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Biology > Homeostasis and Response > Flashcards

Homeostasis and Response Flashcards

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
What is hyperopia?
Long-sightedness Images of near objects brought into focus behind retina Fixed using convex lens
26
What is myopia?
Short-sightedness Image of distant objects brought into focus in front of retina Fixed using concave lens
27
What are the 4 treatments for these eye defects?
1: glasses 2: contact lenses 3: laser eye surgery 4: replacement lens surgery
28
What happens when you get hot?
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
What happens when you get cold?
Effectors reduce the energy transferred to the environment: No sweat Blood vessels constrict (vasoconstriction) and less blood flows close to the skin
30
what is the endocrine system?
Made up of glands that secrete chemicals (known as hormones) directly into the bloodstream, which carries them to the target organs
31
What does the pituitary gland do and where is it?
‘Master gland’ - stimulates other glands In the bottom of the brain
32
What does the thyroid do and where is it?
Produces thyroxine Throat area
33
What does the adrenal gland do and where is it?
Produces adrenaline Near the kidneys
34
What does the pancreas do and where is it?
Produces insulin Near kidneys
35
What does the ovary do and where is it?
Produces oestrogen You know where the ovaries are
36
What does the testis do and where is it?
Produces testosterone You know where the testes are
37
What are the 5 steps to reduce blood glucose?
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
What are the 5 steps to increase blood glucose?
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
Tell me about Type 1 diabetes.
Caused by the pancreas producing little or no insulin Blood glucose can rise to dangerously high levels Can be treated with insulin injections
40
Tell me about Type 2 diabetes.
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
What does adrenaline do?
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
What does thyroxine do?
Thyroxine plays a role in regulating the basal metabolic rate and is important for protein synthesis for growth and development
43
Talk to me about waste substances.
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
What is the cycle for controlling the concentration of urine?
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
What do people with kidney failure have to have regularly?
Dialysis - basically does the same thing as a kidney would
46
What is puberty?
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
What is the main reproductive hormone in men?
Testosterone - stimulates sperm production
48
What is the main reproductive hormone is women?
Oestrogen
49
What is stage 1 of the menstrual cycle and which hormones are in?
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
What is stage 2 of the menstrual cycle and which hormones are in?
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
What is stage 3 of the menstrual cycle and which hormones are in?
Egg develops and is released from the ovary - ovulation FSH spikes slightly LH spikes hugely Oestrogen is decreasing Progesterone remains increasing slowly
52
What is stage 4 of the menstrual cycle and which hormones are in?
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
What is FSH and what does it stimulate / get inhibited by?
Stimulates oestrogen Inhibited by oestrogen and progesterone
54
What is oestrogen and what does it stimulate / get inhibited by?
Causes uterus lining to grow Stimulates LH
55
What is LH and what does it stimulate / get inhibited by?
Stimulates ovulation Inhibited by progesterone
56
What is progesterone and what does it stimulate / get inhibited by?
Maintains the uterus lining Inhibits LH and FSH
57
What is contraception?
Methods of reducting likelihood of spree reaching an ovulated egg
58
What are 4 hormonal methods of contraception?
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
What are 4 non-hormonal methods of contraception?
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
Describe IVF to me.
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
What are 3 negatives to IVF?
1: emotionally and physically stressful 2: low success rate 3: can lead to multiple births - which can be dangerous for mother and babies
62
What is auxin?
A plant hormone that controls growth near the tips of shoots and roots
63
Explain what happens in phototropism.
Shoot tip is exposed to light > auxin accumulates on shaded side > cells grow faster on shaded side > shoot bends towards light
64
Explain geotropism in a shoot.
Auxin accumulates on the lower side of the shoot (towards gravity) > auxin makes lower side grow more quickly > shoot bends upwards
65
Explain geotropism in a root.
Auxin accumulates on lower side of root (towards gravity) > auxin inhibits root growth on the lower side > root bends downwards
66
How is auxin used commercially?
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
How is gibberellin used commercially?
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
How is ethene used commercially?
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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