SKELETON SYSTEM

The stapes or stirrup is a bone in the middle ear of humans and other animals involved in conducting sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the footplate to transmit sound energy through the oval window into the inner ear.

The stapes is the third bone of the three ossicles in the middle ear. The stapes is a stirrup-shaped bone and the smallest in the human body. It rests on the oval window, to which an annular ligament connects it.

The main component of human bone is calcium, a mineral helpful in providing structure and strength of bones. A salt called calcium phosphate is found in the highest amount in human bones.

• Keratin is a protein that forms the cells that make up the tissue in nails and other parts of your body. Keratin plays an important role in nail health. It protects nails from damage by making them strong and resilient.

• There are four distinct phases related to hair growth - the first three phases are Anagen, catagen and Telogen. Under these, the maturation of hair and the generation of individual hairs take place. In the last and fourth stage exogen, old hair falls.

Keratin is a tough, fibrous structural protein that is also found in human hair and makes up the horn of rhinoceroses. It provides strength and resilience.

The covering or protective tissues in the animal body are epithelial tissues. Epithelium covers most organs and cavities within the body. It also forms a barrier to keep different body systems separate. Epithelial cells form a thin layer of cells known as the endothelium, which is continuous with the inner tissue lining of organs such as the brain, lungs, skin and heart.

Epithelial tissue covers and protects many organs and cavities within the body. The linings of blood vessels, lung alveoli and kidney tubules are all made up of epithelial tissue. Blood vessels and lung alveoli are lined by a single layer of squamous epithelial cells whereas kidney tubules are lined by cuboidal epithelial cells that provide mechanical support.

The skin is an epithelial membrane also called the cutaneous membrane. It is a stratified squamous epithelial membrane resting on top of connective tissue. The apical surface of this membrane is exposed to the external environment and is covered with dead, keratinized cells that help protect the body from desiccation and pathogens.

Melanin provides pigmentation to your skin, eyes and hair. The substance also absorbs harmful UV (ultraviolet) rays and protects your cells from sun damage.