Urinary Tract Anatomy and Histology

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Questions and Answers

What is the main function of the proximal convoluted tubules in the nephron?

Secretion of ammonia

Reabsorption of water and sodium

Reabsorption of glucose and amino acids (correct)

Excretion of waste products

What is the characteristic of the cells lining the proximal convoluted tubules?

Cubical with clear boundaries

Triangular with non-clear boundaries (correct)

Columnar with basal striations

Squamous with apical microvilli

What is the primary function of the distal convoluted tubules?

Reabsorption of water and sodium (correct)

Excretion of waste products

Reabsorption of glucose and amino acids

Secretion of ammonia

What is the structure that connects the proximal convoluted tubules and distal convoluted tubules?

Loop of Henle Signup and view all the answers

What is the characteristic of the lumen in the proximal convoluted tubules?

Narrow lumen Signup and view all the answers

What is the main difference between the proximal convoluted tubules and distal convoluted tubules?

Convolutions of the tubules Signup and view all the answers

What is the function of the basal infoldings in the proximal convoluted tubules?

Increase surface area for reabsorption Signup and view all the answers

What is the characteristic of the cells lining the distal convoluted tubules?

Cubical with clear boundaries Signup and view all the answers

What is the function of the longitudinal folds in the mucosa of the urinary tract?

To allow distension during the passage of small stones Signup and view all the answers

What type of epithelium lines the mucosa of the urinary bladder?

Transitional epithelium Signup and view all the answers

What is the name of the muscle layer in the urinary bladder wall?

Detrusor muscle Signup and view all the answers

What happens to the umbrella cells in the mucosa of the urinary bladder when it is full?

They become flat Signup and view all the answers

What is the outermost layer of the urinary bladder wall?

Adventitia Signup and view all the answers

What is the function of the internal sphincter in the urinary bladder?

To prevent the backflow of urine Signup and view all the answers

What type of epithelium lines the thin descending part of the nephron?

Simple squamous Signup and view all the answers

Which part of the nephron is responsible for the concentration and formation of hypertonic urine?

Thick ascending part Signup and view all the answers

What is the function of the juxtaglomerular cells?

Secrete renin Signup and view all the answers

How many nephrons does each collecting tubule receive?

5-10 Signup and view all the answers

What type of epithelium lines the small collecting tubules?

Simple cuboidal Signup and view all the answers

What is the juxtaglomerular apparatus composed of?

Juxtaglomerular cells, macula densa, and extraglomerular mesangial cells Signup and view all the answers

What is the function of the macula densa?

Osmoreceptors Signup and view all the answers

What type of epithelium lines the ureter?

Transitional Signup and view all the answers

Study Notes

Urinary System

The urinary system consists of uriniferous tubules, which include nephrons and collecting tubules.

Nephrons

Nephrons are composed of proximal convoluted tubules and distal convoluted tubules.

Proximal Convoluted Tubules

Length: 15 mm, more convoluted
Diameter: 60 µm
Lined with 3-4 cells with non-clear boundaries, deeply acidophilic and granular, with basal striations and apical brush border
Numerous apical microvilli and pits and vesicles containing reabsorbed proteins
Basal infoldings with numerous mitochondria
Function: reabsorption of H2O and Na, active absorption of glucose and amino acids

Distal Convoluted Tubules

Length: 5 mm, less convoluted
Diameter: 40 µm
Lined with 5-8 cells with clear boundaries, less acidophilic and less granular, with central nucleus
Few microvilli and mitochondria
Function: reabsorption of H2O (ADH), reabsorption of Na (aldosterone), and secretion of ammonia

Renal Tubules

The renal tubules include the loop of Henle, which connects the proximal convoluted tubules and distal convoluted tubules.

Loop of Henle

U-shaped, formed of thick descending, thin descending, thin ascending, and thick ascending parts
Function: concentration and formation of hypertonic urine

Collecting Tubules

Each collecting tubule receives 5-10 nephrons
Small collecting tubules are lined with simple cuboidal epithelium
Large collecting ducts (Ducts of Bellini) are lined with simple columnar epithelium

Juxtaglomerular Apparatus

Definition: complex structure at the vascular pole of some renal corpuscles
Composed of juxtaglomerular cells, macula densa, and extraglomerular mesangial cells (Lacis cells)
Function: secretion of renin, osmoreception, and support

Urinary Passages

Ureter: wall formed of mucosa, musculosa, and adventitia
Mucosa: transitional epithelium and C.T corium, forms longitudinal folds to allow distension
Musculosa: upper 2/3 has 2 layers, lower 1/3 has 3 layers
Adventitia: loose CT rich in BV, nerves, and lymph vessels

Urinary Bladder

Wall formed of mucosa, musculosa, and adventitia
Mucosa: transitional epithelium (urothelium) on C.T corium, with umbrella cells
Musculosa: detrusor muscle, formed of 3 poorly delineated layers, thickened at the bladder neck to form the internal sphincter
Adventitia: loose C.T, superior part covered by peritoneum

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Description

This quiz covers the anatomy of the urinary tract, including the renal cortex and medulla, and the histological structure of nephrons and collecting tubules. It also explores the ultrastructure of podocytes and their role in forming the renal blood barrier.