AL2 - Histology of Urinary System

Filtrate leaks out of glomerulus to enter the urinary space through the filtration barrier. State 3 layers of the filtration barrier.

1. Endothelial wall of capillary. 2. Basal lamina (GBM). 3. Visceral layer of Bowman capsule (Filtration slits).

Name two types of the mesangial cells.

1. Extraglomerular mesangial cells. 2. Intraglomerular mesangial cells.

Renal corpuscle is located in the cortex of kidney. Describe briefly two features of renal corpuscle.

1. Glomerulus - A tuft of fenestrated capillary plexus connected to an afferent arteriole and an efferent arteriole. 2. Glomerular capsule (Bowman capsule) - Blind pouch at proximal end of the nephron.

Juxtaglomerular apparatus is named because it is next to (juxta-) the glomerulus. Name three types of cells of the juxtaglomerular apparatus.

1. Juxtaglomerular cells. 2. Macula dense cells. 2. Extraglomerular mesangial cells.

Urinary bladder is a muscular sac that stores urine, allowing urination to be infrequent and voluntary. State the histological feature of Urinary bladder: 1. Mucosa. 2. Submucosa. 3. Muscularis externa. 4. Adventitia.

1. Mucosa - Transitional epithelium. Lamina propria - No glands except for mucous glands around urethral orifice. 2. Submucosa - Dense irregular connective tissue. 3. Muscularis externa - an inner longitudinal layer, a middle circular layer (which forms internal urethral sphincter) and an outer longitudinal layer. 4. Adventitia - Connective tissue with blood vessels, lymphatics & nerves.

Name 4 parts of the renal tubules that form the Loop of Henle.

1. Proximal straight tubule. 2. Thin descending limb. 3. Thin ascending limb. 4. Distal straight tubule. +Thick ascending and descending tubules resemble convoluted tubules.

Nephron is the structural and functional unit of the kidney. Each kidney consists of 1-4 million nephrons. Name 2 main component of nephron.

1. Renal corpuscle. 2. Renal tubules.

The renal cortex is the outer part of the kidney. Name 4 components of cortex of the kidney.

1. Renal corpuscles. 2. Convoluted tubules (PCT, DCT). 3. Straight tubules. 4. Connecting tubules. 5. Collecting ducts.

Name the structure: 1. Conical structures in the medulla formed by the tubules in the medulla. 2. Cortical tissue contained within the medulla.

1. Renal pyramid. 2. Renal column.

State 3 histological features of the proximal convoluted tubule (PCT).

1. Simple (tall) cuboidal epithelium. 2. Prominent brush border (microvilli). 3. Narrower, star-shaped lumen. 4. 3-5 cells per segment. 5. Cytoplasm is strongly acidophilic. 6. Longest segment of the nephron.

State 3 histological features of the distal convoluted tubule (DCT).

1. Simple cuboidal epithelium. 2. Brush border (microvilli) not visible. 3. Wider, clearly-defined lumen. 4. More than 3-5 cells per segment. 5. Cytoplasm is less acidophilic. 6. Last segment of the nephron

State 3 histological features of the collecting duct.

1. Simple cuboidal to simple columnar. 2. Merge to form bigger papillary ducts which open into minor calyx. 3. Pale staining cells. 4. Well-defined cell margins. 5. Thick basal lamina.

State 2 histological features of the thin tubules.

1. Simple squamous epithelium. 2. Regular rounded shape on transverse section. 3. Nuclei protrude only slightly into the lumen. 4. Absence of RBCs in lumen.

Ureters are fibromuscular tubes that transport urine by peristalsis from the kidney to the bladder. State 2 significant histological features of Ureter.

1. Star-shaped lumen. 2. Thick muscular wall.

Name 3 components of the medulla of kidney.

1. Straight tubules. 2. Collecting ducts. 3. Special capillary network (Vasa recta).

State 3 roles of the mesangial cells.

1. Support the capillary walls where the visceral layer of glomerular capsule does not come into contact with the capillaries. 2. Synthesize amorphous matrix. 3. May act as macrophages (clean the basal lamina of particles that have accumulated during filtration). 4. Contain receptors for vaso-constrictors (e.g. angiotensin II).

Differentiate between the urethra of male & female respectively.

1. The male's urethra is about 18 to 20 cm (7 to 8 inches) long while female urethra is much shorter, being only 4 cm (1.5 inches) long. 2. Male urethra consist of 3 parts: prostatic, membranous & spongy/penile part.

Describe briefly the two poles of renal corpuscle.

1. Vascular pole - where afferent arteriole enters and efferent arteriole leaves the glomerulus. 2. Urinary pole - where the PCT begins.

This part of renal tubules represents a transition region between the distal convoluted tubule and cortical collecting duct.

Connecting tubules.

Describe briefly the cortical labyrinths of cortex.

Cortical labyrinths consist of renal corpuscles and the proximal and distal convoluted tubules.

State the formation of uriniferous tubule.

Each nephron and its connecting tubule (which connects to a collecting duct in the medullary ray) form the uriniferous tubule.

Skeletal muscle sphincter surrounding the membranous urethra is known as?

External urethral sphincter (sphincter urethrae).

Describe briefly the histological feature of Extraglomerular mesangial cells.

Group of cells located in the concavity between: (a) afferent and efferent arterioles. (b) macula densa and glomerulus.

This type of cell of juxtaglomerular apparatus produces the hormone Renin.

Juxtaglomerular cells - produce a hormone Renin in response to a reduction in blood pressure in the afferent arteriole.

This type of cell of juxtaglomerular apparatus is found in the wall of distal convoluted tubule which comes into contact with the afferent arteriole at the vascular pole. State the function of this cell.

Macula densa cells - Detect osmolarity of fluid in distal convoluted tubules (DCT). + Cells of distal convoluted tubule appear columnar due to their compact arrangement.

What is the medullary ray of cortex?

Medullary ray is an aggregation of straight tubules and collecting ducts.

Describe briefly the histological feature of juxtaglomerular cells.

Modified smooth muscle cells of tunica media of afferent arterioles located near the vascular pole.

Cells in the Bowman's capsule in the kidneys that wrap around capillaries of the glomerulus. Name the cell.

Podocytes make up the epithelial lining of Bowman's capsule, the third layer through which filtration of blood takes place.

Name the type of muscle fibers constitute the muscularis externa of Ureter.

Smooth muscle fibers - an inner longitudinal layer, a middle circular layer and an outer longitudinal layer.

What is the umbrella cells lining the urinary bladder?

The upper layer of cells that change shape depending on the distention of the bladder.

State the epithelial lining of Ureter.

Thick epithelial lining - transitional epithelium (urothelium).

Ureter has no distinct submucosa. True or False.

True.

The apical portion of each renal pyramid, which is known as the papilla, projects into a minor calyx. The tip of the papilla is perforated by the openings of the collecting ducts. The tip of the papilla is also known as?

area cribrosa