Good evening everyone, I am so happy for this lifestyle contest organized by @ngoenyi in this community @steem4nigeria.

Here I will continue my tutorial of last week about The Skeleton

SKELETON AND SUPPORTING SYSTEMS IN ANIMALS

THE SKELETON

The skeleton is the bony framework (hard structure) of the body which, protects and maintains the shape of an animal. This skeleton can be found within (endoskeleton) and the outer part of body (exoskeleton).

Endoskeleton: it is found inside the body of animal such as toads, lizards, birds, mammals etc. Examples of endoskeleton are bones and cartilages.

Exoskeleton: This is found outside the body of animal such as millipedes, insects, spiders. Examples of exoskeleton are nails, hoofs, scales, shell in crabs, shell in snail etc.

CARTILAGE AND BONE

Cartilage and bone which are types of endoskeleton perform the following functions:

• Give support to the body and provide it with rigid framework to which soft parts are attached.

• Provide strong areas for attachment of the tendon/muscles.

• Provide system of levers with fulcra at the joints in conjunction with the muscles, i.e. it enables movement.

CARTILAGE

This is a tough and flexible tissue that has great tensile strength .In higher vertebrates, the cartilage consists of an organic matrix (chon Drin). Cartilage acts as a shock absorber. Cartilage forms the entire skeletal system of sharks, dogfish and rays. In mammals, there types of cartilage. Hyaline cartilage, fibrous cartilage and elastic cartilage.

• Hyaline cartilage:
  This cartilage makes up the trachea and bronchi and keep them open.it covers the surfaces of movable joints and supports the protruding part of the nose.

• Fibrous cartilage :
  This is more rigid than hyaline. It is found in disc between the small vertebra (bone) and the vertebral column.

• Elastic cartilage:
  This consists of elastic fibers which enhance its flexibility. It is present in the external ear the epiglottis. It supports the Eustachian tube and the external auditory malletus. Cartilage lacks blood vessels, thus food and oxygen diffuse across from nearby tissues.

BONE

This is the hardest tissue and the major component of the vertebrate skeleton. It consist of living bone cells (osteocytes), protein fibers (collagen) and minerals. The osteocytes secrete the hard bone materials.

Bone are capable of growing, change its shape and repair its fractured parts. Bone have their own blood carried in Haversian canal which supply the living cells with food and oxygen.

I invite @bela90, @oasiskp, to be part of this contest.