Renal Phys Flashcards
What are the 3 functions of the kidney?
- Regulatory
-volume
-Blood composition - Excretory
- Nitrogen excretion, protein breakdown
-drug elimination - Hormonal
-production of erythropoetin, calcitrol, renin
The functional unit of the kidney is the _____________. What does it consist of?
Nephron
consists of:
1. Proximal convoluted tubule (PCT)
2. Loop of Henle
3. Distal convuluted tubule (DCT), which empties into collecting duct
How does the glomerular filtration membrane allow ultrafiltration?
it separates out formed elements and proteins from plasma then sends the plasma to Bowman’s capsule
What is the glomerulus?
it is a network of twisted capillaries which acts as a filter for the passage of protein free and red blood cell free filtrate to the proximal convuluted tubules
_____________ + ______________ = renal corpuscle
Bowman’s capsule, gloerulus
How is the glomerulus clinically significant?
- certain molecular weights are able to get through the glomerulus but some cannot
- sodium/potassium: no problem with passage
- Albumin: too large to get through, if glomerulus damaged, albumin will get through and show up in urine
_________________ supply blood to the glomerulus
Afferent arterioles
capillaries converge into _________________ and form peritubular capillaries
efferent arteriole
Formulation of capillaries lead to the concept of ________________
tubular reabsorption/ tubular secretion
What is tubular reabsorption?
movement of fluids & solutes from tubular lumen to peritubular capillary plasma (urine to blood)
What is tubular secretion?
movements of substances from peritubular capillary plasma to tubular lumen (blood to urine)
What two functions are critical for kidney function?
tubular reabsorption, tubular secretion
What does the glomerular filtration rate measure and what is the goal?
it measures the amount of fluid pushed through the glomerulus per minute. The goal is 120 ml/minute
approx 180L/day of fluid is filtered and reabsorbed
What 3 labs are critical for assessing kidney function?
GFR, BUN, serum creatine
What is the proximal convoluted tubule the site for?
site of reabsorption of glucose, amino acids, metabolites, electrolytes from filtrate.
-reabsorbed substances return to circulation
The major function of the _________________ is to get back fluids and electrolytes while getting rid of waste
Proximal convoluted tubule
The proximal convoluted tubule reabsorbs sodium/water in equal proportions, ______________ is approx the same going in/out of PCT
fluid osmolarity
What is the loop of Henle?
it is a hairpin in the medulla, extending from the PCT to DCT, divided into 3 segments:
1. thin descending
2. thin ascending
3. thick ascending
The loop of henle absorbs more _________ and _________ than __________
sodium and chloride, water
What is the primary function of the loop of henle?
concentration of urine via the countercurrent mechanism
What is the countercurrent mechanism?
exchange occurs between the ascending/descending LOH and ascending/descending sections of vasa recta. Concentrated water collects in the interstitium triggering ADH release.
In the countercurrent mechanism, the degree of concentration depends on the location. What are they?
- thin descending- highly permeable to water however, as urine filtrate moves down, water moves out of filtrate and into surrounding interstitium
- ascending limbs- impermeable to water; solutes are reabsorbed but water cannot follow; result is dilute urine as it enters distal tubule since solutes taken out of tubular lumen
In the countercurrent mechanism, in thin descending, once it reaches the _____________, concentration is at its highest
elbow of LOH
What is the distal convoluted tubule?
site from which the filtrate enters the collecting ducts
