- Introduction
- Rest time! Have fun
- Physics
- Chemistry
- BIOLOGY
- Reaching the age of Adolescence
- CROP PRODUCTION AND MANAGMENT
- Cells : The basic structural unit of life
- Nutrition in human beigns
- RESPIRATION IN HUMAN BEIGNS
- TRANSPORTATION IN HUMAN BEIGNS
- excretory system in human beigns
- NERVOUS SYSTEM
- PHOTOSYNTHESIS
- Respiration in plants
- REPRODUCTION IN PLANTS
- MOVEMENTS IN PLANTS
- Forest our lifeline
- WASTE WATER STORY
- WEATHER,CLIMATE AND ITS ADAPTATION .
- Reaching the age of Adolescence
- Model tests
- Animation time
EXCRETORY SYSTEM IN HUMAN BEIGNS
- Excretion - Excretion is the removal of the metabolic wastes of an organism. Wastes that are removed include carbon dioxide, water, salt, urea and uric acid. All excreted wastes travel at some time in the blood.
2. Liver - produces urea and uric acid as a by-product of the breakdown of proteins
3. Skin - removal of excess water, salt, urea and uric acid
4. Kidney- kidneys filter the blood to form urine, which are excess water, salt, urea and uric acid.
Main waste products
1 nitrogenous waste product
2 carbonic waste products
IN NITROGENOUS WASTE AMINO ACIDS IS BURNT INTO AMMONIA WHICH IS VERY TOXIC TO OUR BODY SO IT SHOULD BE DILLUTED IN LIVER THIS GETS CONVERTED INTO UREA, THEN THE FORMATION OF URINE STARTS
Formation of urine The formation of urine takes place by 3 processes
(a) Ultra filtration or glomerular filtration.
(b) Selective reabsorption
(c) Tubular secretion
(a) Ultra filtration or glomerular filtration –
AFFERENT ARTERIOLE BRINGS BLOOD TO THE glomerulus WHILE EFFERENT ARTERIOLE TAKES BACK THE BLOOD , THE DIAMETER OF AFFERENT ARTERIOLE IS MORE , BLOOD PRESSURE IN glomerulus IS MORE , ABOUT 1/5 PLASMA COMES TO BOWMANS CAPSULE BY FILTRATION . MANY USEFUL MATERIALS ARE FILTERED.
(b) Selective reabsorption
As the nephric filtrate moves in the nephron towards the collecting tubule, about 99% of water, whole of glucose and amino acids, most of the Na+ and Cl, some urea and uric acid are reabsorbed back into the blood. This process by which only useful substances are reabsorbed from the nephric filtrate is called selective reabsorption.
Tubular secretion It is a process by which the glandular cells of nephron especially of DCT, extract the wastes like uric acid, creatinine, hippuric acid, K+, H+, ammonia from the blood in the capillaries by active transport and secrete them in the nephric filtrate. Most of K+ eliminated in urine is secreted by DCT and collecting tubules in exchange with reabsorbed Na+
As a result of these 3 processes the wastes are changed into urine.
THIS URINE PASSES TO URETER THEN TO URINARY BLADDER THEN COMES OUT FROM URETHRA.