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biology > chapter 15 - homeostasis > Flashcards

chapter 15 - homeostasis Flashcards

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1
Q

what is monitored in homeostasis

A

pH of blood
core body temperature
concentration of urea and sodium ions in blood

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2
Q

what is a negative feedback system

A

reverse initial stimulus

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3
Q

what is positive feedback

A

effectors reinforce and increase change detected by stimulus

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4
Q

what is an example of negative feedback system

A

production of insulin to lower blood glucose concentration when it increases

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5
Q

what is an example of a positive feedback system

A

oxytocin produced when head of baby presses againt cervix causing uterus to contract and push baby harder causing even more oxytocin to produce

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6
Q

what is an example of a positive feedback system

A

oxytocin produced when head of baby presses againt cervix causing uterus to contract and push baby harder causing even more oxytocin to produce

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7
Q

what is thermoregulation

A

maintenance of constant core body temperature to maintain optimum enzyme activity

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8
Q

what causes organisms to gain heat

A

waste heat from cellular respiration
conduction from surroundings
convection from surroundings
radiation from surroundings

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9
Q

what causes organisms to lose heat

A

evaporation of water
conduction to surroundings
convection to surroundings
radiation to surroundings

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10
Q

what are ectothermns

A

use mainly surroundings to warm their bodies

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11
Q

why do ectotherms live in water

A

high heat capacity of water means temperature of environment doesnt change much so they dont need to thermoregulate

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12
Q

what are endotherms

A

rely on metabolic processes to warm them up

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13
Q

why do endotherms need to eat more than ectotherms

A

they have higher rate of metabolism to stay warm so has higher metabolic needs

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14
Q

what are behavioural responses

A

bask in sun and orientate to maximise surface area exposed to radiation from sun
press against warm ground to gain heat by conduction
contract muscles to increase cellular metabolism to gain heat

shelter from sun to shade to get cold
hide in cracks in rocks
move to water or mud
orientate so minimum surface area is exposed to sun
minimise movements to decrease metabolic heat

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15
Q

what are physiological reponses

A

lizards living in colder climates have darker skin to absorb more heat
ectotherms can alter heart rate to increase or decrease metabolic rate

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16
Q

what receptors detect change in temperature of surface

A

peripheral receptors in skin

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17
Q

what receptors detect changes in temperature in blood

A

temperature receptors in hypothalamus

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18
Q

how do endotherms cool down

A

vasodilation- artierioles near skin dilate and vessels between arterioles and venules constrict forcing blood to surface of skin to cool
increased sweating
reducing insulating effect of hair by lying flat

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19
Q

how do endotherms warm up

A

arterioles near skin contrict so little blood flows through surface of skin so little radiation take place
decreases sweating
raising body hair
shivering

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20
Q

how is heat loss centre activated

A

when temperature of body flowing through hypothalamus increases it send impulses through autonomic motor neurones to effectors in skin and muscles

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21
Q

how is heat gain centre activated

A

when temperature of blood flowing through hypothalamus decreases

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22
Q

what are the main metabolic waste products in mammals

A

co2-waste product of cellular respiration
bile pigments - from breakdown of haemoglobin
nitrogenous waste - from breakdown of excess amino acids in liver

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23
Q

what does hepatic portal vein do

A

carries blood loaded with products of digestion straight from intestines to the liver for metabolic activities

24
Q

what is the structure of hepatocytes

A

large nuclei
prominent golgi apparatus
lots of mitochondria as they are metabollically active

25
Q

what do sinusoids do

A

mix blood from hepatic artery and hepatic portal vein increasing oxygen content of blood from hepatic portal vein supplying hepatocytes with enough oxygen for their needs

26
Q

what do sinusoids contain

A

contain kupffer cells which act as macrophages and ingest pathogens

27
Q

what is canaliculi

A

bile is stored here and drained into bile ductules which takes it to gall bladder

28
Q

what are functions of liver

A

carbohydrate metabolism
deamination of excess amino acids
detoxification

29
Q

what is transamination

A

conversion of one amino acid to another as diet does not always contain required balance of amino acids

30
Q

what is deamination

A

removal of an amine group from a molecule converting it to ammonia and then to urea

31
Q

where is urea excreted

A

excreted by kidneys

32
Q

what can happen to remainder of amino acid

A

used in cellular respiration
converted into lipids for storage

33
Q

how is ammonia converted to urea

A

placed into ornithine cycle

34
Q

what are the 3 main areas of kidney

A

cortex - dark outer layer where filtering of blood takes place. Carries blood from renal artery to nephrons

Medulla - lighter in colour-contains tubules of nephrons that form kidney and collecting ducts

pelvis - central chamber where urine collects before passing down ureter

35
Q

what is structure of nephron

A

bowmans capsule - contains glomerulus
proximal convulated tubule - where substance needed are reabsorbed into blood. Found in cortex
loop of henle - creates a region of high solute concentration in tissue fluid in medulla
distal convulated tubule - where tuning of water balance takes place
collecting duct - urine passes down collecting duct through medulla to pelvis

36
Q

what is ultrafiltration

A

removal of nitrogenous waste and osmoregulation of blood

37
Q

how is proximal convulated tubule adapted

A

covered with microvili to increase SA
have many mitochondria to provide ATP for active transport

38
Q

where is ADH produced

A

produced by hypothalamus and secreted into posterior pituitary gland

39
Q

what does ADH do

A

increase permeability of distal convulated tubule

40
Q

what is the mechanism for ADH action

A

1)ADH is released from pituitary gland to the collecting duct which binds to receptors on cell membrane to form CAMP which causes events
2) vesicles lining collecting duct fuse with cell surface membrane on the side of the cell in contact with tissue fluid of medulla
3) membranes of these vesicles contain aquaporins which are inserted into cell surface membrane making it more permeable to water
4) this provides a route for water to move out of tubule cells into tissue fluid of medulla and blood capillaries by osmosis

41
Q

what do osmoreceptors do

A

controls permeability of collecting duct by sending nerve impulse to posterior pituitary gland which releases ADH

42
Q

how do osmoreceptors detect short water supply

A

when water is slow, osmoreceptors detect high concentration of inorganic ions making water potential more negative

43
Q

what hormone is found in urine which shows your pregnant

A

hcG produced by uterus 6 days after conception

44
Q

what are monoclonal antibodies

A

antibodies from a single clone of cells that are produced to target particular cells or chemicals in the body

45
Q

how are monoclonal antibodies created

A

hcG in injected into mouse and B-cells that make specific antibody are removed from spleen and fused with cancer cell called myeloma forming hybridoma. This divides very rapidly

46
Q

what are the stages of pregnancy test

A

1) wick is soaked in the first urine passed in morning as it has highest level of hcG
2) test contains mobile monoclonal antibodies that have coloured beads that only attach to hcG forming hcG/antibody complex
3) urine carries on along test structure until it reaches a window containing immobilised monoclonal antibodies that only binds to hcG/antibody complex forming a line
4) urine continues up through test to a second window
5) there is a line of immobilised monoclonal antibodies that bind to mobile antibodies whether they have hcG or not showing that test works

47
Q

what are anabolic steroids

A

mimick the male sex hormone testosterone that stimulates growth of muscles

48
Q

how is urine used to test for anabolic steriods

A

urine is vaporised with known solvent and passed along a tube. The lining of tube absorbs the gases and is analysed to give a chromatogram that can be read to show presence of the drugs

49
Q

what are reasons why kidney fail

A

kidney infections where pedocytes and tubules are damaged

raised blood pressure that can damage epithelial cells and basement membrane of bowmans capsule,

and genetic conditions such as polycystic kidney disease where healthy tissue is replaced by fluid-filled cysts

50
Q

what happens if kidneys are affected by high blood pressure

A

proteins present in urine as basement membrane are damaged and no longer filters

blood in urine as filtering system isnt working

51
Q

what happens if kidney fails completely

A

concentration of urea and mineral ions build up in body causing:
- loss of electrolyte balance causing osmotic balance
- build of toxic urea in blood
- high blood pressure
- weakened bones as calcium balance in blood is lost
- pain and stiffness in joints as abnormal proteins build up in blood
- anaemia - reduces production of red blood cells

52
Q

how is health of kidney measured

A

glomerular filtration rate by measuring level of creatinine in blood

53
Q

how are kidney diseases treated

A

renal dialysis- function of kidney is carried out artificially
kidney transplant

54
Q

what is haemodialysis

A

uses dialysis machine
blood leaves patient body from artery and flows into dialysis machine between partially permeable dialysis membranes mimicking basement membrane of bowmans capsule
no active transport

55
Q

how does haemodialysis make sure glucose isnt removed

A

dialysis fluid has normal plasma levels of glucose so glucose doenst leave blood

56
Q

what is peritoneal dialysis

A

used natural dialysis membrane formed by lining of abdomen, peritoneum
dialysis fluid is introduced into abdomen for dialysis to take place
dialysis fluid is then drained off

biology (17 decks)

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