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Biology AQA GCSE > Homeostasis and Response > Flashcards

Homeostasis and Response Flashcards

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1
Q

What is homeostasis

A

maintaining a stable environment inside your body by regulation of hormone and water levels and more

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2
Q

What happens in a negative feedback loop

A

Receptor detects a stimulus - level is too high/low

The coordination receives and processes the information then organises a response

effector produces a response which counteracts the change and restores the optimal level

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3
Q

What are the parts that make up the nervous system

A

CNS
sensory neurones
motor neurones
effectors

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4
Q

What are receptors

A

cells that detect stimuli

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5
Q

what are effectors

A

things that respond to nervous impulses and bring about change

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6
Q

What is the order of a response

A

Stimulus
Receptor
Sensory neurone
CNS
Motor neurone
Effector
Response

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7
Q

what is a synapse

A

connection between neurones

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8
Q

how do signals pass from nerve to nerve

A

diffuse across the synapse
new electrical signal in the next neurone

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9
Q

how do reflexes prevent injury

A

rapid and automatic responses that bypass the conscious part of the brain to prevent damage

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10
Q

what happens on a reflex arc

A

stimulus
receptor
sensory neurone
relay neurone in cns
motor neurone
effector
response

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11
Q

what does the cerebral cortex do

A

responsible for consciousness, intelligence, memory and language

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12
Q

what does the medulla do

A

unconscious activities such as breathing

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13
Q

what does the cerebellum do

A

muscle coordination, movement and balance

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14
Q

How can scientists study the brain

A

studying patients with brain damage - can help with treatment and mapping

electrically stimulating the brain - can see which parts are responsible for which bits

MRI scans - can help with seeing which bits are active doing certain things

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15
Q

what are some potential issues with messing with the brain

A

can cause difficulties such as speech problems

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16
Q

what is the sclera

A

tough supporting wall of the eye

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17
Q

what is the cornea

A

the transparent outer layer found at the front of the eye

refracts light into the eye

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18
Q

what is the iris

A

contains muscles that allow it to control the diameter of the pupil therefore controls how much light enters the eye

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19
Q

what is the lens

A

focuses the light onto the retina which contains receptor cells sensitive to light and colour

its shape is controlled by the suspensory ligaments and the cilliary muscles

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20
Q

how does the eye change to focus on near objects

A

ciliary muscles contract
slackens suspensory ligaments
lens becomes more curved
increases the amount that it refracts light

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21
Q

how does the eye change to focus on far objects

A

ciliary musles relax
pulls suspensory ligaments tight
lens is less curved
refracts light by a smaller amount

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22
Q

what happens when someone has hyperopia

A

where the image is focused behind the retina

therefore a convex lens is used to correct it and refract the light onto the retina bringing the rays closer together

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23
Q

what happens when someone has myopia

A

the image is formed in front of the retina

therefore a concave lens is used to spread the rays out

24
Q

some treatments for vision defects

A

contact lenses

laser eye surgery - changes shape of cornea

replacement lens surgery - replaces lens

25
Q

how does the body control temperature

A

thermoregulatory centre in brain
receptors detect
thermoregulatory centre acts as a control centre
triggers effectors
response counteracts change

26
Q

what happens when you are too hot

A

sweat - sweat evaporates from the skin

vasodilation - more blood flows and more energy lost to the surroundings

27
Q

what happens when you are too cold

A

hairs stand up - insulating layer of air

no sweat

vasoconstriction - blood vessels constrict to minimise loss on surface

shiver - respiration to transfer some energy to heat the body

28
Q

what are hormones

A

chemical molecules that are released directly into the blood but only affect particular cells in particular organs

29
Q

examples of glands and their functions

A

pituitary gland - ‘master gland’ - produces hormones that regulate body conditions eg ADH

thyroid - thyroxine which controls metabolism, heart rate and temp

adrenal gland - adrenaline which triggers flight or fight

pancreas - insulin for blood glucose levels

ovaries - oestrogen which is needed in the menstrual cycle

testes - testosterone which controls sperm production

30
Q

difference between nerves and hormones

A

nerves:
fast
short operating time
precise area

hormones:
slower
act for a long time
more general area

31
Q

what is glycogen

A

what glucose is stored as

32
Q

what happens if blood glucose level is too high

A

detected by receptors
insulin secreted by pancreas
insulin makes liver turn glucose into glycogen for storage
moves into muscle and liver cells

33
Q

what happens if blood glucose level is too low

A

receptors detect
glucagon is secreted by the pancreas
glucagon makes liver turn glycogen into glucose
moves out of muscle and liver cells into blood

34
Q

what is type 1 diabetes

A

where a person’s pancreas produces little to no insulin

they require shots of insulin

35
Q

what is type 2 diabetes

A

where a person has become resistant to their own insulin

can be controlled naturally

36
Q

what things do the kidneys do

A

filter urea out of the blood

re-absorb the right amount of ions to maintain a healthy balance

re-absorb the right amount of water to maintain a healthy balance

37
Q

what hormone controls water levels

A

ADH

38
Q

what happens if your kidneys don’t work properly

A

waste substances build up and eventually results in death

39
Q

treatment for kidney failure

A

dialysis
kidney transplant

40
Q

what are the downsides to a kidney transplant

A

they can be rejected
long waiting lists

41
Q

how does dialysis work

A

regular process
partially permeable membrane surrounded by dialysis fluid to replicate kidneys
fluid has same concentration of ions and glucose as healthy blood
only waste substances diffuse across the barrier

long process and can cause blot clots or infections

42
Q

What do hormones do at puberty

A

Promote sexual characteristics such as facial hair in men and breasts in women

43
Q

What are the 4 stages of the menstrual cycle

A

Menstruation

Uterus lining starts to build up again

Egg develops and is released from the ovary at day 14

The wall is then maintained from days 14-28

44
Q

What are the 4 hormones involved in the menstrual cycle

A

1) FSH
produced in pituitary gland
causes an egg to mature in a follicle
stimulates the production of oestrogen

2) Oestrogen
produced in the ovaries
causes the lining of the uterus to grow
stimulates the release of LH and inhibits the release of FSH

3) LH
produced by the pituitary gland
stimulates the release of an egg

4) Progesterone
Produced in the ovaries
Maintains the lining of the uterus
Inhibits the release of LH and FSH

45
Q

How can hormones be used to reduce fertility

A

Oestrogen and progesterone

Inhibits egg production and development (oestrogen)

Progesterone reduces fertility by producing more of the thick mucus which prevents any sperm getting through and reaching an egg

46
Q

Other forms of contraception

A

Condoms
Spermicides
Diaphragm
Sterilisation
Timing sex
Abstinence

47
Q

How can hormones be used to increase fertility

A

FSH and LH can be given to stimulate ovulation

However at times it doesn’t always work and can lead to pregnancies with multiple children

48
Q

How does IVF work

A

Collecting eggs from a woman’s uterus
Can be injected with sperm
Grown into embryos
Transferred back into the uterus
FSH and LH are given before egg collection

However it can be expensive and can lead to ectopic pregnancies

49
Q

Why are some people against IVF

A

It can destroy potential human life
Could lead to people choosing preferred characteristics

50
Q

Which hormone stimulates the release of thyroxine

A

TSH

51
Q

Examples of 2 hormones that are controlled by a negative feedback loop

A

Adrenaline
Thyroxine

52
Q

What is auxin

A

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

Controls growth in response to light and gravity

53
Q

What is phototropism

A

When the shoot is exposed to light
Auxin accumulates on the shady side
The shaded side grows faster and the shoot bends towards the light

54
Q

What is gravitropism

A

Where the shoots grow away from gravity and the roots grow towards gravity

In the roots the auxin is on the bottom

In the roots the auxin is on the bottom

55
Q

What is auxin used for commercially

A

Killing weeds - disrupt the normal growth patterns which soon kills them

Growing from cuttings with rooting powder - grows rapidly

Growing cells in tissue culture - used as a growth medium

56
Q

What is gibberellin and what is it used for

A

Stimulates seed germination

Used for:
Controlling dormancy
Induce flowering
Growing larger fruit

57
Q

What is ethene and what is it used for

A

Stimulates fruit ripening by stimulating enzymes that cause the fruit to ripen

Used for:
Speed up ripening

Biology AQA GCSE (7 decks)

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