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Biology > Homeostasis And Response > Flashcards

Homeostasis And Response Flashcards

1
Q

Homeostasis

A

The regulation of internal conditions of a cell or organism in response to internal or external changes

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2
Q

Conditions that are regulated

A

Body temperature

Glucose

Water

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3
Q

Receptors

A

Cells that detect a change (stimuli) in the internal or external environment

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4
Q

Coordination centres

A

Areas that receive and process information from receptors

E.g. the brain, spinal cord

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5
Q

Effectors

A

Muscles or glands that bring out a response to the stimuli (change)

These changes restore conditions of the body to optimum level

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6
Q

Structure of the nervous system

A

Stimulus - receptor - CNS - effector - response

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7
Q

Reflex action

A

Automatic and rapid response that does not involve the conscious part of the brain

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8
Q

Reflex action practical

A

Person A holds out their hand with a gap between their thumb and first finger

Person B holds the ruler with the zero at the top of person A’s thumb

Person B drops the ruler without telling Person A and they must catch it

The number level with the top of person A’s thumb is recorded in a suitable table

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9
Q

Adaptations of a nerve cell

A

They have an long axon so they can carry messages up and down the body over long distances

The axon is insulated by a fatty myelin sheath - the fatty sheath increases the speed of the nerve impulses along the neuron

Dendrites receive incoming nerve impulses from other neurons

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10
Q

Sensory neurone

A

The nerve cell that transmits electrical impulses from receptors in the sense organs to the CNS

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11
Q

Relay neurone

A

The nerve cell that transmits electrical impulses from sensory neurones to motor neurones

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12
Q

Motor neurone

A

The nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands

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13
Q

Synapses

A

A gap between neurones -

An electrical impulse travels along the first neurone

When it reaches the end of the neurone, chemical transmitter molecules called neurotransmitters are released

The neurotransmitters diffuse across the synapse and bind with receptor molecules on the membrane of the second neurone

This stimulates the second neurone to transmit the electrical impulse

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14
Q

Cerebral cortex

A

The outer layer of the cerebrum

It is the centre of conscious thought and recalls memories

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15
Q

Cerebellum

A

Controls balance, co-ordination of movement and muscular activity.

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16
Q

Medulla

A

Controls unconscious activities such as heart rate and breathing rate

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17
Q

MRI scans

A
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18
Q

EEG scan

A
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19
Q

Retina

A

Contains receptors which are sensitive to light

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20
Q

Optic nerve

A

Carries impulses from the retina to the brain

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21
Q

Sclera

A

A tough layer protecting the eye

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22
Q

Iris

A

Changes the size of the pupil to control the amount of light reaching the retina

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23
Q

Ciliary muscles + suspensory ligaments

A

Changes the shape of the lens

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24
Q

Focusing on a near object

A

The ciliary muscles contract

The suspensory ligaments loosen

The lens is then thicker and refracts light rays strongly

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25
Q

Focusing on a distant object

A

The ciliary muscles relax

The suspensory ligaments are pulled tight

The lens is then pulled thin and only slightly refracts light rays

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26
Q

Myopia (short-sightedness)

A

The image is formed in front of the retina

The eyeball is too long

Use a concave lens to fix

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27
Q

Hyperopia (long-sightedness)

A

Image is formed behind the retina

The eyeball is too short

Use a convex lens to fix

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28
Q

Thermoregulatory centre

A

Contains receptors sensitive to the temperature of the blood

The skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre

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29
Q

Vasodilation

A

When the body temperature is too high, blood vessels dilate (vasodilation) and sweat is produced from the sweat glands

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30
Q

Vasoconstrict

A

When the body temperature is too low, blood vessels constrict (vasoconstriction), sweating stops and skeletal muscles contract (shiver)

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31
Q

Water loss

A

Water is lost through sweat, via the lungs through exhalation, and through the kidneys via urine

If body cells lose or gain too much water by osmosis they do not function efficiently

32
Q

Digestion of proteins

A

Excess amino acids need to be excreted safely

Amino acids are deaminated to form ammonia in the liver

Ammonia is toxic so it is immediately converted to urea for safe excretion in the kidneys

33
Q

Kidneys

A

It is an organ in the urinary system - which remove excess water, salts and urea

34
Q

The urinary system

A

Blood is transported to the kidney through the renal artery

The blood is filtered at a high pressure and the kidney selectively reabsorbs any useful materials such as glucose, salt ions and water

After it has been purified, the blood returns to the circulatory system through the renal vein

The kidneys produce urine and this helps maintain water balance

35
Q

ADH (anti-diuretic hormone)

A

Released in the pituitary gland

Controls water level in the body

When the blood is too concentrated, kidney tubules become more permeable

This allows more water to be reabsorbed back into the blood during selective reabsorption

36
Q

Dialysis

A

Medical treatment in which blood is removed from the body and filtered before being returned

37
Q

Dialysis fluid

A

A glucose concentration similar to a normal level in the blood

A concentration of ions similar to that found in normal blood plasma

No urea

38
Q

Process of dialysis

A

Unfiltered blood that is high in urea is taken from a blood vessel in the arm

Mixed with blood thinners to prevent clotting, and pumped into the dialysis machine

Blood and dialysis fluid are separated by a partially permeable membrane

39
Q

Advantages of dialysis

A

Greatly reduced levels of urea – it is ‘cleaned blood’

Would not get rejected by body

40
Q

Disadvantages of dialysis

A

Requires highly specialised and expensive machinery

Patient must be connected to the machine for a long period of time

Must monitor diet

41
Q

Kidney transplant

A

Implanting a kidney from an organ donor into the patient’s body to replace the damaged kidney

42
Q

Advantages of a kidney transplant

A

Cheaper for the NHS overall

Patients can lead a more normal life without having to watch what they eat and drink

43
Q

Disadvantages of a kidney transplant

A

Must take immune-suppressant drugs which increase the risk of infection

Shortage of organ donors

Kidney only lasts 8-9 years on average

44
Q

Endocrine system

A

Made of glands that secrete chemicals called hormones into the blood stream

The blood carries the hormone to the target organ where it produces an effect

45
Q

Pituitary gland

A

The ‘master gland’ located at the base of the brain

46
Q

Pancreas

A

Produces insulin - controls blood glucose levels

47
Q

Type 1 diabetes (inherited)

A

Type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin

Treated with insulin injections

48
Q

Type 2 diabetes (lifestyle)

A

Type 2 diabetes is when the person’s body cells no longer respond to insulin produced by the pancreas

Treated with a healthy diet and exercise

49
Q

Symptoms of diabetes

A

Increased thirst and hunger

Loss of weight, tiredness and nausea

Vomiting and abdominal pain

50
Q

Role of glucagon in control of blood sugar levels

A

If the blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood

If the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes

51
Q

Thyroid gland

A

Produces thyroxine - controls how much energy is used in your body

52
Q

Adrenal gland

A

Produces adrenaline - prepares body for flight or fight

53
Q

Ovary

A

Produces FSH, oestrogen, LH and progestogen

54
Q

FSH hormone

A

Produced in the pituitary gland

Causes an egg to mature in an ovary

Stimulates the ovaries to release oestrogen

55
Q

Oestrogen hormone

A

Produced in the ovaries

Stops FSH being produced (so that only one egg matures in a cycle)

Repairs, thickens and maintains the uterus lining

Stimulates the pituitary gland to release LH

56
Q

LH hormone

A

Produced in the pituitary gland

Triggers ovulation (the release of a mature egg)

57
Q

Progesterone hormone

A

Produced in the ovaries

Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy

58
Q

Oral contraceptives (hormonal)

A

Contains hormones to inhibit FSH production so that no eggs mature

59
Q

Contraceptive injection, patch, implant (hormonal)

A

Where progesterone is slowly released to inhibit the maturation and release of eggs for a number of months or years

60
Q

Barrier methods (non-hormonal)

A

Condoms and diaphragms which prevent the sperm reaching an egg

61
Q

Intrauterine devices (non-hormonal)

A

Prevent the implantation of an embryo or release a hormone

62
Q

Spermicidal agents (non-hormonal)

A

Kill or disable sperm

63
Q

Abstinence (non-hormonal)

A

Abstaining from intercourse when an egg may be in the oviduct

64
Q

Surgical methods

A

Male and female sterilisation

65
Q

IVF

A

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs

The eggs are collected from the mother and fertilised by sperm from the father in the laboratory

The fertilised eggs develop into embryos

At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb)

66
Q

Fertility drug

A

A drug containing FSH and LH to help stimulate the maturity and release of the egg, equalling a higher chance of pregnancy

67
Q

Phototropism

A

A response to the stimulus of light

68
Q

Geotropism

A

A response to the stimulus of gravity

69
Q

Positive tropisms

A

The plant grows towards the stimulus

70
Q

Negative tropisms

A

The plant grows away from the stimulus

71
Q

Auxins

A

Control the growth of plants by promoting cell division and causing elongation in plant cells

Made in the tips of the growing stems and roots

72
Q

Effect of light or gravity on the growth of newly germinated seedlings practical

A

Put cotton wool into three petri dishes, and add the same volume of water to each dish

Add ten seeds to each dish and place them in a warm place where they won’t be disturbed

Allow the seeds to germinate, and add more water if the cotton wool dries out

Once the seeds have germinated, ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary

One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light

Every day for one week, measure the height of each seedling and record the results in a table

73
Q

Auxins

A

Weed killers

Rooting powders

Promoting growth in tissue culture

74
Q

Ethene

A

Used in the food industry to control ripening of fruit during storage and transport

75
Q

Gibberellins

A

End seed dormancy

Promote flowering

Increase fruit size

Biology (10 decks)

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