what is human exceretory system
Answers
Kidney:
The excretory system of human beings includes a pair of kidneys, a pair of ureters,a urinary bladder and a urethra. Kidneys are located on either side of vertebral column. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through urethra.
Just as carbon dioxide is removed from the blood in the lungs , nitrogenous wastes such as urea are removed from blood in the kidneys. A cluster of very thin walled blood capillaries perform this. each capillary cluster is associated with cup shaped end of a tube that collects filtered urine. Each kidney has large number of these filtration units called nephron.Some substances in initial filtrate such as glucose, amino acids , water are selectively reabsorbed as the urine flows through the tube.
The urine forming in each kidney enters ureter which connects the kidneys with urinary bladder. Urine is stored in urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through urethra. The bladder is muscular so we can usually control the urge to urinate as a result of nervous control.
Role of Nephron:
Nephrons are the basic filtering units of kidneys. Each kidney possesses large number of nephrons, approximately 1-1.5 million. The main components of the nephron are glomerulus, Bowman’s capsule, and a long renal tubule
Functioning/Process of a nephron:
The blood enters the kidney through the renal artery, which branches into many capillaries associated with glomerulus.
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The water and solute are transferred to the nephron at Bowman’s capsule. ↓
In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine. ↓
The filtrate then moves down into the loop of Henle, where more water is absorbed. ↓
From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collects urine from many nephrons. ↓
The urine formed in each kidney enters a long tube called ureter. From ureter, it gets transported to the urinary bladder and then into the urethra.
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a system in which wastes are excreted out from the human body by filtration in kidney