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Flashcards in Renal physiology Deck (72)
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1

Bowman's capsule

epithelial wall of the corpuscle, includes glomerulous and whose basement membrane is continuous with the remainder of the renal tubule

2

Mesangium

contains contractile cells between loops that regulate glomerular filtration

3

Renal interstitium

connective tissue made of fibroblast-like cell, cells that secrete EPO, cells that secrete vasomodulators, macrophages that belong to RES

4

Functions of kidneys

regulate electrolyte concentrations in ECF, eliminates waste products, special metabolic functions and hormone secretion

5

Renal artery pathway

renal artery- segmental- interlobar- arcuate- interlobular-afferent arterioles-efferent arterioles- peritubular or vasa recta

6

Afferent arterioles

20% of plasma water in the afferent arterioles is filtered by the glomerulus

7

Efferent arterioles

contain blood cells, unfiltered large substances and ~80% of liquid that had been in afferent arterioles

8

Function in cortical nephrons

delivery of nutrients to epithelial cells and acceptance of reabsorbed and secreted substances

9

Function in medullary nephrons

follow he loop of henle and serve as osmotic exchanger for production of urine

10

Main triggers and place of renin release

dec pressure in afferent arteriole, increased renal sympathetic activity; juxtaglomerular cells (granular) and extraglomerular mesangial cells

11

Causes of poor renal blood perfusion

dec blood volume, movement of fluid from intravascular space to tissue (pancreatitis, peritonitis), decrease circulation (HF), dec GFR (HTN, DM)

12

Blood flow regulation

important because kidneys are so close aorta, every postural change would cause large change, but have myogenic and tubuloglomerular responses

13

Myogenic response

blood vessels inc in size in response to pressure inc, the smooth muscle cells of the vasculature contract, Law of LaPlace, wall tension is proportional to distention pressure

14

Tubuloglomerular feedback mechanism

changes in BP leads to change in GFR, (inc bp- inc GFR), inc capillary hydrostatic pres in peritubular capillaries, which leads to dec reabsorp of Na/ Cl in proximal tubule and inc NaCl delivery to distal tubule, macula densa cells sense high NaCl, response of macula densa facilitates vasoconstricion= autoregulation

15

Angiotensin II variable effects on renal blood flow

Low angII causes vasoconstriction in afferent (less) and efferent (more)-> dec in RBF, inc in GFR; high angII causes vasoconstriction of afferent and efferent, activates mesangial cells, dec in SA of glomerular capillaries, dec GFR, inc sympathetic, dec in RBF

16

Prostaglandins on renal blood flow

PGE and PGI are vasodilators acting on afferent and efferent arterioles-> causing a dampening effect on renal vasoconstriction

17

Dopamine on renal blood flow

at low levels vasodilator for renal arterioles, clinically used as vasoprotector of kidney

18

Renal sympathetic nerves

sympathetic has no part in autoregulation, but raises MAP at the expenxe of renal blood flow, stimulation inc resistance in afferent and somewhat less in efferent arterioles, dec RBF and GFR

19

Very high ADH

cause contraction of afferent and efferent arterioles, cause contraction of mesangial cells to dec GFR, extreme response during shock

20

Renal filtration apparatus

endothelial cells w/ fenestrations of ~ .1um, basal lamina surrounds glomerular cappillaries, epithelial cells with podoctes, that create 25-60 nm wide slits, sieving by size, by charge

21

Advantages of serum CrCl over inulin

no infusion necessary since creatinine is a product of muscle creatine phosphate

22

Disadvantages of serum CrCl over inulin

creatinine is secreted less than PT, may not work in severe CRF, may not work w/ drugs that inhibit tubular secretion of creatinine, not every creatinine comes from kidney problem, creatinine may not inc despite renal prob, bilirubin interferes w/ cr, bacteria break down urinary creatinine

23

BUN plasma level advantages over plasma creatinine

better measurement range, falls and rises faster, slightly more sensitive (BUN can indicate moderate-severe)

24

BUN plasma level disadvantages over plasma creatinine

not every BUN comes from kidney problems, low BUN has little significance for kidney (liver prob or preg), urea is reabsorbed into blood, then inc w/ vol depletion so GFR is underestimated

25

Cystatin C plasma levels advantage over creatinine

cysteine proteinase inhibitor that is produced by all nucleated cells, constantly produced and freely filtered by kidneys, not affected by infection, inflammation, neoplastic states, body mass, diet or drugs, more accurate than creatine w/ sudden changes

26

Cystatin C plasma level disadvantage over creatinine

expensive, less widely available and complex tests

27

Filtration fraction

percentage of plasma that is filtered through the glomerular capillary membrane to become glomerular filtrate

28

Increase of filtration fraction caused by

[albumin] peritubular inc, (pi)c in peritubular capillary inc, Na reabsorption inc

29

Nephrotic syndrome

disruption of glomerular filtering membrane w/out inflammation, marked proteinuria >3.5g/d, small dec in GFR, edema, hypoalbuminemia, lipiduria, hyperlipidemia

30

Nephritic syndrome

disruption of glomerular filtering membrane by inflammation, proteinuria