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Biology GCSE > homeostasis > Flashcards

homeostasis Flashcards

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1
Q

hormones

A

chemical molecules produced by endocrine glands and released into the bloodstream to be carried to their target organs to bring about a response

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2
Q

name 6 endocrine glands

A 
thyroid gland
pituitary gland
pancreas
adrenal gland
testes (male)
ovaries (female)
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3
Q

what does the thyroid gland release

A

thyroxine

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4
Q

what does the pituitary gland release and where is it found

A

releases many hormones

located beneath the hypothalamus in the brain

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5
Q

what does the pancreas release

A

insulin

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6
Q

what does the adrenal gland release

A

adrenaline

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7
Q

what does the testes release

A

testosterone

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8
Q

what is testosterone responsible for

A

responsible for male growth characteristics (puberty)

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9
Q

what do the ovaries release

A

oestrogen

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10
Q

difference between nerves and hormones

A 
nerves 
- fast action
- short lived response
- act on a precise area
- electrical signal
hormones
- slower action
- act for a long time
- act in a more general way
- chemical signal
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11
Q

role of adrenaline

A

prepares the body for a fight or flight response that is needed when a threat or stressor is identified by the hypothalamus

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12
Q

what three areas does adrenaline affect

A

heart
liver
blood vessels

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13
Q

how does adrenaline affect the heart

A

binds to specific receptors
causing heart muscle cells to contract more frequently and more strongly which increases BLOOD PRESSURE and HEART RATE
- this in turn increases blood flow to the muscles so the cells receive more oxygen and glucose for increased respiration

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14
Q

how does adrenaline affect the blood vessels

A

blood vessels in the muscles widen to increase blood flow

blood vessels in the organs narrow so blood flow decreases and blood pressure increases

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15
Q

how does adrenaline affect the liver

A

binds to receptors in the liver
causes the liver to break down GLYCOGEN into GLUCOSE and release it into the blood for respiration ( increasing BLOOD SUGAR CONCENTRATION)

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16
Q

role of thyroxine

A

plays an important role in regulating metabolic rate

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17
Q

metabolic rate

A

the rate at which chemical reactions in the body occur

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18
Q

what are the 6 stages of the thyroxine negative feedback loop

A
  1. low thyroxine levels in the bloodstream
  2. stimulates hypothalamus to release TRH (thyrotropin releasing hormone)
  3. TRH stimulates the pituitary gland to release TSH (thyroid stimulating hormone)
  4. thyroid releases more thyroxine
  5. thyroxine levels in the blood return to normal
  6. when thyroxine levels are normal, thyroxine inhibits the release of TRH and the production of TSH
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19
Q

what happens on day 1 of the menstrual cycle

A

menstruation starts

lining of the uterus breaks down and is released

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20
Q

what happens on days 4-14 of the menstrual cycle

A

uterus lining builds up again to form a thick, spongy layer full of blood vessels, ready for the implantation of a fertilised egg

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21
Q

what happens around day 14 of the menstrual cycle

A

ovulation (egg develops and is released)

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22
Q

what happens on days 14-28 of the menstrual cycle

A

lining of the uterus is maintained

if no fertilised egg has implanted by day 28, lining starts to break down again and the cycle repeats

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23
Q

4 hormones involved in the regulation of the menstrual cycle

A

FSH (follicle stimulating hormone)
LH (luteinising hormone)
oestrogen
progesterone

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24
Q

FSH (released by, target organ, purpose)

A

released by pituitary gland at the start of menstruation
targets ovaries
stimulates follicles to mature and develop

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25
Q

oestrogen (released by, target organ, purpose)

A

produced by egg follicles in the ovaries, increasing in levels from day 1
targets the pituitary gland
stimulates the production of LH and inhibits FSH and causes uterus lining to thicken and grow

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26
Q

LH (released by, target organ, purpose)

A

released by pituitary gland in a surge after stimulation by oestrogen
targets ovaries
causes ovulation by causing the dominant follicle to rupture and release the mature egg into the fallopian tubes

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27
Q

progesterone (released by, target organ, purpose)

A

produced by the corpus luteum (empty follicle)
targets uterus
maintains the uterus lining and inhibits FSH AND LH

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28
Q

what happens if levels of progesterone fall

A

low progesterone levels allow FSH levels to rise and the whole cycle to start again

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29
Q

what happens to progesterone during pregnancy

A

levels of progesterone remain high (they keep FSH and LH inhibited so the menstrual cycle does not start again)

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30
Q

infertile

A

unable to reproduce naturally

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31
Q

ART (assisted reproductive technology)

A

a fertility treatment that involves eggs being handled outside of the body

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32
Q

give 2 examples of ART

A

clomifene therapy

in vitro fertilisation (IVF)

33
Q

what situation causes clomifene therapy to be used

A

if women are infertile due to no or irregular ovulation

34
Q

what happens in clomifene therapy

A

the drug clomifene causes more FSH and LH to be released, stimulating egg maturation and ovulation

this s good because if a couple knows when ovulation will occur, they can have intercourse during this time period to increase the likelihood of becoming pregnant

35
Q

what happens in IVF (preparing the eggs)

A
  • drug is given to stop the natural production of FSH and LH
  • this stops the usual cycle of a single egg maturing in an ovary and being released
  • a larger than usual dose of FSH is given to th ewoman for several days to cause many eggs to grow and mature in both ovaries
  • a larger than usual dose of LH is given to complete egg cell maturation so that many are released at the same time
36
Q

what happens in IVF (after egg collection)

A

egg cells are collected and fertilised with the man’s sperm and grown into embryos
the woman is given progesterone to prepare the uterus for implantation of an embryo by causing it to thicken
embryos are inserted into the woman to hopefully implant and grow into a baby

37
Q

what two hormones can be used as contraceptives

A

oestrogen
progesterone
or both (the combined pill or contraceptive patch)

38
Q

how does oestrogen work as a contraceptive

A

prevents ovulation by keeping levels high permanently, inhibiting FSH
after a while egg development and production stop

39
Q

how does progesterone work as a contraceptive

A

progesterone reduces fertility

it stimulates the production of thick cervical mucus which prevents sperm from entering

40
Q

what is a barrier method of contraception

A

methods of contraception that place a barrier between the sperm and the egg

41
Q

give 2 examples of barrier methods

A

condoms

diaphragms

42
Q

what must diaphragms must be used with

A

spermicide

43
Q

give two strengths of hormonal contraceptives

A

+ when used correctly, they are more effective at preventing pregnancy than barrier contraceptives
+ couple doesn’t have to think about contraception each time they have intercourse

44
Q

give two weaknesses of hormonal contraceptives

A
  • can have unpleasant side effects

- don’t protect against STI’s, only condoms do this

45
Q

homeostasis

A

keeping internal conditions constant

this involves the body responding to both internal and external changes whilst balancing inputs and outputs

46
Q

what is negative feedback

A

if a condition changed away from the normal level, a response is triggered that counteracts that change

47
Q

3 examples of homeostasis

A

blood glucose regulation
thermoregulation
osmoregulation

48
Q

why is thermoregulation important

A

it is vital to control body temperature in order to keep enzymes working at their optimum temperature
(this is typically 37’C)

49
Q

describe the thermoregulatory centre

A

the centre is the hypothalamus

receptors there are sensitive to blood temperature and receives impulses from receptors in the epidermis and dermis

50
Q

what happens in terms of thermoregulation when you are too hot (3)

A

erector muscles relax, so hairs lie flat

lots of sweat is produced and released through pores in the epidermis onto the surface of the skin (once evaporated, it transfers energy from the skin to the environment)

vasodilation - blood vessels near the surface of the skin widen so more blood can flow there and transfer energy to surroundings via radiation - shunt valve has restricted blood flow

51
Q

what happens in terms of thermoregulation when you are too cold

A

erector muscles contract, so hairs stand on end, trapping an insulating layer of air near the surface of the skin to keep you warm

little sweat produced

vasoconstriction - blood vessels near the surface of the skin constrict so less blood can flow there and transfer energy to surroundings via radiation- shunt valve has increased blood flow

you shiver (muscles contract automatically), this increases rate of respiration which releases more energy to warm the body

52
Q

what monitors blood glucose levels

A

the pancreas

53
Q

describe the 5 stages of what happens if there is a high blood glucose concentration

A
  1. high levels of glucose in the blood detected
  2. INSULIN is secreted by the pancreas
  3. insulin causes the liver to turn glucose into glycogen (a storage molecule)
  4. glucose moves out from the blood therefore and into the liver and muscle cells
  5. blood glucose level is reduced
54
Q

describe the 5 stages of what happens if there is a low blood glucose concentration

A
  1. low levels of glucose in blood detected
  2. GLUCAGON is secreted by pancreas
  3. glucagon makes liver turn glycogen back into glucose
  4. glucose is released into the blood from the liver
  5. blood glucose level is increased
55
Q

what causes type 1 diabetes

A

the pancreas producing little or no insulin

56
Q

how can type 1 diabetes be controlled

A

insulin therapy
typically by injection into the subcutaneous tissue
quantity injected depends on diet and activity

they should regularly exercise and limit their consumption of foods high in simple carbohydrates

57
Q

what causes type 2 diabetes

A

the pancreas doesn’t produce enough insulin or is resistant to insulin

58
Q

how can type 2 diabetes be controlled

A

controlled by eating a healthy diet, doing regular exercise and losing weight if necessary

(some people have medication and insulin injections)

59
Q

what increases your chance of having type 2 diabetes

A

waist to hip ratio of over 1.0 for men or over 0.85 for women
BMI of over 30

60
Q

waist to hip ratio

A

hip circumference

61
Q

bmi (formula)

A

height ^2 (m)

62
Q

osmoregulation

A

controlling the water content of the blood

63
Q

what happens to cells if the water concentration is too high or low

A

too high:
water will move into the cells via osmosis, they become turgid, burst/ go through lysis

too low:
water leaves the cells by osmosis and they become flaccid

64
Q

role of kidneys in regulating water concentration

A

control how much water is reabsorbed

control how much water is lost in urine

65
Q

role of kidneys (3)

A

removal of urea from the blood
adjustment of ion levels in the blood
adjustment of water content in the blood

66
Q

renal vein

A

carries deoxygenated blood away from the kidneys

67
Q

renal artery

A

carries oxygenated blood to the kidneys

68
Q

ureter

A

carries urine from the kidneys to the bladder

69
Q

what are the parts of the nephron

A 
the glomerulus
Bowman's capsule
proximal convoluted tubule
distal convoluted tubule
loop of Henle
collecting duct
70
Q

role of the glomerulus and Bowman’s capsule

A

filtration

- the liquid part of the bloods if forced into the Bowman’s capsule, leaving large molecules behind

71
Q

role of the proximal and distal convoluted tubules

A

selective reabsorption of all glucose (using active transport) and sufficient mineral ions

72
Q

role of the loop of henle

A

reabsorption of water

73
Q

role of the collecting duct

A

waste products pass into the ureter and then into the bladder as urine

74
Q

how is water concentration levels monitored and regulated in the blood

A

the amount of water reabsorbed is controlled by ADH
the hypothalamus monitors water content in the blood and instructs the pituitary gland to produce more or less ADH depending on whether levels are too low or high

75
Q

what happens if there is water gain

A

hypothalamus detects water gain
less ADH is released
the collecting ducts are less permeable so less water is reabsorbed

76
Q

what happens if there is water loss

A

hypothalamus detects water loss
more ADH is released
the collecting ducts are more permeable so more water is reabsorbed

77
Q

what are two ways of treating kidey failure

A

dialysis

kidney transplant

78
Q

dialysis

A

filters the bloods for patients who can’ d it themselves
dialysis fluid is personalised to contain the same concentration of glucose and salts in the blood plasms so they aren’t removed form the bloods

79
Q

what is a weakness of having a kidney transplant

A

the patient has to take immunosuppressants for the rest of their life so that the kidney isn’t attacked by their immune system for being a foreign body

Biology GCSE (8 decks)

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