Outline the structure of the main tissues of the body.

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P2 – Outline the structure of the main tissues of the body.

TISSUES

A tissue is an ensemble of similar cells and from the same origin, which together carry out a specific function. There four types of tissues in the human body, which provides diverse functions. The four main types of tissue are:

Epithelial Tissue

Epithelial tissue covers the whole surface of the body.  It is specialized to form the covering or lining of all internal and external body surfaces, it also forms glands. These cells have different functions such as protection, sensation, secretion, absorption, and excretion, diffusion, cleaning and reducing friction. It is classified by the number of cells layers and the shape of surface cells.

Types of Epithelial Tissues

Simple Epithelial cells may be Squamous, cuboidal, columnar or ciliated.

Simple Squamous cells:  They have the appearance of thin, flat plates which allows rapid movement of substances. They tend to have horizontal flattened, elliptical nuclei because of the thin flattened form of the cell. They form the lining of cavities such as the mouth, blood vessels, and heart and air-sacs lungs and make up the outer layers of the skin.

Cuboidal cells: They are roughly square or Cuboidal in shape. Cuboidal cells may have microvilli and are responsible for secretion or absorption. Each cell has a spherical nucleus in the centre. Cuboidal epithelium is found in glands and in the lining of the kidney tubules as well in the ducts of the glands. They also constitute the germinal epithelium which produces the egg cells in the female ovary and the sperm cells in the male testes.

Columnar cells:  These cells are much taller with slightly oval nuclei. Columnar cells may have cilia or microvilli often specialised for secretion and absorption.  Columnar cells are found lining the trachea and bronchi, villi in the small intestine.

Ciliated cells they posses fine hair-like outgrowths, cilia on their free surfaces. These cilia are capable of rapid, rhythmic, wavelike beatings in a certain direction. This movement of the cilia in a certain direction causes the mucus, which is secreted by the goblet cell. Ciliated epithelium is usually found in the air passages like the nose. It is also found in the uterus and Fallopian tubes of females. The movement of the cilia propel the ovum to the uterus.

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Compound Epithelia Tissue

It consists of more than one layer of cells. Its function is to protect deeper structures and multiple layers of cells hamper the passage of materials. These cells are simple, they can be formed from Cuboidal cells, columnar cells, squamous cells or ciliated cells, or they might be keratinised. It can be found lining the urinary tract and keratinised cells form the outer layer of the skin.

                              Cilated cells

               

Connective Tissue        

Connective tissue is ...

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