HUMAN EXCRETORY SYSTEM Made Easy - Human Urinary System Simple Lesson

JOIN OUR CHANNEL
Get the LECTURE HANDOUTS & FLASHCARDS from this topic :

CLICK THE JOIN BUTTON
Or
Join our Community at Patreon :   / medsimplified  

Merch STORE : bit.ly/2KaICaE

Excretion is the process of removal of toxic wastes from the body of an organism. The major wastes produced by us are: Carbon dioxide and Urea. Carbon dioxide is produced by the process of respiration and urea is produced by the decomposition of unused proteins in the liver. There are different organs which removes waste from the body. These are lungs and kidneys. Our lungs excrete carbon dioxide and kidneys urea.

Urinary system
The kidneys are large, bean-shaped organs which are present on each side of the vertebral column in the abdominal cavity. Humans have two kidneys and each kidney is supplied with blood from the renal artery. The kidneys remove from the blood the nitrogenous wastes such as urea, as well as salts and excess water, and excrete them in the form of urine. This is done with the help of millions of nephrons present in the kidney. The filtrated blood is carried away from the kidneys by the renal vein (or kidney vein). The urine from the kidney is collected by the ureter (or excretory tubes), one from each kidney, and is passed to the urinary bladder. The urinary bladder collects and stores the urine until urination. The urine collected in the bladder is passed into the external environment from the body through an opening called the urethra.

Kidneys
The kidney's primary function is the elimination of waste from the bloodstream by production of urine. They perform several homeostatic functions such as:-

Maintain volume of extracellular fluid
Maintain ionic balance in extracellular fluid
Maintain pH and osmotic concentration of the extracellular fluid.
Excrete toxic metabolic by-products such as urea, ammonia, and uric acid.
The way the kidneys do this is with nephrons. There are over 1 million nephrons in each kidney; these nephrons act as filters inside the kidneys. The kidneys filter needed materials and waste, the needed materials go back into the bloodstream, and unneeded materials becomes urine and is gotten rid of.


Ureter
The ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the human adult, the ureters are usually 25–30 cm (10–12 in) long. In humans, the ureters arise from the renal pelvis on the medial aspect of each kidney before descending towards the bladder.

Urinary bladder
The urinary bladder is the organ that collects waste excreted by the kidneys prior to disposal by urination. It is a hollow muscular, and distensible (or elastic) organ, and sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra.

Urethra is a tube which connects the urinary bladder to the outside of the body. In humans, the urethra has an excretory function in both genders to pass.

Respiratory system
One of the main functions of the lungs is to diffuse gaseous wastes, such as carbon dioxide, from the bloodstream as a normal part of respiration.

Biliary system
The liver detoxifies and breaks down chemicals, poisons and other toxins that enter the body. For example, the liver transforms ammonia (which is poisonous) into urea in fish, amphibians and mammals, and into uric acid in birds and reptiles. Urea is filtered by the kidney into urine or through the gills in fish and tadpoles. Uric acid is paste-like and expelled as a semi-solid waste (the "white" in bird excrements). The liver also produces bile, and the body uses bile to break down fats into usable fats and unusable waste.

Skin
Sweat glands in the skin secrete a fluid waste called sweat or perspiration; however, its primary functions are temperature control and pheromone release. Therefore, its role as a part of the excretory system is minimal. Sweating also maintains the level of salt in the body.