What are the 4 functions of the kidney? What does it synthesise? What does it metabolise?
• Regulation – Controls the concentrations of key substances in the ECF, and therefore able to control concentrations of ICF.
• Excretion of waste
• Endocrine – Synthesis of renin, prostaglandins, and erythropoietin (controls RBC production)
• Metabolism – Active form of vit D, catabolism of insulin, PTH, calcitonin
Define osmolarity and osmolality
osmolarity - number of osmoles of solute per LITRE of solution
Osmolality - number of osmoles of solute per KG of solution
How would you distinguish Ureters from arteries?
Ureters are smooth muscles, and therefore undergo peristalsis, allowing it to be distinguished from skeletal muscle or arteries
At what spinal level do the ureters arise?
Give 3 areas where a kidney stone is likely to lodge
1) Junction of the renal pelvis and ureter
2) Where ureters cross the brim of the pelvis
3) Where ureters pass into the wall of the urinary bladder
how would you distinguish between PCT and DCT microscopically?
proximal tubules have microvilli, distal tubules don’t and have wider lumen.
What would movement of ions from: a) arteriole to glomerulus b) Glomerulus to arteriole be considered?
How does filtration occur at the glomerulus?
Blood enters afferent arteriole and exits via efferent arteriole. High pressure forces small molecules into the glomerular capsule.
What is reabsorbed at the PCT?
• Reabsorbs 70% of NA and water, 90% of K and 90% of bicarbonate.
• 100% of glucose and AAs.
Describe the mechanism of reabsorption at the PCT.
• Cells of tubules polarised, meaning different transporters on luminal membrane opposed to basolateral membrane, which cannot move to the other side.
• Cotransporter of Na and glucose on the luminal membrane takes in sodium and glucose.
• Na K ATPase drives transport of sodium into the interstitium and potassium out of the blood, allowing a concentration gradient of sodium to occur between the cell and the lumen. Glucose taken with Na into interstitium.
• Movement of sodium creates osmotic pressure, forcing water into the cell and into the interstitium.
How is sodium and water recovery varied throughout the nephron?
• Sodium recovery controlled by the renin angiotensin system, indirectly controlling ECF volume.
• Water recovery controlled by anti diuretic hormone which controls the permeability of the DCT and collecting duct to water, controlling ECF osomolarity, less water means higher concentration of solutes and therefore higher osmolarity.