Tubular Structure & Function Flashcards
What are the two types of Nephrons? How are they different
Superficial cortical: 85%, short loops of Henle
Juxtaglomerular: 15%, long loops of Henle
What are the two main modes of transport for material to move from the Lumen into the Interstitial fluid?
- Paracellular route (between tight junctions)
- Transcellular route
What is the tubular maximum rate for glucose?
300 mg / min
Where does the drug Furosemide work on in the kidney?
Ascending limb of loop of Henle
Where do Thiazide diuretics work on in the kidney?
Distal convoluted tubule
Where does the drug Amiloride work on in the kidney?
Collecting duct
Which segment of the nephron reabsorbs most of the glomerular filtrate? What proportion?
Proximal Convoluted Tubule, 66%
Which SGLT transporters are located in the early proximal tubule and the late proximal tubules?
Early PCT: SGLT2
Late PCT: SGLT1
SGLT2 shuttles how many ions with glucose into the tubule lumen?
1Na+ with Glucose
SGLT1 shuttles how many ions with glucose into the tubule lumen?
2Na+ with Glucose
In the early proximal tubule, state the three transporters involved in Glucose transport
SGLT2
GLUT2
3Na+/2K+ transporter
In the late proximal tubule, state the three transporters involved in Glucose transport
SGLT1
GLUT1
3Na+/2K+ transporter
Why are polyuria, glucosuria and polydypsia symptoms of Diabetes mellitus?
In DM patients, the plasma glucose exceeds Tm, which leads to glucosuria. Because glucose is osmotically active, water is also moved with it, leading to polyuria. This loss in water leads to polydypsia
How are single amino acids handled by the PCT?
99% is reabsorbed by the PCT, the remaining 1% in the late PCT. Multiple amino acid transporters are involved
How are small peptides handled by the PCT?
99% are reabsorbed by the PCT via brush border enzymes which hydrolyse >4 amino acid peptides into single AAs. Short peptides (2-4 AAs) are reabsorbed by an oligopeptide co-transporter and then metabolised by peptidases
