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gcse revision! > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

what is homeostasis?

A

Keeping internal and external conditions at optimum

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2
Q

what are control systems that maintain your body temperature?

A

blood glucose levels and water content

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3
Q

what are the three main components of an automatic control system?

A

receptors, coordination centres (brain, spinal cord, pancreas) and effectors

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4
Q

How does out automatic control system keep internal environments stable?

A

negative feedback

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5
Q

What happens if something is too high or low in our body?

A

-receptors detect a stimulus-
-coordination centre receives and processes
effector produces response to counteract change and restore optimum levels

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6
Q

what are sensory neurones?

A

carry information as electrical impulses from the receptors to the CNS

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7
Q

what are the motor neurones?

A

carry electrical impulses from the CNS To the effectors?

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8
Q

what are effectors?

A

muscles and glands which respond to nervous impulses.

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9
Q

whats the connection between two neurones?

A

synapse

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10
Q

how is the nerve signal transferred?

A

chemicals that diffuse across the gap that set off a new electrical signal

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11
Q

what are reflexes?

A

rapid and automatic responses to stimuli that dont involve conscious part of the brain

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12
Q

what does the neurones in the reflex arcs go

A

through the spinal cord or through an unconscious part of the brain.

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13
Q

how can you measure caffeine in comparison to someones reaction?

A

-sit with arm resting on edge of table
-hold ruler vertically
-make sure 0 is level with thumb and finger
-let go without warning
-try to catch ruler as fast as possible
-measure number on ruler
-repeat to calc mean
-then have caffeinated drink

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14
Q

what are the control variables of measuring reaction time practical?

A

use the same person
use the same hand
dropped from the same height

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15
Q

How can reaction time be measured on a computer?

A

click a mouse as soon as a stimulus is seen on screen
you remove issue of human error
more accurate measurements
remove person being able to predict when to respond

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16
Q

what is the brain made up of?

A

billions of interconnected neurones

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17
Q

where is the cerebral cortex and what is its function?

A

its at the front
responsible for consciousness, intelligence, memory and language

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18
Q

where is the medulla located and whats its function?

A

its at the bottom
controls unconscious activities like breathing and heartbeat

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19
Q

where is the cerebellum and what does its function?

A

its at the back responsible for muscle coordination

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20
Q

what can docters use the to find whats happened if the small part of the brain is damaged?

A

they can monitor your actions

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21
Q

How can scientists study the brain with electrical stimulation?

A

push tiny electrodes into the tissue giving small zaps of electricity.
Stimulate different parts and see what it does

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22
Q

How scientists study the brain with MRI scans?

A

produces a detailed picture of brain structure so scientists can see areas of the brain that are active when people are doing certain things

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23
Q

What is the sclera?

A

tough, supporting wall of the eye

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24
Q

whats the cornea?

A

transparent outer layer found at front of eye, refracts light

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25
Q

whats the iris?

A

contains mucus to control diameter of pupil, hole is middle, how much light enters the eye.

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26
Q

what does the lens do?

A

focuses light onto the retina

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27
Q

What controls the shape of the lens?

A

ciliary muscles and suspensory ligaments

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28
Q

what happens when light receptors detect a very bright light?

A

Reflex makes the pupil smaller, circular muscles in iris contract and the radial muscles relax, reducing amount of light entering the eye.

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29
Q

What happens when light receptors detect a dim light?

A

Radial muscles contract and the circular muscles relax making the pupil wider

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30
Q

what is accomidation?

A

eye focuses light on the retina by changing shape of the lens

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31
Q

What does the eye do to focus on near objects?

A

1.) ciliary muscles contract, slackens suspensory ligament
2.) lens becomes fat
3.) increases amount of light refracted

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32
Q

What does the eye do to look at distant objects?

A

1.) ciliary muscles relax, suspensory ligaments pull tight
2.) lens goes thin
3.) refracts light by a smaller amount

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33
Q

what can people with long-sightedness not do? (hyperopia)

A

focus on near objects

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34
Q

Why cant people with long-sightedness view near objects?

A

the lens is the wrong shape and doesnt refract the light enough
or eye ball is too short
imagine near objects are brought into focus behind the retina

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35
Q

How can you correct long-sighted people?

A

wear glasses with a convex lens

36
Q

what are short-sighted people unable to do?

A

unable to focus on distant objects

37
Q

why does short-sightedness occur?

A

lens is the wrong shape and refracts light too much, eye ball is too long
imagine of distant object is brought into focus in front of retina

38
Q

what can fix short-sightedness? (myopia)

A

using glasses with a concave lens

39
Q

What are 3 treatments for vision defects?

A

contact lenses: thin lenses that sit on surface of eye to compensate for fault of focusing
laser eye surgery: change shape of cornea
replacement lens surgery: replace lens of eye

40
Q

what happens when your body is too hot?

A

sweat is produced by sweat glands and evaporates from skin
blood vessels dilate so more blood flows close to the surface of skin (vasodilation)
both transfer energy to the environment

41
Q

what happens when your body is too cold?

A

hairs stand up to trap insulating layer of air
no sweat produced
blood vessels constrict to close off skins blood supply (vasoconstriction)
shiver so respiration transfers energy to warm the body

42
Q

whats the difference between hormones and nerves?

A

hormones are slower action, lasting longer, acts more in a general way
nerves are very fast, act for a short time, act on precise areas.

43
Q

what does the pituitary gland (master gland) do?

A

produces many hormones to regulate body conditions

44
Q

what do the ovaries produce?

A

produce oestrogen, involved in menstrual cycle

45
Q

what do the testes produce?

A

testosterone, which controls puberty and sperm production

46
Q

what does the thyroid produce?

A

thyroxine, regulates rate of metabolism, heart rate and temperature

47
Q

what does the adrenal gland produce?

A

adrenaline, prepares body for fight or flight.

48
Q

what does the pancreas do?

A

produces insulin, regulates blood glucose levels

49
Q

where can excess glucose be stored?

A

in the liver as glycogen and in the muscles

50
Q

what happens when blood glucose levels are too high?

A

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

51
Q

what happens when the blood glucose level is too low?

A

glucagon secreted by pancreas
glucose released into bloody by liver
glucagon makes liver turn glycogen into glucose

52
Q

what is type 1 diabetes and how can it be controlled?

A

pancreas produces little to no insulin
insulin injections can help
limit carb intake and regularly exercise

53
Q

what is type 2 diabetes and how can it be controlled?

A

person becomes resistant to their own insulin
obesity increases risk
eat carb controlled diet and regularly exercise

54
Q

how do the kidneys produce urine?

A

taking waste products out of the blood and passes through kidneys (filtration)

55
Q

whats selective reabsorption?

A

useful substances like glucose, ions and right amount of water are reabsorbed into the blood after filtration.

56
Q

what is urea?

A

proteins (amino acids)
cant be stored in body so excess are converted into fats and carbs,
ammonia is produced as a waste of this
ammonia is toxic so converted into urea in liver

57
Q

why are the ions removed during urination?

A

if not removed too much or too little water could be brought into cells by osmosis
sweat loses ions

58
Q

why is water removed by urination?

A

body needs a constant in and out flow of water
lose water from skin in sweat, lungs (breathing)

59
Q

what controls the concentration of urine?

A

anti-diuretic hormone (ADH)
pituitary gland releases into bloodstream

60
Q

how can people with kidney failure be kept alive?

A

dialysis, kidney transplant

61
Q

what are the disadvantages to dialysis?

A

long term expensive
has to be done regularly
takes a long time
can cause bloody clots or infection

62
Q

how does dialysis work?

A

persons blood flows between a partially permeable membrane surrounded by dialysis fluid

63
Q

what is the dialysis liquid made up of?

A

same concentration of dissolved ions and glucose as healthy bloody so useful dissolved ions and glucose wont be lost, only waste products like urea

64
Q

what are the risks/disadvantages of kidney transplants?

A

can be rejected
poses small danger if patient donating is alive
long waiting list

65
Q

what happens in stage 1 of the menstruation cycle?

A

uterus lining breaks down for 4 days

66
Q

what happens in stage 2 of the menstruation cycle?

A

uterus lining builds up, day 4 -14 layer full of blood vessels read to recieve fertalised egg

67
Q

what happens in stage 3 of the menstruation cycle?

A

egg develops and is released from ovary at day 14 (ovulation)

68
Q

what happens in stage 4 of the menstruation cycle?

A

wall is maintained for about 14 days, if no fertalised egg lands on uterus wall by day 28 the lining breaks down.

69
Q

what does oestrogen do?

A

produced in ovaries, causes lining of uterus to grow
stimulates LH release, inhibits FSH release

70
Q

what does progesterone do?

A

produced in ovaries, maintains uterus lining, when progesterone level falls lining breaks down, inhibits release of LH and FSH

71
Q

what does FSH do?

A

produced in pituitary glands, causes egg to mature, stimulates ovaries to produce oestrogen

72
Q

what does LH do?

A

produced in pituitary gland, stimulates egg release at day 14 (ovulation)

73
Q

what can be used to reduce fertility hormonally?

A

taking oestrogen daily to keep levels constantly high inhibiting FSH production
taking progesterone to create thick mucus
taking the pill
contraceptive patch
contraceptive implant
contraceptive injection
IUD

74
Q

what are non-hormonal forms of contraception?

A

condoms
diaphragm
spermicide

75
Q

what is a perm way of avoiding pregnancy and a natural one?

A

sterilisation
abstinence
ryhthem method

76
Q

what causes a woman to be infertile?

A

doesn’t produce high enough levels of FSH so no eggs are released due to them not maturing

77
Q

what are the pros and cons of giving a woman FSH and LH hormones to get pregnant?

A

pros- helps alot of women to start families
cons- doesnt always work, expensive, mentally + physically draining, multiple pregnancies, unethical

78
Q

how is IVF carried out?

A

inject sperm into egg in lab, fertalised eggs grown into embryos in lab, 1 or 2 is transferred to womans uterus, FSH and LH given before egg collection to stimulate several eggs to mature

79
Q

what is auxin and what does it control?

A

controls growth near the tips of shoots and roots
controls growth in plants in response to light

80
Q

what does extra auxin do?

A

promotes growth in shoot but inhibits growth in the root

81
Q

how do you measure for plant growth responses?

A

10 seeds in 3 different petri-dishes
shine light onto 1 of the dishes and put 2 in differnt directions
leave seeds alone for a week

82
Q

what can auxin be used for?

A

killing weeds
growing from cuttings with rooting powder
growing cells in tissue culture

83
Q

what do gibberellins stimulate?

A

seed germination, stem growth and flowering

84
Q

what do gibberellins stimulate?

A

controlling dormancy
inducing flowering
growing large fruit

85
Q

how does ethene stimulate the ripening of fruit?

A

controls cell division and stimulates enzymes that cause fruit to ripen

gcse revision! (50 decks)

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