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biology > B5-homeostasis and response > Flashcards

B5-homeostasis and response Flashcards

1
Q

what is homeostasis?

A

maintaining a stable internal environment

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2
Q

when does your body use negative feedback?

A

when the level of something gets too high or too low it is used to bring it back to normal (eg.water or temperature)

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3
Q

describe negative feedback when it’s too high

A
  1. receptor detects a stimulus-level too high
  2. coordination centre receives information and organises response
  3. effector produces response which counteracts the change-levels decrease
    RESTORES OPTIMUM LEVEL
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4
Q

describe negative feedback when it’s too low

A
  1. receptor detects a stimulus-level too low
  2. coordination centre receives information and organises a response
  3. effector produces a response which counteracts the change-level increases
    RESTORES OPTIMUM LEVEL
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5
Q

what is the central nervous system? (CNS)

A

in vertebrates it consists of the brain and spinal cord. In mammals the CNS is connected by sensory and motor neurones

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6
Q

what are sensory neurones?

A

neurones that carry information in electrical impulses from the receptors to the CNS

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7
Q

what is the motors neurones

A

neurones that carry electrical impulses from the CNS to effectors

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8
Q

what are effectors

A

all your muscles and glands which respond to nervous impulses

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9
Q

How do you get an response from a stimulus using the CNS

A

stimulus -> receptor -> sensory neurone -> CNS -> motor neurone -> effector -> response

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10
Q

What is the connection between two neurons called?

A

synapse

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11
Q

How is the nerve signal transferred across the gap?

A

By chemicals which diffuse across

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12
Q

What are reflexes?

A

rapid unconscious responses - no thinking required

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13
Q

Briefly describe a reflex arc

A
  • neurones in reflex arc go through spinal cord
  • when a stimulus is detected by receptors, impulses are sent along a sensory neurone to a relay neurone in the CNS
  • when impulse reaches a synapse they trigger the release of chemicals
  • chemicals cause impulses to be sent along the relay neurone
  • the impulses reach synapse between relay neurone and motor neurone the same thing happens (chemicals released cause impulses to be sent the motor neurone)
  • this impulse travels along to the effector
  • the muscle the contracts and moves away
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14
Q

What does the cerebral cortex responsible for

A

Consciousness, intelligence, memory and language

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15
Q

What is the SCLERA

A

Supporting wall of the eye

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16
Q

What is the CORNEA

A

Transparent outer layer of the eye which refracts light into the eye

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17
Q

What is the IRIS

A

Contains muscle which controls the diameter of the pupil and therefore how much light enters the eye

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18
Q

What is the LENS

A

Focuses light onto the retina

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19
Q

What controls the shape of the lens

A

Ciliary muscles and suspensory ligaments

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20
Q

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

A

optic nerve

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21
Q

What does your eye do in very bright light

A

circular muscles in iris contact and the radial muscles relax

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22
Q

What does your eye do in dim light

A

The radial muscles contract and the circular muscles relax

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23
Q

What does the eye do when looking at near objects

A

The ciliary muscles contract which slackens the suspensory ligaments
The lens fat and rounded
Increases the amount by which it refracts light

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24
Q

What does the eye do when looking at distant objects

A

The ciliary relaxes which allows the the suspensory ligaments pull tight
This causes the lens to become thin
So it refracts light by a smaller amount

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25
Q

What is long-sightedness

A

When person is unable to focus on near objects

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26
Q

What is short sightedness

A

When a person cannot focus on distant objects

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27
Q

Where are the images brought if you are longsighted

A

The image focus is behind the retina

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28
Q

Where is the focus if you are short sighted

A

image focus is in front of the retina

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29
Q

What lens is used to correct long sightedness

A

convex lens

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30
Q

what lens is used to correct short sightedness

A

Concave lens

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31
Q

What are the 3 possible treatments for vision defects

A
  • contact lenses
  • laser eye surgery
  • replacement lens surgery
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32
Q

What are some things the body does when you are too HOT

A

Sweat-evaporates energy to environment
Blood vessels dilate-more blood flows close to surface of skin which transfer energy from skin to environment. This is called vasodilation

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33
Q

What are some things the body does when you are too COLD

A

Hair stands up- traps an insulating layer of air
No swear
Blood vessels contract- close of skin’s blood supply. This is called vasoconstriction
Shiver-muscles contract. Needs respiration which transfers some energy to warm the body

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34
Q

What are hormomes?

A

Chemical messages sent in the blood stream

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35
Q

What are hormone secreted by called

A

Endocrine glands

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36
Q

what does the thyroid gland produce?

A

Thyroxine which regulates heart rate, temperature and rate of metabolism

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37
Q

What does the pituitary gland produce?

A

Many hormones that regulate body conditions

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38
Q

What do ovaries produce?

A

Produce oestrogen which is involved in the menstraul cycle

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39
Q

What do testes produce?

A

Testosterone which controls puberty and sperm production

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40
Q

What does the adrenal gland produce?

A

adrenaline, which is used to prepare the body for a ‘fight or flight’ response

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41
Q

What does the pancreas produce?

A

Produces insulin which is used to regulate blood glucose levels

42
Q

What are 3 things that can help you identify if it is nerves responding

A

very fast action
act for a short amount of time
act on a very precise area

43
Q

What are 3 things to help identify hormonal response

A

slower action
acts for a long time
acts in a more general way

44
Q

What removes glucose from the blood normally?

A

metabolism

45
Q

What can increase the amount of glucose is removed from the blood

A

vigorous exercise

46
Q

Where can excess glucose be stored?

A

As glycogen in the liver and the muscles

47
Q

Where are the changes monitored and controlled in the body and ehat hormones are used?

A

By the pancreas using insulin and glucagon in a negative feedback cycle

48
Q

If blood glucose levels are too high what is added?

A

insulin

49
Q

Describe what happens when blood glucose levels are too high

A

insulin secreted by the pancreas
glucose moves from blood into liver and muscle cells
insulin makes liver turn glucose into glycogen
blood glucose levels decreased

50
Q

Describe what happens when blood glucose levels are too low

A

glucagon secreted by pancreas
glucagon makes liver turn glycogen into glucose
glucose released into blood by liver
blood glucose levels increased

51
Q

What is diabetes?

A

When you can’t control your blood sugar levels

52
Q

What is type 1 diabetes?

A

The pancreas produces little to no insulin which means blood glucose levels rise to a point where it could kill them

53
Q

What can you take to prevent blood glucose levels rising too high in a person with type 1 diabetes?

A

Insulin injections throughout the day most likely at mealtimes
The amount of insulin to take depends on the persons diet and how active they are

54
Q

What is type 2 diabetes?

A

Where a person becomes resistant to their own insulin (cells don’t respond properly to the hormone)

55
Q

What can this cause in a person?

A

For the blood sugar levels to rise to a dangerous level

56
Q

What increases your chances of developing type 2 diabetes?

A

Being overweight

57
Q

How can type 2 diabetes be controlled?

A

By eating a carbohydrate controlled diet and regular exercise

58
Q

What substances do the kidneys filter out?

A

waste products like urea and excess water

59
Q

What is selective reabsorption?

A

When the kidneys absorb useful substances like glucose some ions and the right amount of water back into the blood

60
Q

What are 3 substances that are removed from the body by urine?

A

Urea, ions and water

61
Q

Why is urea removed from the body?

A

Proteins can’t be stored by the body so any excess amino acids are converted into fats and carbohydrates which can be stored
This process happens in the liver and is called deamination
Ammonia is produced as a water product but is toxic
Instead it’s converted into urea in the liver then transported to the kidneys to be filtered out in urine

62
Q

How are some ions lost but not through urine?

A

In sweat

63
Q

How can we lose water from our bodies?

A

Through sweat and from our lungs when breathing out

64
Q

Which hormone controls the concentration of urine?

A

ADH (anti-diuretic hormone)

65
Q

What is ADH released by?

A

The pituitary gland

66
Q

Whats process controls water content regulation?

A

Negative feedback

67
Q

What happens if water levels are too high?

A

Receptor in brain detects water content is too high
coordination centre in brain receives information and coordinates a response
pituitary gland releases less ADH so less water is reabsorbed from the kidney tubules

68
Q

What happens if water levels are too low?

A

Receptor in brain detects water content is too low
coordination centre in brain receives information and coordinates a response
pituitary gland releases more ADH so more water is reabsorbed from the kidney tubules

69
Q

How are people worh kidney failure treated?

A

With dialysis or a kidney transplant

70
Q

What happens in a dialysis machine?

A

A persons blood flows between partially permeable membranes surrounded by dialysis
The fluid is the same concentration of dissolved ions amd glucose as healthy blood
This means useful dissolved ions and glucose won’t be lost in the process
Only waste substances (urea) and excess ions and water diffuse accross the barrier

71
Q

What are some negatives of dialysis?

A

Multiple sessions a week each taking a long time
Could cause blood clots or infections
Expensive to run

72
Q

What is a positive of dialysis?

A

It buys valuable time to find an orgam donor

73
Q

What is a risk with kidney transplants? What is also a problem with transplants?

A

The kidney could be rejected by the patient’s immune system

A long waiting list for donors

74
Q

What are the 4 hormones involved in the menstrual cycle

A

FSH
LH
Progesterone
Oestrogen

75
Q

Where is FSH produced?

A

The pituitary gland

76
Q

What 2 things does FSH do?

A

Causes egg to mature in ovaries

Stimulates the ovaries to produce oestrogen

77
Q

Where is oestrogen produced?

A

In the ovaries

78
Q

What 3 things does oestrogen do?

A

Causes lining of uterus to grow

Stimulates the release of LH and inhibits release of FSH

79
Q

Where is LH produced?

A

By the pituitary gland

80
Q

What does LH hormone do?

A

Stimulates the release of an egg at day 14 which is ovulation

81
Q

Where is progesterone produced?

A

In the ovaries by the remains of the follicle after ovulation

82
Q

What 2 things does progesterone do?

A

Maintains lining of the uterus during the second half of the cycle
Inhibits the release of LH and FSH

83
Q

What can oestrogen do and what does this mean it is used for?

A

Can be used to prevent the release of an egg so it is a method of contraception

84
Q

What are 4 types of hormonal contraception?

A

The contraceptive patch - contains oestrogen and progesterone
The contraceptive implant - Releases progesterone
The contraception injection - Contains progesterone
An IUD (intrauterine device) - T-shaped device, either a plastic one or copper

85
Q

What are 3 barrier methods of contraception?

A

Condoms
A diaphragm
Spermicide

86
Q

What is sterilisation?

A

The cutting or tying of fallopian tubes in a female or the sperm duct in a male. This is a permanent procedure

87
Q

What hormones can be given in a fertility drug?

A

FSH and LH

88
Q

What are the pros to fertility drugs? What are the cons of fertility drugs?

A

It helps women get pregnant when they previously couldn’t
It doesn’t always work which means if you do it repeatedly it can get expensive
Too many eggs can be stimulated resulting in multiple pregnancies

89
Q

What does IVF stand for?

A

in vitro fertilisation

90
Q

What does IVF involve?

A

Collecting eggs from the woman’s ovaries and fertilising them in a lab

91
Q

When is the embryo transferred to the woman’s uterus?

A

When the embryos are tiny balls of cells

92
Q

What is a pro of fertility treatment? What are the cons?

A

PROS
It can give an infertile couple a child
CONS
Multiple births can happen if more than one embryo grows into a baby which is risky for the mother and the child
Success of IVF is low
Can be physically stressful for the woman because of the hormones and emotionally stressful if there are multiple failures

93
Q

Why are some people against IVF?

A

IVF often results in unused embryos that are eventually destroyed, because of this some people think it is unethical because each embryo is a potential human life
Genetic testing of embryos also raise ethical issues as some people think it could lead to the selection of preferred characteristics

94
Q

What is auxin?

A

A plant hormone that controls growth near the tips of shoots and roots

95
Q

What are the scientific names for a response to light and gravity?

A

phototropism and geotropism or gravitropism

96
Q

What happens when a shoot tip is exposed to light?

A

More auxin accumulates on the side that’s in the shade which makes the cells grow faster on the shaded side so the shoot bends towards the light

97
Q

What happens when a shoot is growing sideways?

A

Gravity produces an unequal distribution of auxin with more auxin on the lower side which causes the shoot to grow upwards

98
Q

What happens to a root growing sideways?

A

More auxin gathers on its lower side but the extra auxin inhibits growth so the cells on top elongate faster and the roots ben downwards

99
Q

What are 3 things auxins are used in?

A
  • Killing weeds
  • Growth from cuttings with rooting powder
  • Growth cells in tissue culture
100
Q

Gibberellin is another plant hormone. What does it stimulate?

A

seed germination, stem growth and flowering

101
Q

What are the uses of gibberellin?

A

Controlling dormancy
Inducing flowering
Growing larger fruit

102
Q

What does ethene stimulate?

A

The ripening of fruit by controlling cell division

biology (6 decks)

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