how does excretion in human beings occur
Answers
Answer:
The removal of waste products from the body is known as excretion. In the human body, kidneys, lungs and skin perform the function of excretion. Lungs remove carbon dioxide as waste. Skin helps in the removal of waste in the form of sweat. However, the major organ involved in excretion is the urinary system, which contains the kidneys to filter the blood and form urine.
In human beings, excretion is performed by the excretory system consisting of a pair of kidneys, a pair of ureters, a urinary bladder and urethra.
The urine is formed in kidneys and passes on to the urinary bladder via the ureters. The urinary bladder stores the urine until it is excreted through the urethra.
The kidney contains numerous filtration units called the nephrons. Nephron is the structural and functional unit of the kidney. The nephrons consist of a network of capillaries associated with a cup-shaped end of a tube in which the filtered urine is collected. When the blood passes through the tube, some substances such as glucose, amino acids, salts, and water are selectively reabsorbed. The final filtrate is collected in the collecting tubule and eventually enters the ureters.
The other organs which are involved in the excretory process include:
(i) Lungs: They remove CO
2
and water. About 18 L of carbon dioxide is eliminated per day with the help of lungs.
(ii) Liver: It excretes bile pigments (such as bilirubin, biliverdin), vitamins, cholesterols and drugs along with digestive wastes.
(iii) Skin: Sweat and sebaceous glands present on the skin eliminate substances such as sterols, hydrocarbons, sebum, etc.
Answer:
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.