Microscopic Structure of the Kidney
Functional Unit: _____________________
 > 1 _____________________ in a kidney
 Can be cortical or
_____________________
 “Tiny funnel” with a very long stem
 Highly convoluted (many bends)
 2 principal components:
 Renal _____________________
 Renal _____________________
Renal corpuscle components
 _____________________ capsule
 Cup/sac-like-shaped top of a
nephron
 _____________________
 Ball of capillaries, lined with _____________________
 Found in Bowman’s capsule
 _____________________, _____________________ arterioles
Renal Tubule
 Composed of:
 Proximal _____________________ tubule (PCT)
 Loop of _____________________ (longer in Juxtamedullary)
 Distal convoluted tubule (DCT)
 _____________________ tubule
Formation of Urine: Overview
 _____________________
 _____________________
 _____________________
 All occur within the functional unit of the kidney, the _____________________
Filtration
 Of _____________________, _____________________ substances out of blood into Bowman’s capsule
 Occurs in “renal corpuscles”
 Contains larger afferent, smaller efferent arterioles
 Creates _____________________ pressure in glomerulus
 Filters blood across _____________________ capillaries, lined w/ podocytes
 Hold in _____________________, _____________________
 Lose water, ions = _____________________
Glomerular Filtration Rate
 120 ml/minute = _____________________ liters/day!
 Must maintain a minimum blood pressure for kidneys to filter
 _____________________, etc., can cause kidney function (and urine output) to cease
180 L of urine a day?
 No…
 Luckily, most of the fluid that leaves blood during filtration returns to the blood during reabsorption…
Reabsorption
 Movement of substances out of renal tubules into the blood (into _____________________ capillaries)






_____________________
_____________________
_____________________
_____________________, other ions
Begins in proximal convoluted tubule, continues in loop of Henle, distal convoluted tubule, and collecting
tubule
Reabsorb ~178 L/day (97-98% of water)
Mechanism?
Several…
 Active Transport
 Active transport of ______________ ions from _______________ into _____________________ fluid
 Passive Transport
 Creates high concentration of ______________, which ______________ into bloodstream
 Sodium (Na+) in blood attracts ______________ ions (Cl, PO4), which diffuse into blood
Another Mechanism?
 _____________________! (Flow of water from High to Low)
 Attracted to blood due to ion flow
Another, another Mechanism?
Facilitated diffusion
 Amino acids
 Glucose:
 ______________ /symported with ______________
 Almost all glucose reabsorbed (340 mg/min)
 Exceptions exist!
 _____________________ – too much sugar in bloodstream, exceeds ability of kidney tubule
cells to reabsorb (not enough Na+ to cotransport)
 _____________________ (glucose in blood)
 Water is lost along with glucose transport… most people with diabetes mellitus
_____________________excessively!
Loop of Henle
 Descending loop:
 _____________________ water, large ions and molecules
 Ascending loop:
 Final adjustment
 _____________________ regulate the amount of sodium, water reabsorption
Water reabsorption
 90% passive thru _____________________ in PCT, descending Loop of Henle, DCT
 10% occurs in last parts of DCT, collecting ducts
Secretion
 Substances move into urine in distal, collecting tubules from blood in capillaries around tubules
 “_____________________ in reverse”
 Urea, H+, K+ ions, ammonia, drugs
 (Bold = _____________________; non-bold = _____________________)