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Biology > B5- Homeostasis > Flashcards

B5- Homeostasis Flashcards

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1
Q

What is homeostasis

A

The regulation of conditions inside the body to maintain a stable internal environment, in response to both internal and external conditions

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2
Q

What 3 internal factors are maintained by homeostasis

A
  • Body temperature
  • Blood glucose
  • water content
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3
Q

Why is a constant internal environment important

A

Your cells need the right conditions in order to function properly, including the right conditions for enzyme action

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4
Q

What 2 automatic control systems are involved in homeostasis

A

Nervous and hormonal systems

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5
Q

What is the order of components in control systems

A
  1. Receptor detects a stimulus - level is too high/low
  2. The coordination centre receives and processes the information, then organises a response
  3. Effector produces a response, which counteracts the change and restores the optimum level- the level decreases/increases
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6
Q

What are receptors

A

Cells that detect changes in the internal and external environment.

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7
Q

What do coordination centres do

A

Areas that receive and process the information from the reports. They send out signal and coordinate the responses of the body

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8
Q

State 3 coordination centres in your body

A
  • Brain
  • Spinal cord
  • Pancreas
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9
Q

What are the 2 types of effectors

A
  • Muscle

- Gland

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10
Q

What does homeostasis maintain optimum

conditions for?

A

Enzyme action, cell structure and chemical reactions.

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11
Q

State what the two types of effectors do to bring

about a response.

A
  1. Muscle will contract

2. Gland secretes enzymes/hormones

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12
Q

What is a negative feedback loop?

A

A continuous cycle of events that responds when
conditions change away from the set point and
causes it to return conditions to this set point.

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13
Q

Reactions to remove your body from danger

A

Enables humans to react to their surroundings and to coordinate their behaviour

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14
Q

What is the CNS

A

The central nervous system, includes the brain and spinal cord.

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15
Q

To summarise the order of how the human nervous system works, fill in the missing words: a -> b -> c -> d -> e

A

a) Stimulus
b) Receptor
c) Coordinator
d) Effector
e) Respons

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16
Q

Name the three types of neurone.

A

Sensory
Relay
Motor

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17
Q

What is a synapse

A

The gap between two neurones, where a signal passes from one neurone to the next.

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18
Q

Summarise in five steps how a synapse works.

A
  1. Impulse arrives at the end of one neurone,
  2. Neurotransmitter is released into the synaptic gap,
  3. Neurotransmitter diffuses across the synaptic gap,
  4. Neurotransmitter binds to receptors on a second neurone,
  5. A new electrical impulse is generated in the second neurone.
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19
Q

Why are reflex actions rapid

A

They do not involve the brain, therefore no conscious thought.

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20
Q

What do you use reflex actions for

A

Reactions to remove your body from danger

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21
Q

Name the hormone which controls the “fight or flight” reaction in humans

A

Adrenaline

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22
Q

Explain two effects adrenaline has on the body

A

Increased heart rate

Therefore increases delivery of oxygen and glucose to the brain and muscles

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23
Q

Where is thyroxine made

A

Thyroid gland

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24
Q

What does thyroxine do in the body

A

Increase the basal (base) metabolic rate, therefore increasing growth and development

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25
Q

Define negative feedback

A

The mechanism used by the body to bring its internal environment back to normal when the level of something gets too high or too low

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26
Q

State examples of internal conditions controlled by negative feedback

A

Thyroxine levels, temperature, water levels, blood sugar

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27
Q

Define Glucose

A

is a simple sugar which is a monomer.

It is soluble and can travel in the blood.

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28
Q

Define glycogen

A

Is a polymer of glucose and is a storage molecule found in an animal. It is insoluble

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29
Q

Define “homeostasis”.

A

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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30
Q

What is the endocrine system composed of?

A

Glands which secrete chemicals called hormones.

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31
Q

How is a chemical “message” transported to

the target organ in animals?

A

Via the bloodstream.

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32
Q

What is monitored for changes in glucose

concentration?

A

The blood.

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33
Q

What controls the response to changes in blood

glucose concentration?

A

The pancreas.

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34
Q

What is produced if the blood glucose

concentration is too high?

A

Insulin, a hormone.

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35
Q

State two ways insulin helps to lower blood

glucose concentration.

A

Causes glucose to move from the blood to the cells AND

triggers the conversion of glucose into glycogen.

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36
Q

What is produced if the blood glucose

concentration is too low?

A

Glucagon, a hormone.

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37
Q

State how glucagon helps to increases blood

glucose concentration.

A

Triggers the breakdown of glycogen into glucose, which is

released into the blood.

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38
Q

Name two places in the body glycogen is

stored.

A

Muscle cells and the liver.

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39
Q

What is the process called which responds to a
change from the normal levels in the body by
restoring them back to the normal levels?

A

Negative feedback.

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40
Q

Define “homeostasis”.

A

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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41
Q

What is the endocrine system composed of?

A

Glands which secrete chemicals called hormones.

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42
Q

How is a chemical “message” transported to the

target organ in animals?

A

Via the bloodstream.

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43
Q

Compare the speed and duration of hormonal

control to nervous control.

A

(Hormonal) Slower but act for longer.

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44
Q

What is monitored for changes in glucose

concentration?

A

The blood.

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45
Q

What controls the response to changes in blood

glucose concentration?

A

The pancreas.

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46
Q

What is produced if the blood glucose

concentration is too high?

A

Insulin, a hormone.

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47
Q

State two ways insulin helps to lower blood

glucose concentration.

A

Causes glucose to move from the blood to the cells AND

triggers the conversion of glucose into glycogen.

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48
Q

What is produced if the blood glucose

concentration is too low?

A

Glucagon, a hormone.

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49
Q

State how glucagon helps to increases blood

glucose concentration

A

Triggers the breakdown of glycogen into glucose, which is

released into the blood.

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50
Q

Name two places in the body glycogen is stored

A

Muscle cells and the liver.

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51
Q

What is the process called which responds to a
change from the normal levels in the body by
restoring them back to the normal levels?

A

Negative feedback.

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52
Q

Type 1 diabetes is caused by…..

A

An inability to make insulin in the pancreas.

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53
Q

Type 2 diabetes is caused by….

A

A lack of response by cells to insulin.

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54
Q

State 3 secondary sexual
characteristics that occur during
puberty for males?

A

Hair growth on face, hair growth on
pubic area and under arms, voice
deepens, growth spurt, sperm
production

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55
Q

State 3 secondary sexual
characteristics that occur during
puberty for females?

A

Breasts develop, hips widen, hair
growth in pubic region and under arms,
growth spurt, menstrual cycle

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56
Q

Name the main female hormone
involved in development and
reproduction.

A

Oestrogen

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57
Q

Name the main male hormone
involved in development and
reproduction.

A

Testosterone

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58
Q

Name the gland which produces

testosterone.

A

Testes

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59
Q

Name the gland which produces

hormones such as oestrogen?

A

Ovary

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60
Q

What does testosterone cause to

happen in men?

A

Stimulates sperm production.

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61
Q

What does oestrogen cause to

happen in women?

A

Menstrual cycle

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62
Q

Approximately how often is an egg released from the ovaries in a female and what is this process called

A

Every 28 days, ovulation

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63
Q

What does the release of FSH cause

A

Maturation of an egg in the ovaries

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64
Q

The release of which hormone stimulates the release of an egg from the ovaries

A

Luteinising hormone (LH)

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65
Q

Which hormones are involved in the maintenance of the uterus lining

A

Oestrogen and progesterone

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66
Q

How do oral contraceptives containing hormones prevent pregnancy

A

Inhibits FSH production do no egg matures

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67
Q

How does an injection,implant or skin patch containing slow-release progesterone prevent pregnancy

A

Inhibits the maturation of eggs

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68
Q

How do barrier methods, such as condoms and diaphragms, prevent pregnancy

A

Prevent the sperm reaching the egg

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69
Q

How do intrauterine devices prevent pregnancy

A

Prevent the implantation of an embryo AND/OR release hormones

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70
Q

How do spermicidal agents prevent pregnancy

A

Kills or disable

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71
Q

How does abstaining from sexual intercourse prevent pregnancy

A

Reduces the chance of sperm meeting an egg in the oviduct

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72
Q

How does surgical sterilisation prevent pregnancy

A

Prevents the sperm or egg being released by the male or female

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73
Q

What is the Sclera

A

The tough supporting wall of the eye

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74
Q

What is the Cornea

A

Transparent outer layer found at the front of the eye. It refracts (bends) light into the eye

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75
Q

What is the Iris

A

The Iris contains contains muscles that allow it to control the diameter of the pupil (the hole in the middle of the eye) and therefore how much light enters the eye

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76
Q

What does the lense do

A

It focuses on the light onto the RETINA (which contains receptor cells sensitive to light intensity and colour)

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77
Q

What is shape of the lens controlled by

A

Ciliary muscles and suspensory ligaments

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78
Q

What is the optic nerve

A

It carries impulses from the receptors on the retina to the brain

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79
Q

What can very bright light damage

A

The retina

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80
Q

What does being longsited mean

A

You are unable to focus on near objects

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81
Q

What is wrong with the person’s eye who is long-sighted

A

The lense is the wrong shape and doesn’t refract (bend) the light enough or the eyeball is too short

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82
Q

What is meant by the term “short-sighted”

A

You are unable to focus on distant objects

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83
Q

What is wrong with the person’s eye who is short-sighted

A

The occurs when the lense is the wrong shape refracts the light too much or the eyeball is too long

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84
Q

What do the kidneys do

A

Acts as filters to “clean the blood”

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85
Q

How to kidneys work

A

They make urine by taking waste products out of your blood. Substances are filtered out of the blood as it passes through the kidneys

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86
Q

What happens when your kidneys fails

A

Kidneys remove waste products from the blood this means that if they fail waste substances would build up in the blood and you lose your ability to control the levels of ions and water in your body. You would eventually die

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87
Q

What is the machine called that can filter your blood

A

A dialysis machine

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88
Q

Can you get a kidney transaplant

A

Yes

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89
Q

What is the only cure for kidney failure

A

Kidney transport

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90
Q

What is the biggest issue with kidney transplants

A

They can be rejected

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91
Q

What two hormones are often prescribed to women to increase fertility

A

FSH and LH

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92
Q

What are pros to giving women FSH and LH

A

It helps a lot women to get pregnant when previously they couldn’t

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93
Q

What are cons to giving women FSH and LH

A
  • It doesn’t always work -some women may have to do it many times, which can be expensive
  • Too many eggs could be simulated, resulting in unexpected multiple pregnancies
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94
Q

What might be used if the women can’t get pregnant

A

IVF

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95
Q

What is IVF

A
  • Collecting the egg from a women and sperm from the man and putting them in a lab
  • It involves using a treatment called Intra Cytoplasmic Sperm injection (ICSI) where the sperm is injected into the egg
  • The fertilised eggs are then grown into embryos in a lab incubator
  • Once the embryos are tiny balls of cells, one or two of them are transferred to the women’s uterus to improve the chance of pregnancy
  • FSH and LH are given before egg collection to stimulate several eggs to mature (so more that one egg can be collected)
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96
Q

What are cons of IVF

A
  • Multiple births which can increase the chances of miscarriage and stillbirth
  • The success rate of IVF is low
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97
Q

Why are some people against IVF

A
  • Can result in unused embryos

- Designer babies

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98
Q

What is Auxin

A

A plant growth hormone

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99
Q

What do shoots grow towards

A

The sun

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100
Q

What are commercial uses for auxins

A
  • Killing weeds
  • Growing from cutting with rooting powder
  • Growing cells in tissue culture
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101
Q

What does gibberellin do

A

Stimulates plant stems to grow

102
Q

What is gibberellin

A

A type of plant growth hormone

103
Q

What does Ethene do

A

Can stimulate ripening fruit

104
Q

How is Ethene produced

A

A gas produced by aging parts of a plant

105
Q

What does the acronym Dairy Milk Ice Cream stand for

A

Dependent
Measured
Independent
Change

106
Q

What does the acronym SPLAT stand for (to do with graphs)

A 
Scale- go up in equal amounts
Plot
Line of best fit
Axis- variable & units
Title
107
Q

What does the menges control (it’s part of the brain)

A

Membrane that surrounds the brain. Provides protection against infection

108
Q

What does the cerebral cortex control (it’s part of the brain)

A

Highly folded nerves tissues with large surface area for connections to be made

109
Q

What does the cerebellum control (it’s part of the brain)

A

“mini brain” that receives information from eyes and ear and it’s responsible for balance, coordination and fine motor skills

110
Q

What does the medulla oblogla control (it’s part of the brain)

A

Top of spinal cord responsible for involuntary motion such as breathing

111
Q

What does the hypothalamus control (it’s part of the brain)

A

Involved in homeostasis

112
Q

What does the frontal lobe control (it’s part of the brain)

A

Concerned with reasoning, planning, parts of speech and movement (motor conext) emotions and problem solving

113
Q

What does the temporal lobe control (it’s part of the brain)

A

Concerned with perception and recognition of auditory stimuli (chewing) and memory

114
Q

What does the parietal lobe control (it’s part of the brain)

A

Concerned with perception of stimuli such as touch, pressure, temperature and pain

115
Q

What does the optical lobe control (it’s part of the brain)

A

Concerned with many aspects of vision

116
Q

List all the different glands

A 
Pituitary
Thyroid
Adrenal
Pancreas
Testes
Ovaries
Pituitary
117
Q

Where is the Pituitary gland located

A

Brain

118
Q

Where is the Thyroid gland located

A

Throat

119
Q

Where is the Adrenal gland located

A

Above kidneys

120
Q

Where is the Pancreas gland located

A

Behind kidneys

121
Q

What is the pituitary gland

A

Master that causes other glands to release their hormones

122
Q

What is the thyroid gland

A

Produces thyroxine to control the rate of metabolism

123
Q

What does the pancreas do (regarding homeostasis)

A

Produces blood glucose levels

124
Q

What is glucoregulation

A

The regulating glucose levels

125
Q

What is homeostasis

A

Homeostasis is the maintenance of a
constant internal environment in order to
maintain optimum conditions for enzyme
and cellular function

126
Q

Give examples of conditions maintained by

homeostasis in the body

A

● Blood glucose concentration
● Body temperature
● Water levels

127
Q

What two types of responses are used in body

control systems

A

Nervous and chemical

128
Q

What three components do all control systems

have

A

● Receptors
● Coordination centres
● Effectors

129
Q

What is the function of a receptor

A

Receptors detect changes in the

environment (stimuli).

130
Q

What is the function of a coordination centre

A

Coordination centres obtain and process

information from receptors

131
Q

What is the function of an effector

A

Effectors (muscles or glands) bring about

responses to stimuli.

132
Q

What is the function of the nervous system?

A

The nervous system allows the body to
react to its surroundings and coordinate an
appropriate response

133
Q

How does a stimulus lead to a response being carried

out by the body?

A

● Stimulus is converted into an electrical impulse by the
receptors.
● The electrical impulse passes along sensory neurones to
the central nervous system (CNS).
● The CNS coordinates an appropriate response and an
electrical impulse is sent along motor neurones to the
effector, which carries out the response.

134
Q

What sequence of events describes how the

nervous system works

A

Stimulus → receptor → coordinator →

effector → response

135
Q

What is a reflex action

A

A reflex action is an automatic and rapid
response which does not involve any
conscious input from the brain

136
Q

Why are reflex actions important

A

Reflex actions aid survival by preventing

harm to the body

137
Q

Describe how a reflex action occurs via a reflex arc

A

● The stimulus is detected by a receptor.
● An electrical impulse passes along a sensory neurone to the spinal cord
(part of the CNS).
● At a synapse between a sensory neurone and a relay neurone, a
chemical diffuses across the gap and stimulates a new impulse which
passes along the relay neurone.
● The same process occurs at a synapse between a relay neurone and a
motor neurone.
● At the effector, an appropriate response is carried out.

138
Q

What is the difference between a reflex pathway

and a conscious pathway

A

Within a reflex pathway, the coordination centre
is a relay neurone found in the spinal
cord/unconscious parts of the brain. In a
conscious pathway, the coordination centre is in
the conscious part of the brain

139
Q

What is the function of the cerebral cortex?

A

controls consciousness,
intelligence, memory and
language.

140
Q

What is the function of the cerebellum?

A

controls muscular coordination

141
Q

What is the function of the medulla

A

controls unconscious activities eg.breathing, heart rate

142
Q

Why is the investigation and treatment of the

brain difficult

A

● The brain is a complex and delicate organ.
● The brain is easily damaged and destroyed.
● Certain membranes prevent drugs from reaching
the brain.
● The exact function of each part of the brain is not
known.

143
Q

What methods are used by scientists to determine

brain function

A

● Studying patients with brain damage
● Electrical stimulation of the brain
● MRI scans

144
Q

What stimuli are the receptors of the eye

sensitive to

A

Light intensity and colour

145
Q

What are the two main functions of structures

found within the eye

A

● Focusing on near or distant objects -
accommodation.
● Adaptation to dim light.

146
Q

Describe the structure and function of the

retina

A 
F - The retina is a light-sensitive
layer found at the back of the
eye.
Light stimulates the retinal cells,
resulting in impulses being sent
to the brain
147
Q

Describe the structure and function of the optic

nerve

A

The optic nerve connects the eye and the brain.
It carries impulses to the brain so that an image can
be visualised

148
Q

Describe the structure and function of the sclera

A

The sclera is the tough outer layer of the eye

which protects its internal structures

149
Q

Describe the structure and function of

the cornea

A

The cornea is the curved transparent layer at the front

of the eye. It lets light into the eye and allows light to be focused onto the retina.

150
Q

Describe the structure and function of

the iris

A

The iris is a muscle which controls the size of
the pupil by contracting or relaxing. This allows the
eye to adjust to bright and dim lighting

151
Q

Describe the structure and function of the ciliary muscles and suspensory ligaments

A

The ciliary muscles (C) and suspensory
ligaments (E) hold the lens in place and control
its shape.

152
Q

Describe how the iris alters the size of the pupil in both

bright and dim light

A

● Bright light: circular muscles contract and radial
muscles relax - makes pupil smaller to avoid retinal
damage.
● Dim light: circular muscles relax and radial muscles
contract - makes pupil larger so more light can
enter the eye

153
Q

What is accommodation?

A

Accommodation is the alteration of the
lens’ shape in order to focus on near or
distant objects

154
Q

How does the eye focus on a nearby object?

A

● Ciliary muscles contract.
● Suspensory ligaments loosen.
● Lens becomes thicker and more curved -
light rays are refracted strongly.

155
Q

How does the eye focus on a far away object

A

● Ciliary muscles relax
● Suspensory ligaments tighten
● Lens becomes thinner - light rays are
refracted weakly

156
Q

What is myopia

A

Myopia (short-sightedness) usually occurs
when the lens of the eye is too curved. As a
result, light is focused in front of the retina so
images appear blurry

157
Q

How can myopia be treated

A

Myopia can be treated using glasses with a
concave lense, which spreads out light rays
so they can be focused on the retina.

158
Q

What is hyperopia?

A

Hyperopia (long-sightedness) usually occurs
when the lens of the eye is too flat. As a
result, light is focused behind the retina so
images appear out of focus

159
Q

How can hyperopia be treated?

A

Hyperopia can be treated using glasses with
a convex lense, which brings the light rays
together so they can be focused on the
retina

160
Q

What are the two types of contact lenses

A

Contact lenses are lenses that are placed on the eye.
There are two types:
● Hard - rigid material, last a long time, must be kept
sterile.
● Soft - flexible material, last for a shorter time, more
comfortable

161
Q

What is laser eye surgery

A

Laser eye surgery is the use of lasers to fix visual
defects in adults. To treat myopia, lasers reduce the
thickness of the cornea so light is refracted less
strongly. To treat hyperopia, lasers alter the
curvature of the cornea so that light is refracted
correctly

162
Q

How can replacement lenses be used to treat

visual defects

A

A replacement lens can either implanted into the
eye (along with the natural lens) or it may replace
the natural lens altogether. Risks of lens
replacement include retinal damage, cataracts
and infections

163
Q

What are the risks of lens replacement

A

Risks of lens replacement include retinal

damage, cataracts and infections

164
Q

Where is body temperature controlled in the body

A

Body temperature is controlled by the
thermoregulatory centre in the hypothalamus
of the brain

165
Q

How is temperature monitored by the body

A 
● Thermoregulatory centre has receptors
sensitive to blood temperature.
● Skin has receptors sensitive to skin
temperature - sends impulses to
thermoregulatory centre
166
Q

What physiological changes occur when the body

temperature is too high

A

● Vasodilation - blood vessels near the surface
of the skin dilate - more heat is radiated away.
● Sweating - evaporation of water takes away
heat energy from the surface of the skin

167
Q

What physiological changes occur when the body

temperature is too low

A

● Vasoconstriction - blood vessels near the surface
of the skin constrict - less heat radiated away.
● Shivering - respiration allows muscles to contract.
It is an exothermic process, so heat energy is
released.
● Sweating stops

168
Q

Give the name of the body’s coordination system

which involves hormones

A

The endocrine system

169
Q

What is a hormone

A

A hormone is a chemical messenger
secreted by a gland. It travels in the blood to
a target organ, where it causes a response

170
Q

What type of organ secretes hormones?

A

Glands

171
Q

Which gland controls many other glands in the

body

A

The pituitary gland

172
Q

Why is the pituitary gland considered a ‘master

gland’

A

It secretes a wide range of hormones,
some of which may stimulate other
endocrine glands

173
Q

What is the role of the pituitary gland in the endocrine

system

A

● Secretes human growth hormone - controls human
growth.
● Stimulates the thyroid gland.
● Stimulates ovulation and the production of oestrogen in
the ovaries.
● Stimulates the production of sperm and testosterone in
the testes

174
Q

What is the role of the thyroid gland in the

endocrine system

A

Secretes the hormone thyroxine - controls
metabolism, heart rate and body
temperature

175
Q

What is the role of the pancreas in the

endocrine system

A

Secretes the hormone insulin - controls

blood glucose levels

176
Q

What is the role of the adrenal gland in the

endocrine system

A

Secretes adrenaline - controls the body’s

‘fight or flight’ response

177
Q

What is the role of the ovaries in the endocrine

system

A

Secrete oestrogen, which coordinates the
menstrual cycle and the development of
female secondary sexual characteristics

178
Q

What is the role of the testes in the endocrine

system?

A

Secrete testosterone, which coordinates the
production of sperm and the development of
male secondary sexual characteristics

179
Q

Which organ monitors and controls blood glucose

concentration

A

The pancreas

180
Q

How does the pancreas respond when blood

glucose levels are too high

A

The pancreas secretes the hormone insulin.
Insulin binds to receptors on the liver and
muscles, causing excess glucose to be
converted into glycogen and stored

181
Q

How does the pancreas respond when blood

glucose levels are too low?

A

The pancreas secretes the hormone
glucagon. Glucagon binds to liver cells,
causing glycogen to be converted into
glucose and released into the blood

182
Q

How is blood glucose concentration controlled using

a negative feedback loop

A

● When the blood glucose concentration rises or falls
below the optimum, a hormone is secreted by the
pancreas.
● The action of either hormone (insulin or glucagon)
helps bring back the concentration to the correct
level.

183
Q

What is Type 1 diabetes?

A

Type 1 diabetes is an autoimmune disorder in
which the pancreas does not produce sufficient
insulin to control the blood glucose concentration.
As a result, blood glucose levels are often very
high, leading to excessive urination, tiredness and
weight loss

184
Q

How can Type 1 diabetes be treated

A

● Insulin injections before meals - allows
glucose to be converted into glycogen.
● Limiting carbohydrate intake.
● Attempts using pancreas and pancreatic cell
transplants; investigations into genetic
engineering of pancreatic cells

185
Q

What is Type 2 diabetes?

A 
Type 2 diabetes is a disorder in which the
body’s cells stop responding to insulin,
leading to an uncontrolled blood glucose
concentration. Its onset is linked with
increasing age and obesity
186
Q

How can Type 2 diabetes be treated

A 
● Following a carefully-controlled diet
● Doing regular exercise
● Losing weight
● Use of drugs which increase insulin
production and effectiveness
187
Q

What is osmosis?

A

Osmosis is the movement of water from a
dilute solution to a concentrated solution
through a partially permeable membrane

188
Q

In what ways is water lost from the body

A

● During exhalation via the lungs
● Sweating
● Urine (some reabsorbed in the kidney)

189
Q

In what ways are ions lost from the body

A

● Sweating

● Urine (some reabsorbed in the kidney)

190
Q

How are excess amino acids excreted from the

body

A

● Excess amino acids are deaminated in the liver to
form ammonia.
● Ammonia is toxic, therefore it is converted into urea
● Urea is excreted from the body via sweat and urine

191
Q

How do the kidneys maintain the balance of water

and other substances in the body

A

● Filter blood in order to remove waste
products eg. urea.
● Selectively reabsorb useful molecules eg.
glucose, water, ions

192
Q

What is the full name of the hormone ADH?

A

Anti-diuretic hormone

193
Q

Where is ADH secreted in the body

A

The pituitary gland of the brain

194
Q

How does ADH affect the reabsorption of water in

the kidneys

A

● When the blood is too concentrated, the pituitary
gland secretes more ADH.
● ADH travels in the bloodstream to the kidney and
increases the permeability of kidney tubules to water.
● More water is reabsorbed in the kidneys, resulting in
a smaller volume of more concentrated urine

195
Q

Why is kidney failure dangerous

A

When the kidneys are damaged, they may be unable
to filter the blood properly. This may lead to:
● A build-up of toxic molecules (eg. urea) in the
body.
● An uncontrolled ion and water balance and cells
being damaged as a result of osmosis

196
Q

What are the two main ways of treating kidney

failure

A

● Dialysis

● Transplant

197
Q

What is kidney dialysis?

A

Kidney dialysis is the use of a specialist machine
to carry out the function of kidneys. Dialysis fluid
contains the same concentration of glucose and
ions as healthy blood. As a result, only excess
and waste molecules are lost from the blood, and
glucose and ions remain.

198
Q

What is the function of reproductive hormones

during puberty?

A 
● Males: cause the development of secondary
sexual characteristics.
● Females: cause the development of
secondary sexual characteristics and the
maturation of eggs
199
Q

What is the main male reproductive hormone?

A

The main male reproductive hormone is
testosterone, which is produced by the
testes and controls sperm production

200
Q

What is the main female reproductive hormone

A

The main female reproductive hormone is
oestrogen, which is produced by the ovaries
and is involved in the menstrual cycle

201
Q

What is the menstrual cycle

A

The menstrual cycle is the monthly cycle of
physiological changes that occur in females,
involving the shedding of the uterus lining
(menstruation) and ovulation

202
Q

Describe the events of the menstrual cycle

A

● Uterus lining thickens and eggs begin to mature in the
ovaries.
● An egg is released from one of the ovaries (ovulation)
- uterus lining remains thick.
● If the egg is fertilised, pregnancy may occur. If not,
both the egg and the uterus lining are shed during
menstruation

203
Q

What is ovulation?

A

Ovulation is the release of a mature egg from
the ovaries, which occurs approximately every
28 days

204
Q

Name the four main hormones involved in the

menstrual cycle

A

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

205
Q

What is the role of FSH in the menstrual cycle?

A

FSH is secreted by the pituitary gland. It
controls the maturation of eggs within the
ovaries (inside a follicle) and triggers the
production of oestrogen by the ovaries

206
Q

What is the role of oestrogen in the menstrual

cycle

A

Oestrogen is produced by the ovaries and
released due to the action of FSH - it causes
the regrowth of the uterus lining.
It triggers the production of LH and restricts the
release of more FSH

207
Q

What is the role of LH in the menstrual cycle?

A

LH is produced in the pituitary gland as a
result of oestrogen. Its release triggers
ovulation

208
Q

What is the role of progesterone in the menstrual

cycle

A

Progesterone is secreted from the follicle of
the ovary. It sustains the uterus lining and
inhibits FSH and LH

209
Q

What is contraception

A

Contraception refers to any method of

preventing pregnancy

210
Q

What are the two types of oral contraceptives

A

● Combined contraceptive pill (contains
oestrogen and progesterone).
● Mini pill (contains only progesterone)

211
Q

How does the contraceptive pill prevent

pregnancy

A

● Inhibits FSH - eggs do not mature.
● Prevents the development of the uterus lining -
eggs cannot implant.
● Increases the thickness of cervical mucus -
immobilises sperm cells.

212
Q

What is the contraceptive patch?What is the contraceptive patch?

A

● Contains both oestrogen and
progesterone.
● It is a patch that is placed onto the skin
for 7 days at a time

213
Q

What is the contraceptive implant

A

A small rod inserted under the skin which
continuously releases the hormone
progesterone - lasts for 3 years

214
Q

What is the contraceptive injection

A

An injection containing the hormone
progesterone - lasts for approximately 3
months

215
Q

What is the IUS?

A 
The IUS (intrauterine system) is a small
plastic device that is inserted into the
uterus. It releases progesterone which
thickens cervical mucus and prevents the
build-up of the uterine lining
216
Q

What is the IUD

A

The IUD (intrauterine device) is a small
copper-containing device inserted into the
uterus, which prevents the implantation of
embryos

217
Q

What is a spermicide

A

A spermicide is a chemical that kills or
immobilises sperm cells - however, they
are not very effective, and work better
when combined with barrier methods.

218
Q

What is a barrier method of contraception

A

A barrier method of contraception involves a physical
separation between the sperm and the egg. They
include:
● Condoms - thin sheath worn on the penis or inside
the vagina - protects against STIs but may tear/break.
● Diaphragms - a thin cap placed over the cervix -
prevent entry of sperm.

219
Q

What surgical methods of contraception are

available?

A

Sterilisation - in males, the sperm ducts
are tied (vasectomy) and in females, the
oviducts are tied.

220
Q

What is abstinence

A 
Abstinence is the practice of not having sex,
which also avoids pregnancy. Some people
abstain from sex around the time of
ovulation - this is known as the rhythm
method, but it is quite unreliable
221
Q

What are the advantages of fertility treatment

A

● Allows infertile couples to have children

● Can store a woman’s eggs for later

222
Q

What are the disadvantages of fertility treatment

A

● It can be a very expensive process.
● It has a low success rate - especially for older
couples.
● Increases chance of multiple pregnancies -
dangerous for mother and babies.
● Side effects of fertility drugs

223
Q

What is negative feedback

A

Negative feedback is a type of control where
the body responds to an increase or
decrease in a factor by returning it to the
optimum level

224
Q

What is thyroxine

A

Thyroxine is a hormone released by the
thyroid gland. Its release is triggered by the
thyroid stimulating hormone (TSH). Thyroxine
controls the body’s metabolic rate, growth and
development

225
Q

How is the release of thyroxine controlled by negative

feedback

A

● Levels of blood thyroxine falls - detected by
receptors in the brain.
● Pituitary gland releases more TSH.
● More thyroxine produced and released by the
thyroid gland.
● Blood thyroxine level returns to normal.

226
Q

What is adrenaline?

A

Adrenaline is a hormone secreted by the
adrenal gland in times of stress. It is
responsible for the ‘fight or flight response’.

227
Q

What are the effects of adrenaline?

A

● Increase in heart and breathing rate - delivers oxygen
and glucose to the body.
● Stored glycogen converted to glucose.
● Dilation of pupils.
● Increased mental awareness.
● Blood diverted away from digestive system to
muscles

228
Q

What is a tropism

A

A tropism is the response of a plant to a

specific stimulus

229
Q

What is phototropism

A

Phototropism is the response of a plant’s

shoot or root to light

230
Q

What is gravitropism

A

Gravitropism is the response of a plant’s

shoot or root to gravity

231
Q

What is auxin

A

Auxin is a hormone which controls the
growth of a plant’s shoots and roots. When
auxin is unevenly distributed in a growing
plant, the rate of growth will also be unequal

232
Q

How do plant shoots show positive phototropism

A

● One side of the shoot is in the light, causing auxin
to move to the shaded side.
● At the shaded side, the cells are stimulated to
grow - the shoot bends towards the light.
● As a result, photosynthesis can occur at a faster
rate.

233
Q

How do plant shoots show negative gravitropism

A

● In a horizontal shoot, auxin accumulates in the
lower side due to gravity.
● Cells on the lower side of shoot grow more, causing
the shoot to bend away from the direction of gravity.
● As a result, more light is usually available for
photosynthesi

234
Q

How do plant roots show positive gravitropism

A

● In a horizontal root, auxin accumulates in the
lower side, causing cells to grow less.
● The root bends in the direction of gravity
● As a result, more water and nutrients are
available to the plant roots

235
Q

What are gibberellins

A

Gibberellins are a type of plant hormone

involved in seed germination

236
Q

What is ethene

A

Ethene is a type of plant hormone

involved in cell division and ripening

237
Q

What are the uses of auxins

A

● Weedkillers - auxin causes cells to grow at a
rapid rate, causing plant death.
● Rooting powder - auxin causes new plant to
grow very quickly.
● Tissue culture - auxin promotes growth of
roots and shoots.

238
Q

What are the uses of ethene?

A

● Control of food ripening in the food industry -
allows fruit to be ripened just before they are
sold.

239
Q

What are the uses of gibberellins

A

● Termination of seed dormancy
● Promotion of flowering
● Increase of fruit size

240
Q

What is the function of the retina

A

Light is focused here. Contains photoreceptive cells which detect colour and light intensity

241
Q

What is the function of the optic nerve

A

Carries impulses from the retina to the brain

242
Q

What is the function of the sclera

A

The tough, supporting wall of the eye

243
Q

What is the function of the cornea

A

Transparent region of the sclera at the front of the eye. Refreacts light-bends it as if it enters the eye

244
Q

What is the function of the iris

A

Has sets of muscles that control the size of the pupil and regulate the light reaching the retina

245
Q

What are the function of the ciliary muscles and suspensory ligament

A

Muscles connected to the lens by suspensory ligaments. Control the shape of the lense. Connected the ciliary muscles to the lens and hold the lens and hold the lens in place. Control the shape of the lens

246
Q

What happens to the size of the pupil when it is dim

A

Dilated

247
Q

What happens to the size of the pupil when it is bright

A

Contracts

248
Q

What do the circular muscles do with dim light

A

Relax

249
Q

What do the circular muscles do with bright light

A

Contract

250
Q

Do the radial muscles contract or relax in dim light

A

Contract

251
Q

Do the radial muscles contract or relax in bright light

A

Relax

252
Q

Define accommodation

A

This process of changing the shape of the lense o focus on near or distant objects

Biology (7 decks)

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