Question

Evaluate the processes of excretion through kidneys and sweat glands by which an animal removes waste from its body

Answer 1

Answer to the Question :

Kidneys are the primary organ that's concerned with the excretion of waste materials from the body. Along with kidneys, there are other organs like skin, lungs and liver which helps in excretion of the wastes. Here we've to focus on kidney and sweat glands present in skin and their role in excretion.

Kidneys works by the formation of urine to excrete waste products. It filters out different types of water soluble waste materials other toxins into the urine. And then the urine is passed out of the body. The main function of kidney is therefore formation of urine and excretion of body wastes and harmful chemicals into them. In most of the higher animals urea and uric acid and other nitrogenous wastes are the main excretory material and is excreted out mainly with the help of kidneys.

Nephrons are the functional unit of kidney responsible for excretion. They're present in millions in number.

Urine formation is a basically three step process namely filtration, secretion and reabsorption which occurs in different regions of the nephrons. Glomerulus is responsible for filtration. About 45 gallons of filtrate is filtered everyday about which 99 percent is reabsorbed. Which means urine consists of only one percent of the total amount of filtrate. 1 to 1.5 litre of urine is excreted per day on an average by an adult human and 25-30 gram urea is excreted per day on an average.

Skin also play a role in excretion by production of sweat through sweat glands. Sweating is responsible for eliminating excess amount of water, salts and some amount of urea. But its main function is cooling and temperature regulation. Sweat consists of a watery fluid in which NaCl , small amount of urea and lactic acid are present. So sweat glands also helps in the removal of toxins and waste materials from the body.