Bladder in the context of "Nitrogenous waste"

Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. For example, placental mammals expel urine from the bladder through the urethra, which is part of the excretory system. Unicellular organisms discharge waste products directly through the surface of the cell.

During life activities such as cellular respiration, several chemical reactions take place in the body. These are known as metabolism. These chemical reactions produce waste products such as carbon dioxide, water, salts, urea and uric acid. Accumulation of these wastes beyond a level inside the body is harmful to the body. The excretory organs remove these wastes. This process of removal of metabolic waste from the body is known as excretion.

Urine, excreted by the kidneys, is a liquid containing excess water and water-soluble nitrogen-rich by-products of metabolism including urea, uric acid, and creatinine, which must be cleared from the bloodstream. Urinalysis detects these nitrogenous wastes in mammals.

In placental mammals, urine travels from the kidneys via the ureters to the bladder and exits the urethra through the penis or vulva during urination. Other vertebrates excrete urine through the cloaca.

Metabolic wastes or excrements are substances left over from metabolic processes (such as cellular respiration) which cannot be used by the organism (they are surplus or toxic), and must therefore be excreted. This includes nitrogen compounds, water, CO₂, phosphates, sulphates, etc. Animals treat these compounds as excretes. Plants have metabolic pathways which transforms some of them (primarily the oxygen compounds) into useful substances.

All the metabolic wastes are excreted in a form of water solutes through the excretory organs (nephridia, Malpighian tubules, kidneys), with the exception of CO₂, which is excreted together with the water vapor throughout the lungs. The elimination of these compounds enables the chemical homeostasis of the organism.

Urination is the release of urine from the bladder through the urethra in placental mammals, or through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, or, rarely, emiction, and known colloquially by various names including peeing, weeing, pissing, and euphemistically number one. The process of urination is under voluntary control in healthy humans and other animals, but may occur as a reflex in infants, some elderly individuals, and those with neurological injury. It is normal for adult humans to urinate up to seven times during the day.

In some animals, in addition to expelling waste material, urination can mark territory or express submissiveness. Physiologically, urination involves coordination between the central, autonomic, and somatic nervous systems. Brain centres that regulate urination include the pontine micturition center, periaqueductal gray, and the cerebral cortex.

Bladder cancer is the abnormal growth of cells in the bladder. These cells can grow to form a tumor, which eventually spreads, damaging the bladder and other organs. Most people with bladder cancer are diagnosed after noticing blood in their urine. Those suspected of having bladder cancer typically have their bladder inspected by a thin medical camera, a procedure called cystoscopy. Suspected tumors are removed and examined to determine if they are cancerous. Based on how far the tumor has spread, the cancer case is assigned a stage 0 to 4; a higher stage indicates a more widespread and dangerous disease.

Those whose bladder tumors have not spread outside the bladder have the best prognoses. These tumors are typically surgically removed, and the person is treated with chemotherapy or one of several immune-stimulating therapies. Those whose tumors continue to grow, or whose tumors have penetrated the bladder muscle, often have their bladder surgically removed (radical cystectomy). People whose tumors have spread beyond the bladder have the worst prognoses; on average they survive a year from diagnosis. These people are treated with chemotherapy and immune checkpoint inhibitors, followed by enfortumab vedotin.

The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In adult humans, the ureters are typically 20–30 centimeters long and 3–4 millimeters in diameter. They are lined with urothelial cells, a form of transitional epithelium, and feature an extra layer of smooth muscle in the lower third to aid peristalsis.The ureters can be affected by diseases including urinary tract infections and kidney stones. Stenosis is the narrowing of a ureter, often caused by chronic inflammation. Congenital abnormalities can cause development of two ureters on the same side or abnormally placed ureters. Reflux of urine from the bladder into the ureters is common in children.

The ureters have been identified for at least two thousand years, with the word ureter stemming from the stem uro- relating to urinating and seen in written records since at least the time of Hippocrates. It is, however, only since the 16th century that the term "ureter" has been consistently used to refer to the modern structure, and only since the development of medical imaging in the 20th century that techniques such as X-ray, CT, and ultrasound have been able to view the ureters. The ureters are also seen from the inside using a flexible camera, called ureteroscopy, which was first described in 1964.

The prostate is an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemically, and physiologically. Anatomically, the prostate is found below the bladder, with the urethra passing through it. It is described in gross anatomy as consisting of lobes and in microanatomy by zone. It is surrounded by an elastic, fibromuscular capsule and contains glandular and connective tissue.

The prostate produces and contains fluid that forms part of semen, the substance emitted during ejaculation as part of the male sexual response. This prostatic fluid is slightly alkaline, and milky or white in appearance. The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. The prostatic fluid is expelled in the first part of ejaculate, together with most of the sperm, because of the action of smooth muscle tissue within the prostate. In comparison with the few spermatozoa expelled together with mainly seminal vesicular fluid, those in prostatic fluid have better motility, longer survival, and better protection of genetic material.