Excretion IN Humans and Animals

Excretion In Humans

Excretion is one of the essential life processes which is required for a living organism to survive.

     Excretion is defined as the process of removal of toxic waste materials from one's body.In humans,the nitrogenous waste products,i.e,urea,is excreted through a well established system called urinary system or excretory system.

Human Excretory System consists of a pair of Kidneys and ureters,a Urinary bladder ,and Urethra.Waste is filtered from the blood and is collected in the form of urine in each Kidney. Urine leaves the kidneys through the ureters and is temporarily stored in the Urinary Bladder. From here the urine leaves the body through urethra.

Components of Urinary System and their Functions

The human Urinary system has following main components-

• Kidneys
• Nephrons and Nephric tubules
• Collecting Tubules
• Ureters
• Urinary Bladder
• Urethra

[If you want to read about MECHANISM of urine formation then click here::Mechanism of urine formation]

1.Kidneys

Kidneys are Reddish Brown ,bean-shaped paired organs and are about 10 cm long and 6 cm wide.These lie along the posterior abdominal wall on either side of the backbone. They are protected by last two pairs of ribs. The right kidney is located at a slightly lower level than the left one, as the right side of the abdominal cavity is occupies by the Liver.In the median surface of each kidney ,a north called hilum is present. Hilum acts as a route of entry and exit for the blood vessels,lymph vessels, nerves and ureters of the kidney. The renal artery branching out from the Aorta brings oxygenated blood containing waste to the kidneys, and the renal vein takes deoxygenated and filtered blood from kidney towards heart.

     Internal Structure of Kidney
The longitudinal region of kidney shows two dsistinct regions- an outer cortex and an inner medulla. The outer cortex has a dark red colour, while the inside of the medulla is the in pale colour. The cortex region consists Malphagian body, proximal; and distal convoluted tubules and the Medulla contains Henle's Loop and the main collecting ducts.