Main Functions Of The Urinary System

Published Date: 02 Nov 2017

The primary function of the digestive system is to break down food both mechanically and by the use of enzymes, so that it can be used by the body for energy and cell growth and repair. The human digestive system consists of a large number of organs and processes with the combined functions of breaking down our food into smaller molecules which can be used to produce energy and for other nutritional purposes; and excreting the waste consumed and produced by the system. Basically, the digestive system can be considered as a food pipe initiating from the mouth and terminating in the anus with diversifications at different stages of its progression from the mouth to anus.

The start of the process - The mouth: The digestive process begins in the mouth. Food is partly broken down by the process of chewing and by the chemical action of salivary enzymes (these enzymes are produced by the salivary glands and break down starches into smaller molecules).

The esophagus - After being chewed and swallowed, the food enters the esophagus. The esophagus is a long tube that runs from the mouth to the stomach. It uses rhythmic, wave-like muscle movements (called peristalsis) to force food from the throat into the stomach. This muscle movement gives us the ability to eat or drink even when we're upside-down.

In the stomach - The stomach is a large, sack-like organ that churns the food and bathes it in a very strong acid (gastric acid). Food in the stomach that is partly digested and mixed with stomach acids is called chyme.

In the small intestine - After being in the stomach, food enters the duodenum, the first part of the small intestine. It then enters the jejunum and then the ileum (the final part of the small intestine). In the small intestine, bile (produced in the liver and stored in the gall bladder), pancreatic enzymes, and other digestive enzymes produced by the inner wall of the small intestine help in the breakdown of food.

In the large intestine - After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food. Many microbes (bacteria like Bacteroides), in the large intestine help in the digestion process. The first part of the large intestine is called the Cecum (the appendix is connected to the Cecum). Food then travels upward in the ascending colon. The food travels across the abdomen in the transverse colon, goes back down the other side of the body in the descending colon, and then through the sigmoid colon.

The end of the process - Solid waste is then stored in the rectum until it is excreted via the anus.

Urinary System [P7]

The body takes nutrients from food and uses them to maintain all body functions including energy and self-repair. After the body has taken what it needs from the food, waste products are left behind in the blood and in the bowel. The urinary system works with the lungs, skin, and intestines all of which also excrete wastes to keep the chemicals and water in your body balanced. Adults eliminate about a quart and a half of urine each day. The amount depends on many factors, especially the amounts of fluid and food a person consumes and how much fluid is lost through sweat and breathing. Certain types of medications can also affect the amount of urine eliminated.

Main functions of the urinary system are:

Kidneys - The kidneys are two bean-shaped organs that lie just below the ribs on your back. The kidneys are filled with Nephrons that filter urea from blood. The million Nephrons in each kidney perform the complicated task of removing the urea from blood and putting the correct electrolytes back in. The kidneys also release important hormones for red blood cell production, blood pressure regulation and calcium regulation.

Ureter - Each kidney contains a tube called a Ureter, measuring up to 18 inches long. The Ureter transports the waste liquid, in small gushes, to your body's holding tank, called the bladder.

Bladder – The bladder is a small hollow balloon like structure located in the lower abdomen. The bladder's function is to store urine until your body is ready to excrete it. The bladder is made of smooth muscles that can expand as more urine enters and contract to empty urine from the body.

Urethra - The urethra, like the Ureter, is a tube that connects to the bladder, but this tube opens up to the outside world, allowing the removal of waste liquid outside the body.

Renal Artery and Renal Vein - are the blood vessels responsible for bringing blood to and taking blood away from the kidneys, respectively. Blood in the Renal Artery contains glucose, oxygen, and cellular waste products. In the Renal vein, the blood has been filtered, and is free of cellular waste and any other impurities.

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Body Fluid Compartments

Water and ions dissolved in it are distributed in the intracellular and extracellular fluid compartments.

Approximately 60% of the total body water is found within cells.

Approximately 40% of the total body water is found outside cells, mainly in interstitial fluid, plasma of blood, and lymph.

Fluid balance is the concept of human homeostasis that the amount of fluid lost from the body is equal to the amount of fluid taken in. Water is necessary for all life on Earth. Humans can survive for 4–6 weeks without food, but for only a few days without water.

The amount of water varies with the individual, as it depends on the condition of the subject, the amount of physical exercise, and on the environmental temperature and humidity. The common misconception that everyone should drink two litres of water per day is not supported by scientific research. For example, people in hotter climates will require greater water intake than those in cooler climates. An individual's thirst provides a better guide for how much water they require rather than a specific, fixed number. A more flexible guideline is that a normal person should urinate 4 times per day, and the urine should be a light yellow colour.

The urinary system should also regulate the chemical composition of body fluids by removing metabolic wastes and retaining the proper amounts of water, salts, and nutrients. Components of this system in vertebrates include the kidneys, liver, lungs, and skin.

The total amount of water and electrolytes in the body does not change unless the person is growing, gaining weight, or losing weight.

Thirst - The sensation of thirst increases if extracellular fluid becomes more concentrated or if blood pressure decreases.

Ions - Sodium ions are one of the dominant extracellular ions. ADH increases water reabsorption from the nephron, and the hormone increases sodium loss in the urine. When phosphate and sulphate levels in the filtrate are low, nearly all phosphate and sulphate ions are reabsorbed. When levels are high, excess is lost in the urine.