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Biology > Homeostasis and Response > Flashcards

Homeostasis and Response Flashcards

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1
Q

What is homeostasis?

A

The regulation of the conditions inside your body and cells. It maintains a stable internal environment in response to changes in internal and external conditions.

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2
Q

What is the function of receptors?

A

To detect stimuli (changes in environment)

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3
Q

What is the function of coordination centres?

A

To receive and process information from receptors and organise a response

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4
Q

What is the function of effectors?

A

To produce a response to counteract change and restore optimal conditions

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5
Q

What 3 things are maintained by control systems in the body?

A

1: body temperature
2: blood glucose level
3: water content

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6
Q

What are neurones?

A

Cells that carry information as electrical impulses in the nervous system. The nervous system means that humans can react to their surroundings and coordinate their behaviour

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7
Q

What is the central nervous system (CNS)?

A

Consists of the brain and spinal cord. It is connected to the body by sensory neurones and motor neurones.

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8
Q

What is the order of things in the nervous system?

A

Stimulus > receptor > sensory neurone > CNS > motor neurone > effector > response

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9
Q

What is a synapse?

A

The connection between two neurones. A nerve signal is transferred across a synapse by the diffusion of chemicals

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10
Q

What are reflexes?

A

Rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain. They can reduce the chance of injury.

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11
Q

What are the 5 steps in a reflex arc?

A

1: stimulation of pain receptor
2: impulses travel along sensory neurone
3: impulses passed along relay neurone
4: impulses travel along motor neurone
5: muscle contracts and arm moves

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12
Q

What is the brain?

A

The organ in charge of all our complex behaviours. It is made up of billions of interconnected neurones.

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13
Q

What are the 3 methods of studying the brain?

A

1: observe patients with brain damage
2: electrically stimulate parts of the brain
3: use MRI scanners

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14
Q

Name 3 parts of the brain and their uses.

A

Cerebral cortex - consciousness, intelligence, memory, language
Medulla - unconscious activities
Cerebellum - muscle coordination

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15
Q

What is the sclera for?

A

Tough, supporting wall

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16
Q

What is the cornea for?

A

Transparent outer layer at front

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17
Q

What is the iris for?

A

Contains muscles controlling pupil size

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18
Q

What is the retina for?

A

Contains receptor cells sensitive to light intensity and colour

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19
Q

What is the optic nerve for?

A

Carries impulses from receptor cells to the brain

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20
Q

What does the pupil do in bright light?

A

Shrinks

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21
Q

What does the pupil do in dim light?

A

Dilate

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22
Q

What is accommodation?

A

The lens changing shape to focus light on the retina

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23
Q

What happens for a near object?

A

Ciliary muscles contract
Suspensorio ligaments relax
Lens becomes thicker
Light refracted more

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24
Q

What happens for a distant object?

A

Ciliary muscles relax
Suspensory ligaments tighten
Lens becomes thinner
Light refracted less

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25
Q

What is hyperopia?

A

Long-sightedness
Images of near objects brought into focus behind retina
Fixed using convex lens

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26
Q

What is myopia?

A

Short-sightedness
Image of distant objects brought into focus in front of retina
Fixed using concave lens

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27
Q

What are the 4 treatments for these eye defects?

A

1: glasses
2: contact lenses
3: laser eye surgery
4: replacement lens surgery

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28
Q

What happens when you get hot?

A

Effectors help to transfer energy form the skin to the environment:
Sweat glands produce sweat
Blood vessels dilate (vasodilation) and more blood flows close to the skin

29
Q

What happens when you get cold?

A

Effectors reduce the energy transferred to the environment:
No sweat
Blood vessels constrict (vasoconstriction) and less blood flows close to the skin

30
Q

what is the endocrine system?

A

Made up of glands that secrete chemicals (known as hormones) directly into the bloodstream, which carries them to the target organs

31
Q

What does the pituitary gland do and where is it?

A

‘Master gland’ - stimulates other glands
In the bottom of the brain

32
Q

What does the thyroid do and where is it?

A

Produces thyroxine
Throat area

33
Q

What does the adrenal gland do and where is it?

A

Produces adrenaline
Near the kidneys

34
Q

What does the pancreas do and where is it?

A

Produces insulin
Near kidneys

35
Q

What does the ovary do and where is it?

A

Produces oestrogen
You know where the ovaries are

36
Q

What does the testis do and where is it?

A

Produces testosterone
You know where the testes are

37
Q

What are the 5 steps to reduce blood glucose?

A

1: Blood with too much glucose
2: Pancreas detects high blood glucose and secretes insulin
3: Insulin causes glucose to move into cells
4: Insulin makes the liver turn glucose into glycogen, which is stored in the liver and muscles
5: Blood glucose reduced

38
Q

What are the 5 steps to increase blood glucose?

A

1: Blood with too little glucose
2: Glucagon secreted by the pancreas
3: Too little glucose but glucagon as well
4: Glucagon makes the liver turn glycogen into glucose, which is released from the liver
5: Blood glucose increased

39
Q

Tell me about Type 1 diabetes.

A

Caused by the pancreas producing little or no insulin
Blood glucose can rise to dangerously high levels
Can be treated with insulin injections

40
Q

Tell me about Type 2 diabetes.

A

Caused by cells no longer responding to insulin properly
Blood glucose can rise to dangerously high levels
Can be treated by carbohydrate-controlled diet and regular exercise

41
Q

What does adrenaline do?

A

Adrenaline is released in response to fear or stress > increases heart rate > increases supply of O2 and glucose to muscle and brain > Readies body for ‘fight or flight’

42
Q

What does thyroxine do?

A

Thyroxine plays a role in regulating the basal metabolic rate and is important for protein synthesis for growth and development

43
Q

Talk to me about waste substances.

A

Unregulated amount of water lost in exhalation
Unregulated amounts of water, ions and glucose reabsorbed into blood by kidneys after filtration (the rest is removed by urine)
Excess amino acids delaminated in liver to form toxic ammonia, which is converted into urea
Urea filtered out by kidneys and excreted in urine

44
Q

What is the cycle for controlling the concentration of urine?

A

Brain detects blood’s water content is too high > pituitary gland releases less ADH > less water is reabsorbed from kidney tubules > water content decreases >
Brain detects blood’s water content is too low > pituitary gland releases more ADH > more water is reabsorbed from kidney tubules > water content increases >

45
Q

What do people with kidney failure have to have regularly?

A

Dialysis - basically does the same thing as a kidney would

46
Q

What is puberty?

A

When the body starts releasing sex hormones, which trigger the development of secondary sexual characteristics (eg, facial hair in men and breasts in women)

47
Q

What is the main reproductive hormone in men?

A

Testosterone - stimulates sperm production

48
Q

What is the main reproductive hormone is women?

A

Oestrogen

49
Q

What is stage 1 of the menstrual cycle and which hormones are in?

A

Menstruation starts. Uterus lining breaks down.
Oestrogen is low but starts rising at the end
FSH is higher but as an after-effect
Progesterone is slightly increasing

50
Q

What is stage 2 of the menstrual cycle and which hormones are in?

A

Uterus lining builds up into thick sponges later full of blood vessels ready to receive a fertilised egg.
FSH is decreasing
LH is slightly increasing with a huge spike towards the end
Oestrogen sky-rockets then begins to decrease just before the end
Progesterone is still slightly increasing

51
Q

What is stage 3 of the menstrual cycle and which hormones are in?

A

Egg develops and is released from the ovary - ovulation
FSH spikes slightly
LH spikes hugely
Oestrogen is decreasing
Progesterone remains increasing slowly

52
Q

What is stage 4 of the menstrual cycle and which hormones are in?

A

Wall is maintained. If no fertilised egg lands on wall, lining breaks down and cycle starts again
FSH slowly begins to increase
LH is decreasing
Oestrogen is decreasing
Progesterone is very prominent and then slowly declines at the end

53
Q

What is FSH and what does it stimulate / get inhibited by?

A

Stimulates oestrogen
Inhibited by oestrogen and progesterone

54
Q

What is oestrogen and what does it stimulate / get inhibited by?

A

Causes uterus lining to grow
Stimulates LH

55
Q

What is LH and what does it stimulate / get inhibited by?

A

Stimulates ovulation
Inhibited by progesterone

56
Q

What is progesterone and what does it stimulate / get inhibited by?

A

Maintains the uterus lining
Inhibits LH and FSH

57
Q

What is contraception?

A

Methods of reducting likelihood of spree reaching an ovulated egg

58
Q

What are 4 hormonal methods of contraception?

A

1: Oral contraceptive pills contain hormones that inhibit FSH and stop eggs maturing
2: The contraceptive implant releases progesterone continuously to stop maturation and release of eggs
3: Injections or skin patches work in a similar way to implants but do not last as long
4: Intrauterine devices are inserted into uterus to prevent eggs implanting (may also release hormones)

59
Q

What are 4 non-hormonal methods of contraception?

A

1: condoms and diaphragms physically prevent sperm from reaching egg
2: sterilisation - a permanent surgical procedure to stop a man or woman from being fertile
3: spermicides disable or kill sperm
4: abstaining from sexual intercourse completely

60
Q

Describe IVF to me.

A

The woman is given FSH and LH to stimulate several eggs to mature > the eggs are collected from the woman’s ovaries > the eggs are fertilised in a lab using the man’s sperm > the fertilised eggs are grown into embryos > once the embryos are tiny balls of cells, one or two of them are transferred to the woman’s uterus

61
Q

What are 3 negatives to IVF?

A

1: emotionally and physically stressful
2: low success rate
3: can lead to multiple births - which can be dangerous for mother and babies

62
Q

What is auxin?

A

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

63
Q

Explain what happens in phototropism.

A

Shoot tip is exposed to light > auxin accumulates on shaded side > cells grow faster on shaded side > shoot bends towards light

64
Q

Explain geotropism in a shoot.

A

Auxin accumulates on the lower side of the shoot (towards gravity) > auxin makes lower side grow more quickly > shoot bends upwards

65
Q

Explain geotropism in a root.

A

Auxin accumulates on lower side of root (towards gravity) > auxin inhibits root growth on the lower side > root bends downwards

66
Q

How is auxin used commercially?

A

1: developed to selectively kill weeds whilst leaving crops untouched
2: added to rooting powders to promote root growth in plant cuttings
3: stimulates cell division in tissue culture so plants can be cloned from a few cells

67
Q

How is gibberellin used commercially?

A

1: stimulates seeds to germinate at any time of year
2: induces flowering without the need for specific conditions
3: added to fruits to make them grow larger

68
Q

How is ethene used commercially?

A

1: speeds up ripening of fruits in transport to shops
2: its effect can be blocked to delay ripening in storage

Biology (8 decks)

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