Human Excretion and Kidney Physiology

The average volume of urine excreted by a healthy adult per day is typically between 1 and 2 liters.

An artificial kidney, or hemodialysis machine, uses the principle of dialysis to remove waste products and excess fluids from the blood when the natural kidneys fail.

Birds and lizards are uricotelic, meaning they excrete nitrogenous waste primarily in the form of uric acid. This is a water-conserving adaptation, as uric acid is relatively insoluble and excreted as a white paste.

Dialysis is a medical procedure used to perform the functions of the kidneys, specifically filtering waste products and excess fluid from the blood when the kidneys fail.

Chlorella is very popular in Japan. It is also used as a nutritional supplement with possible effects on the metabolic rate. It can reduce mercury levels in humans by chelation of mercury to the cell wall of the organism.

In adult frogs, the functional and permanent kidney is the mesonephros, which is also commonly referred to as the opisthonephros in comparative anatomy. Pronephros is functional only in embryonic or larval stages of lower vertebrates. Metanephros is characteristic of amniotes like reptiles, birds, and mammals.

The kidneys are the primary organs responsible for filtering metabolic waste products from the blood and excreting them as urine.

Kidney stones are most commonly composed of calcium oxalate. These form when high levels of calcium and oxalate are present in the urine.

Cuboidal epithelium is composed of cube shaped cells that provide mechanical support to the various organs such as kidney tubules, ducts of salivary glands, etc. The nuclei of these cells are usually located at the centre.

The skin is an excretory organ that eliminates waste products, primarily water, salts, and small amounts of urea, through sweat.

It is the metanephros which goes on to become the adult kidney.

For nephrons which are in the outer cortex and do not have vasa recta or long loops of Henle, the efferent arterioles supply the peritubular capillaries. Flow occurs when the pressure at one end of a tube is made greater than that at the other end.

The ureteric bud forms the collecting system and if it splits before it enters the kidney, the result, which is not uncommon, is that the kidney will have two ureters.

As erythropoietin is a protein, it cannot be given orally as it would be digested in the gut. It is usually given subcutaneously or less commonly, intravenously.

Potassium is freely filtered and then most of the filtered potassium is reabsorbed. Potassium excretion is then controlled by the secretion of potassium by the principal cells in the collecting ducts.