SFP: overview of the kidneys Flashcards
What is the basic job of the kidney?
Filtering plasma and reabsorbing it!
What are major functions of the kidney?
- Regulation of water and electrolyte balance
- Regulate BP
- Excrete wastes
- Acid-base balance
- Regulate calcium and phosphate balance and vitamin D
- Metabolism
- RBC production
What hormone works with the kidney to regulate water and electrolyte balance?
ADH
How does the kidney regulate acid-base balance?
Mostly by removing non-volatile acids. They also dial up their generation of ammonium from ammonia, and reabsorb/generate HCO3.
What vitamin is synthesized in the kidney?
Active vitamin D
How is the kidney involved in regulation of RBC production?
Erythropoietin is made in the kidney, which stimulates RBC production.
What metabolic processes occur in the kidney?
Gluconeogenesis, synthesis of ammonia, generation of bicarb
Where are the kidneys located?
Retroperitoneal space between T12-L3
Compare the positioning of right and left kidneys.
The right kidney is slightly inferior to the left due to displacement by the liver.
Describe the structure of the medulla of the kidney.
It contains pyramids with renal papillae at the base of each pyramid.
Describe renal papillae.
They contain bundles of collecting ducts that transport urine to calyces (funnel-like). The urine is then drained to the ureter and the bladder.
Where is the adrenal gland in relation to the kidney?
It sits superior; one for each kidney.
Describe the blood supply of the kidneys.
The main supply is the renal artery. This then branches into a segmental artery, interlobar artery (between pyramids), arcuate artery (arcs around the pyramid), interlobular artery, and finally the afferent arteriole.
What are the inputs and outputs of the glomerulus?
The afferent arteriole feeds into the glomerulus, and the efferent arteriole exits the glomerulus.
What are the vasa recta?
A second capillary network formed by the efferent arteriole.
What is the functional unit of the kidney?
The nephron
Compare the diameter of the afferent and efferent arterioles, and describe the effect of this.
The afferent arteriole has a slightly larger diameter. This increases hydrostatic pressure in the glomerulus, allowing for the filtration function.
What is the function of the proximal tubule?
Large-scale reabsorption of filtered water and solutes.
What helps the process of reabsorption in the proximal tubule?
Angiotensin II
What is the site of action for carbonic anhydrase inhibitors and osmotic diuretics?
Proximal tubule
What is the site of action of loop diuretics?
Loop of Henle
What is the medullary interstitum?
Area with salty liquid generated by the loop of Henle that helps concentrate urine in the distal nephron and helps us hold onto water.
Where is the site of action of thiazide diuretics?
Distal tubule
Describe the distal tubule.
It has a low permeability to water, so filtrate is further diluted due to ions leaving but water staying in the lumen.
Where in the kidney can PTH enhance calcium reabsorption?
Distal tubule
What hormones target the collecting tubule?
Aldosterone, ADH, vasopressin
What does aldosterone do in the kidney?
Regulates sodium reabsorption and secretion of potassium and protons.
What does ADH do in the kidney?
Regulates water reabsorption by enhancing functions of aquaporin; this concentrates the urine.
Describe the locations of transporters in tubular epithelial transport.
They’re usually restricted to one side of the cell or the other!
Where is the sodium-potassium pump on the epithelium?
Basolateral membrane
What is transcellular transport?
Movement of a solute through the cell.
What is paracellular transport?
Movement of solute through a tight junction.
What is solvent drag?
Water moves from the lumen to the interstitium transcellularly and through tight junctions to reach osmotic equilibrium. This flow pulls solutes down their concentration gradients across tight junctions and into the interstitium to be absorbed.
What is secretion?
Movement of solute from peritubular capillaries into the tubular lumen; this is across epithelial cells or tight junctions.
