… Flashcards
Clearance test spx
24-hour urine
Gold standard for measuring GFR
Inulin
• A small protein produced by all nucleated cells
• Cystatin C
• most widely used endogenous procedure
Creatinine
COMPUTE FOR GLOMERULAR FILTRATION RATE
• Reported in______;
ml/min
GFR
Normal is______
Males_______;
Females_______
120ml/min
107-139ml/min
87-107ml/min
GFR formula
Urine conc x Urine vol
————-
Plasma conc.
• Can be used to estimate kidney function for CKD staging or whether to adjust or discontinue medications based on kidney function
COCKCROFT-GAULT FORMULA
COCKCROFT-GAULT FORMULA is used for
• Can be used to estimate kidney function for CKD staging or whether to adjust or discontinue medications based on kidney function
• eGFR =
175 x serum creatinine -1154 x age -0.203 x 0.742 (if female) x 1.202 (if black)
• As previously mentioned, the ultrafiltrate that enters the tubules has a specific gravity of______ and it is expected that the final urine is more concentrated or diluted depending on hydration
1.010
evaluate the ability of renal tubular cells to selectively absorb and secrete solutes.
Fluid deprivation tests
• About_____% of filtered water reabsorbed
•_______ make the largest contribution in REABSORPTION
99
Proximal convoluted tubule cells
- returns of most of the filtered water and many solutes to the bloodstream
TUBULAR REABSORPTION
• Needs a carrier protein to transport substance and requires energy (e.g. hydrolysis of ATP)
Active transport
- Movement of a substance across a cell membrane and against an osmotic gradient (always transcellular)
Active transport
• Carries glucose into the tubular cell cytoplasm
SGLT (sodium glucose linked transporter)
• Helps glucose diffuse out of the cell (facilitated diffusion)
GLUT (glucose transporter)
Glucose is renal threshold
160-180 mg/dL
Early PCT: Reabsorbs???
sodium reabsorption and co-transport with glucose, amino acids, other solutes
Late PCT: Reabsorbs???
sodium and chloride reabsorption
____ is impermeable to water
ALoH
As filtrate moves through the ascending limb,______ moves out making the filtrate more and more dilute
NaCl
Virtually impermeable to water (requires ADH for water reabsorption) and urea
DCT
DCT
Virtually impermeable to water (requires______ for water reabsorption) and urea
ADH
DCT is impermeable to
Water and Urea
DCT
Permeability to water depends on_____ (binds only to______)
ADH
aquaporin-2
DCT
Permeability to water depends on_____ (binds only to______)
ADH
aquaporin-2
Normal blood pH:
7.4 (excess acids must be eliminated)
• responsible for buffering capacity
• Readily filtered and reabsorbed
Bicarbonate ions
: secreted by renal tubular epithelial cells into the filtrate (sodium-hydrogen exchanger)
• Hydrogen ions
• Hydrogen ions: secreted by RTE cells into the filtrate (sodium-hydrogen exchanger)
• Prevents the filtered bicarbonate from being excreted
• Excreted via:
• Filtered phosphate ion
• Ammonia
: secrete hydrogen ions and reabsorb bicarbonate
Alpha-intercalated cells
: secrete bicarbonate and reabsorb hydrogen ions
• Beta-intercalated cells
• Passage of substances from the blood in the peritubular capillaries into the tubules.
• Elimination of waste products not filtered by the glomerulus
• Regulation of acid-base balance in the body through the secretion of hydrogen
Tubular secretion
