Saturday, 28 January 2017

The structure of hair

Hair is made of a tough protein called keratin. A hair follicle anchors each hair into the skin. The hair bulb forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the hair shaft. The hair is made up of 95% keratin, a fibrous, helicoidal protein (shaped like a helix) that forms part of the skin and all its appendages (body hair, nails, etc.).
Keratin is synthesized by keratinocytes and is insoluble in water, thus ensuring impermeability and protection for the hair. Some 18 amino acids can be found in the hair, such as proline, threonine, leucine and arginine. Keratin is particularly rich in cysteine (a type of sulfurated amino acid), which forms disulfide bonds between molecules, adding rigidity and resistance to the entire structure.

Information from: 
http://www.webmd.com/skin-problems-and-treatments/picture-of-the-hair#1
http://activilong.com/en/content/95-structure-composition-of-the-hair

Image from: https://thekinkandi.wordpress.com/tag/structure-of-hair/

Thursday, 19 January 2017

The human skeleton

It is composed of around 300 bones at birth – this total decreases to 206 bones by adulthood after some bones have fused together. The bone mass in the skeleton reaches maximum density around age 20. The human skeleton can be divided into the axial skeleton and the appendicular skeleton. skeletal system definition. The framework of the body, consisting of bones and other connective tissues, which protects and supports the body tissues and internal organs. Voluntary muscles are also called skeletal muscles as they are attached to bones, by rule, so as to move the bone hence the body. ... The skeletal system performs vital functions— support, movement, protection, blood cell production, calcium storage and endocrine regulation — that enable us to survive.

The main bones of the human skeleton are:
The Skull - Cranium, Mandible and Maxilla.
Shoulder girdle - clavicle and scapula.
Arm - humerus, radius and ulna.
Hand - Carpals, Metacarpals and Phalanges.
Chest - Sternum and Ribs.

Information from: 
https://en.wikipedia.org/wiki/Human_skeleton
https://www.quora.com/What-are-the-main-functions-of-the-skeletal-system
http://www.teachpe.com/anatomy/skeleton.php
http://www.dictionary.com/browse/skeletal-system
Image from: http://www.teachpe.com/anatomy/skeleton.php

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