With a neat labelled diagram describe the Excretory system in human beings
Answers
Answer:
The excretory system of humans collects fluid wastes from the body and helps them to be excreted. It consists of the following main organs – two kidneys, two ureters, bladder and urethra.
Explanation:
The kidneys are bean-shaped organs located in the back of the human body, just above the waist. Every human has two kidneys. Blood flows continuously in our kidneys. The renal artery or kidney artery brings dirty blood containing waste materials to the kidney. Therefore, the function of the kidney is to excrete toxins such as urea and some other waste salts and excess water present in the blood in the form of a yellowish liquid called urine. Renal Vein or Kidney Vein carries the cleaned blood by the kidney.
A ureter from each kidney opens into the bladder. It carries urine into bladder.Here urine accumulates. The bladder is large and stores urine until we go to the toilet. Urine exits the human body through a tube called the urethra, which is connected to the bladder. The structure of the kidney shows that each kidney is made up of a large number of excretory units called nephrons. On the upper part of the nephron there is a cup-shaped bag, which is called 'Bowman's capsule'. At the bottom of Bowman's capsule is a tubule. Together these two form nephrons. One end of the tube is attached to Bowman's capsule and the other to the urine-collecting collection tube of the kidney. Bowman's capsule contains a bundle of blood capillaries, it is called 'Glomerulus'.
One end of the glomerulus is attached to the renal artery which carries dirty blood containing urea waste and the other end is connected to the renal vein for urea-free blood. The job of the glomerulus is to clean the blood flowing through it. Only small molecules of elements such as glucose, amino acids, salts, urea and water present in the blood pass through it and get cleaned and deposited in Bowman's capsule. Large molecules like proteins and blood cells cannot pass through the glomerulus capillaries and remain in the blood. The tubule of the nephron allows the reabsorption of select useful substances such as glucose, amino acids, salts and water into the blood cells. However, urea remains in the tubule and cannot be reabsorbed into the blood capillaries.
As discussed above, dirty blood containing wastes such as urea enters the glomerulus and cleans the blood. During filtration, glucose, amino acids, salts, urea and water present in the blood pass through the Bowman's capsule and then enter the tubule of the nephron. Here the useful substances are reabsorbed into the blood through the blood capillaries surrounding the tubule. The liquid left in the tubule of the nephron is urine. The nephron carries this urine to the collecting duct of the kidney, from where it is carried to the ureter and from here the urine goes to the bladder. After some time urine is expelled from the body through the urethra.
