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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
oestrogen (released by, target organ, purpose)
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
26
LH (released by, target organ, purpose)
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
27
progesterone (released by, target organ, purpose)
produced by the corpus luteum (empty follicle) targets uterus maintains the uterus lining and inhibits FSH AND LH
28
what happens if levels of progesterone fall
low progesterone levels allow FSH levels to rise and the whole cycle to start again
29
what happens to progesterone during pregnancy
levels of progesterone remain high (they keep FSH and LH inhibited so the menstrual cycle does not start again)
30
infertile
unable to reproduce naturally
31
ART (assisted reproductive technology)
a fertility treatment that involves eggs being handled outside of the body
32
give 2 examples of ART
clomifene therapy | in vitro fertilisation (IVF)
33
what situation causes clomifene therapy to be used
if women are infertile due to no or irregular ovulation
34
what happens in clomifene therapy
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
what happens in IVF (preparing the eggs)
- 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
what happens in IVF (after egg collection)
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
what two hormones can be used as contraceptives
oestrogen progesterone or both (the combined pill or contraceptive patch)
38
how does oestrogen work as a contraceptive
prevents ovulation by keeping levels high permanently, inhibiting FSH after a while egg development and production stop
39
how does progesterone work as a contraceptive
progesterone reduces fertility | it stimulates the production of thick cervical mucus which prevents sperm from entering
40
what is a barrier method of contraception
methods of contraception that place a barrier between the sperm and the egg
41
give 2 examples of barrier methods
condoms | diaphragms
42
what must diaphragms must be used with
spermicide
43
give two strengths of hormonal contraceptives
+ 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
give two weaknesses of hormonal contraceptives
- can have unpleasant side effects | - don't protect against STI's, only condoms do this
45
homeostasis
keeping internal conditions constant | this involves the body responding to both internal and external changes whilst balancing inputs and outputs
46
what is negative feedback
if a condition changed away from the normal level, a response is triggered that counteracts that change
47
3 examples of homeostasis
blood glucose regulation thermoregulation osmoregulation
48
why is thermoregulation important
it is vital to control body temperature in order to keep enzymes working at their optimum temperature (this is typically 37'C)
49
describe the thermoregulatory centre
the centre is the hypothalamus | receptors there are sensitive to blood temperature and receives impulses from receptors in the epidermis and dermis
50
what happens in terms of thermoregulation when you are too hot (3)
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
what happens in terms of thermoregulation when you are too cold
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
what monitors blood glucose levels
the pancreas
53
describe the 5 stages of what happens if there is a high blood glucose concentration
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
describe the 5 stages of what happens if there is a low blood glucose concentration
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
what causes type 1 diabetes
the pancreas producing little or no insulin
56
how can type 1 diabetes be controlled
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
what causes type 2 diabetes
the pancreas doesn't produce enough insulin or is resistant to insulin
58
how can type 2 diabetes be controlled
controlled by eating a healthy diet, doing regular exercise and losing weight if necessary (some people have medication and insulin injections)
59
what increases your chance of having type 2 diabetes
waist to hip ratio of over 1.0 for men or over 0.85 for women BMI of over 30
60
waist to hip ratio
waist circumference ----------------------------- hip circumference
61
bmi (formula)
mass (kg) -------------- height ^2 (m)
62
osmoregulation
controlling the water content of the blood
63
what happens to cells if the water concentration is too high or low
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
role of kidneys in regulating water concentration
control how much water is reabsorbed | control how much water is lost in urine
65
role of kidneys (3)
removal of urea from the blood adjustment of ion levels in the blood adjustment of water content in the blood
66
renal vein
carries deoxygenated blood away from the kidneys
67
renal artery
carries oxygenated blood to the kidneys
68
ureter
carries urine from the kidneys to the bladder
69
what are the parts of the nephron
``` the glomerulus Bowman's capsule proximal convoluted tubule distal convoluted tubule loop of Henle collecting duct ```
70
role of the glomerulus and Bowman's capsule
filtration | - the liquid part of the bloods if forced into the Bowman's capsule, leaving large molecules behind
71
role of the proximal and distal convoluted tubules
selective reabsorption of all glucose (using active transport) and sufficient mineral ions
72
role of the loop of henle
reabsorption of water
73
role of the collecting duct
waste products pass into the ureter and then into the bladder as urine
74
how is water concentration levels monitored and regulated in the blood
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
what happens if there is water gain
hypothalamus detects water gain less ADH is released the collecting ducts are less permeable so less water is reabsorbed
76
what happens if there is water loss
hypothalamus detects water loss more ADH is released the collecting ducts are more permeable so more water is reabsorbed
77
what are two ways of treating kidey failure
dialysis | kidney transplant
78
dialysis
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
what is a weakness of having a kidney transplant
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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