Urinary Anatomy and Kidney Dissection Lab 40. Urinary Anatomy and Kidney Dissection

Urinary Anatomy Kidneys: filters blood, produces urine Ureters: convey urine to bladder Bladder: holding tank Urethra: carries urine to the outside for elimination

Kidneys One on each side, between T12 and L3 Left sits higher than right (due to ?) Retroperitoneal: behind the peritoneal cavity (so has no serous membranes) Between peritoneum and dorsal body wall

Nephrons Kidney cells called nephrons filter the blood Each consists of: renal corpuscle Bowman’s Capsule glomerulus renal tubule (PCT, DCT, loop of Henle)

Renal Corpuscle Glomerulus = tangled mass of 50 or so fenestrated capillaries that receive blood from an afferent vessel. Bowman’s capsule: kind of like a really tiny pericardium for the glomerulus Capsular space: like pericardial space, between glomerulus and Bowman’s capsule Fluid is squeezed out of glomerular caps into the capular space, then enters the tubule

Renal Corpuscle

Renal Histology Bowman’s capsule: Parietal epithelium (tissue type?) Visceral epithelium (continuous with parietal at vessel points)

43.2 - Kidney Section Examine the slide on low power. Try to identify by sight: capsule, renal cortex, glomeruli and tubules. On medium or high power, draw and clearly label a portion of the renal cortex that includes a glomerulus. In your drawing, include and label: glomerulus, Bowman’s capsule, renal corpuscle, parietal layer of Bowman’s capsule (type of epithelium here), capsular space, and tubules. Indicate the type of epithelia found in the tubules and the type of epithelia that lines the capsular space (same as above, in the parietal layer).

43.3 – Urinary Tract Ureter  bladder  urethra Mucosa lined with a transitional epithelium (almost everywhere). Why mucosa? Lamina propria (Smooth) muscle layer Outer connective tissue layer

Ureter Ureter has two layers of smooth muscle: concentric and longitudinal

A. Ureter Start by looking at the slide on low power. At medium power, draw and label: the lumen, epithelial layer (indicate the type), lamina propria, smooth muscle layer and outer connective tissue layer (if present). Using the high power objective, take a good look at the epithelial layer of the ureter. Rhetorical question- Could you tell this apart from stratified squamous; how?

Bladder Mucosa of bladder has rugae Bladder muscle layers = detrussor muscle, which contracts to force urine into the urethra

B. Urinary Bladder Draw and clearly label the urinary bladder. In your sketch, include the following: epithelia (and the type!), lamina propria, detrusor muscle. I recommend using the medium power, but you can choose.

Urethra Males have longer urethras that carry semen as well as urine. The female urethra is only about 2 inches long and carries urine only. Both have external urethral sphincter made of skeletal muscle, allowing for conscious control of urination Urethral lining is transitional at neck, stratified columnar in the middle, and stratified squamous near the external orifice Lamina propria is very elastic, mucin secreting cells in the pockets of longitudinal folds Males: mucous glands extend into lamina propria Females: lamina propria has lots of veins and is surrounded by layers of concentric smooth muscle

C. Urethra (female) On medium power, draw and clearly label the urethra. In your sketch, include: epithelia (type), lamina propria and muscle (is this smooth muscle or skeletal, or both?) Be sure to take a close look at the epithelial layer. NOTE: The urethral lining consists of a stratified epithelium that varies from: transitional at the neck of the bladder to stratified squamous near the external urethral orifice (in females). If this is the case, where are you in the urethra?

Kidneys

External anatomy Connective tissue layers Renal capsule (inner layer): collagen fibers Adipose capsule: thick layer of adipose around renal capsule Renal fascia: Dense irregular CT, penetrates down to renal capsule Hilum: medial surface indentation; entry/exit point of blood vessels, lymph, nerves, ureter

Internal Anatomy Renal cortex: Outer layer just under caspule, reddish brown. Renal medulla: 6 to 18 renal pyramids (point toward hilum) Tips are called renal papilla Pyramids separated by renal columns “Renal lobe” = one pyramid, overlying cortex and adjacent renal columns

Interlobar arteries

Internal Anatomy – urine flow Renal papilla in each pyramid contain ducts that drain into a minor calyx 4 - 5 minor calyces combine to form a major calyx 2 - 3 major calyces combine to form the renal pelvis, a funnel-shaped chamber found at the hilum. Renal pelvis is connected to ureter

Kidney Dissection Working in groups of two or three, examine the kidney. Locate the hilum. What major ‘pipes’ enter and exit the kidney here? Can you see the adipose capsule and the renal capsule? Follow the procedures in your lab notebook. Be sure to look for: the cortex, medulla, renal columns, renal pyramids, renal papilla, minor and major calyces, renal pelvis and interlobar arteries.

Dissection Glove up Get tools, kidney and rinse it off Look at external anatomy: hilum, connective tissue layers Cut in half longitudinally (into ant/post halves) Internal anatomy: cortex, medulla, renal columns, renal pyramids, renal papilla, minor and major calyces, renal pelvis and interlobar arteries.

To turn in: Four drawings Review Sheet 40 Due next Thurs