Final: Cont. Flashcards
Hydrostatic P in glomerular capillaries
45 mm HG
Hydrostatic P in Bowman’s space
10 mm HG
Glomerular filtration rate
180 L day = 125 ml/min
Filtered load
Amount of substance filtered across glomerular capsule
Tubular fluid
Fluid in Bowman’s space and lumen of nephron
Mechanisms of action for reabsorption
Transporters in membrane of tubular epithelial cells
Most important function of kidneys and why
Reabsorb Na -> drives reabsorption of everything else
Major cation in ECF
Na
Increase in Na intake = increase in
Volume
Examples of substances secreted from peritubular blood into tubular fluid via tubular epithelium
Organic acids
Organic bases
K+
Cellular mechanism for glucose reabsorption
Carrier mediated along with Na in early PT
- from tubular fluid into tubular cell via Na/glucose symporter SGLT
- 2 Na (downhill) and 1 glucose (uphill)
- Na/K pump on peritubular capillaries side keeps Na low in ICF
- secondary active transport
Glucose transported from tubular cell into peritubular blood by
Facilitated diffusion
GLUT 1 and 2 ( insulin dependent)
Splay on glucose titration curve
Bending of reabsorption curve
Threshold - not all glucose reabsorbed
Reasons for splay
Low affinity of Na glucose cotransporter
Heterogeneity of nephrons
Glucosuria definition and observed in what conditions
High plasma glucose >200 mg/dL (DM)
Pregnancy (increased GFR which increases filtered load)
Congenital abnormalities of Na/glucose cotransporter
___ freely filtered across glomerular capillaries
Urea
__ transported in most segments of nephron
Urea
Concentration of urea increases in tubular fluid as water is
Reabsorbed from tubule
Urea secreted in
Thin descending limb
Structures impermeable to urea
Thick ascending limb
Distal tubule
Cortical CD
Outer medullary CD
More urea is secreted than was reabsorbed by
PCT
Inner medullary collecting ducts have urea transporter 1 which is activated by
ADH
Urea can by __ at high levels
Toxic
__ and __ help create osmotic gradient at loop of Henle so water can be reabsorbed
Urea and salt
Para-aminohippuric acid (PAH)
Used to measure renal plasma flow
90% of PAH in blood bound to
Plasma proteins - not filterable
Only ___ of PAH is filterable
10%
PAH secretion
Transporters in peritubular membranes of PT cells
Inhibited by probenecid
Excretion of PAH
Rises sharply as unbound plasma PAH levels rise
Weak acids
PAH
Salicylic acid
Weak bases
Quinine
Morphine
Only ____ species of weak acids and bases can diffuse across tubular cells
Uncharged species
Aspirin reabsorption
HA form = salicylic acid - reabsorbed
A- form = salicylate = not reabsorbed
Positive Na balance
Excretion < intake