Biology - Animal Tissues

Muscle Cells

The contraction and relaxation of the cells results in movement in our body.

Epithelial Tissue

The covering or protective tissue in the animal body are epithelial tissues. Epithelium covers most organs and cavities between the body. Forms a barrier to keep different body forms separate.

Examples of Epithelial tissues

The skin, Lining of the mouth, Lining of blood Vessels, Lung alveoli and kidney tubules.

Characteristics of Epithelium Tissue Cells

They are tightly packed and form a continuous sheet. They have a small amount of cementing material in between them. Almost no intercellular spaces.

Permeability in Epithelium Cells

Regulating the exchange of materials between different parts of the body and the external body as well as in between different parts of your body.

Basement Membrane

All epithelium is separated from underlying tissue by an extracellular fibrous basement membrane.

Simple Squamous Epithelium

In cells lining blood vessels or lung alveoli, where transportation of substances occurs through a selectively permeable surface, there is a simple flat kind of epithelium. Squama means scale of skin). Simple squamous epithelial cells are extremely thin and flat and form a delicate lining. The oesophagus and the lining of the mouth are also covered with squamous epithelium. The skin, which protects the body, is also made of squamous epithelium.

Stratified Squamous Epithelium

Skin epithelial cells are arranged in many layers to prevent wear and tear. Since they are arranged in a pattern of layers, the epithelium is called stratified squamous epithelium.

Columnar Epithelium

Where absorption and secretion occur, as in the inner lining of the intestine, tall epithelial cells are present. This columnar (meaning ‘pillar-like’) epithelium facilitates movement across the epithelial barrier.

Ciliated Columnar Epithelium

In the respiratory tract, the columnar epithelial tissue also has cilia, which are hair-like projections on the outer surfaces of epithelial cells. These cilia can move, and their movement pushes the mucus forward to clear it. This type of epithelium is thus ciliated columnar epithelium.

Cuboidal Epithelium

Cuboidal epithelium (with cube-shaped cells) forms the lining of kidney tubules and ducts of salivary glands, where it provides mechanical support.

Glandular Epithelium

Epithelial cells often acquire additional specialisation as gland cells, which can secrete substances at the epithelial surface. Sometimes a portion of the epithelial tissue folds inward, and a multicellular gland is formed. This is glandular epithelium.

Connective Tissue

The cells of connective tissue are loosely spaced and embedded in an intercellular matrix. The matrix may be jelly like, fluid, dense or rigid. The nature of matrix differs in concordance with the function of the particular connective tissue.

Blood

Blood has a fluid (liquid) matrix called plasma, in which red blood corpuscles (RBCs), white blood corpuscles (WBCs) and platelets are suspended. The plasma contains proteins, salts and hormones. Blood flows and transports gases, digested food, hormones and waste materials to different parts of the body.

Bone

Bone is another example of a connective tissue. It forms the framework that supports the body. It also anchors the muscles and supports the main organs of the body. It is a strong and nonflexible tissue - gives support to our body. Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds.

Ligament

Two bones can be connected to each other by another type of connective tissue called the ligament. This tissue is very elastic. It has considerable strength. Ligaments contain very little matrix and connect bones with bones.

Tendons

Tendons connect muscles to bones and are another type of connective tissue. Tendons are fibrous tissue with great strength but limited flexibility.

Cartilage

Another type of connective tissue, cartilage, has widely spaced cells. The solid matrix is composed of proteins and sugars. Cartilage smoothens bone surfaces at joints and is also present in the nose, ear, trachea and larynx. We can fold the cartilage of the ears, but we cannot bend the bones in our arms.

Areolar Tissue

Areolar connective tissue is found between the skin and muscles, around blood vessels and nerves and in the bone marrow. It fills the space inside the organs, supports internal organs and helps in repair of tissues.

Adipose Tissue

Fat-storing adipose tissue is found below the skin and between internal organs. The cells of this tissue are filled with fat globules. Storage of fats also lets it act as an insulator.