GENITO-URINARY SYSTEM

Under this topic, we will discuss the structure and functions of the kidneys, ureters, bladder, and urethra. This system produces urine.

1. Kidneys: These are bean-shaped organs that are about the size of a fist. They are located near the middle of the back, just below the rib cage, one on each side of the spine. The kidneys basic functional unit of the kidney is the nephron. 

2. The nephrons produce the urine. Every day, a the kidneys process about 200 quarts of blood to filter out about 2 quarts of waste products and extra water. The wastes and extra water become urine, which flows to the bladder through tubes called ureters. 

3. The ureters are the narrow tubes that carry urine from the kidneys to the bladder. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters. 

4. The bladder stores urine until it is released  through urination. 

5. The urethra is a tube which connects the urinary bladder to the outside of the body, and carries semen in men, and urine in women and men. 

6. The external urethral sphincter is a muscle that allows voluntary control over urination.

STRUCTURE OF THE NEPRON

Diagram of nephron

The nephron consist of the:

1. Bowmans capsule: This is the cup-like structure that house the glomerulus (tuft of capillaries). Filtration of the blood occurs in the glomerulus. This is the first step in the urine production.

2. Proximal convoluted tubule: Re-absorption of nutrients filtered out occurs here. This include glucose, calcium, potassium, water, and amino acids.

3. Loop of Henle; Pumping out of sodium and water occurs here.

4. Distal convoluted tubule: Secretion of into the urine of hydrogen and potassium occurs here.

5.  Collecting duct:  More water is pump out here leading to urine concentration.

Diagram summarizing the functions of the nephron.