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Excretion
The removal of harmful and unwanted toxic waste products of metabolism is
known as excretion Osmoregulation
The process by which the water content and the ion concentration is regulated and kept constant in the cell is known as osmoregulation Excretory wastes
This consists of respiratory wastes, nitrogenous wastes and bile pigments - The kidneys function as a pair of filters through which about one litre of blood circulates each minute. The entire blood in the body passes through them in 5 - 6 minutes. In a day it filters 1800 litres of blood which is 400 times the blood volume.
- Tea, coffee and alcohol are beverages that increase the formation of urine. They are termed diuretics.
- The human kidney contains more than 1.2 million nephrons
- When a
kidney is damaged or diseased, the other kidney is able to compensate for
it. So a person can lead a normal life with only one kidney
- A normal adult excretes 1 - 1.8 litres
of urine per day
- An artificial kidney (dialysing machine) is used for dialysis. When the kidneys of a patient stop functioning, life can be prolonged through dialysis.
- Kidney transplants have had good success rates and have given fresh
lease of life to patients
- Nitrogenous wastes consists of ammonia, urea, uric
acid and amino acids
- Excretion and osmoregulation takes place in the
amoeba through the contractile vacuole
- Excretion and osmoregulation takes place in the earthworm through the nephridia
and skin
- Excretion and osmoregulation in man takes place through the kidneys. Excretion also takes place through the skin, lungs and liver.
- The urinary system in man consists of a pair of kidneys, a pair of ureters,
a urinary bladder and a urethra
- Each kidney has three distinct
regions, cortex, medulla and pelvis
- The nephron is the structural
and functional unit of the kidney
- Each nephron has a network of capillaries called glomerulus which fits into a cup called the Bowman's capsule and a long tubule consisting of proximal convoluted tubule, Henle's loop, distal convoluted tubule and connecting tubule.
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