Renal 2 Tubular Function and Micturition Flashcards
(93 cards)
what is the function of the nephron?
3 primary functions: filtering, reabsorbing, secreting.
The glomerulus filters blood. Reabsorption occurs along in the convoluted tubules and Loop of Henle. Secretion occurs in the PCT & DCT, and collecting duct. Anything not reabsorbed (urea) becomes the urine + is secreted through the collecting duct.
what materials are completely reabsorbed from the filtrate?
glucose, amino acids and bicarbonate
what materials within the filtrate are regulated and partially reabsorbed?
water, sodium, potassium, chloride
what materials from waste are excreted as waste?
urea, creatinine, drugs, drug metabolites
which section of the Loop of Henle is water-permeable?
the descending limb; lots of water reabsorption and when we reabsorb substances like Na+, K+, or a.a.’s and glucose, water follows it
which section of the Loop of Henle is impermeable to water?
the thicker ascending limb; ions are still pulled out of the filtrate for reabsorption but water cannot follow it
collecting duct
able to modify water reabsorption in the presence of ADH (reabsorb water, w/o ADH water in filtrate ends up in bladder)
interlobular artery
become afferent arterioles feeding the glomerulus
arcuate artery
become efferent arterioles away from the glomerulus, dives down into glomerulus to form peritubular capillaries
recta vasa
straight vessels that collect the stuff we want back
obligatory water reabsorption
occurs when water is “obliged” to follow the solutes being reabsorbed, as aquaporins are always present in the PCT
facultative water reabsorption
aquaporins are inserted in collecting ducts only if ADH is present
where does most obligatory reabsorption occur?
PCT and descending LOH (tubules permeable to water)
where does most facultative reabsorption occur?
in the collecting duct
osmosis and the PCT
movement of water will always be able, linked to passive reabsorption of a number of ions as well as the waste product urea
- by the end of the PCT most organic solutes have been reabsorbed as well as 65% of the water
passive transport
the movement of substances across a cell membrane without the use of energy by the cell, simple diffusion or facilitated diffusion, or leak channels
passive sodium reabsorption
from high [ ] in fluid to low [ ] in tubule cells; sodium may pass through via paracellullar route and pull water with it to end up in the blood
what type of epithelium is the apical border of the tubular cell?
simple cuboidal epithelium
paracellular route
between epithelial cells of PCT
transcellular route
substances pass through the cytoplasm of the PCT epithelial cells and out their base
primary active transport
active transport that relies directly on the hydrolysis of ATP
secondary active transport
uses energy of the movement of ions down their concentration gradient to transport other solutes (like ions and larger uncharged molecules like glucose or a.a.’s)
symporter
when the secondary active transport protein moves both the ion and the solute in the same direction
antiporter
when the secondary active transport protein moves the ion in one direction and the solute in the opposite direction