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OCR A GCSE Biology (B1-B3) > B3.3 - maintaining internal environments > Flashcards

B3.3 - maintaining internal environments Flashcards

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1
Q

what temperature may you have a risk of hypothermia by?

A

35°C

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2
Q

explain how exposure to extreme cold can lead to death (3)

A
  • core temperature may reduce
  • causes enzyme reactions to occur too slowly
  • respiration does not release energy fast enough
  • cells begin to die
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3
Q

explain how exposure to high temperature leads to death (3)

A
  • body overheats
  • energy transfer to molecules is too much
  • enzymes may denature
  • respiration cannot occur (idk abt this one -> sounds decent)
  • death
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4
Q

what area in your brain is responsible for regulating body temperatures?

A
  • thermoregulatory centre

hypothalamus

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5
Q

what is a change in temperature detected by?

A
  • skin receptors (external temperature)

- internal receptors (blood temperature)

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6
Q

how does the brain respond to a stimulus? (1)

A

the brain sends impulses to effectors

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7
Q

what happens to your body when you get too hot (in order to cool it down)? (3)

A
  • body hair lowers
  • vasodilation
  • sweat glands produce swear
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8
Q

how does body hairs lowering cool you down?

A

prevents layer of insulating air being trapped around body

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9
Q

how does vasodilation cool you down?

A
  • increases blood flow to capillaries (surface of skin)

- increasing heat loss via radiation

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10
Q

how does sweating cool you down?

A
  • water in sweat evaporates

- energy is transferred by heating from body to environment

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11
Q

what happens when you get too cold? (to warm up)

A
  • body hairs rise
  • blood vessels = vasoconstriction
  • shivering begins
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12
Q

how does body hair rising keep you warm?

A
  • traps a layer of insulating air close to the skin
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13
Q

how does vasoconstriction keep you warm?

A

reduces blood flow through the capillaries (less heat lost)

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14
Q

how does shivering keep you warm?

A
  • cells respire more quickly

- transfer extra energy by heating

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15
Q

what are the effects on the body if blood glucose levels are too high?

A
  • affects concentration gradient in blood (negative impact on osmosis)
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16
Q

what are the effects on the body of blood glucose levels are too low?

A
  • organism cannot produce enough energy

- prevents cell from respiring effectively

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17
Q

what happens when blood glucose levels are too high?

A
  • pancreas detects change
  • releases (hormone) insulin
  • insulin travels in blood to liver
  • liver is stimulated to turn glucose into glycogen
  • glycogen stored in liver
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18
Q

what happens if blood glucose levels are too low?

A
  • pancreas detects change
  • releases glucagon (hormone)
  • hormone makes liver change glycogen into glucose
  • released into blood
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19
Q

what causes blood sugar levels to drop?

A

exercise (glucose used more during respiration)

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20
Q

what is the difference between glycogen, glucose and glucagon?

A
  • glucose is released during digestion (sugar)
  • glycogen is glucose stored in the liver
  • glucagon is the hormone released by the pancreas to stimulate glycogen to be changed into glucose
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21
Q

Which organ helps to restore our glucose levels to normal when they fluctuate?

A

liver/pancreas

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22
Q

what does insulin do?

A
  • bind to cells in body

- tells them to absorb excess glucose and turn it into glycogen

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23
Q

causes of type 1 diabetes

A
  • Cannot produce insulin or very little insulin produced

- Immune system has destroyed pancreatic cells that make insulin

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24
Q

causes of Type II diabetes

A
  • Cells do not produce enough insulin
  • cells do not respond properly to insulin (may be resistant)
  • cells won’t take in glucose from bloodstream
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25
Q

how is type 1 diabetes controlled?

A
  • injecting insulin
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26
Q

how is type 2 diabetes controlled?

A
  • healthy, low sugar diet

- regular exercise

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27
Q

how does vasodilation work?

A

muscular walls relax

28
Q

how does vasoconstriction work?

A

muscular walls contract

29
Q

what happens if too much water is present in plasma?

A
  • water would move into cells
  • cells would burst/swell
  • LYSIS
30
Q

what happens if too little water is present in blood?

A
  • water diffuses out of cells

- cells shrink

31
Q

what does urine contain?

A

urea, excess salts, excess water, waste products

32
Q

what brings ‘unclean’ blood to the urea?

A

renal artery

33
Q

what carries ‘clean’ blood away from the kidneys?

A

renal vein

34
Q

what is the tube through which urine passes from the kidney to the bladder?

A

ureter

35
Q

what is the tube which urine passes to the outside of your body?

A

urethra

36
Q

what is the ring of muscle that control the opening and closing of the bladder?

A

urethral sphincter

37
Q

what happens during filtration in the kidneys?

A
  • small molecules are absorbed into the tubule

- large molecules remain in the capillaries (proteins/cells)

38
Q

what is absorbed during selective reabsorbtion?

A
  • some water
  • all glucose
  • some ions
  • salts
39
Q

how does the body maintain water levels?

A

breathing/ sweating/ amount of water in urine

40
Q

describe the capsule of the kidney

A
  • outer membrane
  • protect kidney’s shape
  • protect from damage
41
Q

where is the cortex of the kidney?

A

outer part

42
Q

where is the medulla of the kidney?

A

inner part

43
Q

where is urine produced? (1)

A

microscopic tubules (nephrons)

44
Q

where is the top of the nephron found?

A

cortex

45
Q

where is the loop of Henlé found?

A

medulla (lower section)

46
Q

where does blood go to first from the renal artery?

A

glomerulus (a knot of capillaries)

47
Q

how does filtration occur?

A

1) exit of glomerulus blood vessels are narrow = high blood pressure
2) pressure forces small molecules out of capillary wall (glomerulus) to Bowman’s capsule
3) travel to nephron tubules
4) large molecules stay in bloodstream/ glomerulus

48
Q

how does selective reabsorption occur?

A

1) filtrate moves through nephron tubules/ loop of Henlé

2) glucose/ water/ salts are absorbed by body into capillaries

49
Q

how is urine collected?

A

1) urine collects in collecting duct
2) travels in ureter (tube)
3) stored in bladder

50
Q

what is the volume of urine produced controlled by?

A

a negative feedback loop

51
Q

what detects the water potential of blood?

A

hypothalamus (when passes through brain)

52
Q

how does the hypothalamus react to water potential?

A
  • by producing ADH

- getting the pituitary gland to secrete it

53
Q

what happens if the blood water potential is too low?

A
  • more ADH produced
  • increased permeability of kidney tubules
  • less water lost = less urine produced = more concentrated urine
54
Q

what happens if there is too much urea in the bloodstream?

A

harms cells and tissues

55
Q

how is urea formed?

A

1) digestion of protein results in an excess of amino acids
2) In the liver, amino acids go through deamination, and the waste product is ammonia.
3) ammonia is then converted into urea

56
Q

what happens if the blood water potential is too high?

A
  • The hypothalamus triggers the pituitary gland to stop the release of (ADH).
    2) reduces permeability of the kidney tubules.

3) This means that less water reabsorbed back into the bloodstream.
= more dilute urine

57
Q

when is urea formed?

A

excess of animo acids

58
Q

what does a reduction of water potential in blood plasma or increase of salt concentration trigger?

A

thirst response

59
Q

what happens if you drink too much water?

A
  • more urine produced
  • cells may burst (osmosis)
  • concentration of sodium in blood drops
  • muscle cramping
  • seizures
  • confusion
60
Q

what happens in extreme cases of too much water?

A

death, water moves into brain cells

61
Q

what is a hypotonic solution?

A

solution = high water concentration (low ion)
cell = low water potential (high ion)
GAIN WATER - lysis

62
Q

what is a hypertonic solution?

A

solution = low water potential (high ion)
cell = high water potential (low ion)
SHRINK - lose water

63
Q

what is a solution that has the same water and ion concentration as cells?

A

Isotonic

64
Q

How does homeostasis affect the blood?

A

regulates water and ions concentration (constant)

65
Q

what controls osmosis and diffusion between cells in the body.

A

ion levels in plasma vs cells

66
Q

what do kidneys control in the body?

A

ion/water levels

67
Q

what is the function of the kidneys?

A
  • regulate the volume and concentration of urine

- remove waste + regulate body water content

OCR A GCSE Biology (B1-B3) (12 decks)

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