Glomerular Filtration

Question 0

Glomerular Mesangial Cells

Answer 0

Two types:
1. Phagocytic

2. Contractile

Question 1

Functions of the Kidneys

Answer 1

• Regulation of water and electrolyte concentrations
• Removal and excretion of metabolic waste products
• Regulation of arterial pressure via aldosterone and renin secretion
• Secretion of EPO
• Secretion of Vitamin D
• Gluconeogenesis

Question 2

Layers of glomerular membranes

Answer 2

1. Endothelium: fenestrated; large molecules can pass thru
2. Basement membrane: thick; prevents lipids and proteins from passing
3. Podocytes: specialized epithelium that contain filtration slits that lead into Bowman’s space

Question 3

Glomerulonephritis

Answer 3

Inflammation of the glomeruli => decreased urine output, hematuria, and proteinuria

Question 4

Nephrotic Syndrome

Answer 4

Damage to the glomeruli usually resulting from hyperlipidemia; also causes hypoalbuminemia, proteinuria, and edema

Question 5

Nephritic Syndrome

Answer 5

Hypertension causing hematuria, elevated creatinine, azotemia, and oliguria

Question 6

Proximal tubule

Answer 6

Major site for the reabsorption of fluid; has a large surface area

*Apical membrane= non-motile brush border
Basolateral membrane= lined by mitochondria; interdigitations allow for passage of molecules

Question 7

Juxtaglomerular Apparatus cell types

Answer 7

1. Macula densa- provide info on urine flow, volume, and concentration
2. Granular- secrete RENIN
3. Extraglomerular mesangial cells- primarily phagocytic

Question 8

Papillary ducts of Bellini

Answer 8

Fusion of several collecting ducts near the papillae; site of “fine tuning” of the fluid composition

Question 9

Lining of Collecting Ducts

Answer 9

Principal cells are responsive to ADH, ANP, and aldosterone

alpha-Intercalated cells secrete H+

beta-Intercalated cells secrete HCO3-

Question 10

Cortical/Superficial Nephrons

Answer 10

7/8 of nephrons

-Glomeruli lie in outer 2/3 of cortex; have no thin ascending loop of Henle

Question 11

Juxtamedullary Nephrons

Answer 11

Glomeruli lie in inner 1/3 of cortex

• Loop of Henle reaches tip of papillae (papillary ducts of Bellini)
• # of juxtamedullary nephrons directly related to ability to make concentrated urine

Question 12

Blood supply to the kidney

Answer 12

Renal artery => Interlobar artery => Arcuate Arteries => Interlobular arteries => Afferent arterioles => glomerular capillaries => efferent arterioles => peritubular capillaries => venules => interlobular veins => arcuate veins => interlobar veins => Renal vein

Question 13

Vasa recta

Answer 13

Peritubular capillaries found only in the juxtamedullary nephrons

Question 14

Filtration Fraction

Answer 14

FF= GFR/RPF

Question 15

GFR in glomerular capillaries

Answer 15

GFR= Kf x (Pc-Pb-Pic)

Question 16

AA Resistance changes

Answer 16

Increased: Decreased RBF and GFR; same FF

Decreased: Increased RBF and GFR; same FF

Question 17

EA resistance changes

Answer 17

Increased: Decreased RBF; Increased GFR and FF

Decreased: Increased RBF; Decreased GFR and FF

Question 18

Mechanisms of renal autoregulation

Answer 18

1. Myogenic: change in pressure => smooth muscle contraction
2. Tubuloglomerular feedback => macula densa causes intrarenal vasoconstriction by using adenosine and decreases GFR
   • In response to increased tubular flow or increased NaCl

Question 19

Renal Clearance

Answer 19

Volume of plasma from which all of a substance has been removed and excreted into the urine per unit of time

Ca= (Ua)(V)/ Pa

• = (mg/ml)(ml/min)/(mg/ml)

Question 20

Creatinine

Answer 20

Endogenous substance used to estimate GFR

Question 21

Ca>Cin

Answer 21

Ca is being actively secreted

Question 22

Ca<Cin

Answer 22

Ca is being actively reabsorbed

Question 23

Fractional Excretion

Answer 23

The degree of net reabsorption/secretion of a substance relative to GFR

FE= (Ua)(V)/(GFR)(Pa)

*FE > 1 => secretion FE < 1 => reabsorption

Question 24

Clearance Ratio

Answer 24

FEa= (U/P)a/(U/P)in

Represents the fraction of filtered “a” remaining at the end of the proximal tubule

*This eliminates the effect of water transport on the measured concentration of “a”

Question 25

Tracheal tumor

Answer 25

Example of an intrathoracic lesion; causes problems on expiration