Human Excretion and Kidney Physiology

Dialysis works by using a semipermeable membrane to separate waste products from the blood. The movement of small molecules through this membrane based on concentration gradients is known as osmosis.

Dialysis is a medical procedure used to perform the function of the kidneys for patients whose kidneys are failing, specifically to remove waste products and excess fluid from the blood.

This is because some glucose is used up in respiration of kidney cells.

The main excretory organ in man, are the kidneys. They excrete urine. The right kidney is lower than the left because of the presence of liver, in the abdominal cavity.

Gout is a medical condition, usually characterized by recurrent attacks, of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe, is most commonly affected.

The glomerulus lining is such that it only allows small molecules to filter through, like glucose, plasma, ions like sodium and potassium, urea, etc. The larger molecules, like blood cells and protein, cannot pass through the glomerulus. Thus protein is not present in urine.

The human spleen is an organ, that creates lymphocytes for the destruction and recycling, of old red-blood cells. The spleen is also a blood reservoir. It supplies the body with blood in emergencies, such as, a bad cut. The spleen does not help in excretion.

Anthrax is an acute disease, caused by the bacterium, Bacillus anthracis. Most forms of the disease are lethal, and it affects both humans and other animals. There are effective vaccines against anthrax, and some forms of the disease respond well, to antibiotic treatment. A diuretic may not be effective in anthrax.

The process by which, the water content and the ion concentration is regulated and kept constant, in the cells is known as osmoregulation. Kidneys perform both excretion and osmoregulation.

The final passageway for the flow of urine, is the urethra, a thin-walled tube that conveys urine, from the floor of the urinary bladder, to the outside. The opening to the outside is the external urethral orifice. The mucosal lining of the urethra is transitional epithelium. The wall also contains smooth muscle fibers, and is supported by connective tissue.

The urinary bladder is a temporary storage reservoir for urine. It is located in the pelvic cavity, posterior to the symphysis pubis, and below the parietal peritoneum. The size and shape of the urinary bladder, varies with the amount of urine it contains, and with pressure it receives from surrounding organs.

The gallbladder is a small pear-shaped organ, that stores and concentrates bile. The gallbladder is connected to the liver by the hepatic duct. It is approximately 3 to 4 inches (7.6 to 10.2 cm) long and about 1 inch (2.5 cm) wide. The function of the gallbladder, is to store bile and concentrate.

Each ureter is a small tube, about 25 cm long, that carries urine from the renal pelvis, to the urinary bladder. It descends from the renal pelvis, along the posterior abdominal wall, behind the parietal peritoneum, and enters the urinary bladder, on the posterior inferior surface.

It is the type of excretion, in which ammonia is the main nitrogenous waste material. Such animals are called ammonotetic. It is found in aquatic animal groups like, sponges, coelentrates, crustaceans, echinoderms, bony fish, tadpole larvae and salamander.

Urea is the major end product of nitrogen metabolism, in humans and mammals. Ammonia, the product of oxidative deamination reactions, is toxic in even small amounts, and must be removed from the body. The urea cycle or the ornithine cycle, describes the conversion reactions of ammonia into urea. Since these reactions occur in the liver, the urea is then transported to the kidneys, where it is excreted.