Physiology > Renal > Flashcards

Renal Flashcards

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1
Q

Urinary excretion rate =

A

Urinary excretion rate = Filtration rate - (Reabsorption rate + Secretion rate)

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2
Q

Creatinine in kidneys

A

Are only filtered not reabsorbed nor excreted

Filtration = Excretio

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3
Q

Na, Cl ions and others are

A

Freely filtered and partially reabsorbed

Excretion = Rate of filtration - Rate of reabsorption

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4
Q

Amino acids and glucose

A

Freely filtered and completely reabsorbed from tubules

No excretion

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5
Q

Organic acids and bases

A

Freely filtered not reabsorbed but additional substances secreted from capillary to tubule

Excretion rate = Filtration + secretion rate

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6
Q

Filtration fraction =

A

Filtration fraction = GFR/Renal plasma flow

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7
Q

The GC has 3 layers

A

1 endothelium
2 basement membrane
3 epithelial cell podocyte

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8
Q

Normal GFR

A

125 ml/min 180L/day

Filtrate devoid of protein, rbc, half of Ca bound and fatty acid

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9
Q

Fenestrations in gc are endowed with

that hinder passage of plasma proteins

A

negative charges

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10
Q

Filterability of solutes are determined by

A

Size

Electrical charge

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11
Q

Proteinuria/Albuminuria occurs in minimal change disease bec of

A

loss of negative charge on the basement membrane proteoglycan

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12
Q

Net filtration pressure =

A

Net Filtration Pressure = (GCh - Bh) - (GCc+Bc)

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13
Q

Glomerular Filtration Rate =

A

Glomerular Filtration Rate =

Kf x (Net filtration pressure)

Kf x [(GCh-Bh)-(GCc+Bc)]

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14
Q

Kf normal

A

12.5 ml/min/mmHg

Kf = GFR/NFP
Kf = 125/10mmHg
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15
Q

DM alters Kf by

A

Inc thickness of bm and damaging functional capillary less surface area

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16
Q

In obstructive renal disease such as calcium or uric stones, GFR is markedly dec bec of

A

Inc Bowman capsule hydrostatic pressure from backflow limiting filtration

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17
Q

Inc glomerular capillar colloid osmotic pressure : GFR

A

Decreases GFR

BY:
Inc arterial plasma colloid osmotic pressure, inc glomerular capillary colloid osmotic and dec GFR
Inc filtration fraction concentrating plasma proteins, inc colloid osmotic, dec GFR

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18
Q

A greater rate of blood floe into glomerulus: GFR

Lower rate of blood flow into glomerulus: GFR

A

Increases

Decreases

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19
Q

Primary means of physiologic regulation of GFR

A

Glomerular hydrostatic pressure

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20
Q

Glomerular hydrostatic pressure is determined by (3)

A

1 arterial pressure (inc AP, inc GFR)
2 afferent arteriole (vasoconstriction dec GFR and vice versa)
3 efferent arteriole (vasoconstriction inc GFR slightly as long as the inc does not reduce renal blood flow)

too much efferent vasoconstriction eventually dec GFR bec dec renal blood flow can promote inc filtration fraction and inc colloid osmotic pressure DEC GFR)

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21
Q

Oxygen consumption of kidney is related to

A

High rate of active sodium reabsorption by tubule

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22
Q

Renal blood flow =

A

Renal blood flow =

(Renal artery pressure1 - Renal vein pressure2)/Total renal vascular resistance

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23
Q

Total renal vascular resistance come from

A

Interlobular arteries
Afferent arteriole
Efferent arteriole

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24
Q

Strong activation of renal sympathetic nerves and autacoids (NE, Epi, Endothelin) such as in defense rx, ischemia brain, or severe hemorrhage

A

Dec GFR

Otherwise in mild to mod vasoconstriction, little influence on blood flow

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25
Angiotensin II acts preferentially on the efferent arteriole when activated to
Promote flow in the glomerulus Prevent dec glomerular hydrostatic pressure and prevent dec GFR Efferent constriction causes reduction in renal blood flow leading to dec flow in peritubular capillaries and sodium and water reabsorption increases
26
Autoregulation of kidneys depend on:
1 sodium chloride concentration at macula densa | 2 control of renal arteriolar resistance
27
GFR autoregulation is accomplished by
1 renal autoregulation | 2 glomerulotubular balance (adaptive mech in renal tubules)
28
Tubuloglomerular feedback components:
1 afferent arteriolar feedback 2 efferent arteriolar feedback depending on juxtaglomerular complex
29
JGC components
1 macula densa (initial distal tubule) | 2 juxtaglomerular cell (afferent and efferent)
30
Macula densa cells sense change in volume delivery at distal tubule when
Dec GFR slows flow rate at LOH INC reabsorption of NaCl ions in ascending LOH Dec concentration of NaCl at macula densa
31
Dec of NaCl at macula densa cause:
Dec resistance to blood flow in afferent arteriole Inc GFR | Inc renin release in JGC (RAAS)
32
Angiotensin II inc GFR by
Vasoconstricting afferent arterioles
33
Myogenic mechanisms in renal arteriole has important protective function against
Hypertension-induced kidney i
34
Filtration =
Filtration = Glomerular filtration x Plasma conc
35
Reabsorption across tubular epi into interstitial fluid occurs by
active or passive transport
36
Transport from interstitial fluid into peritubular capillary involve
ultrafiltration (bulkflow)
37
Moves solute against electrochemical gradient requires energy from metabolism
active transport
38
Transport coupled to an energy source such as hydrolysis of ATP is called
Primary Active Transport
39
Transport coupled indirectly to energy source such as ion gradient
Secondary active transport ex glucose
40
Diffusiob from a region of low solute to high solute concentration
Diffusio
41
Primary active transport in kidneys (4)
Na/K H ATPase H/K Ca ATPase
42
Na enters apical membrane from tubular lumen by
Electrochemical gradient established by NaK ATPase
43
Na is transported across basolateral membrane by
Electrochemical gradient by NaK ATPase
44
Na is reabsorbed from interstitial fluid into peritubular capillary by
Ultrafiltration
45
Reabsorption or secretion of solutes across cells
Transcellular
46
Transport of solutes between cells across tight junctions and intercellular spaces
Paracellular
47
Located on brushborder of proximal tubular cells carry glucose into cytoplasm against concentration gradient
Na-glucose co transporter SGLT2 (90%) and SGLT1
48
Glucose diffuses out into interstitial space with help
GLUT1 and GLUT2
49
Substances are secreted into tubules by secondary transport Ex. Sodium reab in luminal membrane coupled with H extrusion from cell by Na-H
Countertransport Na H exhanger
50
Amount of solute delivered to tubuke exceeds capacity of carrier proteins and specific enzymes involved in transport
Transport maximum
51
Appearance of glucose in urine occurs before transport max is reached
Glucose threshold
52
Overall transport maximum 375mg/min is reached when
All nephrons have exceeded maximal capacity to reabsorb
53
When rate of transport is determined by electrochemical gradient for diffusion, permeability of membrane for substance and time that the substance remains within tubule
Gradient-time transport
54
PCT Reabsorption and transport
65% water, Na, Cl, bicarbonate, K, glucose and AA NaCl Na/K ATPase Na-Glucose and Na-AA co transport Na-H exchange
55
H secretion to lumen of PCT is important for
Removal of bicarb
56
First half of proximal tubule reabsorption
Co transport with Na, glucose, AA, bicarbonate
57
Second half of PCT
Na with Cl
58
Organic solute that remains highly concentrated at PCT
Creatinine
59
Total solute conc and osmolarity remains the same along PCT bec
It is extremely permeable to water
60
PCT excretes
Bile salt oxalate urate and catecholamine
61
Used to estimate renal plasma flow bec of rapid secretion in PCT
PAH Para-aminohippuric acid
62
Filters 20% of water and allows simple diffusion
Thin descending limb of LOH
63
Impermeable to water bec
Thick and thin ascending limb of LOH concentration of urine
64
The thick ascending limb reabsorbs
25% of Na, Cl, K, Ca, bicarb, magnesium
65
Transporter in the thick ascending limb of LOH mediating Na transport
NaK2Cl co transporter
66
Site of action of furosemide, ethacrynic acid and bumetanide
Thick ascending limb of LOH
67
Thick ascending limb also has Apart from NaK2Cl
Na-H counter transport
68
Paracellular reabsorption of Ca, Mg, Na and K in thick ascending limb occurs bec of
Slight + charge of lumen with slight backleak of K into lumen creating + charge of 8mv This forces cations to diffuse from lumen to paracellular space
69
First portion of distal tubule:
Reabsorbs 5% of NaCl | Contains distal tubule from macula densa of JGC
70
Second portion of the DCT reabsorbs most ions but impermeable to water bec
It acts as diluting segment
71
Transporters in the DCT
Na-Cl co transporter | Cl channels
72
Site of action of thiazide diuretics
DCT
73
Thiazide inhibit
Na-Cl co transporter
74
Cell types of late distal and cortical collecting tubule
1 principal cell | 2 intercalated cell
75
Reabsorb sodium and water and secrete K into lumen
Principal cell
76
Reabsorb K and secrete H ion into lumen
Intercalated cell
77
Principal cells are sites of action of
``` K sparing diuretics Spironolactone Eplerenone Amiloride Triamterene ```
78
Mineralocorticoid antagonist that compete with aldosterone for receptor sites at principal cells
Spironolactone Eplerenone Inhibit sodium reabsorption and K SECretion hence sparing
79
Sodium channel blockers that directly inhibit entry of sodium and reduce transport of K secretion into cells
Amiloride | Triamterene
80
H ion secretion in the intercalated cell is mediated by
H ATPase transporter Capable of secreting H ions against a large conc gradient 1000:1 Key role in acid base
81
For each H ion secreted,
a bicarbonate ion becomes available for reabsorption across basolateral membrane
82
Site of action of aldosterone
Late distal tubule | Cortical collecting tubule
83
Site of action of ADH
Late distal tubule Cortical collecting duct Medullary CD
84
ADH/Vasopressin MOA
makes the late distal tubule and cortical collecting duct permeable to water
85
Final site processing of urine and plays important role in determining final urine output Reabsorbs
Medullary Collecting Duct <10% of water and sodium
86
Unique to medullary collecting duct are
Urea transporters that permit urea reabsorption
87
Urea reabsorption in MCD helps
Raise osmolality forming concentrated urine
88
MCD also secretes
H ions
89
Polysaccharide used to measure GFR not reabsorbed nor secreted Reflect changes in water present in tubule
Inulin
90
Total rate of reabsorption increases as filter load increases despite constant GFR in PCT at 65%
Glomerulotubular balance
91
Inc arterial pressure effect on peritubular capillary hydrostatic pressure reabsorption rate
inc hydrostatic pressure dec reabsorption rate
92
inc in resistance of afferent or efferent arteriole effect on pretubular capillary hydrostatic pressure reabsorption rate
Dec hydrostatic pressure Inc reabsorption rate
93
Inc in arterial pressure causes pressure natriuresis bec (3)
Impaired autoregulation Inc hydrostatic pressure of renal interstitial fluid causing Na backleak to lumen Reduced angiotensin II
94
Aldosterone Site of action Effect
Collecting tubule and duct Inc NaCl and water reabsorption Inc K SECRETION
95
Important regulator of K
Aldosterone
96
Angiotensin II site Effects
PCT, TAL of LOH, DCT AND CT 1 Inc Aldosterone secretion - Inc NaCl and water reabsorption 2Constriction of efferent arterioles - inc peritubular capillary reabsorption and inc filtration fraction to inc colloid osmotic pressure in peritubular capillary all leading to inc reabsorption 3 Inc H secretion 4 Direct stimulation of Na reabsorption in PCT, LOH, DCT and CT
97
Angiotensin II exerts direct effect on transporters
Na-H exchange NHE Na/K ATPase Na-HCO3 co transport
98
ADH site of action Effect
DCT, CT, CD Inc water reabsorption
99
ADH binds to what receptor in the DCT, CT and CD
V2 receptor
100
ADH MOA
V2 receptor binding coupled with Gs activating adenylate cyclase Inc cAMP and activation of Protein Kinase Movement of AQP2 on luminal side of cell Exocytosis forms water channels permiting rapid diffusion of water through cells
101
Plasma volume expansion leading to cardiac atria distention stimulate release of
Atrial natriuretic peptide
102
ANP site Effect
DCT, CT and CD Dec NaCl reabsorption
103
PTH site Effect
PCT, TAL of LOH, DCT Dec phosphate reabsorption Inc Ca reabsorption
104
Sympthetic effect on Na reabsorption
Constriction of renal arteriole leads to dec GFR from dec Na and water excretion Inc renin and Angiotensin II formation
105
Renal clearance =
Renal clearance = Volume of plasma completely cleared of substance by kidney/unit time
106
Clearance rate of a substance =
Cs = (urine concentration x urine flow rate)/plasma concentration Cs = urinary excretion rate (U x V) / plasmac
107
GFR =
GFR = (urine concentration of substance x urine flow rate)/plasma concentration of substance
108
Susbtances used to measure GFR (3)
Inulin Creatinine Radioactive iothalamate
109
Creatinine clearance isn’t perfect marker of GFR because
Small amount is secreted by tubules so amount excreted slightly exceeds the amount filtered Overestimation of GFR
110
Used to estimate renal plasma flow bec of its 90% clearance from plasma
Para-ammino hippuric acid
111
Filtration fraction=
Fraction of plasma that filters through glomerular membrane FF = GFR/RPF
112
Causes of K shift into cell
Insulin Beta adrenergic agonist Alkalosis (H-K exchange) Hypoosmolarity
113
Causes of K shift out/Hyperkalemia
``` Insulin deficiency Beta adrenergic antagonist Acidosis Hyperosmolarity Inhibitors of Na-K pump eg digitalis Exercise Lysis ```
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