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Biology Paper 2 > 5- Homeostasis And Response > Flashcards

5- Homeostasis And Response Flashcards

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1
Q

What is homeostasis

A

Maintaining a stable internal environment

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2
Q

What are the three main components in automatic control systems

A

Receptors,
Coordination centres,
Effectors

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3
Q

What is a stimulus

A

A change in the environment

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4
Q

What is negative feedback

A

When the receptor detects that a stimulus is too high or too low and your body brings it back to normal

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5
Q

What is the central nervous system (CNS)

A

In vertebrates, it consists of the brain and spinal cord only but in mammals it also connected to the body by sensory and motor neurones

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6
Q

What is the role of a sensory neurone

A

They carry information as electrical impulses from the receptors to the CNS

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7
Q

What is the role of the motor neurone

A

They carry electrical impulses from the CNS to the effector

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8
Q

What is an effector

A

All muscles and glands.

They respond to nervous impulses and bring about a change

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9
Q

What is the role of receptors

A

They detect stimuli

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10
Q

What is a synapse

A

The connection between two neurones

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11
Q

How does a synapse transport the signal

A

The nerve signal is transferred by chemicals that diffuse across the gap. These chemicals then set off a new electrical signal in the next neurone

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12
Q

What are reflexes

A

A rapid automatic response to certain stimuli that don’t involve the conscious part of the brain.
They reduce the chances of being injured

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13
Q

What is a reflex arc

A

The passage of information in a reflex from receptor to effector

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14
Q

What is the order of response in the reflex arc

A 
Stimulus,
Receptor,
Sensory neurone,
Synapse 
Relay neurone
Synapse
Motor neurone
Effector
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15
Q

Why is a reflex quicker than a normal response

A

Because you do not have to think about a response

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16
Q

What is reaction time

A

The time it takes to respond to a stimulus

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17
Q

What can effect reaction time

A

Age, gender, drugs etc

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18
Q

How does caffeine affect reaction time

A

Speeds up reaction time

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19
Q

How can u test the effect of caffeine on reaction time

A

Drop test

Have a person do the drop test and then have a caffeinated drink and repeat the test

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20
Q

Why are computers better for testing reaction time than a drop test

A

Remove the possibility of human error,
Can record in milliseconds,
More accurate,
Remove chance that the person can predict when to respond

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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

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23
Q

What is the role of the medullla

A

Controls unconscious activities like breathing and your heartbeat

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24
Q

What are different methods of studying the brain

A

Studying patients with brain damage,
Electrically stimulating the brain,
MRI scans

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25
Q

What is the sclera

A

The tough, white, supporting wall of the eye

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26
Q

What is the cornea and its role

A

The transparent outer layer at the front of the eye.

It refracts light into the eye

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27
Q

What is the role of the iris

A

It contains muscles that allow it to control the diameter of the pupil

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28
Q

What the pupil

A

The hole in the middle of the eye that lets light through

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29
Q

What is the role of the lens

A

It focuses the light onto the retina

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30
Q

What is the retina

A

It contains receptor cells sensitive to light intensity and colour

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31
Q

What is the role of the optic nerve

A

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

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32
Q

When light receptors detect very bright light, what happens to the circular muscles and radial muscles

A

The circular muscles in the iris contract and the radial muscles relax.
This makes the pupil smaller

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33
Q

What happens to the circular and radial muscles when in dim lighting

A

The circular muscles relax and the radial muscles contract

This makes the pupil wider

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34
Q

What is accommodation (in terms of eyes)

A

Changing the shape of the lens so that light focuses on the retina

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35
Q

What happens to the ciliary muscles and suspensory ligaments when trying to focus on near objects

A

The ciliary muscles contract and the suspensory ligaments relax

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36
Q

What shape is the lens when focusing on a near object

A

Fat, more curved

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37
Q

What happens to the ciliary muscles and the suspensory ligaments when looking at a distant object

A

The ciliary muscles relax and the the suspensory ligaments pull tight

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38
Q

What shape is the lens when looking at a far object

A

Thin, less curved

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39
Q

What is the medical name for long-sightedness

A

Hyperopia

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40
Q

What lens is used to correct long-sightedness

A

Convex (curves outward)

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41
Q

What is the medical name for short-sightedness

A

Myopia

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42
Q

What lens is used to correct short-sightedness

A

Concave lens (curves inward)

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43
Q

What are treatments for vision defects

A

Contact lenses,
Laser eye surgery,
Replacement lens surgery

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44
Q

How does laser eye surgery work

A

A laser can be used to vaporise tissue, changing the shape of the cornea and so how strongly it refracts the light

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45
Q

What are the two types of lenses

A

Hard and soft lenses

46
Q

What are the risks of laser eye surgery

A

Infection or the eye reacting in a way that makes ur vision worse than before

47
Q

What is involved in replacement lens surgery

A

The natural lens of the eye is removed and an artificial lens is inserted in its place

48
Q

What is the thermoregulatory centre

A

It contains receptors that are sensitive to temperature of the blood flowing through the brain

49
Q

What are the responses to when u are too hot

A

Sweat is produced and evaporates from the skin which transfers energy to the environment.
Vasodilation.

50
Q

What are responses to being too cold

A

Hair stand up to trap an insulating layer of air,
No sweat produced,
Vasoconstriction,
Shivering

51
Q

What is vasodilation

A

Blood vessels supplying the skin dilate so more blood flows close to the surface of the skin

52
Q

What is vasoconstriction

A

The blood vessels supplying in no the skin constrict to close off the skin’s blood supply

53
Q

What is a hormone

A

A chemical messenger that is sent in the blood

54
Q

Give 4 glands

A 
Any from:
Pituitary gland,
Thyroid gland
Ovaries,
Adrenal gland,
The pancreas,
Testes,
Hypothalamus,
etc.
55
Q

Where is the pituitary gland

A

In the brain

56
Q

Why is the pituitary gland sometimes called the ‘master gland’

A

Because it releases hormones that act on other glands, making them release hormones

57
Q

What hormone does the thyroid gland produce

A

Thyroxine

58
Q

What is the function of thyroxine

A

Regulates things like rate of metabolism, heart rate and temperature

59
Q

What hormone does the adrenal gland produce

A

Adrenaline

60
Q

What hormone is produced by the ovaries

A

Oestrogen

61
Q

What hormone is produced by the testes

A

Testosterone

62
Q

What hormone does the pancreas produce

A

Insulin

63
Q

What are the differences between hormones and nerves

A

Hormones:

  • Slower action
  • Act for a long time
  • Act in a more general way

Nerves:

  • Very fast action
  • Act for a very short time
  • Act on a very precise area
64
Q

How and where is excess glucose stored

A

Stored as glycogen in the liver

65
Q

Where are glucagon and insulin produced

A

The pancreas

66
Q

What does insulin do

A

It makes the liver turn glucose into glycogen

67
Q

What does glucagon do

A

It makes the liver turn glycogen into glucose

68
Q

When is insulin secreted

A

When the blood glucose level is too high

69
Q

When is glucagon secreted

A

When the blood glucose level is too low

70
Q

What is the problem in type 1 diabetes

A

The pancreas produce little or no insulin, which means that the person’s blood glucose levels are high

71
Q

What are the treatments for type 1 diabetes

A

Insulin injections,
Reducing intake of food rich in sugars,
Regular exercise

72
Q

What is the problem in type 2 diabetes

A

The person becomes resistant to their own insulin.

This can cause blood sugars to rise to a dangerous level

73
Q

What can increase the chance of getting type 2 diabetes

A

Obesity

74
Q

How can type 2 diabetes be controlled

A

Eating a carbohydrate-controlled diet and regular exercise

75
Q

What is filtration in terms of kidneys

A

When kidneys filter out waste products from the blood

76
Q

What is selective reabsorption

A

When useful substances like glucose are absorbed back into the blood

77
Q

What is deamination

A

Turning excess amino acids into fats and carbohydrates

This occurs in the liver

78
Q

What is a waste product of deamination

A

Ammonia

79
Q

What is ammonia converted into and where

A

Converted into urea in the liver

80
Q

What is wrong with having too high or too low ion content in the body

A

Upset the balance between water and ions and could mean that too much or too little water is drawn into cells by osmosis and having the wrong amount of water damages cells

81
Q

What are two ways that water leaves the body with uncontrolled quantities

A

Sweating,

Breathing out

82
Q

What hormone controls the concentration of urine

A

Anti-diuretic hormone (ADH)

83
Q

What gland releases ADH

A

The pituitary gland

84
Q

How does ADH work

A

The more ADH released then the more water is reabsorbed

85
Q

If lots of ADH is released, with the urine be diluted or concentrated

A

It will be concentrated because the water has been reabsorbed so there is less water in the urine

86
Q

What is in dialysis fluid

A

It has the same concentration of glucose and dissolved ions as healthy blood

87
Q

What happens in a dialysis machine

A

The person’s blood flows between partially permeable membranes, surrounded in dialysis fluid.
The membrane is permeable to ions and waste substances and the dialysis fluid carries this out

88
Q

What are the problems with dialysis

A

Many need to have it 3 times a week and each session takes 3-4 hours,
Can cause blood clots or infections,
Expensive for the NHS

89
Q

What are the problems with kidney transplants

A

The kidney can be rejected by the patient’s immune system,

Long waiting lists for transplants

90
Q

What r the positives of kidney transplants

A

They are cheaper in the long run than dialysis,
They cure kidney failure,
Patients do not have to spend hours on dialysis,
Rejection of the kidney can be treated by drugs

91
Q

How many stages of the menstrual cycle is there

A

4

92
Q

Describe stage 1 of the menstrual cycle

A

The uterus lining breaks down for about 4 days

93
Q

Describe stage 2 of the menstrual cycle

A

The uterus lining builds up again, from day 4-14, into a thick spongy layer full of blood vessels ready to receive a fertilised egg

94
Q

Describe stage 3 of the menstrual cycle

A

An egg develops and is released from the overt at day 14 - this is called ovulation

95
Q

Describe stage 4 of the menstrual cycle

A

The uterus lining is maintained from day 14 to 28.
If no fertilised egg has landed in the uterus wall by day 28 then the lining starts to break down and the cycle starts again

96
Q

Where is FSH produced

A

The pituitary gland

97
Q

What is the role of FSH (Follicle-Stimulating Hormone)

A

It causes the egg to mature in one of the ovaries in a structure called a follicle,
Stimulates the ovaries to produce oestrogen

98
Q

Where is oestrogen produced

A

The ovaries

99
Q

What is the role of oestrogen

A

Causes the lining of the uterus to grow,

Stimulates the release of LH and inhibits the release of FSH

100
Q

Where is LH produced

A

The pituitary gland

101
Q

What is the role of LH (Luteinising Hormone)

A

Stimulates the release of an egg at day 14

102
Q

Where is progesterone produced

A

The ovaries

103
Q

What is the role of progesterone

A

It maintains uterus lining during the second half of the cycle,
Inhibits the release of LH and FSH

104
Q

How does oestrogen reduce fertility

A

If the level is permanently high, it inhibits the production of FSH and egg development and production stop

105
Q

How does progesterone reduce fertility

A

It inhibits FSH and LH

And it stimulates the production of thick mucus that prevents any sperm getting through and reaching the egg

106
Q

What hormones does the pill contain (combined oral contraceptive pill)

A

Oestrogen and progesterone

107
Q

What are the problems with the pill

A

Headaches and nausea,

Does not protect against STDs and STIs

108
Q

Give examples of contraceptives that use hormones

A 
The combined pill
The mini pill (progesterone only)
Contraceptive patch
Contraceptive implant 
Contraceptive injection
Intrauterine device (IUD)
109
Q

What does a plastic IUD do

A

Releases progesterone

110
Q

What does a copper IUD do

A

Prevents sperm from surviving in the uterus

Biology Paper 2 (3 decks)

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