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Biology AQA GCSE > Homeostasis and Response > Flashcards

Homeostasis and Response Flashcards

(57 cards)

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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

Study These Flashcards
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

Study These Flashcards
A

contact lenses

laser eye surgery - changes shape of cornea

replacement lens surgery - replaces lens

25
how does the body control temperature
thermoregulatory centre in brain receptors detect thermoregulatory centre acts as a control centre triggers effectors response counteracts change
26
what happens when you are too hot
sweat - sweat evaporates from the skin vasodilation - more blood flows and more energy lost to the surroundings
27
what happens when you are too cold
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
what are hormones
chemical molecules that are released directly into the blood but only affect particular cells in particular organs
29
examples of glands and their functions
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
difference between nerves and hormones
nerves: fast short operating time precise area hormones: slower act for a long time more general area
31
what is glycogen
what glucose is stored as
32
what happens if blood glucose level is too high
detected by receptors insulin secreted by pancreas insulin makes liver turn glucose into glycogen for storage moves into muscle and liver cells
33
what happens if blood glucose level is too low
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
what is type 1 diabetes
where a person's pancreas produces little to no insulin they require shots of insulin
35
what is type 2 diabetes
where a person has become resistant to their own insulin can be controlled naturally
36
what things do the kidneys do
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
what hormone controls water levels
ADH
38
what happens if your kidneys don't work properly
waste substances build up and eventually results in death
39
treatment for kidney failure
dialysis kidney transplant
40
what are the downsides to a kidney transplant
they can be rejected long waiting lists
41
how does dialysis work
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
What do hormones do at puberty
Promote sexual characteristics such as facial hair in men and breasts in women
43
What are the 4 stages of the menstrual cycle
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
What are the 4 hormones involved in the menstrual cycle
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
How can hormones be used to reduce fertility
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
Other forms of contraception
Condoms Spermicides Diaphragm Sterilisation Timing sex Abstinence
47
How can hormones be used to increase fertility
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
How does IVF work
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
Why are some people against IVF
It can destroy potential human life Could lead to people choosing preferred characteristics
50
Which hormone stimulates the release of thyroxine
TSH
51
Examples of 2 hormones that are controlled by a negative feedback loop
Adrenaline Thyroxine
52
What is auxin
A plant hormone that controls growth near the tips of shoots and roots Controls growth in response to light and gravity
53
What is phototropism
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
What is gravitropism
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
What is auxin used for commercially
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
What is gibberellin and what is it used for
Stimulates seed germination Used for: Controlling dormancy Induce flowering Growing larger fruit
57
What is ethene and what is it used for
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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