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communication, homeostasis and energy > gaystasis > Flashcards

gaystasis Flashcards

very homosexual body processes (me fr)

1
Q

what is homeostasis?

A

an organisms tendency to maintain a constant internal environment within tolerance limits (dynamic equilibrium)

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2
Q

what processes are included in homeostasis?

A
  • body temp
  • CO2 conc
  • blood pH
  • blood glucose
  • water
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3
Q

what type of feedback are the homeostasis processes?

A

negative

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4
Q

why is body temp regulated and maintained in a narrow range?

A

maintain a temperature that is optimum for enzyme activity in the body

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5
Q

what are endotherms?

A

organisms that use internally generated heat to maintain body temp, and the temp remains constant regardless of the environment

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6
Q

what are ectotherms?

A

depends on mainly external sources and so their temp changes with the temp of the environment

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7
Q

why dont ectotherms that live in water need to thermoregulate?

A

-water has a specific capacity so takes a lot of energy to change temp
- water has a relatively constant temp

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8
Q

by what method do ectotherms regulate their body temperature?

A

behaviourally and physiologically

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9
Q

what are the behavioural strategies of ectotherms to control temp?

A
  • basking in sun by displaying maximum surface area
  • press bodies against the ground to increase conduction of heat
  • decrease temp by seeking shade
  • minimise movement to reduce generation of metabolic heat
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10
Q

what are the physiological strategies of ectotherms to control temp?

A
  • change colour because darker colours absorb more heat via radiation
  • alter heart rate to change metabolic rate
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11
Q

why can ectotherms survive in harsher habitats?

A

they need less food because they use less energy regulating temperature

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12
Q

what detects peripheral temp changes in endotherms?

A

receptors in the skin

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13
Q

what detects changes in core temp in endotherms?

A

hypothalamus

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14
Q

what happens in the heat loss centre?

A
  • activated when temp of blood increases
  • send impulses to effectors to lower temp
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15
Q

what happens in the heat gain centre?

A
  • activated when core temp decreases
  • send impulses to effectors to raise core temp
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16
Q

what are active methods of regulation?

A

internal exothermic metabolic activities to warm up and energy requiring physiological responses to cool down

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17
Q

what are passive methods of regulation?

A

behavioural methods eg
- basking
- huddling
- hibernation/aestivation

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18
Q

what is thermogenesis?

A

increasing temperature of the body

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19
Q

what are two methods of thermogenesis?

A
  • produce metabolic heat through muscle contraction
  • deliberate movements to stimulate muscle contraction
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20
Q

what is brown fat?

A

specialised fat tissue found in (mostly) hibernators and baby animals

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21
Q

why does brown fat have
- more mitochondria
- smaller fat droplets
- more capillaries

A
  • higher respiration rates
  • SA:V ratio for faster diffusion
  • provide oxygen
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22
Q

what is the role of special proteins in brown fat?

A

promote release of energy directly as heat instead of using it to form ATP

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23
Q

what are general physiological responses to cool down?

A
  • vasodilation to maximise heat loss through the skins surface
  • increased sweating so more evaporation to release energy
  • reduce effect of insulating hair
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24
Q

what are general physiological responses to warm up?

A
  • vasoconstriction to reduce heat lost through the skin
  • decrease sweating
  • raising hair to create an insulating layer
  • shivering
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25
Q

what causes hair to stand on end?

A

contraction of errector pili muslces

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26
Q

how does hair limit heat transfer?

A

traps an insulating layer of air to limit heat conduction

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27
Q

what property of water makes evaporation so effective in limiting heat transfer?

A

high SHC

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28
Q

how does a counter current in birds that stand for a long time aid thermoregulation?

A

as warm blood goes down into the legs it transfers heat to the cold blood returning to the heart so it isnt as much of a shock to the heart

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29
Q

what is excretion?

A

removal of waste products of metabolic activity

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30
Q

what are the two functions of the excretory system?

A
  • remove nitrogenous waste that may be toxic (urea)
  • remove excess water to maintain suitable osmolarity
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31
Q

what are the key metabolic waste products?

A
  • CO2 from cellular respiration
  • bile pigments from haemoglobin
  • nitrogenous waste from excess proteins
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32
Q

suggest why fish gather around the pump of their tank in cold weather

A

fish are ectothermic and the pump will generate heat so the fish gather to warm up

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33
Q

explain the effect sweating has on the body

A

evaporation will cool body temperature as heat is needed for it

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34
Q

why is it a bad idea to give alcohol to someone with hypothermia?

A
  • alcohol causes vasodilation which increases the amount of heat loss from the body
  • causes enzyme activity to stop, and organ failure to occur
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35
Q

explain how positive feedback can accelerate hypothermia

A
  • positive feedback is when an initial change in the body is increased further#
  • lower temp reduces KE and enzyme activity
  • respiration is reduced so doesn’t produce as much internal heat
  • body temp drops further
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36
Q

why can aquatic animals flush out ammonia without detoxifying it?

A

ammonia is very water soluble and so toxic effect is limited

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37
Q

what form is nitrogenous waste released as in mammals?

A

urea

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38
Q

what form is nitrogenous waste released as in reptiles?

A

uric acid

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39
Q

how are carbs metabolised in the liver?

A

-glycogenesis
- excess glucose in blood is take up by liver and stored as glycogen
- when blood glucose levels drop, liver breaks down glycogen to glucose

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40
Q

how are proteins metabolised in the liver?

A
  • deamination of proteins occurs because they cant be stored
  • removes an amine group and a hydrogen which produces ammonia and keto acid
  • triggers the ornithine cycle
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41
Q

what is the ornithine cycle?

A

breakdown of ammonia into urea

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42
Q

what happens to keto acid after deamination?

A

recycled to produce a compound that can enter krebs

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43
Q

what is detoxification?

A

breakdown of substances that arent needed or toxic

44
Q

what are the substances broken down in detoxification?

A
  • urea
  • lactate
  • alcohol
  • hormones
  • medicinal drugs
  • hydrogen peroxide
45
Q

how is hydrogen peroxide broken down?

A

uses catalase to break it down into water and oxygen

46
Q

how are hormones metabolised?

A

hydrolysed into amino acids to be broken down into urea

47
Q

how is lactate metabolised?

A

converted to pyruvate by hepatocytes

48
Q

how is alcohol metabolised?

A

uses alcohol dehydrogenase to convert ethanol to ethanal then ethanoate

49
Q

what are the two sources of blood that enter the liver?

A
  • oxygenated blood from the heart via the hepatic artery
  • deoxygenated blood from the digestive system via hepatic portal vein which allows liver to absorb and metabolise nutrients
50
Q

what are bile pigments?

A

waste product from the breakdown of haemoglobin

51
Q

what is stored in the gall bladder?

A

bile salts and bile pigments

52
Q

what is the liver made up of?

A

lobules separated by connective tissue

53
Q

what supplies the lobules with blood?

A

branches of hepatic artery (for oxygen) and portal vein (for nutrients)

54
Q

what shape are lobules

A

roughly hexagonal

55
Q

what do the vessels in the lobules drain into?

A

capillary like structures called sinusoids which drain into the central vein as well as a bile duct

56
Q

what is the identifying factor of a lobule in a microscope image?

A

central vein

57
Q

what are the sinusoids lined with?

A
  • endothelial cells which allows blood to reach hepatocytes to ensure exchange of substances
  • incomplete basement membrane
58
Q

what are kuppfer cells?

A

act as resident macrophages of the liver

59
Q

what are the two main functions of the kidneys?

A
  • osmoregulation which is vital for maintaining blood pressure
  • excretion
60
Q

what structures make up the kidneys?

A
  • renal artery
  • renal medulla
  • renal cortex
  • renal pelvis
  • ureter
  • renal vein
  • fibrous capsule
61
Q

where are nephrons located?

A

over the membrane between medulla and cortex

62
Q

why is the kidney covered in a layer of fat?

A

protection as its not protected by bony structures

63
Q

what are nephrons made up of?

A
  • glomerulus
  • bowmans capsule
  • proximal convoluted tubule
  • loop of genle
  • distal convoluted tubulue
  • collecting duct
64
Q

what is the function of a nephron?

A
  • ultrafiltration (blood is filtered out of glomerulus into bowmans capsule)
  • selective reabsorption (usable material reabsorbed in convoluted tubules)
  • osmoregulation (salt gradient draws water out of collecting duct)
65
Q

how are the blood vessels in the glomerulus organised?

A
  • afferent arteriole brings blood into the glomerulus from the renal artery
  • capillaries then rejoin to form the efferent arteriole which takes blood out to the renal vein
66
Q

what will be in the blood in the renal vein?

A
  • less urea
  • less water and ions
  • slightly less glucose
  • more carbon dioxide
67
Q

how do substances move from the glomerulus to the bowmans capsule?

A

afferent arteriole is wider than efferent arteriole so hydrostatic pressure builds in the glomerulus and forces substances into the bowmans capsule down the pressure gradient

68
Q

what do substances moving out of the glomerulus need to pass through?

A
  • endothelium lining of blood vessels
  • basement membrane
  • podocytes in the bowmans capsule
69
Q

what is the mixture of substances in the lumen of the bowmans capsule called?

A

glomerular filtrate

70
Q

what is ultrafiltration?

A

non specific filtration of the blood under high pressure into the bowmans capsule

71
Q

what is the structure of the bowmans capsule?

A
  • fenestrated endothelium
  • inner epithelium called podocytes which have cellular extensions called pedicils that wrap around blood vessels of glomerulus
  • basement membrane between glomerulus and podocytes
72
Q

what is the importance of the basement membrane?

A
  • its size selective so restricts blood cells and plasma proteins
  • hence glomerular filtrate has no blood, platelets or plasma
73
Q

how does water move into the bowmans capsule?

A
  • higher solute conc in blood than filtrate due to plasma proteins
  • water moves down its water potential gradient into bowmans capsule
74
Q

where does most selective reabsorption occur?

A

proximal convoluted tubule

75
Q

what are the adaptations of the proximal convoluted tubule?

A
  • mitochondria for ATP
  • many cotransporter proteins
  • microvilli to increase SA for diffusion
  • one epithelial cell wide for shorter diffusion distance
  • capillaries right by it
76
Q

what is reabsorbed in selective reabsorption?

A
  • all glucose, amino acids, vitamins and hormones
  • 80% minerals
  • water
77
Q

what is the process of selective reabsorption?

A
  • sodium ions in epithelial cell are actively transported to the blood via sodium potassium pumps
  • conc grad established so Na2+ move through cotransporters into epithelial cell (facilitated diffusion)
  • cotransporters transport sodium ions and another useful substance eg. some take glucose or specific amino acid
  • susbtances now in epithelial cells diffuse down their conc grad into blood
  • this lowers Ψ in epithelial cell so water moves down Ψ grad from tubule to epithelial cell to blood
78
Q

what is the vasa recta?

A

blood network surrounding loop of henle

79
Q

what is the descending limb of the loop of henle permeable and impermeable to?

A
  • permeable to water
  • impermeable to Cl- Na2+ and salts
80
Q

what is the ascending limb of the loop of henle permeable and impermeable to?

A
  • permeable to salt
  • impermeable to water
81
Q

how does the loop of henle create a high solute conc in medulla?

A

sodium ions are actively transported out of the ascending limb and chloride ions follow which decreases Ψ of medulla

82
Q

what does the high solute conc mean for the movement of water?

A

leaves the descending limb via osmosis down a Ψ grad

83
Q

what happens to filtrate as it climbs the ascending limb?

A

becomes increasingly dilute and hypotonic to the blood and enters distal convoluted tubule

84
Q

what kind of flow occurs in the loop of henle?

A

countercurrent

85
Q

what affects permeability of distal convoluted tubule?

A

ADH

86
Q

what is the effect of increased ADH?

A

higher permeability in distal convoluted tubule so more water enters blood

87
Q

what happens if the body lacks salt?

A

sodium ions actively transported into blood with chloride ions down the electrochemical gradient

88
Q

how would blood cells appear in dehydration?

A

crenated

89
Q

how would blood cells appear in overhydration?

A

swollen

90
Q

what is ADH released in response to?

A

decreased Ψ in blood

91
Q

what is the mechanism of ADH?

A
  • osmoreceptors decect water potential decrease in blood
  • ADH released from posterior pituitary gland
  • targets collecting duct cells by binding to receptor on proteins of cell membrane
  • triggers formation of cAMP as a second messenger
92
Q

what is the overall effect of ADH?

A

causes luminal membranes of collecting duct to become more permeable to water by increasing number of aquaporins

93
Q

what are aquaporins and where are they located?

A

water permeable channels in the membranes of vesicles in the collecting duct

94
Q

what happens when ADH binds to receptor proteins?

A
  • causes cascade of signals which results in phosphorylation of aquaporin molecules
  • this causes vesicles containing aquaporins to fuse with luminal membrane which increases water permeability
95
Q

what are two factors that need to be controlled in an experiment investigating effect of temp on glucose diffusion through dialysis tubing?

A
  • diameter of tubing
  • initial glucose concentration
96
Q

what is the effect of sulthiame on reabsorption of sodium ions in proximal convoluted tubule?

A

less reabsorption as fewer hydrogen ions in PCT cells so less facilitated diffusion of sodium ions into epithelial cells so no diffusion into blood

97
Q

which property of hCG allows it to be detected in urine?

A

molecular mass of less than 69000

98
Q

explain why podocytes are usually unable to undergo mitosis

A
  • already specialised so cannot divide
  • G0
  • mitosis would alter the number of fenestrations and affect ultrafiltration
99
Q

what features of adult stem cells make them suitable for regeneration of kidney tissue?

A

multipotent so can become any type of cell within the kidney

100
Q

describe the similarities and differences between ultrafiltration and the formation of tissue fluid

A

similarities:
- small molecules are filtered our of the blood
- occurs in capillaries
- large molecules remain in blood
- high hydrostatic pressure
- involve basement membranes

differences:
- UF filtrate enters the bowmans capsule and then PCT but TF
enters intercellular spaces
- UF molecules that arent reabsorbed become urine but TF forms lymph
- UF has knot of capillaries TF has network of capillaries

101
Q

why do some foods affect urine production?

A
  • food with higher salt conc reduces Ψ of blood
  • osmoreceptors in hypothalamus detect change in Ψ and release ADH
  • more water reabsorbed into capillaries due to more aquaporins so urine more concentrated
102
Q

compare processes in proximal and distal convoluted tubules

A
  • both use active transport
  • both involve selective reabsorption
  • PCT involves glucose and ions but DCT only involves ions
103
Q

describe how the endocrine and nervous system work together to increase reabsorption from the collecting duct

A

endocrine:
- hypothalamus triggers release of ADH from pituitary gland and aldosterone from adrenal cortex
- ADH binds to receptors and increases permeability to water

nervous:
- hypothalamus in nervous
- osmoreceptors detects lower Ψ

aldosterone:
- sodium ions pumped out of collecting ducts and potassium pumped in
- higher solute conc tissue fluid
- sodium reabsorbed into collecting duct
- water moves into blood via osmosis

104
Q

why is it harder for moths and bees to maintain their temperature than mammals and birds?

A

they have greater heat loss through skin as they have less effective insulating layers

105
Q
A

communication, homeostasis and energy (6 decks)

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