Renal Flashcards

Question

high osmolarity

Answer 1

solution = low water concentration + high solute addition of solute to solvent (water) lowers [water]

Answer 2

partition between compartments is permeable to water and to solute both water + solute move from high to low [] movement of water and solute equalizes concentrations on both sides of partition = diffusional equilibrium

Answer 3

net diffusion of water across a selectively permeable membrane from high to low concentration

Answer 4

pressure necessary to prevent solvent movement acts against osmosis

Answer 5

determined by [non-penetrating solutes] of an extracellular solution relative to the intracellular environment of a cell [solute] may influence changes in cell vol

Answer 6

electrolytes ex. Na+, K+

Answer 7

isoosmotic same concentration of NPS outside and inside the cell cell vol does not change

Answer 8

hyperosmotic solution has high osmolarity higher [NPS] outside than inside the cell cells shrink (low [water] outside = water moves out of cell)

Answer 9

hypoosmotic solution has low osmolarity lower [NPS] outside than inside of cell cells swell (high [water] outside = water moves into cell)

Answer 10

movement of solute/water out of blood plasma into ISF

Answer 11

movement of solute/water into blood plasma from ISF

Answer 12

act as membrane between plasma + ISF highly permeable to water + most plasma solutes

Answer 13

P(c) = capillary hydrostatic pressure P(IF) = ISF hydrostatic pressure πc = osmotic force due to plasma protein concentration πIF = osmotic force due to ISF protein concentration

Answer 14

higher pressure more filtration

Answer 15

lower pressure more absorption

Answer 16

net filtration pressure = outward pressures - inward pressures = (Pc + πIF) - (PIF + πc)

Answer 17

total body balance of any substance balance - gain = ingestion or product of metabolism - loss = excretion or get metabolized goal is to maintain homeostasis

Answer 18

location of kidneys behind peritoneal cavity (containing GIT) = towards back wall of abdomen

Answer 19

ureter: collect product from kidneys; carry to bladder bladder: storage for urine urethra: carry urine from bladder to outside of body

Answer 20

process of emptying bladder involves autonomic control

Answer 21

outer capsule = protection outer cortex = thinner inner medulla = thicker, made of nephrons nephrons

Answer 22

functional unit of kidneys ~ 1 mil in one kidney basic functions: filtration, reabsorption, secretion renal corpuscle renal tubule

Answer 23

filtering unit glomerulus (capillary bed) + Bowman's capsule

Answer 24

proximal descending tubule + loop of Henle (descending + ascending limbs) + distal convoluted tubule + collecting duct lined with epithelial cells → vary in structure + function along length of tubule

Answer 25

Bowman's space inner wall = podocytes outer wall = epithelial cells

Answer 26

continuous epithelial cell layer forms inner wall of Bowman's capsule = closest to glomerulus have cytoplasmic extensions "feet"

Answer 27

- basal lamina is trapped between endothelial cells of capillaries + epithelial layer = basement membrane - epithelial cell layer differentiates into parietal + visceral layer → parietal layer flattened to become wall of Bowman's capsule → visceral layer becomes podocyte cell layer

Answer 28

afferent arteriole carries blood in efferent arteriole carries blood out rate of flow: 1200 mL/min cardiac output: 5600 mL/min

Answer 29

% of cardiac output going to kidneys ~ 20% = high blood flow

Answer 30

fenestrated endothelial layer (inside) basement membrane podocytes with filtration slits (outside)

Answer 31

85% of nephrons performs basic functions majority of nephron is in cortex collecting duct + small part of loop of Henle are in medulla

Answer 32

15% performs basic functions + regulates concentration of urine (reg of osmolarity in medulla) corpuscle is closer to medulla all of loop of Henle + collecting duct lie in medulla proximal + distal tubule are in cortex

Answer 33

glomerulus

Answer 34

in cortex + are proximal to PCT

Answer 35

capillaries in medulla only in juxtamedullary nephrons run parallel to loop of Henle

Answer 36

entry into lumen from glomerular capillaries into Bowman's space

Answer 37

large proteins or albumin - too large for pores - neg charge of pores + BM repel neg charged proteins - semiporous membrane covers podocyte slits

Answer 38

nephrins + podocins selective filtration of blood proteins should not be in blood → less selective membrane

Answer 39

carries blood to glomerulus large molecules stay in blood: blood cells, plasma proteins, large anions

Answer 40

passed through filter molecules with low MW; water, electrolytes, glucose, aas, fatty acids, vitamins, urea, uric acid, creatinine

Answer 41

condition with proteins in the urine indicates poor kidney function

Answer 42

P(GC) pushes fluid out of capillary into B. space favours filtration

Answer 43

P(BS) opposes filtration

Answer 44

πGC plasma proteins accumulate = ↑ osmolarity opposes filtration ~0 due to low [protein] in B. space

Answer 45

vol of fluid filtered from glomerulus into B. space per unit time ~125 mL/min in avg man (70 kg) = 180L/day → plasma filtration occurs ~60x/day

Answer 46

1. net glomerular filtration pressure 2. permeability of corpuscular membrane 3. surface area available for filtration 4. neural + endocrine control

Answer 47

= P(GC) - [P(BS) + πGC] always positive GF pressure initiates urine formation by forcing protein-free filtrate from plasma

Answer 48

(-) charges repel proteins small pores prevent passage of large proteins

Answer 49

↑ SA = ↑ filtration

Answer 50

not part of filtration layers contraction reduces surface area of glomerular capillaries = ↓ GFR

Answer 51

modulation of arteriolar resistance → changes blood flow + GFR ↑ arteriolar resistance = ↓ renal blood flow + ↑ flow to other organs

Answer 52

constriction of afferent / dilation of efferent = ↓ P(GC) = ↓ GFR

Answer 53

dilation of afferent / constriction of efferent = ↑ P(GC) = ↑ GFR

Answer 54

changes to renal blood vessel resistance to compensate for changes in blood pressure → maintenance of GFR = protection of glomerular capillaries from hypertension trauma independent of neuronal + hormonal control

Answer 55

quick autoregulation inherent muscle elasticity in blood vessels

Answer 56

effect caused by increased tubular flow signals paracrine response on juxtaglomerular apparatus causes constriction of afferent arteriole = ↓ GFR

Answer 57

constant GFR over 80-180mm Hg maintained by autoregulation

Answer 58

macula densa juxtaglomerular cells mesangial cells

Answer 59

chemoreceptors on wall of distal tubule sense increased flow ([Na+] + [Cl-]) secrete vasoactive compounds (adenosine) → paracrine signal = vasoconstriction signals JG cells

Answer 60

granular cells mechanoreceptors on wall of afferent arteriole sense circulating plasma vol controls renin release based on [Na+]

Answer 61

total amount of non-protein or non-protein-bound substance filtered into Bowman's space = GFR x [substance in plasma]

Answer 62

[glucose] = 1g/L GFR = 180L/day = 180 g/day

Answer 63

indicates reabsorption has occurred

Answer 64

indicates secretion has occurred

Answer 65

inulin, creatinine excreted

Answer 66

organic acids (para-amino hippuric acid) and bases drugs, food additives = excreted

Answer 67

water, electrolytes depends on body's need

Answer 68

glucose, amino acids essential for body → returned to blood after filtration

Answer 69

water: 180L filtered/day → 99% reabsorbed sodium: 630g filtered/day → 99.5% reabsorbed glucose: 180g filtered/day → 100% reabsorbed urea: 54g filtered/day → only 44% reabsorbed

Answer 70

movement out of lumen into blood mediated by transepithelial mediated transport + paracellular diffusion

Answer 71

on apical side between tubular lumen and epithelial cell

Answer 72

on blood side between epithelial cell and interstitial space (3 sides)

Answer 73

mediated transport transepithelial = across apical + basolateral membranes driven by Na+/K+ ATPase active transport on basolateral side movement across apical side varies between regions

Answer 74

mediated transport: from filtrate to ISF enters cell through membrane proteins, moving down its electrochemical gradient (diffusion across apical side) pumped out basolateral side by Na+/K+ ATPase diffusion + bulk transport: from ISF to blood plasma

Answer 75

channel-facilitated diffusion

Answer 76

all filtered glucose is reabsorbed dependent on Na+

Answer 77

luminal side: SGLT protein = secondary active transport - Na+/glu cotransport basolateral side: GLUT carrier protein = facilitated diffusion driven by Na+/K+ ATPase

Answer 78

zero at normal plasma concentration

Answer 79

glucose in urine when above renal threshold

Answer 80

~300mg/100mL plasma glucose limit for reabsorption beginning of glucose excretion (proportional increase)

Answer 81

max capacity of transport proteins for reabsorption= full saturation reabsorption rate of glucose = 375 mg/min reach when plasma glucose > 300

Answer 82

capacity to reabsorb glucose is normal filtered load is beyond threshold level = tubules cannot reabsorb glucose

Answer 83

genetic mutation of SGLT normal blood glucose level = no glucose reabsorption → excreted benign / familial renal glucosuria

Answer 84

Na+/glu cotransporter mediates active reabsorption of glucose in proximal tubules

Answer 85

Na+ reabsorption (driven by active transport) creates electrochemical gradient = anion reabsorption → solute diffusion creates osmotic gradient = leads to water reabsorption by osmosis

Answer 86

easily filtered through glomerulus permeable solute

Answer 87

by diffusion; dependent on water reabsorption ↑ [urea] as ↓ fluid vol = diffusion

Answer 88

from bloodstream into lumen coupled to reabsorption of Na+ involves active transport mostly H+ and K+ choline, creatinine, penicillin

Answer 89

quantifies kidney function → removal of substances from plasma measure of vol of plasma that passes through nephron from which substance is completely removed by the kidney per unit time ml/min of L/h clearance of S = U(s)V/P(s) = [substance in urine] x vol of urine passed / [substance in plasma]

Answer 90

polysaccharide not found in body (IV injection to measure GFR) readily filtered but not reabsorbed, secreted, or metabolized by tubule

Answer 91

U(in) = 300mg/L V = 0.1L/h P(in) = 4mg/L C(in) = 7.5 L/h = 180L/day = GFR → can be used to measure GFR

Answer 92

product of muscle metabolism clearance can be used to measure GFR clinically (slight overestimate) filtered, no reabsorption (slight secretion) GFR ∝ 1/P(cr) ↑ P(cr) = ↓GFR → indicated ↓ nephron function

Answer 93

X must undergo secretion

Answer 94

X must undergo reabsorption

Answer 95

Na+ is actively reabsorbed Cl- is transported passively when Na+ is pumped out of cell K+ is secreted into tubules mainly by cells of distal tubule + collecting ducts

Answer 96

(80%) reabsorbs most of the water and non-waste plasma solutes ~ 67% of water reabsorbed in PCT (aqp-1 = always open) major site of solute secretion (except K+)

Answer 97

creates osmotic gradient (in jm nephrons) reabsorbs large amounts of ions + less amounts of water different transport capabilities on each side of tubule = countercurrent

Answer 98

thin water reabsorption aqp-1 on luminal + basolateral side of epithelial cell allows passive water transport

Answer 99

thick salt reabsorption (Na+, Cl-, K+) impermeable to water (no aquaporins)

Answer 100

major homeostatic mechanisms of fine control of water and solute to produce urine 12-15% of reabsorption

Answer 101

between sources of water gain (input = 1. ingested liquid 2. water from oxidation of food) and water loss (output = 1. insensible: skin, resp airways 2. sweat 3. GI tract, urinary tract, menstrual flow)

Answer 102

cortical + medullary cells lining duct are under physiological control

Answer 103

PCT: 67% reabsorped passively (Aqp-1) LofH: 15% reabsorped passively in descending limb (Aqp-1) distal tubule: none collecting duct: remaining (8-17%) reabsorped passively (Aqp-2, -3, -4) → controlled by vasopressin

Answer 104

aquaporin always open no hormonal control

Answer 105

structure function relationship in loop of Henle creates osmotic gradient fluid streams in opposite directions in desc vs asc limbs multiplication of osmolarity gradient down LofH

Answer 106

filtrate entering desc limb = isoosmotic (300 mOsm/L) active transport of NaCl in asc limb = ↓ osmolarity in tubule net: ↑ [salt] in ISF (compared to asc limb) = gradient difference of 200 mOsm

Answer 107

lives in desert environment longer loop of Henle = larger interstitial osmolarity gradient to reabsorb maximum water → produce concentrated urine (conserve water) higher osmolarity in ISF deep in medulla

Answer 108

descending limb = concentrated fluid ascending limb = dilute fluid distal convoluted tubule = dilute fluid (100 mOsm/L)

Answer 109

regulates water reabsorption in CD uses established osmolarity gradient to promote osmosis from tubule of CD through opened aqp-2 = becomes isoosmotic with IS space

Answer 110

established in ISF helps water permeate out of medullar collecting tubule reabsorption through aqp

Answer 111

flows in opposite direction of filtrate flow in LofH removes water leaving LofH = serves as counter-current exchangers → maintain Na+ + Cl- gradient (gradient is not washed away)

Answer 112

low less than 5% of total renal blood flow sluggish prevents solute loss

Answer 113

freely permeable to ions, urea, + water → move in + out of capillaries in response to [] gradients does not create medullary hyperosmolarity but prevents it from being washed out = maintained

Answer 114

NaCl moves out of ascending limb into ISF → enters descending limb water diffuses out of desc into asc = reinforces gradient created by renal tubules = ↑ [Na+] + [urea] in medullary interstitial space

Answer 115

100% filtered through glomerulus 50% reabsorbed in PCT 50% is secreted back into loop of Henle (55% reabsorbed from MCD by ADH → 50% f. diffusion; 5% removed by vasa recta) 30% reabsorbed from CCD

Answer 116

by vasa recta (5%) helps maintain high osmolarity in medulla = only 15% excreted

Answer 117

kidneys save water by producing hyperosmotic urine

Answer 118

1. counter current anatomy + opposing fluid flow through LofH in JM nephrons 2. reabsorption of NaCl in asc 3. impermeability of asc to water 4. trapping of urea in medulla 5. hairpin loop of vasa recta

Answer 119

vasopressin (controls b.p.) peptide hormone that regulates water reabsorption through control of aquaporin-2 prevents water loss ↑ ADH = ↑ water retention (less water excreted)

Answer 120

osmoreceptors in hypothalamus sense ↑ plasma osmolarity cells in supraoptic nucleus (hypot) produce ADH secreted from posterior pituitary

Answer 121

acts on collecting duct cells to alter water permeability of luminal membrane binding of ADH to receptor on basolateral side triggers AQP-2 gene transcription: AC → cAMP → PKA → phosphorylation = insertion of aqp-2 in luminal membrane

Answer 122

diffusion through open aqp-2 channels (by ADH) diffusion across cells + through aqp-3 + 4 channels into ISF

Answer 123

large volume of urine absence of ADH = CD cells are impermeable to water

Answer 124

lack of ADH causes water diuresis central: failure to release ADH from post. pituitary (either synthesis or release is affected) nephrogenic: ADH has no effect on CD cells (either mut in receptor or affected cascade)

Answer 125

excretion of excess water no excess solute in urine diabetes insipidus

Answer 126

excess solute + excess water are excreted in urine uncontrolled diabetes mellitus (excretion of glucose = water follows)

Answer 127

shock, pain, warm or hot weather, dehydration = pee less ADH acts in CD to ↑ water reabsorption

Answer 128

cold, humid enviro, alcohol, caffeine = pee more ↓ effect of ADH = smaller gradient created

Answer 129

suppresses ADH secretion

Answer 130

plasma osmolarity ~ plasma [Na+] changes in [Na+] cause changes in blood vol + bp

Answer 131

nerve endings sensitive to stretch located in carotid sinus, aortic arch, major veins + intrarenal = JG cells sense changes in blood vol + peripheral resistance

Answer 132

↓ plasma [Na+] = ↓ plasma vol = ↓ arterial bp = ↓ stretch = baroreceptors ↓ nerve impulse frequency ↑ activation of sympathetic ANS constriction of afferent arteriole = ↓ GFR = ↓ Na+ filtered = ↓ Na+ excreted ↑ plasma [Na+]

Answer 133

steroid hormone (synthesis requires gene reg. = longer to act) secreted from adrenal cortex synthesis triggered by low Na+ (indirectly) long term effect

Answer 134

acts on late distal tubule + CCD induces synthesis of Na+ transporter = stimulates Na+ reabsorption + ↓ Na+ excretion (also stimulates K+ secretion)

Answer 135

renin-angiotensin aldosterone system liver produces angiotensinogen protein = released into blood low [NaCl] is sensed by kidney = JC cells release renin renin converts angiotensinogen into angiotensin I ACE converts ATI → ATII ATII acts on adrenal cortex to control aldosterone secretion (also causes vasoconstriction; ↑ bp)

Answer 136

low [Na+] triggers juxtaglomerular cells to stimulate renin release: - sympathetic input from external baroreceptors - intrarenal baroreceptors - macula densa signals

Answer 137

↓ plasma [Na+] = ↓ GFR → activation of RAAS = ↑ aldosterone → ↑ Na+ transporter synthesis in CCD cells = ↑ Na+ reabsorption + ↓ Na+ excretion

Answer 138

↑ plasma [Na+] = ↑ ANP secretion = - inhibition of aldosterone - inhibition of Na+ reabsorption - ↑ GFR + Na+ excretion

Answer 139

peptide hormone secretion stimulated by ↑ [Na+], ↑ blood vol → atrial distension synthesized + secreted by cardia atria acts on kidney cells

Answer 140

acts on kidney arterioles → afferent dilation + efferent constriction = ↑ GFR acts on tubules → ↓ Na+ reabsorption (also through ↓ aldosterone) = ↑ Na+ excretion

Answer 141

most reabsorption = in PCT + LofH secretion in CD (aldosterone) [K+] in urine is regulated by CCD

Answer 142

↑ K+ intake = ↑ plasma [K+] → ↑ aldosterone secretion from adrenal cortex + ↑ K+ secretion from CCD = ↑ K+ excretion

Answer 143

excess K+ in blood

Answer 144

aldosterone secreting cells in adrenal cortex are sensitive to extracellular [K+] direct release

Answer 145

maintain ECF pH between 7.35 and 7.45 small changes in pH cause proteins to change shape → alter activity coupled to K+ imbalances irregular cardiac beats

Answer 146

arterial plasma pH < 7.35

Answer 147

arterial plasma pH > 7.45

Answer 148

pH < 6.8 pH > 7.8

Answer 149

releases H+ in solution

Answer 150

accepts H+ in solution

Answer 151

CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+ reversible reactions catalyzed by carbonic anhydrase

Answer 152

CO2 gas at room temp produces carbonic acid when reacted with H2O

Answer 153

organic + inorganic acids from other sources than CO2 phosphoric acid sulfuric acid

Answer 154

metabolism of sulfur-containing amino acids (cysteine, methionine)

Answer 155

metabolism of lysine, arginine, and histidine

Answer 156

metabolism due to intense exercise

Answer 157

1. generation of H+ from CO2 2. production of nonvolatile acids from the metabolism of proteins and other organic molecules 3. due to loss of HCO3- in diarrhea or other nongastic GI fluids 4. due to loss of HCO3- in the urine

Answer 158

1. utilization of H+ in the metabolism of various organic anions 2. in vomiting (high [H+] in gastric contents) 3. secretion = excreted in urine 4. hyperventilation (↑ CO2 release)

Answer 159

any substance that binds to H+ buffer + H+ ↔ Hbuffer weak acid + its conjugate base modify change in pH following addition of acids or bases = prevents quick change in pH

Answer 160

phosphate ions + proteins ex. hemoglobin

Answer 161

both kidneys and lungs are responsible within narrow range lungs = short term kidneys = long term (ultimate balancers)

Answer 162

homeostatic role = short term regulation of H+ ↑ [H+] = stimulates ventilation (↑ resp rate) ↓ [H+] = inhibits ventilation

Answer 163

hyper/hypo ventilation, respiratory malfunction non-respiratory causes: fasting, diabetes mellitus = reflex change in ventilation

Answer 164

↓ plasma [H+] (= ↑ HCO3-) → kidneys excrete more bicarbonate = ↓HCO3- results in restoration of acid-base balance

Answer 165

↑ plasma [H+] (= ↓ HCO3-) → kidney cells synthesize new bicarbonate + send it to blood = ↑ HCO3- results in restoration of acid-base balance

Answer 166

dependent on H+ secretion active process most of HCO3- is reabsorbed occurs in proximal tubule, ascending loop of Henle, + CCD different transport mechanism of H+ depending on part of tubule

Answer 167

if not enough bicarbonate excess H+ secreted into lumen → binds to HPO42- HCO3- is generated by tubular cells from CO2 + H2O and diffuses into plasma net gain of HCO3- in plasma

Answer 168

cells from proximal tubule uptake of glutamine from glomerular filtrate or peritubular plasma (filtration + secretion) NH4+ and HCO3- are formed from glutamine inside cells NH4+ is actively secreted via Na+/NH4+ countertransport into lumen HCO3- is added to plasma

Answer 169

more bicarbonate synthesized by tubular cells + reabsorbed = plasma bicarbonate increased plasma pH returns to 7.4 urine pH is acidic

Answer 170

bicarbonate is lost in the urine plasma bicarbonate decreases plasma pH returns to 7.4 urine pH is alkaline

Answer 171

decreased ventilation = ↑ blood PCO2 occurs in emphysema kidneys compensate by secreting H+ to lower plasma [H+]

Answer 172

hyperventilation = ↓ blood PCO2 happens at high altitudes (body adaptation to ↑ resp rate) kidneys compensate by excreting HCO3-

Answer 173

diarrhea = loss of bicarbonate ions severe excercise = generate lactic acid diabetes mellitus lungs: ↑ ventilation (get rid of CO2 to ↓ [H+]) kidneys: ↑ H+ secretion

Answer 174

prolonged vomiting = ↓ [H+] lungs: ↓ ventilation (↑ CO2) kidneys: ↑ HCO3- excretion