Urinary System Anatomy and Function: Kidneys, Nephrons, and Urine Pathways

What are the main organs of the urinary system?

2 kidneys, 2 ureters, urinary bladder, and urethra.

What functions does the urinary system perform to maintain homeostasis?

Regulates blood volume, pressure, pH, and concentration of electrolytes; reabsorbs glucose; excretes wastes; releases hormones like renin and EPO.

Where are the kidneys located?

Just above the waist between the peritoneum and the posterior wall of the abdomen (retroperitoneal space).

What is the anatomical position of the right kidney compared to the left?

The right kidney is slightly lower than the left due to the position of the liver.

What is the path of urine drainage starting from the nephron?

Nephron → Collecting duct → Renal hilum → Minor calyx → Renal cortex → Major calyx → Renal artery → Renal medulla → Renal pelvis → Renal vein → Ureter → Urinary bladder.

What are the main components of a nephron?

Proximal convoluted tubule (PCT), Loop of Henle, distal convoluted tubule (DCT), and collecting duct.

What type of epithelium lines the ureters?

Transitional epithelium.

What are the three layers of the ureter?

Mucosa (transitional epithelium), Muscularis (2 layers of smooth muscle), Adventitia (connective tissue layer).

What is the function of the detrusor muscle in the urinary bladder?

It contracts to facilitate the expulsion of urine.

What is the trigone in the urinary bladder?

A smooth-surfaced triangular area marked with openings of the ureters and urethra.

What is the length of the female urethra?

3 to 4 cm long.

What are the components of the male urethra?

Prostatic urethra (2.5 cm), Membranous urethra (0.5 cm), Spongy (penile) urethra (15 cm).

What is the internal urethral sphincter?

A smooth muscle structure under involuntary control located at the base of the bladder.

What is the external urethral sphincter?

A skeletal muscle structure under voluntary control located in the pelvic floor.

What is the role of the juxtaglomerular apparatus?

It regulates blood pressure and filtration rate in the kidneys.

What is the significance of microvilli in the nephron?

They increase the surface area for reabsorption in the proximal convoluted tubule.

What is the renal pelvis?

The funnel-shaped structure that collects urine from the renal calyces and leads to the ureter.

What is the renal hilum?

The entry and exit point for blood vessels, nerves, and the ureter in the kidney.

What is the function of the renal column?

It separates the renal pyramids and contains blood vessels and cortical tissue.

What are the renal pyramids?

Triangular structures in the renal medulla that contain the nephron loops and collecting ducts.

What is the renal capsule?

A fibrous outer layer that protects the kidney.

What is the function of the collecting duct?

It collects urine from multiple nephrons and channels it into the renal pelvis.

What is the role of the loop of Henle?

It concentrates urine and reabsorbs water and salts.

What is the significance of the macula densa?

It senses sodium concentration and helps regulate glomerular filtration rate.

What are mesangial cells?

Cells located between the capillaries of the glomerulus that help regulate blood flow.

What is the function of the renal artery?

It supplies blood to the kidneys.