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71 Cards in this Set
- Front
- Back
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What are the 5 main roles of the kidney? |
- regulate volume/composition of internal env - regulate arterial blood pressure - regulate rbc production - regulate vitamin D activity - gluconeogenesis |
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How does the kidney regulate arterial blood pressure? |
releases renin -> angiotensin II -> vasoconstriction |
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How does the kidney regulate red blood cell production? |
fibroblasts release erythropoietin in hypoxia -> more rbcs made |
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How does the kidney regulate vitamin D activity? |
hydroxylates inactive vitamin D3 -> regulates Ca2+ levels |
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What is gluconeogeneis? |
formation of glucose from amino acids |
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How many nephrons are there in each kidney? |
1.2mil |
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Why would an animal have more juxtamedullary nephrons? |
area of low water levels |
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What is the distal end of the collecting duct called? |
papillary duct |
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What do juxtaglomerular cells do? |
release renin |
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What do juxtaglomerular cells respond to? |
baroreceptors (pressure) |
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What happens to JG cells in high pressure? |
stop releasing renin |
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How does the macula dense make blood vessel smooth muscle contract? |
high sodium -> high Ca in MD -> neurotransmitter -> high Ca in mesangial cells -> high Ca in smooth muscle -> contraction |
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What does renin do? |
catalyses reaction of angiotensinogen to angiotensin I |
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What does ACE do? |
catalyses reaction of ANGI to ANGII |
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Why is renin released? |
- low blood pressure - low NaCl - sympathetic B adrenergic stimulation |
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What are 3 effects of ANGII? |
- increase blood pressure - increase Na reabsorption - increases aldosterone (does both of above) |
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How much urine is produced per minute? |
1ml |
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What are the 3 layers in the glomerular filtration barrier? |
- endothelium (with fenestrae) - basement membrane - podocytes |
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What are the properties of the endothelium? |
collagen mesh with sialic acid making it negative |
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What are the gaps between podocytes called? |
split pores |
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What are the projections of podocytes called?
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pedicels |
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What molecules are left in the blood after ultrafiltration? |
- r>4nm - anions - haemoglobins |
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What molecules go into the filtrate after ultrafiltration? |
- r<2nm - cations |
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How is the glomerular filter cleaned? |
phagocytosis by mesangial and epithelial cells |
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What does hydrostatic pressure do? |
keeps vessels turgid |
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What does capsular pressure do? |
pushes fluid around nephron |
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What does colloid osmotic pressure do? |
reabsorption along nephron |
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What is the glomerular hydrostatic pressure? |
60mmHg |
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What is the capsular pressure? |
18mmHg |
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What is the average colloid osmotic pressure? |
32mmHg |
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What is the net filtration pressure? |
10mmHg |
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What is the equation for glomerular filtration rate? |
GFR = NFP x Kf |
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What is Kf a function of |
filtration area and conductance |
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How can you measure GFR? |
clearance of insulin as it is filtered at glomerulus but not reabsorbed |
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What 4 ways are molecules reabsorbed across simple epithelium? |
- primary AT - secondary AT - transcellular - paracellular |
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Where is sodium ATPase found? |
on the basolateral membrane |
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What is reabsorbed in the PCT? |
- all glucose and protein - some HCO3, Na, Cl, H20, K, Ca |
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How is glucose reabsorbed? |
sodium symports |
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How are anions and cations reabsorbed? |
organic transporters |
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How is water reabsorbed? |
passively through endothelial cells and tight junctions |
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What pressure means water flows into capillaries? |
capillary has high colloid osmotic pressure (contains a lot of protein) |
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What is bulk movement? |
movement of water into cells alongside other substances |
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How are proteins reabsorbed? |
endocytosis |
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What anti port is involved in bicarbonate reabsorption? |
NHE3 |
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How does NHE3 aid reabsorption? |
pumps out protons which turn HCO3- into CO2 which freely diffuses into the cell |
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Can CO2 flow through the apical and basolateral membranes? |
no, CO2 flows through the apical but not the basolateral membrane |
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What are the 2 types of sodium-glucose transporter and how do they differ? |
- SLT1: for low glucose, slow - SLT2: for high glucose, fast |
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What is the normal plasma glucose conc? |
3.3-5.9mM |
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What is the tubular maximum? |
the maximum rate of secretion/absorption of a substance in a renal tubule |
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What are the two types of cell in the collecting duct and what do they do? |
- principal cells: water permeability, reabsorb Na, secrete K - intercalated cells: mitochondria, reabsorb K |
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What are the two types of intercalated cells and what do they do? |
- A type: acid secreting, apical H pumps - B type: base secreting, basolateral H pumps |
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How is acid taken in in the diet buffered? |
bicarbonate |
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What is the role of type A intercalated cells? |
produce acid in order to reabsorb K and reproduce HCO3- |
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What is the role of type B intercalated cells? |
to reproduce HCO3- |
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What sort of diets rely on type A and B cells? |
- type A: meat eaters, acid - type B: vegetarians, little acid |
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How much potassium is reabsorbed by the time urine reaches CD? |
90% |
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What is the apical potassium channel abbreviated to? |
ROMK |
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What cells secrete potassium into the urine and why? |
principal cells, if the body has an excess |
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What is required for potassium uptake? |
sodium |
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What is the affect of diuretics on potassium? |
too much lost in urine, unless it is a K-sparing diuretic |
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Why is aldosterone released? |
- increased [K] - increased [ANGII] - decreased [Na] |
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What affect does aldosterone have in the kidney? |
- increases K + H+ excretion - increases Na + water reabsorption |
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What effect does angiotensin have? |
increases Na reabsorption |
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What effect does noradrenaline have? |
- increases Na reabsorption - increases renin |
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What effect does atrial natriuretic peptide (ANP) have? |
promotes Na and water loss |
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What effect does vasopressin have? |
increases water loss vasopressin + V2R -> AC -> cAMP -> PKA ->AQP2 |
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What are the two ways of concentrating urine? |
- single effect - counter-current multiplication |
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Describe the single effect |
DL lets water out, AL lets NaCl out overall loss of water to salty interstitium makes urine more conc |
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What stimulates the breakdown of ADH, maintaining a low water permeability in CD?
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cortisol |
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Where is ADH effective? |
DCT and CD |
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What is the shape of the vasa recta, in order to not effect the medullary gradient? |
hairpin loop |
