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Biology > Mr Allsop- Homeostasis > Flashcards

Mr Allsop- Homeostasis Flashcards

1
Q

what is the definition of homeostasis

A

maintaining a dynamic equilibrium with small fluctuations over a narrow range of conditions
- not maintaining constantly but regulating- cannot be completely stable

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2
Q

factors controlled by homeostasis

A

temp, hormones, blood glucose conc., PH

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3
Q

what is negative feedback

A

if increase/ decrease is detected responses lower/ increase levels to bring it back to ideal conditions

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4
Q

explain how negative feedback works for blood glucose levels

A

too much - insulin released to decrease as it causes glucose to be stored glycogen
too little- glucagon released to liver to break down glycogen back to glucose

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5
Q

what is positive feedback and examples

A

change detected, responses reinforce the change
-labour contractions
-blood clotting- cut- collagen exposed- platelets bind to it forming plug

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6
Q

what is thermoregulation

A

maintenance of a relatively constant core body temperature, to maintain optimum enzyme activity

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7
Q

what is an ectotherm

A

use surroundings to warm up their body- invertebrates

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8
Q

what is an endotherm

A

rely on metabolic rate to warm up- humans

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9
Q

what are behaviourist responses

A

changing behaviour to increase or reduce radiation they should absorb from sun

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10
Q

what are physiological responses

A

autonomic response to stimulus due to physiological factors

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11
Q

what are some behavioural responses to warm up ectotherms

A

basking in the sun
press body against warm ground
increase SA to sun

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12
Q

what are some physiological responses to warm up ectotherms

A

dark colours, increase heart rate

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13
Q

what are some behavioural responses to cool down ectotherms

A

orientate away from the sun
reduce movements
digging burrows

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14
Q

what is a physiological response to cool down ectotherms

A

decrease metabolic rate

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15
Q

what is meant by fever and hypothermia

A

fever- above average body temp
hypothermia- below average body temp

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16
Q

what does the hypothalamus do

A

constantly measures temperature - receptors detect change in temp in blood/brain

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17
Q

behavioural responses to warm up in endotherms

A

movement, wear clothes, sunbathing, going to shade, huddle, wallow in mud/water, hibernation

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18
Q

what is the heat loss centre

A

activated when blood temperature increases sending impulses through autonomic motor neurones to effectors in skin and muscles to lower temperature

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19
Q

what is the heat gain centre

A

when hypothalamus detects cooling in blood temp, sends an impulse to increase temp

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20
Q

how do endotherms cool down physiologically

A

vasodilation- arterioles near the surface of the skin dilate when temperature rises. vessels providing contact between arterioles and the venules contract to force blood up to top of capillary network close to skin surface. the skin flushes and cools as a result of increased radiation

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21
Q

how does increase sweating cool endotherms down

A

sweating increases as temperature spreads out across surface of skin. As sweat is lost by evaporation , heat is lost, so cools blood below the surface

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22
Q

how does reducing insulating hairs cool down endotherms

A

As temperature increases the erector pili muscles in skin relax, so hairs/feathers lay flat to avoid trapping air

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23
Q

how do endotherms warm up physiologically

A

vasoconstriction- arterioles near surface of skin constrict. whereas vessels providing contact between arterioles and venules dilate so blood can flow back. So little blood flows through capillary networks close to skin, so very little radiation takes place.

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24
Q

how does decreasing sweating warm up endotherms

A

sweating decreases as temperature falls, this decreases cooling by the evaporation of water from the surface of the skin

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25
Q

how does raising the body hair warm up endotherms

A

As temp falls erector pili muscles in skin contract, making hair erect, trapping a conducting layer of air and so reduces cooling through skin.

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26
Q

how does shivering warm up endotherms

A

As temperature falls the body begins to shiver (rapid, involuntary contracting and relaxing of large voluntary muscles in the body). the metabolic heat from the endothermic reactions warm up body instead of moving it.

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27
Q

what are the roles of the liver

A

stores glycogen, regenerates, breaks down alcohol, detoxification, deamination- takes amine group away from amino acid.

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28
Q

what is excretion

A

removal of waster products of metabolism

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29
Q

what % of body mass does the liver take up

A

5%

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30
Q

how is oxygenated blood supplied to the liver

A

hepatic artery

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31
Q

how is deoxygenated blood returned to the heart

A

hepatic vein

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32
Q

what is the hepatic portal vein

A

blood loaded with products of digestion from intestine

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33
Q

what are hepatocytes

A

liver cells that have a large nuclei, prominent Golgi apparatus and lots of mitochondria, regenerate

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34
Q

what is a sinusoid

A

surround hepatocytes where blood from hepatic artery and portal vein mixes

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35
Q

what are Kupffer cells

A

ingest foreign particles found in sinusoid

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36
Q

what are the canaliculi

A

regions where bile is secreted which then flows into bile ducts and taken to gall bladder

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37
Q

what is meant by carbohydrate metabolism

A

hepatocytes convert glucose into glycogen when levels rise and then back to glucose when it falls

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38
Q

what is transamination

A

conversion of amino acids into acid

39
Q

what is detoxification

A

conversion of toxic substances into harmless ones

40
Q

what is deamination

A

amino acids absorbed for ileum (small intestine)
excess amino acids to liver
amino acids split - rest of molecule used in respiration
amino acid combines with carbon dioxide to form urea to go to kidneys to be excreted.

41
Q

what is the ornithine cycle

A

ammonia is produced by deamination of proteins is converted into urea in a set of enzyme controlled reactions called orthine cycle

42
Q

explain the ornithine cycle

A

ammonia and co2- h20 leaves- citrulline- h20 is released and NH3 arrives to form arginine- h20 added and urea leaves cycle forming ornithine

43
Q

what is the bowman’s capsule

A

cup-shaped structure that contains glomerulus, a tangle of capillaries. where ultrafiltration

44
Q

what is the proximal convoluted tubule

A

first coiled region of the tubule after the bowman’s capsule. where reabsorption takes place

45
Q

what is the loop of Henle

A

long loop of tubule that creates a region with a very high solute concentration in the tissue fluid deep in the kidney medulla.

46
Q

what is the distal convoluted tubule

A

second twisted tubule where fine-tuning of water balance takes place

47
Q

what is the collecting duct

A

urine passes down here through medulla to pelvis. more fine tuning of water balance takes place

48
Q

what is the structure of kidneys

A

pair of reddish- brown organs attached to back of abdominal cavity.

49
Q

what is the function of kidneys

A

involved in excretion and osmoregulation
supplied with blood by renal arteries that branch from abdominal aorta
after circulating, blood leaves via renal vein and drains into inferior vena cava.
then filtered by the nephron and urine passes through tubes called ureters
urine is collected in the bladder where it passes through urethra

50
Q

what is the job of the nephron

A

filters out waste products in the blood

51
Q

what is the first stage of the nephron

A

afferent arteriole which has a wide lumen to bring blood to glomerulus

52
Q

what is the efferent arteriole

A

thicker lumen to force fluid out under high pressure

53
Q

what is the role of the glomerulus

A

ultrafiltration which filters products out of the blood

54
Q

what is a podocyte

A

finger like projections that help filter out products in blood at glomerulus by putting pressure on capillaries

55
Q

what is the bowman’s capsule

A

c shaped structure that filters out waste products such as glucose, urea, amino acids, water and mineral ions

56
Q

what is the proximal convoluted tubule responsible for

A

selective reabsorption- 100% glucose and amino acids are reabsorbed and 83% of water/mineral ions

57
Q

what are the features of the loop of Henle and their roles

A

ascending limb ( going up) which is impermable to water to sodium and chloride ions are actively pumped out creating a low water potential where water from the descending limb moves out

58
Q

what is the distal convoluted tubule and collecting duct responsible for

A

finishing tweaks

59
Q

what features of the nephron are in the cortex ( upper half)

A

glomerulus, bowman’s capsule, proximal convoluted tubule, distal convoluted tubule ( most of it)

60
Q

what features of the nephron are in the medulla ( bottom half)

A

loop of Henle ( ascending/descending limb)
collecting duct

61
Q

what is osmoregulation

A

water potential of the blood needs to maintained regardless of levels of water taken in or lost

62
Q

what is water potential and how is it measured

A

the pressure of water exerted on membrane or container
measured in kpa

63
Q

what number is the highest water potential

A

0- pure water

64
Q

what does ADH stand for

A

Anti-diuretic hormone

65
Q

where is ADH produced

A

hypothalamus

66
Q

where is ADH released

A

pituitary gland

67
Q

what is the role of ADH

A

increase permeability of collecting duct and distal convoluted tube cell surface membrane

68
Q

what is cAMP

A

a secondary messenger- signalled by ADH to trigger vesicles to fuse

69
Q

outline the process of how ADH increases permeability of CD and DCT

A

ADH binds to receptors on CD and DCT membrane
this signals cAMP to cause vesicles containing aquaporins to fuse to membrane
cell surface membrane of CD and DCT now contains aquaporins so water leaves via osmosis into the blood.

70
Q

what happens when a high potential is detected (opposite for low)

A

osmoreceptors in hypothalamus detects change, less ADH is released so there are less aquaporins, less water is reabsorbed (leaves) so there is a large volume of dilute urine.

71
Q

what is urine

A

contains breakdown products of a whole range of chemicals along with water, urea, mineral salts - if you are affected by disease, new substances will show up in you urine

72
Q

how much glucose is reabsorbed in a healthy person vs diabetes

A

100%- healthy person - less in unhealthy meaning it is found in the wee

73
Q

what is hCG

A

human chorionic gonadotrophin is a hormone found in blood and urine of only pregnant women

74
Q

how did they test if women are pregnant up to 1960’s

A

hCG would be injected into African Clawed toad- if pregnant toad produced eggs

75
Q

how are false negative tests caused

A

low concentration of hCG

76
Q

what is the the first stage of monoclonal antibody production

A

hCG injected into mouse - produces antibodies that bind to hCG- B-cells that make this antibody are removed from mouse

77
Q

what is the second stage of monoclonal antibody production

A

myeloma (cancer cells) divide rapidly adn grown in culture medium

78
Q

what is the third stage of monoclonal antibody production

A

B-cell from mouse and myeloma is fused together to make hybridoma cell.

79
Q

what happens at the reaction site of a pregnancy test

A

urine added to wick
hCG bind to mobilised antibodies forming hCG antibody-complex

80
Q

what happens at the test site of a pregnancy test

A

hCG antibody complex binds to immobile antibodies activating the dye so the line appears

81
Q

what happens at the control site of a pregnancy test

A

excess mobilised antibodies bind to immobilised antibodies activating dye so line appears- this tests if it is faulty

82
Q

what are anabolic steroids

A

test urine by gas chromatography where it is vapourised with known solvent - lining of tube absorbs gases and analysed to give chromatogram to show presence of drugs

83
Q

what are the effects of kidney failure on the body

A

low blood glucose concentration
build up of urea
increase blood pressure as water makes up plasma in blood- to much increases pressure
weakened bones - loss of calcium ions
loss of electrolyte balance (ions)
anaemia - erythropoietin creates RBC- less of it
pain and inflammation - build up of abnormal proteins

84
Q

why may the kidneys fail

A

infection, raised blood pressure and genetic conditions

85
Q

what is a symptom of kidney failure

A

protein or blood in urine are common symptoms as ultrafiltration isn’t occurring

86
Q

how is kidney failure assessed

A

GFR- glomerular filtration rate which measures levels of creatinine in blood to estimate glomerular filtration rate
creatinine- breakdown product made in muscles
age is a measure of what the GFR should be

87
Q

why may men have higher GFR

A

increased muscle mass so more creatinine

88
Q

what is haemodialysis and how does it work

A

artificial kidney that takes blood from artery and goes through tubes surrounded by dialysis fluid that keeps a typical concentration of water, glucose and electrolytes so there is no concentration gradient established, meaning they remain in the blood
no urea in the fluid , meaning a steep concentration gradient is established and urea moves out of blood, where it is returned into a vein

89
Q

why is the urea and blood counter current flow

A

so their is a steep concentration gradient across whole surface

90
Q

what is peritoneal dialysis

A

inside the body using internal membranes formed by abdomen lining, peritoneum
catheter inserted into abdomen, diacetate injected into abdomen excess fluid is drained out after 6hours

91
Q

how and why are transplants used

A

given by living or dead donor
gives better quality of life as dialysis requires regular trips to hospital and has some serious long-term side effects

92
Q

what are advantages to transplant

A

no need for regular sessions
no dietary restrictions
less expensive than long term dialysis
long term dialysis can damage body

93
Q

what are some disadvantages to transplants

A

less readily available
don’t last forever e.g., if donor was dead
risk of infection due to new antigens ( use family)
immunosuppressants taken which increase risk of infection by disease as immune system is weak

Biology (18 decks)

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