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Biology > GCSE P2 HOMEOSTASIS > Flashcards

GCSE P2 HOMEOSTASIS Flashcards

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1
Q

what is homeostasis?

A

maintaining a stable internal environment

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2
Q

describe negative feedback cycle

A
  1. receptor detects stimulus (e.g too high)
  2. coordination centre receives + processes info and brings about a response
  3. effector produces response which counteracts the change (level decreases)
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3
Q

what does the CNS consist of?

A

the brain and spinal cord

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4
Q

what are sensory neurones

A

carry electrical impulses from receptors to the CNS

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5
Q

what are motor neurones

A

carry electrical impulses from the CNS to effectors

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6
Q

what is an effector?

A

muscle (contracts) or a gland (secretes a hormone)

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7
Q

what are synapses?

A

connection between two neurones. nerve signal transferred by chemicals which diffuse across gap - set off new electrical signal in next neurone

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8
Q

what are reflexes?

A

rapid automatic responses (doesn’t involve conscious part of the brain)

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9
Q

what would happen if you were stung by a bee?

A 
stimulation of pain receptor
sensory neurone
relay neurone
motor neurone
muscle contracts
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10
Q

what is the front part of the brain called? whats its function

A

cerebral cortex

consciousness, memory, intelligence and language

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11
Q

what is the back part of the brain called?

A

cerebellum

muscle co-ordination

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12
Q

what is the part of the brain called near the spinal cord?

A

medulla

unconscious activities - breathing and HR

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13
Q

what is the sclera

A

tough supporting wall of the eye

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14
Q

what is the cornea

A

transparent outer layer (refracts light into eye)

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15
Q

what is the iris

A

contains muscles that allow it to control the diameter of the pupil

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16
Q

what is the lens

A

focuses the light onto the retina

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17
Q

what is the optic nerve

A

carries impulses from receptors (on retina) to the brain

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18
Q

what happens when there is too much light

A

light receptors detect bright light
circular muscles contract
radial muscles relax
reduces amount of light that can enter the eye

19
Q

what happens when you look at a near object?

A

ciliary muscles contract
suspensory ligaments slacken
lens becomes more fat and curved
increases amount of light refracted

20
Q

what is changing the shape of the lens called?

A

accommodation

21
Q

what happens when you look at a far away object?

A

ciliary muscles relax
suspensory ligaments are pulled tight
lens becomes more thin and less curved
refracts light by a smaller amount

22
Q

what is long-sightedness called?

A

hyperopia (convex lens)

23
Q

what is short-sightedness called?

A

myopia (concave lens)

24
Q

contact lenses

A

lightweight + almost invisible

soft lenses could cause eye infection

25
Q

laser eye surgery

A

will correct vision

infection/eye could react badly and vision could become worse

26
Q

replacement lens surgery

A

could possibly damage the retina –> loss of sight

27
Q

what detects body temperature

A

thermoregulatory centre in the brain

receptors in the skin

28
Q

what happens when you’re too hot

A

sweat produced (evaporates –> energy transferred to environment)
vasodilation (blood vessels dilate moving towards surface of the skin)
hair erector muscle relaxed

29
Q

what happens when you’re too cold

A

hairs stand up (trap insulating layer of air)
no sweat produced
vasoconstriction (blood vessels constrict to close off skin’s blood supply)
muscles contract –> shivering –> needs respiration (transfers energy to warm body)

30
Q

what are hormones

A

chemical messengers that are sent in the blood which act on a target organ (long lasting effects)

31
Q

pituitary gland

A

master gland –> produces many hormones

32
Q

thyroid

A

thyroxine (regulates metabolism, HR and temp)

33
Q

ovaries

A

estrogen

34
Q

adrenal gland

A

adrenaline –> fight or flight

35
Q

testes

A

testosterone

36
Q

pancreas

A

insulin

37
Q

nerves

A

fast action
act for short time
act on precise area

38
Q

hormones

A

slower action
act for long time
act in a general way

39
Q

what happens when blood glucose levels are too high?

A

insulin secreted by pancreas
glucose moves from blood –>liver and muscle cells
insulin turns glucose to glycogen
blood glucose reduced

40
Q

what happens when blood glucose levels are too low?

A

pancreas releases glucagon
glucagon makes the liver turn glycogen into glucose
glucose released into blood by liver
blood glucose increased

41
Q

type 1 diabetes

A

pancreas produces little/no insulin

42
Q

type 2 diabetes

A

body cells don’t respond to insulin

43
Q

what happens when water content is too high?

A

receptor in brain detects level is too high
pituitary gland releases less ADH
less water is reabsorbed from kidney tubules
increased volume of urine

Biology (5 decks)

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