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UK GCSE Biology > B5 Homeostasis > Flashcards

B5 Homeostasis Flashcards

1
Q

What is homeostasis?

A

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 4 internal features are maintained by homeostasis?

A

Temperature
Water
Glucose
pH

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3
Q

Why is a constant intenal environment important?

A

So that cells are able to function normally and effectively in any conditions

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4
Q

Why is it important to have a constant glucose level?

A

Too much glucose can cause diabetes

Too little glucose can cause sweating or trembeling

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5
Q

Why is it important to have a constant water level?

A

Too much water can cause cells to burst

Too little water may mean they can not function correctly

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6
Q

Why is it important to have a constant body temperature?

A

High temperature increases kinetic energy of enzymes so they react faster
Low temperature may denature enzymes

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7
Q

What two automatic control systems are involved in homeostasis?

A

Nervous System

Endocrine System

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8
Q

What are receptors?

A

They sense external change

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9
Q

What do coordination centres do?

A

They decide what to do, depending on signals they recieve

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10
Q

Name 3 coordination centres

A

Brain
Spinal Cord
Pancreas

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11
Q

What are the two types of effectors?

A

Muscles

Glands

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12
Q

What is the order of compounds in a control centre?

A 
Stimulus
Receptor
Coordinator
Effector
Response
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13
Q

What does homeostasis maintain optimum conditions for?

A

Enzyme Action
Cell Structure
Chemical Reactions

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14
Q

What is a negative feedback loop?

A

A continuous cycle of events that respond when conditions change away from a set point and causes it to return to a set point

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15
Q

What is the use of the nervous system?

A

It allows humans to react to their surroundings

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16
Q

What is the CNS?

A

Central Nervous System - It works as a coordination centre

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17
Q

What does the CNS consist on in vertebrates?

A

The Brain and Spinal Cord

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18
Q

What are sensory neurones?

A

Neurnones that carry information as electrical impulses from the receptors to the CNS

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19
Q

Where are receptors located?

A

In and on organs

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20
Q

What are motor neurones?

A

Neurones that carry electrical impulses from the CNS to effectors

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21
Q

What are effectors?

A

Muscles or glands that carry out a response to a nervous impulse

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22
Q

What is a receptor?

A

Cells that detect a stimuli

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23
Q

What is a synapse?

A

The connection between two neurones

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24
Q

How does a signal travel across a synapse?

A

It is transfered into chemicals and diffuses across the gap before setting of a new electrical signal in the next cell

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25
Q

What is a reflex?

A

A rapid and automatic response that does not involve the concious part of the brain

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26
Q

What is a reay neurone?

A

A neurone in the spinal cord that allow the CNS to be bypassed and send stimuli from the sensory nerone straight to the motor neurone

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27
Q

What is reaction time?

A

The time taken to respond to the stimulus

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28
Q

What an reaction time be effected by?

A

Age, gender or drugs

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29
Q

How can we test reaction time and how caffeine effects it?

A

Ruler drop test

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30
Q

How do we carry out the ruler drop test?

A

One person must hold a ruler between anothers thumb and finger at 0cm
They must then drop it without warning and the other person must catch it as quickly as possible
They should then try it after drinking a caffinated drink

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31
Q

Most effective ways of testing reaction time?

A

Computer tests

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32
Q

What is the brain made up of?

A

Billiones of nterconnected neurones

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33
Q

Where is the Celebral Cortex?

A

It is the outer wrinkly section of the brain

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34
Q

What is the function of the Celebral Cortex?

A

It is responsible for the conciousness, intelligence, memory and language

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35
Q

Where is the Cerebellum?

A

In the back and lower section of the brain

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36
Q

What is the function of the Cerebellum?

A

Responsible for muscle coordination

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37
Q

Where is the Medulla?

A

In front of the spinal cord, below the main section of the brain

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38
Q

What is the function of the Medulla?

A

Controls unconcious activities (breathing anf heartbeat)

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39
Q

How do we study a brain?

A

Studying patients with brain damage
Electrically Stimulating the brain
MRI Scans

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40
Q

What does MRI stand for?

A

Magnetic Resonance Imaging

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41
Q

What does an MRI scan show?

A

Which area of the brain is active

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42
Q

How do we elctricall stimulate a brain?

A

Pushing tiny electrodes into the tissue and zapping it with electricty to observe how the body reacts.

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43
Q

Where is the sclera located?

A

Around the eye

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44
Q

What is the function of the sclera?

A

It is a tough supporting wall

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45
Q

Where is the cornea located?

A

It is a transparent, outer layer at the front of the eye

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46
Q

What is the function of the cornea?

A

It refracts light into the eye

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47
Q

Where is the iris located?

A

Muscles just below the surface of the eye at the fron that can change size

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48
Q

What is the function of the iris?

A

Controls the diameter of the pupil and thus the light that goes into the eye

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49
Q

Where is the lens located?

A

Behind the iris but in front of the main bulk of the eye

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50
Q

What is the function of the lens?

A

Focuses the light on the retina

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51
Q

Where are the ciliary muscles located?

A

Behind the iris, on either side of the suspensory ligaments

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52
Q

What is the function of the ciliary muscles?

A

Help control the shape of the lens and thus helps focus

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53
Q

Where is the suspensory ligament located?

A

Between the cilliary muscles and the lens, behind the iris

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54
Q

What is the function of the suspensory ligament?

A

Help control the shape of the lens and thus helps focus

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55
Q

Where is the optic nerve located?

A

Behind the eye

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56
Q

What is the function of the optic nerve?

A

Carries impulses to the brain

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57
Q

Where is the retina located?

A

At the back of the eye

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58
Q

What is the function of the retina?

A

It has receptor cells that understand the colour and light and understand the image

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59
Q

What damages the retina?

A

Bright lights

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60
Q

Which reflex protects oour retina?

A

When there are bight lights a reflex is triggeres that make the pupil smaller so less light enters.

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61
Q

What is the pupil size controlled by?

A

The Iris contracting/ relaxing

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62
Q

What happens in the eye when you look at a near by object?

A

The cillary muscle tightens
The suspensory ligament slakens
The lens becomes fatter (more curved)
Therefore light is refacted more

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63
Q

What happens in the eye when you look at a far away object?

A

The cillary muscle relax
The suspensory ligament pull tight
The lens becomes thinnes (less curved)
Therefore light is refacted less

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64
Q

Why does eye sight get worse with age?

A

The lens become less flexible and cannot easily spring back into shape and ths cannot focus

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65
Q

What does it mean to be long sighted?

A

You cannot focus on nearby objects

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66
Q

What causes long-sightedness?

A

The lens is the wrong shape and doesn’t refact light enough or the eyeball is too short

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67
Q

What does it mean to be short sighted?

A

You cannot focus on far away objects

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68
Q

What causes short-sightedness?

A

The lens is the wrong shape and refacts light too much or the eyeball is too long

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69
Q

How can we treat long-sightedness?

A

A convex lens which curves outwards

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70
Q

Medical name for being long-sighted?

A

Hyperopia

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71
Q

How can we treat short-sightedness?

A

A concave lens which curves inwards

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72
Q

Medical name for being short-sighted?

A

Myopia

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73
Q

Advantages of contact lenses

A

Lightweight
Good for sport
Comfortable
Invisible

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74
Q

Didvantages of contact lenses

A

High risk of eye infection

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75
Q

What happens during laser eye surgery?

A

A laser is used to vaporise tissue, changing the shape of the cornea

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76
Q

Advantages of laser eye surgery

A

Long term solution

Work for multiple eye problems

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77
Q

Disadvantages of laser eye surgery

A

Risk of surgical complications

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78
Q

What can be treated by doing surgery to replace the lens?

A

Long sighted

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79
Q

What are replacement eye lenses made from?

A

Clear plastic

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80
Q

Advantages of surgically replacing the eye lens

A

More effective

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81
Q

Disadvantages of surgically replacing the eye lens

A

Higher risk of complications including damage to the retin

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82
Q

What is our optimum body temperature?

A

37°C

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83
Q

What part of the brain controls temperature?

A

The thermoregularity centre

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84
Q

How does the thermoregularity centre calculate our internal body temperature?

A

It has receptors that are sensitive to the temperature of blood

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85
Q

Responses to high body temperature

A

Sweat

Vasodilation

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86
Q

Responses to low body temperature

A

Hairs stand up to trap air
No Sweat
Vasoconstriction
Shiver

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87
Q

Define hormones

A

Chemical molecules released into the bood that effect certain organs/ tissues and make them change

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88
Q

What is the endocrine system?

A

The system which links hormones, glands and their targets

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89
Q

What type of effect do hormones give?

A

Long lasting

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90
Q

Where is the pituitary gland located?

A

Below the brain

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91
Q

What does the pituitary gland do?

A

Regulates body conditions

Regulates other glands

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92
Q

Which is the ‘master gland’?

A

Pituitary Gland

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93
Q

What do the ovary glands do?

A

Produce oestrogen (needed for the menstrual cycle)

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94
Q

What do the testes glands do?

A

Produce testosterone (needed for puberty ad sperm production)

95
Q

Where is the thyroid located?

A

Near the voice box

96
Q

What does the thyroid gland do?

A

Produces thyroxine which regulates temperature, metabolism and heart rate

97
Q

Where is the adrenal located?

A

Above the kidney

98
Q

What does the adrenal gland produce?

A

Adreneline

99
Q

Function of Adreneline

A

Flight or fight instincts

100
Q

Where is the pancreas located?

A

Near the kidney

101
Q

What does the pancreas produce?

A

Insulin

102
Q

Function of insulin

A

Regulates blood glucose levels

103
Q

Which type of response acts faster?

A

Nerves

104
Q

Which type of response lasts longer?

A

Hormone

105
Q

Which type of response is more precise?

A

Nerves

106
Q

How is excess glucose delt with?

A

Stored as glycogen in the livers and muscles

107
Q

Which hormone lowers blood sugar levels?

A

Insulin

108
Q

Which hormone increases blood sugar levels?

A

Glucagon

109
Q

How does insulin work?

A

It is secreted by the pancreas and turns glucose into glycogen

110
Q

How does glucagon work?

A

It is secreted by the pancreas and turns glycogen into glucose

111
Q

What is type 1 diabetes?

A

When the body produces little or no insulin

112
Q

What is type 2 diabetes?

A

When a body becomes resistent to their own insulin and this becomes uneffective

113
Q

How are type 1 diabetes treated?

A

Insulin injections

114
Q

How are type 1 dibetes controlled?

A

Diet

Excersise

115
Q

Risk factors for type 1 diabetes?

A

Genetics

116
Q

Risk factors for type 2 diabetes?

A

Age
Weight
Genetics

117
Q

How are type 2 diabetes controlled?

A

Diet

Excersise

118
Q

What does the kidney do?

A

Filter the blood

119
Q

What three substances are removed from the blood in urine?

A

Urea
Ions
Water

120
Q

What substance is converted into urea in the liver?

A

Ammonia

121
Q

How are excess amino acids delt with?

A

Converted to fats and carbohydrates

122
Q

What is a by product of deamination?

A

Ammonia

123
Q

What is deamination?

A

The conversion of proteins to fats and carbohydrates

124
Q

Why is an excess or deficit of mineral ions?

A

It throws of the water - ions balance for osmosis

125
Q

Why must ions by regulated in the kidney constantly?

A

The amount of ions lost during sweat are not regulated

126
Q

When do we loose water in the body?

A

Sweat and breathing out

127
Q

Which hormone controls urine concentration?

A

ADH

128
Q

What does ADH stand for?

A

Anti-diuretic hormone

129
Q

What gland releases ADH?

A

Pituitary Gland

130
Q

How does ADH change the concentration of urine?

A

When water content is low, more is released so that the kidneys absorb more water
When water content is high, less is released so that the kidneys absorb less water

131
Q

What are the treatments for kidney faliure?

A

Regular Dialysis

Kidney Transplant

132
Q

What does dyalisis consist of?

A

A machiene doing the job of the kidney - keep levels of dissolved substances at normal levels

133
Q

Why is kidney faliure so serious?

A

You lose the ability to control levels of ions and water in your blood and therefore intoxicate yourself

134
Q

What happens in a dyalisis machine?

A

The persons blood flows between partially permeable membrane surrounded by dyalisis fluid
Waste fuids diffuse back across the barrier

135
Q

What are dyalisis machines permeable to?

A

Ions and water substances

136
Q

What are dyalisis machines not permeable to?

A

Proteins and such larger molecules

137
Q

What does dyalisis fluid contain?

A

Healthy blood concentrations of dissolved ions and glucose

138
Q

How often are regular dyalisis?

A

Up to 3 times a week

139
Q

How long does dyalisis last?

A

3-4 hours per session

140
Q

Disadvantages of using dyalisis?

A

Not pleasent
Expensice
Cause blood clots
Infections

141
Q

Advantages of using dyalisis?

A

Gives valuable time until the organ donor is found

142
Q

Why are most kidneys donated by people who are decesed?

A

There is a small risk to living donors

143
Q

How come living donors can donate a kidney with minor risk to temselves?

A

Adults only require one

144
Q

What is the greatest risk to someone recieving a donor kidney?

A

The body may reject it

145
Q

How can a rejected kidney be prevented?

A

Drugs but it is not fully effective

146
Q

Advantages of kidney trnsplants

A

Long term
Cheaper
Less time spent in hospitals

147
Q

What is the monthly release of an egg reffered to as?

A

Menstrual Cycle

148
Q

What is an example of a secondary characteristic?

A

Facial Hair
Breasts
etc…

149
Q

What happens during puberty?

A

Release of sex hormones
Triggers secondary sexual characteristics
(Eggs mature on women)

150
Q

What hormone is produced in males during puberty?

A

Testotorone

151
Q

Where is testosterone produced?

A

Testes

152
Q

What does testosterone do?

A

Stimulates sperm production

153
Q

What hormone is produced in females during puberty?

A

Oestrogen

154
Q

Where is oestrogen produced?

A

Ovaries

155
Q

What does oestrogen do?

A

Brings about physical changes and the menstrual cycle

156
Q

What happens roughly between days 1-4 of the menstruel cycle?

A

Uterus limimg breaks down

157
Q

What happens roughly between days 4-14 of the menstruel cycle?

A

The uterus builds up again with a spongy layer full of blood, getting ready to recieve a fertilised egg.

158
Q

What happens roughly on day 14 of the menstruel cycle?

A

An egg is released

159
Q

What is the release of an egg called?

A

Ovulation

160
Q

What happens roughly between days 14-28 of the menstruel cycle?

A

The wall is maintained awaiting fertilisation

161
Q

What 4 hormones control menstruation

A

FSH
Oestrogen
LH
Progesterone

162
Q

What does FSH stand for?

A

Follicle-Stimulating Hormone

163
Q

What does LH stand for?

A

Lutenising Hormone

164
Q

What does FSH do?

A

Causes an egg to mature (in a structure called a follicle)

Stimulates ovaries to produce oestrogen

165
Q

What does Oestrogen do?

A

Causes the lining of the uterus to grow

Stimulates the release of LH and stops the release of FSH

166
Q

What does LH do?

A

Stimulates the release of an egg

167
Q

What does Progesterone do?

A

Maintains the liningof the uterus during the second half of the cycle. When this falls so does the lining.
Inhibits (stops) the release of LH and FSH

168
Q

Where is FSH produced?

A

Pituitary gland

169
Q

Where is LH produced?

A

Pituitary gland

170
Q

Where is Oestrogen produced?

A

Ovaries

171
Q

Where is Progesterone produced?

A

Ovaries

172
Q

How does Oestrogen work as a contreceptive?

A

It prevents the release of an egg when used every day as it inhibits the production of FSH and eventually egg production and delopment stops.

173
Q

How does Progesterone work as a contreceptive?

A

It stimulates a think mucus that prevents sperm reaching the egg.

174
Q

What does the combined oral contraceptive pill consist of?

A

Progesterone and Oestrogen

175
Q

What other type of contracetptive pill is there other than the combined oral contraceptive pill?

A

A prgesterone-only pill which has fewer side effects and is as effective

176
Q

What is a contreceptive patch?

A

A 5cmx5cm patch with oestrogen and progesterone that lasts 1 week

177
Q

What is a contreceptive implant?

A

A plastic implant that is placed under the skin on the arm that continualy releases progesterone for up to 3 years.

178
Q

What is a contraeptive injection?

A

A dose of progesterone that is needed every 2 - 3 months.

179
Q

What does IUD stand for?

A

Intrauterine device

180
Q

What is an IUD?

A

A T-shaped device inserted in the uterus that kills sperm and prevent implantation of fertilised egg.

181
Q

What do plastic IUDs do?

A

Release progesterone.

182
Q

What do copper IUDs do?

A

Prevent sperm surviving in the uterus.

183
Q

What are the two different forms of contraception?

A

Hormonal and non-hormonal

184
Q

Why are barrier methods often important even when hormonal contraception used?

A

They protect against STDs

185
Q

What is a condom?

A

A latex worn over the pens or inside the vagina

186
Q

What is a diaphragm?

A

A shallow plastic ups that fits over the opening to the cervix

187
Q

What is spermicide?

A

A sperm killing cream

188
Q

Negative side-effects of spermicide

A

Only 70-80% effect

Can cause rashes and infections

189
Q

What is steralistaion?

A

Cutting off or tying the fallopian tubes in women

Cutting off the sperm duct (between the testes and penis) in men

190
Q

What is the ‘natural method’ of avoiding pregnancy?

A

Trying not to have sex during fertile days

191
Q

What does abstinence mean (in terms of avoiding pregnancy)?

A

Not having sex

192
Q

How permenant is steralisation?

A

There is a small chance to reverse it in men but it is very permenant

193
Q

What is the only method of ‘contreception’ that has 100% effectivness?

A

Abstinence

194
Q

What are the positives of using hormones to increase fertility?

A

It helps people get pregnant when they couldn’t

195
Q

What are the negatives of using hormones to increase fertility?

A

It doesn’t always work (doing it several time can be expensice)
Too many eggs can be stimulated resulting in unexpected multiple pregnancies (twins, triplets etc…)

196
Q

What happens during an IVF?

A

Eggs are fertilised and grown into embryos in a lab and then introduced into a womans body which improves the chances of pregnancy

197
Q

What does ICSI stand for?

A

Intra-Cytoplasmic Sperm Injection

198
Q

What is ICSI?

A

A technique used during IVF where sperm are directly injected innto the egg

199
Q

When is ICSI most effective?

A

When a man has a low sperm count

200
Q

Positive of IVF?

A

Can give an infertile coulpe a child

201
Q

Negatives of IVF?

A

Multiple births can happen if more than one embryo growns wich causes complications to mother and babies
Sucess rate is low (26%)
Emotionally and physically stressful
Side effeects to the hormones

202
Q

Why are some peopke against IVF?

A

Unused embryos are eventually destroyed

Geetic testing can lead to selecting preffered characteristics

203
Q

How are levels of hormones controlled by the body?

A

Negative feedback loops

204
Q

What is thyroxine released in response to?

A

TSH which is released in the pituitary gland

205
Q

What does TSH stand for?

A

Thyroid Stimulating hormone

206
Q

What does auxin control?

A

Growth near tips and shoots of plants

207
Q

What does auxin control the growth of plants in response to?

A

Light (phototropism)

Gravity (gravitropism and geotropism)

208
Q

Where is auxin produced?

A

Tips

209
Q

What does auxin do after production?

A

Move backwars to stimulate the cell elongation process whichoccurs just behind the tips

210
Q

What happens if the tips of a shoot are removed?

A

No auxin is produced and the shoot may stop growing

211
Q

What happens if extra auxin is produced?

A

Promotes growth at the shoot

Inhibits growth at the root

212
Q

What results does the extra production if auxin produce?

A

Shoots grow towards light

Shoots grow away from gravity and roots grow towards it.

213
Q

How do shoots grow towards light?

A

More auxin accumulates on the shaded side thna that exposed to the sun causing this side to grow faster and therefore bending it towards the light.

214
Q

How do shoots grow away from gravity?

A

More auxin accumulates on the lower side of the shoot causing that to grow faster and thus bend the shoot upwards.

215
Q

How do roots grow towards gravity?

A

More auxin accumulates on the lower side of the root causing that to growth to inhibit and thus bend the root downwards.

216
Q

What practical do we do to investigat plant growth response?

A

Cress Practical

217
Q

What do wedo to investigate plant growth response?

A

Put 10 cress seeds in 3 different petri dishes with moist filter paper
Shine a light onto each dish at a different angle
Leave for a week and observe the response

218
Q

What are some of the control variables in the investigation into plant growth response?

A 
Number of seeds
Type of seed
Temperature
Water 
Light intensity
219
Q

Name 3 commercial uses of auxin

A

Killing Weeds
Growing from cuttings with root powder
Growing cells in tissue culture

220
Q

How can auxin be used as a weed killer?

A

It can be targeted to broad-leaved plants and disrupt their growth (killing them) without disrupting grass and crops

221
Q

How can auxin be used to grow from cuttings with root powder?

A

Cuttings alone tend to die but if you add root powder (which contains auxin) it will

222
Q

Define cutting

A

A part of a plant that has been cut off (like a branch with a few leaves)

223
Q

How can auxin be used to grow cells in tissue culture?

A

They are added to growth mediums to stimulate cells to divide to form both roots and shoots

224
Q

What are tissue cultures?

A

Can be used to clone plants from a few cells

225
Q

What is gibberlin?

A

A hormone which stimulates
Stems growth
Seed germination
Flowering

226
Q

Name 3 comercial uses of gibberlin

A

Controlling dormancy
Inducing flowering
Growing larger fruit

227
Q

What is dormancy?

A

The specific conditions needed for seeds to germinate

228
Q

How does gibberlin control dormancy?

A

Seeds can be treated with gibberlin to make them fertile all year and also means all seeds become fertile at the same time.

229
Q

How does gibberlin induce flowering?

A

It can allow flowers to flower without change in environment

230
Q

How does gibberlin help grow larger fruit?

A

Can help grow seedless fruit (which tend to be smaller)

231
Q

What is ethene?

A

A gas produced by aging parts of a plant.

232
Q

What does ethene do?

A

Influences growth of a plant by controlling cell division. It also stimmulates enzymes that cause fuit to ripen.

233
Q

How is ethene used commercially?

A

It helps ripen fruit either on the plant or during transportation

234
Q

What is the function of the cerebellum?

A

Controls movement and balance

UK GCSE Biology (9 decks)

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