Biology

General Knowledge

Introduction to Biology Important Terms of Biology

Classification of Organism Five Kingdom Classification Scientific Names of Organisms

Study of cell Types of Cell,Structure of cell Difference between Plant and Animal cells

Dihybrid cross Law of paired unit Law of dominance Law of segregation Law of Indp. assortment

Sex determination in Human Klinefelter Syndrome Turner's Syndrome Color blindness

Organic Evolution Theories of evolution Carolus Linnaeus Jean Baptist Lamarck Charles Robert Darwin

Cryptogamous plants Phanerogamous or Floral plant Virus and Bacteria

Morphology Root & Stem Leaf & Flower Formation of fruits

Meristematic tissue Permanent tissue Photosynthesis Dark chemical reaction

Plant Hormones Auxins Gibberellins Cytokinins Plant Diseases

Ecology Biotic component Abiotic components Food Chain

Air pollution Water pollution Sound pollution Soil pollution Nuclear pollution

Classification of animals Phylum Protozoa Phylum Porifera Phylum Coelenterate

Animal Tissue Epithelial Tissue Connective Tissue Muscular Tissue Nervous Tissue

Red Blood Corpuscles White Blood Corpuscles Blood Platelets Thrombocytes Plasma

Digestive System Circulatory System Lymph Circulatory System Excretory System Nervous System

Nutrients & Nutrient Carbohydrate Protein Fats & Vitamins Minerals and Water

Medicinal Discoveries Important Informations about animals Important Facts of biology

Excretory System

Removal of nitrogenous substances formed during metabolism from the body of human is called excretion. Normally excretion means the release of nitrogenous excretory substances like urea, ammonia, uric acid etc.
The main excretory organs of human are as follows—
1. Kidneys
2. Skin
3. Liver
4. Lungs

1. Kidneys

The main excretory organ in human and other mammals is a pair of kidneys. Its weight is 140 grams. There are two parts of it. Outer part is called cortex and the inner part is called medulla. Each kidney is made up of approximately 1,30,00000 kidney ducts which are called nephrons. Nephron is the structural and functional unit of the kidney. There is a cup like structure in the every nephron called Bowman's capsule. Glomerulus is made up of thin blood vessels found in the Bowman's capsule which is made up of two types of arterioles.

(a) Afferent arteriole : Which carries the blood to the glomerulus.
(b) Efferent arteriole : By which the blood is taken out of the glomerulus.

» The process of filtration of liquids into the cavity of Bowman's capsule, is called ultra filtration.
» The main function of the kidneys is purification of blood plasma i.e. to excrete the unwanted nitrogenous waste substances through urination.
» Supply of blood to kidneys takes place in large quantity in comparison to other organs.
» In the kidneys average 125 ml per minute blood is filtrated i.e. 180 litres per day. Our of it 1.45 liters urine is formed daily and the remaining is absorbed back by the cells of nephron and mix into blood.
» In the normal urine there is 95% water, salt, 2.7% urea and 0.3% uric add.
» Urine is acidic. Its pH value is 6.
» The stone formed in the kidneys is made up of calcium oxalate.

2. Skin

Oil glands and sweet glands found in the skin respectively secretes sebrum and sweat.

3. Liver

Liver cells play the main role in excretion by converting more and more amino acids and ammonia of blood into urea.

4. Lungs

The lungs excretes two types of gaseous substances carbon dioxide and water vapor. The excretion of some substances like garlic, onion and some spices in which vapour component is present excreted by the lungs.

Hemodialysis

Process of removal of excess urea from the blood of patient using artificial kidney.

Biology

Excretory System