Health and Social Care Unit 5 P2

A tissue is one of the building blocks of an organism (either an animal or a plant). An organism is comprised of tissues, which are made up of individual cells. These cells share a similar structure and function. In humans, there are four basic tissue types, which are: Epithelial Tissue, Connective Tissue, Muscle Tissue and Nervous Tissue.

Epithelial tissue covers the whole surface of the body. It is made up of cells closely packed and ranged in one or more layers. This tissue is specialised to form the covering or lining of all internal and external body surfaces. Epithelial tissue that occurs on surfaces on the interior of the body is known as endothelium. Epithelial cells are packed tightly together, with almost no intercellular spaces and only a small amount of intercellular substance. Epithelial tissue, regardless of the type, is usually separated from the underlying tissue by a thin sheet of connective tissue; basement membrane. The basement membrane provides structural support for the epithelium and also binds it to neighbouring structures. Epithelial tissue can be divided into two groups depending on the number of layers of which it composes. Epithelial tissue which is only one cell thick is known as simple epithelium. If it I two or more cell thick such as the skin, it is known as stratified epithelium. The skin has a huge composition of epithelial cells and this protects the body from invasion of germs, as well as from the sunlight. Epithelial cells form glands of the body and these glands secrete hormones and enzymes. Epithelium may also secrete wax, perspiration and digestive enzymes. The organs of the digestive tract have an abundance of epithelial cells, which function to absorb water and digested food. These cells play a large part in the proper digestion of food. Simple Squamous epithelium cells have the appearance of thin, flat places. The shape of the nucleus usually corresponds to the cell form and help to identify the type of epithelium. Squamous cells, for example, tend to have horizontal flattened nuclei because of the thin flattened form of the cell. They form the lining of cavities such as the mouth, blood vessels, heart and lungs and make up the outer layer of the skin. These cells provide a thin membrane that allows for the passage of small molecules into the body.

Simple Cuboidal cells are roughly square or cuboidal in shape. 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 as in the ducts of the glands. They also form the germinal epithelium which produces the egg cells in the female ovary and the sperm cells in the male testes. It is a very important type of tissue in the human body, they are found inside the kidneys, in parts of the eye, the thyroid, in the ovaries and testes, in parts if the brain and lungs, and in the ducts of exocrine glands. Simple cuboidal epithelial tissue has the function of secretion and