Structure of a typical long bone

Comments

Post a Comment

Popular posts from this blog

Biodiversity Explanation and Biodiversity in India

  Biodiversity   Our planet, earth, is occupied by diverse kinds of living organisms. They live in various environments. The world is estimated to have 5 to 30 million species of living organisms. At present about 2.5 million species of living organisms have been given scientific names. Over 1.5 million of them are animal species and out of which 750,000 belong to insect species alone. There are 350,000 species of plants including algae, fungi, mosses and higher forms of plants. Thus the existence of different forms of a species or genus and diverse adaptations for, varied surroundings are referred to as 'biodiversity'.   The survival of such a vast range of living beings could be ensured only when their habitats and environmental conditions remain without alterations. The term '  biosphere ' had been coined to highlight the interdependence of living and non-living world. It represents a stable environment of various physical and biological factors which have been op...
Read more

Quantitive inheritance - GENETICS

  Quantitive inheritance -   GENETICS   :-   Charles Darwin  while working on his theory of Natural selection,   recognised two principal types of variations, namely  continuous  and  discon-tinuous . The continuous variations show the whole range of variations in a   particular character. The discontinuous variations would appear all of a sud-den and show no gradation.   Mendel  in his work depended on sharp or alternate characters com-prising discontinuous variations. For example, when tall and dwarf plants were crossed, in F 1  only tall plants appeared. Crossing F 1  plants, produced only tall and dwarf plants in the F 2  generation. Mendel discarded intermediate charac-ters if any, seen.   However, by the end of the 19 th  century  Galton , a British geneticist and statistician was interested in the study of continuous variations. He tried to find an answer for its origin. He called these char...
Read more

The Integumentary System - hypodermis, Epidermis, Callus, Skin color, Hair, glands, Nails

Image
  The Integumentary System   The word integument means covering. The integumentary system cov-ers the outside of the body. It protects internal structures, prevents the entry of infectious agents, reduces water loss, regulates body temperature, produces vitamin D and detects stimuli such as touch, pain and temperature. Since the integument performs several functions, it is commonly referred to as  Jack of   all trades .   The sk in or integument rests on layers of cells called  hypodermis . The hypodermis attaches the skin to underlying bones and muscles. It supplies blood vessels and nerves to the skin. The skin is composed of two major tissues, namely  dermis  and  epidermis . The dermis is mostly formed of connective tissue having fibro-blasts, adipose cells and macrophages. It provides the structural strength to the skin. The dermis accommodates nerve endings, hair follicles, smooth muscles and glands.   It is divided into two layers...
Read more