Types of Animal tissue:
Animal tissue are grouped into four basic types:
Epithelial tissue: The covering or protective tissues in the animal body are epithelial tissues.Epithelium covers most organs and cavities within the body.
It also forms a barrier to keep different body systems separate.The skin, the lining of the mouth, the lining of blood vessels, lung alveoli and kidney tubules are all made of epithelial tissue.
There are three principal shapes of epithelial cell:
(a) Squamous: 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.
(b) Columnar: A simple columnar epithelium is a columnar epithelium that is unilayered.In humans, a simple columnar epithelium lines most organs of the digestive tract including the stomach, small intestine, and large intestine. Simple columnar epithelial line in the uterus.
(c) Cuboidal: Cuboidal epithelium (with cube-shaped cells) forms the lining of kidney tubules and ducts of salivary glands, where it provides mechanical support.
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.
Muscular tissues: Muscular tissues consists of elongated cells, also called muscle fibers. This tissue is responsible for movement in our body.
Muscles contain special proteins called contractile proteins, which contract and relax to cause movement.
The body contains three types of muscle tissue:
(i) Skeletal muscle: Skeletal muscle is called “striated” because of its appearance consisting of light and dark bands visible using a light microscope. As shown in the diagram (on the right), a single skeletal muscle cell is long and approximately cylindrical in shape, with many nuclei located at the edges (periphery) of the cell.
(ii) Cardiac muscle: Cardiac muscle fibers are striated, branched (sometimes described as Y-shaped), and have a single central nucleus. These fibers are attached at their ends to adjoining fibers by thick plasma membranes called intercalated discs.
(iii) Smooth muscle: Unlike Skeletal and Cardiac muscle tissue, smooth muscle is not striated. Smooth muscle fibers are small and tapered – with the ends reducing in size, in contrast to the cylindrical shape of skeletal muscle. Each smooth muscle fiber has a single centrally located nucleus
Connective tissues: Tissue that connects, supports, binds, or separates other tissues or organs, typically having relatively few cells embedded in an amorphous matrix, often with collagen or other fibres, and including cartilaginous, fatty, and elastic tissues.
Types of connective tissue:
(i) Areolar tissue: Areolar tissue is a common form of loose connective tissue.
Areolar tissue is found in many locations around the body.
One important area is the skin.The Areolar tissue located in the skin binds the outer layers of the skin to the muscle beneath.
Areolar tissue is also found in or around mucous membranes, and around blood vessels, nerves, and the organs of the body.
(ii) Adipose tissue: Adipose tissue, or fat, is an anatomical term for loose connective tissue composed of adipocytes.
Its main role is to store energy in the form of fat, although it also cushions and insulates the body.
Obesity in animals, including humans, is not dependent on the amount of body weight, but on the amount of body fat – specifically adipose tissue.
Adipose tissue is primarily located beneath the skin, but is also found around internal organs.
In the integumentary system, which includes the skin, it accumulates in the deepest level, the subcutaneous layer, providing insulation from heat and cold.
Around organs, it provides protective padding.
It also functions as a reserve of nutrients
(iii) Compact bone: Compact bone is made of concentric layers of osteocytes and bony matrix. Compact bones provide support to mammalian limbs.
Moreover, it is a storehouse of calcium and phosphorus.
(iv) Hyaline cartilage: A type of cartilage found on many joint surfaces; it contains no nerves or blood vessels, and its structure is relatively simple.
(v) Blood cell: Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets.
Blood has many different functions, including:
transporting oxygen and nutrients to the lungs and tissues.
carrying cells and antibodies that fight infection.
regulating body temperature.
forming blood clots to prevent excess blood loss.
bringing waste products to the kidneys and liver, which filter and clean the blood.
Muscular tissue: muscular tissue consists of elongated cells, also called muscle fibers. This tissue is responsible for movement in our body.
Muscles contains special proteins called contractile proteins, which contract and relax to cause movement.
Types of muscular tissue:
(i) Striated muscle: muscle tissue in which the contractile fibrils in the cells are aligned in parallel bundles, so that their different regions form stripes visible in a microscope.
Muscles of this type are attached to the skeleton by tendons and are under voluntary control. Also called skeletal muscle
(ii) Smooth muscle: muscle tissue in which the contractile fibrils are not highly ordered, occurring in the gut and other internal organs and not under voluntary control.
(iii) Cardiac muscle: The muscles of the heart show rhythmic contraction and relaxation throughout the life. These involuntary muscles are called cardiac muscles.
Nervous tissue: A cells posses the ability to respond to stimuli.
However, cells of the nervous tissue are highly specialised for being stimulated and then transmitting stimulus very rapidly from one place to another within the body.
The brain, spinal cord and nerves are all composed of the nervous tissue. The cells of this tissue are called nerve cells or Neurons.