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)
2
Q
what processes are included in homeostasis?
A
- body temp
- CO2 conc
- blood pH
- blood glucose
- water
3
Q
what type of feedback are the homeostasis processes?
A
negative
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
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
6
Q
what are ectotherms?
A
depends on mainly external sources and so their temp changes with the temp of the environment
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
8
Q
by what method do ectotherms regulate their body temperature?
A
behaviourally and physiologically
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
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
11
Q
why can ectotherms survive in harsher habitats?
A
they need less food because they use less energy regulating temperature
12
Q
what detects peripheral temp changes in endotherms?
A
receptors in the skin
13
Q
what detects changes in core temp in endotherms?
A
hypothalamus
14
Q
what happens in the heat loss centre?
A
- activated when temp of blood increases
- send impulses to effectors to lower temp
15
Q
what happens in the heat gain centre?
A
- activated when core temp decreases
- send impulses to effectors to raise core temp
16
Q
what are active methods of regulation?
A
internal exothermic metabolic activities to warm up and energy requiring physiological responses to cool down
17
Q
what are passive methods of regulation?
A
behavioural methods eg
- basking
- huddling
- hibernation/aestivation
18
Q
what is thermogenesis?
A
increasing temperature of the body
19
Q
what are two methods of thermogenesis?
A
- produce metabolic heat through muscle contraction
- deliberate movements to stimulate muscle contraction
20
Q
what is brown fat?
A
specialised fat tissue found in (mostly) hibernators and baby animals
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
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
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
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
25
what causes hair to stand on end?
contraction of errector pili muslces
26
how does hair limit heat transfer?
traps an insulating layer of air to limit heat conduction
27
what property of water makes evaporation so effective in limiting heat transfer?
high SHC
28
how does a counter current in birds that stand for a long time aid thermoregulation?
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
29
what is excretion?
removal of waste products of metabolic activity
30
what are the two functions of the excretory system?
- remove nitrogenous waste that may be toxic (urea)
- remove excess water to maintain suitable osmolarity
31
what are the key metabolic waste products?
- CO2 from cellular respiration
- bile pigments from haemoglobin
- nitrogenous waste from excess proteins
32
suggest why fish gather around the pump of their tank in cold weather
fish are ectothermic and the pump will generate heat so the fish gather to warm up
33
explain the effect sweating has on the body
evaporation will cool body temperature as heat is needed for it
34
why is it a bad idea to give alcohol to someone with hypothermia?
- alcohol causes vasodilation which increases the amount of heat loss from the body
- causes enzyme activity to stop, and organ failure to occur
35
explain how positive feedback can accelerate hypothermia
- 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
36
why can aquatic animals flush out ammonia without detoxifying it?
ammonia is very water soluble and so toxic effect is limited
37
what form is nitrogenous waste released as in mammals?
urea
38
what form is nitrogenous waste released as in reptiles?
uric acid
39
how are carbs metabolised in the liver?
-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
40
how are proteins metabolised in the liver?
- 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
41
what is the ornithine cycle?
breakdown of ammonia into urea
42
what happens to keto acid after deamination?
recycled to produce a compound that can enter krebs
43
what is detoxification?
breakdown of substances that arent needed or toxic
44
what are the substances broken down in detoxification?
- urea
- lactate
- alcohol
- hormones
- medicinal drugs
- hydrogen peroxide
45
how is hydrogen peroxide broken down?
uses catalase to break it down into water and oxygen
46
how are hormones metabolised?
hydrolysed into amino acids to be broken down into urea
47
how is lactate metabolised?
converted to pyruvate by hepatocytes
48
how is alcohol metabolised?
uses alcohol dehydrogenase to convert ethanol to ethanal then ethanoate
49
what are the two sources of blood that enter the liver?
- 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
what are bile pigments?
waste product from the breakdown of haemoglobin
51
what is stored in the gall bladder?
bile salts and bile pigments
52
what is the liver made up of?
lobules separated by connective tissue
53
what supplies the lobules with blood?
branches of hepatic artery (for oxygen) and portal vein (for nutrients)
54
what shape are lobules
roughly hexagonal
55
what do the vessels in the lobules drain into?
capillary like structures called sinusoids which drain into the central vein as well as a bile duct
56
what is the identifying factor of a lobule in a microscope image?
central vein
57
what are the sinusoids lined with?
- endothelial cells which allows blood to reach hepatocytes to ensure exchange of substances
- incomplete basement membrane
58
what are kuppfer cells?
act as resident macrophages of the liver
59
what are the two main functions of the kidneys?
- osmoregulation which is vital for maintaining blood pressure
- excretion
60
what structures make up the kidneys?
- renal artery
- renal medulla
- renal cortex
- renal pelvis
- ureter
- renal vein
- fibrous capsule
61
where are nephrons located?
over the membrane between medulla and cortex
62
why is the kidney covered in a layer of fat?
protection as its not protected by bony structures
63
what are nephrons made up of?
- glomerulus
- bowmans capsule
- proximal convoluted tubule
- loop of genle
- distal convoluted tubulue
- collecting duct
64
what is the function of a nephron?
- 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
how are the blood vessels in the glomerulus organised?
- 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
what will be in the blood in the renal vein?
- less urea
- less water and ions
- slightly less glucose
- more carbon dioxide
67
how do substances move from the glomerulus to the bowmans capsule?
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
what do substances moving out of the glomerulus need to pass through?
- endothelium lining of blood vessels
- basement membrane
- podocytes in the bowmans capsule
69
what is the mixture of substances in the lumen of the bowmans capsule called?
glomerular filtrate
70
what is ultrafiltration?
non specific filtration of the blood under high pressure into the bowmans capsule
71
what is the structure of the bowmans capsule?
- 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
what is the importance of the basement membrane?
- its size selective so restricts blood cells and plasma proteins
- hence glomerular filtrate has no blood, platelets or plasma
73
how does water move into the bowmans capsule?
- higher solute conc in blood than filtrate due to plasma proteins
- water moves down its water potential gradient into bowmans capsule
74
where does most selective reabsorption occur?
proximal convoluted tubule
75
what are the adaptations of the proximal convoluted tubule?
- 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
what is reabsorbed in selective reabsorption?
- all glucose, amino acids, vitamins and hormones
- 80% minerals
- water
77
what is the process of selective reabsorption?
- 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
what is the vasa recta?
blood network surrounding loop of henle
79
what is the descending limb of the loop of henle permeable and impermeable to?
- permeable to water
- impermeable to Cl- Na2+ and salts
80
what is the ascending limb of the loop of henle permeable and impermeable to?
- permeable to salt
- impermeable to water
81
how does the loop of henle create a high solute conc in medulla?
sodium ions are actively transported out of the ascending limb and chloride ions follow which decreases Ψ of medulla
82
what does the high solute conc mean for the movement of water?
leaves the descending limb via osmosis down a Ψ grad
83
what happens to filtrate as it climbs the ascending limb?
becomes increasingly dilute and hypotonic to the blood and enters distal convoluted tubule
84
what kind of flow occurs in the loop of henle?
countercurrent
85
what affects permeability of distal convoluted tubule?
ADH
86
what is the effect of increased ADH?
higher permeability in distal convoluted tubule so more water enters blood
87
what happens if the body lacks salt?
sodium ions actively transported into blood with chloride ions down the electrochemical gradient
88
how would blood cells appear in dehydration?
crenated
89
how would blood cells appear in overhydration?
swollen
90
what is ADH released in response to?
decreased Ψ in blood
91
what is the mechanism of ADH?
- 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
what is the overall effect of ADH?
causes luminal membranes of collecting duct to become more permeable to water by increasing number of aquaporins
93
what are aquaporins and where are they located?
water permeable channels in the membranes of vesicles in the collecting duct
94
what happens when ADH binds to receptor proteins?
- 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
what are two factors that need to be controlled in an experiment investigating effect of temp on glucose diffusion through dialysis tubing?
- diameter of tubing
- initial glucose concentration
96
what is the effect of sulthiame on reabsorption of sodium ions in proximal convoluted tubule?
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
which property of hCG allows it to be detected in urine?
molecular mass of less than 69000
98
explain why podocytes are usually unable to undergo mitosis
- already specialised so cannot divide
- G0
- mitosis would alter the number of fenestrations and affect ultrafiltration
99
what features of adult stem cells make them suitable for regeneration of kidney tissue?
multipotent so can become any type of cell within the kidney
100
describe the similarities and differences between ultrafiltration and the formation of tissue fluid
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
why do some foods affect urine production?
- 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
compare processes in proximal and distal convoluted tubules
- both use active transport
- both involve selective reabsorption
- PCT involves glucose and ions but DCT only involves ions
103
describe how the endocrine and nervous system work together to increase reabsorption from the collecting duct
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
why is it harder for moths and bees to maintain their temperature than mammals and birds?
they have greater heat loss through skin as they have less effective insulating layers
105
