60
Q

what does diabetes mean

A

the body can’t regulate the levels of glucose properly

61
Q

Glucose is a type of

A

carbohydrate

62
Q

What is the underlying issue in type 1 diabetes

A

The pancreas doesn’t release enough insulin

63
Q

How is type 1 diabetes managed

A
  • Inject insulin
  • Monitor diet
  • Exercise regularly
64
Q

What is the underlying issue in type 2 diabetes

A

The body’s tissues become resistant to insulin

65
Q

What factors increase the risk of type 2 diabetes

A

Poor diet
Lack of exercise

66
Q

What are the functions of the kidneys

A
  • Remove urea
  • Regulate water levels
  • Regulate ion levels
67
Q

Describe the process of deamination

A

If the body has more amino acids than it needs, it can convert them into lipids or carbohydrates, which can be stored as an energy source for later

68
Q

Where does deamination take place

A

in the liver

69
Q

What is the downside to the process of deamination

A

It produces the waste product urea, which has to be excreted by the kidney

70
Q

How are ions removed from the body

A

By sweating
By the kidneys

71
Q

If we have too much water in the body, what could happen to our cells

A

They could gain water and burst

72
Q

Each kidney contain millions of tiny units called

A

nephrons

73
Q

Describe the process of filtration in the kidneys

A

As blood passes through the kidneys, small substances like glucose, amino acids, and water, are absorbed from the blood into the kidneys.

74
Q

Describe the process of selective reabsorption in the kidneys

A

As the filtrate passes through the kidneys, useful substances like glucose are reabsorbed from the tubules, into the blood.

75
Q

What substances are not filtered from the blood into the kidney tubules and why

A

Large proteins and red blood cells because they are too large to pass across

76
Q

Which hormone is responsible for regulating water levels in the body

A

ADH

77
Q

Which part of the brain detects the level of water in the body

A

Hypothalamus

78
Q

Describe how the body responds to low water levels

A

A part of the brain called the hypothalamus detects the low concentration of water in the bloodstream.
This causes it to send a signal to the pituitary gland, which tells it to release more antidiuretic hormone (ADH).
The ADH travels around the body in the blood, and stimulates the kidneys to reabsorb more water from the tubules into the blood.
This means that less urine will be made, and the concentration of water in the blood rises.

79
Q

Does ADH increase or decrease the concentration of water in our bloodstream

A

increase

80
Q

What are the consequences of kidney failure

A

Increase in waste products like urea
Poor regulation of ion levels

81
Q

Treatments for kidney failure

A

dialysis
kidney transplant

82
Q

In a dialysis why is the membrane between the blood and the dialysis fluid partially permeable?

A

To only allow some substances to diffuse across

83
Q

Why is fresh dialysis fluid continually pumped through the dialysis machine?

A

To maintain a concentration gradient for diffusion across the membrane

84
Q

What are the disadvantages of dialysis

A

It is time consuming
There is a risk of infection
It is expensive to run

85
Q

Disadvantages of kidney transplant

A
  • The patient will be required to take immunosuppressants for the rest of their lives
  • Risk of kidney being rejected by immune system
86
Q

How long does the average menstrual cycle last?

A

28 days

87
Q
A
87
Q

What happens in stage one of the menstrual cycle and what is the name for this stage

A

Period of bleeding as the uterus lining breaks down - menstruation

88
Q

What happens in stage two of the menstrual cycle

A

Building up of the uterus lining

89
Q

What happens in stage three of the menstrual cycle - what is this stage called

A

release of the egg from the ovaries - ovulation

90
Q

What happens in stage 4 of the menstrual cycle

A

Maintenance of uterus lining

91
Q

Which hormone stimulates the uterus lining to develop

A

Oestrogen

92
Q

What does LH do

A

Stimulates the egg to be released around day 14 (ovulation)

93
Q

What does FSH do

A

Stimulates the egg follicle to mature

94
Q

Which hormone maintains the lining of the uterus?

A

Progesterone

95
Q

What must occur for somebody to become pregnant naturally?

A

The fertilised egg must implant into the uterus lining
An egg must be released from the ovaries
Sperm must reach and fertilise the egg

95
Q
A
96
Q

Which hormones can hormonal contraceptives contain

A

oestrogen
progesterone

97
Q

How can oestrogen act as a contraceptive

A

Inhibits FSH production so the egg can’t mature

98
Q

How can progesterone act as a contraceptive?

A

Stimulates the production of mucus in the cervix so sperm can’t enter the uterus

99
Q

What is the longest lasting contraceptive method

A

Intrauterine device

100
Q

How does a spermicide act as a contraceptive

A

Destroys the sperm cells

101
Q

What is often prescribed to a women that cannot conceive naturally

A

If a women cannot conceive naturally she can be given FSH and LH which in many cases will restore fertility

102
Q

What are the stages of IVF

A

A women is given FSH and LH to stimulate their eggs to mature
These eggs can then be collected from the woman’s series. Sperm is also collected from the male.
The eggs are then fertilised by the sperm
These fertilised eggs are then left to grow into embryos in a laboratory incubator
Once the embryos are large enough, they are transferred to the women’s uterus, so that they can develop into a foetus

103
Q

Why are embryos kept in an incubator whilst in a laboratory

A

To provide the optimum temperature for the enzymes and thus cell growth

104
Q

What are the cons of IVF

A
  • It is stressful
  • emotionally and physically painful (can cause abdominal pains and vomiting)
  • only 25% success rate
  • there is a high chance of multiple births and associated complications
105
Q

Why do some people think that IVF is unethical

A

Some embryos (which had the potential for human life) are destroyed
It could lead to ‘designer babies’ if parents can select embryos with certain traits

106
Q

What does adrenaline do

A
  • increases hart rate
  • increases blood pressure
  • increases blood flow to muscles
  • increases blood sugar levels by stimulating the liver to break glycogen down into glucose
107
Q

Adrenaline causes the conversion of which substance?

A

Glycogen to glucose

108
Q

What will the pituitary gland do if thyroxine levels are too low?

A

The pituitary gland will release TSH. This will stimulate the thyroid gland to release more thyroxine.

109
Q

What does the pituitary gland do if thyroxine levels are too high

A

The thyroxine will inhibit the pituitary gland from producing TSH. Less TSH means that the thyroid gland will release less thyroxine.

110
Q

What is the main role of thyroxine

A

To increase metabolic rate

111
Q

What stimuli can plants detect

A
  • light
  • gravity
  • touch
112
Q

What are auxins

A

Auxins are a family of plant hormones

113
Q

Where are auxins produced

A

In the tips and shoots of roots.

114
Q

Shoots are considered …(tropic)

A

Positively phototropic and negatively geotropic

115
Q

Auxins always accumulate on the …

A

Lower side and shaded side of the plant

116
Q

What is phototropism

A

A response to light

117
Q

Where are auxins made in the plant

A

In the growing tip of a stem or root

118
Q

What happens to make a root grow in the direction of the force of gravity

A

The top side grows more than the bottom side

119
Q

What is positive phototropism

A

Plants grow towards the light

120
Q

What effects do auxin have on plants

A

Shoot - cell growth
Root - cell inhibition

121
Q

What are the 3 uses of auxin in agriculture and horticulture?

A

In weedkillers, rooting powders and to promote growth in tissue culture

122
Q

Auxins stimulate cells to grow and divide ,so how can they be used as weedkiller?

A

If large amount of auxins are added to plants, it can disrupt their growth process by overstimulating them. This can kill the plant.

123
Q

What is the benefit of selective weedkiller

A

The kill some plants but not all

124
Q

What is dormancy

A

Seeds are inactive and depo not grow or develop

125
Q

What is germination

A

Seeds begin to develop and grow

126
Q

Which plant hormone can stimulate a plant to germinate

A

Gibberellin

127
Q

Which hormone is responsible for inducing fruit to ripen

A

Ethene

128
Q
A
129
Q
A
130
Q
A
131
Q
A

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