Flashcards in Session 3 - Filtration Deck (95)
Give three examples of things actively secreted
What are two methods of secretion into the PCT?
• Entry by passive carrier
• Secretion into the lumen
What is entry by passive carrier?
• Diffusion across basolateral membrane down conc grad created by Na+/K+ ATPase
How does entry by active secretion differ to passive?
• Directly uses ATM and H+ gradient creat by Na+-H+ antiporter
Give two forms of reabsorption?
How easy is it for a cation to get through the filter compared to an anion?
• Positive charge of cation allows slighty bigger molecules through than anions
What is reabsorption in PCT driven by?
• Sodium uptake
How is Na+ reabsorbed in tubular cells
• 3Na-2K-ATPase (Na into ECF, K+ into cell)
• Na+ moves across the apical membrane from tubule lumen down its concentration gradient
• Water follows into cell
In what way do solutes move in the PCT?
• Tubular lumen -> Intersticium -> Capillaries
What are the three mechanisms via which tubular reabsorption occurs?
• Active transport
What does iso-osmotic mean when applied to reabsorption?
• Osmosis does not take effect
Where does unregulated absorption occur?
• Proximal convoluted tubule
What is the method via which reabsorption occurs?
• Co-transport, following active transport
What is the transport maximum?
• If plasma conc exceeds Tm, the rest spills over into urine
What is the reabsorption path?
• Lumen -> Intersticium -> Peritubular capillaries
How is reabsorption different from glomerula filtration?
• Occurs primarily through cells
What 7 main substances are secreted into glomerula filtrate?
• Ammonium ions
• Some hormones
• Some drugs
Why do we need kidney secretion?
• Only 20% of plasma filtered in renal corpuscle each time
From where does tubular secretion occur?
• From the epithelial cells that line the renal tubules and collecting duct into the glomerular filtrate
How are organic cations secreted?
1) Entry by passive carrier into tubular lumen cell
a. Positive cation from ECF moves into negative cell down electrical gradient. This is as a result of basolateral 3 Na+/2 K+ ATPase
2) Secretion into the lumen
a. H-OC exchanger driven by H+ gradient created by the Na+-H+ antiporter
b. Na+ into cell from lumen, H+ out cell into lumen
c. Drives H+ into cell from lumen by creating conc grad
d. Organic Cation out by active transporter
Name three endogenous cations
Name three cationic drugs
Name three endogenous anions
• Bile salts
• Fatty acids
Name two anionic drugs
What is secondary active transport?
• Na+/K+ ATPase used to generate Na+ gradient
Where is glucose reabsorbed in the nephron?
• Proximal convoluted tubule
Through what transporter is glucose reabsorbed in the proximal convoluted tubule?
What is SGLUT?
• 2 Na+ ions and 1 glucose
• Glucose travels from lumen of tubule to the peritubular capillaries (moves into peritubular capillaries by facillitated diffussion
What is Tm?
• Transport maximum from tubule to capillaries