Exercise 40

Kidneys are located in retroperitoneal position (between the dorsal body wall and the parietal peritoneum) in the superior lumbar region. Extending approximately from T12 to L3, the kidneys receive some protection from the lower part of the rib cage. The right kidney is crowded by the liver and lies slightly lower than the left.

Ureters are located at the level of L2 as a continuation of the renal pelvis. It descends behind the peritoneum and runs obliquely through the posterior bladder wall. This arrangement prevents backflow of urine because an increase in bladder pressure compresses and closes the distal ends of the ureters. They are a paired tubes that transport urine from the kidneys to the urinary bladder.

Urinary bladder is located retroperitoneally on the pelvic floor just posterior to the pubic symphysis. In male, the prostate lies inferior to the bladder neck which empties into the urethra. In females, the bladder is anterior to the vagina and uterus. It is a temporary storage reservior for urine.

Urethra is located below the bladder. It is located at the pelvic floor cavity. It is a tube that carries urine from the bladder to the body exterior. In males, it is located at the front of rectum. In female, it is located at the anterior end of the uterus in the upper region of vagina.

Female urethra is only 3-4 cm (1.5 inches) long and fibrous connective tissue binds it tightly to the anterior vaginal wall.

Male urethra is approximately 20 cm (8 inches) long and has three regions:

• 1. The prostatic urethra about 2.5 cm (1 inch) long, runs within the prostate
• 2. The intermedate part of the urethra (or membranous urethra), which runs through teh urogenital diaphgram, extends 2 cm from the prostate to the beginning of the pelvis.
• 3. The spongy urethra, about 15 cm long, passes through hte penis and opens at its tip via the external urethral orifice.

By virtue of the processes of cleansing the blood of waste, removing excess fluids and generally keeping other fluids in balance.

To protect the kidney from possible damage and injuries and help support the weight of the organ.

To transport urine from the kidneys to the urinary bladder.

The indentation of the bean shape is called the 'hilum.' The hilum is the site where the renal artery enters the kidney and both the renal vein and ureter exit.

The outer region of the kidney; extensions of the cortical tissue, contains about one million blood filtering nephrons.

The inner region of the kidney contains 8-12 renal pyramids. The pyramids empty into the calyx. They are responsible for maintaining the balance of water and salt within the blood.

Areas of tissues that are more like the cortex in appearance, which segregate and dip inward between the pyramids.

To collect urine, which drains continuously from the papillae, and empty it into the renal pelvis

To collect urine, which drains continuously from the papillae, and empty it into the renal pelvis

CORTEX ONLY: PCT (proximal convoluted tubule), DCT (distal convoluted tubule), afferent arterioles, efferent arterioles, glomerulus, peritubular capillaries, interlobular artery, interlobular vein.

MEDULLA and/or CORTEX: vasa recta, nephron loop, collecting duct.

To move deoxygenated blood from arcuate vein to renal vein

To move oxygenated blood from segmental artery to arcuate artery

To carry blood into the glomerulus of the nephron.

To carry blood away from the glomerulus.

To reabsorb Sodium and Water, and secrete Hydrogen, and Potassium and it is lined with simple cuboidal epithelium. It is confined to the cortex, and lack microvilli

ADH --> more permeable to waterAldosterone --> fine tunes reabsorption of the remaining Na+.ANP --> exerts serveral effects that lower blood Na+ content, including direct inhibition of Na+ reabsorption at the CD.

Responsible for the reabsorption of glucose, amino acids, various ions, and water and the walls of the PCT are formed by cuboidal epithelial cells with large mitochondria, and their apical (luminal) surfaces bear dense microvilli. This brush border dramatically increases the surface area and capacity for reabsorbing water and solutes from the filtrate and secreting substances to it.

to produce filtrate.

To reabsorb Na+, K+, Cl- and secrete urea and it is line with simple squamous epithelium.

To reabsorb water.

To play an important role in forming concentrated urine and to preserve the gradient by preventing rapid removal of salt from the medullary interstitial space and by removing reabsorbed water.

To help transport urine and reabsorb water.

Principal cells: have sparse, short microvilli, responsible for maintaining the body's water and Na+ balance.

Intercalated cells: cuboidal cells, maintain the acid - base balance of the blood.

to cling closely to adjacent renal tubules and empty into nearby venules

A cup shaped hollow structure, to completely surrounds the glomerulus. It also has an external parietal layer and a visceral layer that clings to the glomerular capillaries.

It is simple squamous epithelium and to contribute to the capsule structure, but plays no part in forming filtrate.

It consists of highly modified, branching epithelial cells called podoctes and to cling to the glomerular capillaries.

They are cuboidal epithelial cells with large mitochondria, and their apical surfaces bear dense microvilli. To reabsorb all of the glucose and amino acids in the filtrate and 65% of the Na+ and water.

1. cortical nephron: accounts for 85% of the nephrons in the kidneys. They are located entirely in the cortex.

2. juxtamedullary nephron: originate close to the cortex - medulla junction, and they play an important role in the kidney's ability to produce concentrated urine. They have long nephron loops that deeply invade the medulla.

To propel urine from the kidneys to the urinary bladder.

To carry glandular secretions to areas where they are needed and act as a supporting layer that holds the epithelium in place.

To surround the ureter and encompass the blood vessels and lymphatics that travel along the ureter.

To secrete mucus, which coats and protects the surface of the cells.

To store fat to keep visceral organs in position.

To change volume of the bladder for storage capacity of urine.

To act as a supporting layer that holds the epithelium in place.

To surround and encompass the blood vessels and lymphatics that travel along bladder.

To elongate when the bladder starts to fill, allowing an increase in bladder volume.