Lecture 32 4/4/24

Question 1

What are the characteristics of the Loop of Henle?

Answer 1

-in medulla
-parallel with the course of vasa recta
-U-shaped
-lining varies; simple squamous in thin segments, simple cuboidal in thick segments

Question 2

What are the functions of the Loop of Henle?

Answer 2

-establish extracellular tonicity gradient
-concentration
-facilitation of ion and water exchange

Question 3

How does the Loop of Henle length impact water retention?

Answer 3

the longer the Loop of Henle, the more water retention that occurs

Question 4

What are the characteristics of the distal tubules?

Answer 4

-active transport: reabsorption, secretion, and exchange
-main target of aldosterone
-present in cortex only
-less numerous than proximal convoluted tubules
-lined by single layer of cuboidal epithelial cells
-contain specialized cells of macula densa

Question 5

What are the functions of the distal tubules?

Answer 5

-adjust ion and urea concentrations
-maintain acid-base balance

Question 6

What are the characteristics of the distal tubule epithelium?

Answer 6

-no brush border
-many mitochondria
-basolateral interdigitations

Question 7

What is the location of juxtaglomerular apparatus?

Answer 7

site of physical contact between distal tubule and renal corpuscle in the same nephron

Question 8

What is the function of the juxtaglomerular apparatus?

Answer 8

sensor for urine ion concentration and blood pressure

Question 9

What are the macula densa?

Answer 9

chemoreceptors to sense sodium concentration in filtrate

Question 10

How does the macula densa work?

Answer 10

-elevated NaCl triggers macula densa contraction of afferent arteriole
-leads to decreased GFR and volume concentration

Question 11

What are the juxtaglomerular cells?

Answer 11

baroreceptors that sense blood pressure in afferent arterioles

Question 12

How do the juxtaglomerular cells work?

Answer 12

-low blood pressure leads to the secretion of renin to the vessel lumen
-renin triggers aldosterone release, which increases sodium and water resorption in DCT
-resorption increases blood pressure

Question 13

What are the characteristics of the collecting ducts?

Answer 13

-run from cortex to medulla
-continuous with papillary ducts
-primarily principal cells
-contain intercalated cells

Question 14

What are the functions of collecting ducts?

Answer 14

-concentration
-acid-base
-immune response
-transportation of filtrate to papillary ducts into renal pelvis

Question 15

How can cortex be distinguished from medulla?

Answer 15

-cortex contains proximal and distal tubules and collecting ducts
-medulla contains LOH and collecting ducts

Question 16

What are the steps of renal blood flow?

Answer 16

-renal artery
-interlobular artery
-arcuate artery
-interlobular artery
-afferent arteriole
-glomerular capillaries
-efferent arteriole
-peritubular capillaries
-interlobular vein
-arcuate vein
-interlobular vein
-renal vein

Question 17

What is the venous blood flow of the juxtamedullary nephrons?

Answer 17

descending vasa recta to ascending vasa recta

Question 18

What is the clinical significance of renal blood flow?

Answer 18

-tubules are supplied by blood that has already gone through glomerulus
-blood cannot go through damaged/scarred glomerulus, leading to the tubules not being well perfused

Question 19

What is the function of the renal pelvis and calyces?

Answer 19

-collects urine from the kidneys
-passes urine to ureters

Question 20

What is unique about the renal pelvis and ureter in the horse?

Answer 20

they contain mucous glands

Question 21

What are the characteristics of transitional epithelium?

Answer 21

-special type of stratified epithelium called urothelium
-only in the urinary system
-shape change with pressure allows structures to distend
-contributes immune properties

Question 22

What are the characteristics of the ureters?

Answer 22

-carry urine to urinary bladder
-characteristic star shaped lumen
-oblique entrance into urinary bladder

Question 23

What are the characteristics of the urinary bladder?

Answer 23

-stores urine
-urothelium mucosa
-detrusor muscle to allow bladder control

Question 24

What are the characteristics of the urethra?

Answer 24

-carries urine from bladder to exterior
-mucosa transitions from urothelium to squamous
-muscularis transitions from smooth to skeletal muscle