Tissues

An aggregation of morphologically similar cells and associated intercellular matter acting together to perform one or more specific functions in the body. There are four basic types of tissue: muscle, nerve, epidermal, and connective.

muscle tissue

4 types of tissue

Epithelial tissue

Connective tissue

Muscle tissue

Nerve tissue

Function and classification of tissues

Epithelial tissue- covers the body surface and forms the lining for most internal cavities. The major function of epithelial tissue includes protection, secretion, absorption, and filtration. The skin is an organ made up of epithelial tissue which protects the body from dirt, dust, bacteria and other microbes that may be harmful. Cells of the epithelial tissue have different shapes as shown on the student's worksheet. Cells can be thin, flat to cubic to elongated.

Connective tissue- is the most abundant and the most widely distributed of the tissues. Connective tissues perform a variety of functions including support and protection. The following tissues are found in the human body, ordinary loose connective tissue, fat tissue, dense fibrous tissue, cartilage, bone, blood, and lymph, which are all considered connective tissue.


Muscle tissue: skeletal, smooth, and cardiac. Skeletal muscle is a voluntary type of muscle tissue that is used in the contraction of skeletal parts. Smooth muscle is found in the walls of internal organs and blood vessels. It is an involuntary type. The cardiac muscle is found only in the walls of the heart and is involuntary in nature.

Nerve tissue- is composed of specialized cells which not only receive stimuli but also conduct impulses to and from all parts of the body. Nerve cells or neurons are long and string-like.

epithelial tissue- the epithelium is a layer of contiguous cells that covers the external and internal free surfaces of the body, e.g., surface of skin or inner surface of a small blood vessel. The epithelium rests on a supporting extra cellular layer called a basement membrane. The free or apical surface of the epithelial cell often shows specializations in structure which relate to the function of the tissue.


Specialization of epithelial tissue-

Epithelial cells line the major cavities of the body.

Epithelia form the structure of the lung, including the alveoli or air sacs where gas exhange occurs.

Cells line most organs, such as the stomach and small intestine, kidney, and pancreas. They also line the esophagus.

Cells are also found in ducts and glands, like the bile duct and sailvary glands.

Epithelia can specialize to act as sensory receptors. They form taste buds, line the nose, and are in the ear. They are also found in the eye.

Female reproductive organs are lined with ciliated epithelial cells.

The skin is made of epithelial cells. Its striated layers demonstrate the extensive morphology of epithelia.

Capillary beds are made of epithelium.

Epithelia is the first type of cell to differentiate in the embryo. This occurs during the eight-cell stage.

examples of tissues in the human body-

The skin is an organ made up of epithelial tissue

ordinary loose connective tissue, fat tissue, dense fibrous tissue, cartilage, bone, blood, and lymph, which are all considered connective tissue.

Skeletal muscle is a voluntary type of muscle tissue that is used in the contraction of skeletal parts. Smooth muscle is found in the walls of internal organs and blood vessels. It is an involuntary type. The cardiac muscle is found only in the walls of the heart and is involuntary in nature.

Nervous Tissue Senses stimuli and sends signals from one part of the body to another. The cells are called neurons

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