These tissues cover line or an organ. They consist of renewable sheets of cells they are classified based on shape and the number of layers of cells. Epithelial tissue absorbs, transport, excrete, protect, and contain nerve cell for sensory reception.
Simple squamous epithelium:
It consists of a tightly packed single layer of the cell with a disk shape central nucleus. They are located in the sacs of the lungs. It allows passage of material by diffusion and filtration.
Simple cuboidal epithelium:
It consists of a single layer of tightly packed cube shape cells. They are located in kidney tubules and the surface of the ovary. They are responsible for secretion and absorption.
Simple columnar epithelium:
It consists of a single layer of elongated cells. These cell bear minute finger-like projections called microvilli. They are also responsible for the absorption of different materials and enzyme secretion.
Pseudostratified ciliated columnar epithelium:
It consists of columnar cells with a tuft of cilia at the top of the cell. In this, each layer has two nuclei. They are located in the lining of bronchi. They help the cell to move biliary action.
Stratified Squamous Epithelium:
It consists of many layers of the cell. They form the lining of the oral cavity, esophagus, and vagina. They protect the underlying tissues against absorption
They serve various binding and supportive functions. It is composed of a small population of cells and a large number of fibers. It consists of three types of fibers. It may be classified based on a loose and dense arrangement of these fibers.
Loose Connective Tissue:
In this strong, flexible fibers of protein collagen that are interwoven with fine elastics and fibers It is widely distributed under the epithelia of the human body. It acts as a cushion for the organs.
Fibrous Connective Tissue:
In this collagen fiber are densely packed and may lie parallel to each other, creating very strong code. The number of connective tissue is higher than loose connective tissue. It is located in the dermis of the skin, in bones, and around the kidney and heart. They also support and protect the organs.
Cartilage is hard but flexible tissue comprising of a few cells. In cartilage, there are present a large number of small spaces called the lacunae where chondrocytes. Fishes like sharks, rays, and stakes have a cartilaginous skeleton.
These cells are located in lacunae surrounded by intercellular material containing fine collagenous fibers. It forms the embryonic skeleton. It also maintains the shape of this structure and also provides support.
It contains fine collagenous fibers and many elastic fibers in its intracellular material, located in the external ear. It maintains the shape of the structure and also provides great flexibility.
It contains many large collagenous fibers in its intercellular material. They are present in fibrocartilage. They are present in the intervertebral disk. It is responsible for absorbing the compression shock. therefor it is fibrous.
It is the strongest of the vertebrate connective tissue containing mineralized collagen fibers. Bones also knew as osteocytes are located within lacunae. Bone give support, provide protection, and store calcium and fat and form blood cells.
Blood is also a connective tissue having a fluid matrix in the form of plasma. The matrix plasma consists of water, salt, and a variety of dissolved proteins. It is located in blood vessels in higher organisms. It transport substances like oxygen, water, nutrient, and minerals, etc.
It is composed of several types of cells but two are important NEURON and NEUROGLIA. The neuron is impulse conducting cells and consists of three parts dendrites, cell body, and axon. Neuroglia is the non -nervous cell that insulates the membranes of neurons, provides protection, support, and nourishment to the neurons. The nervous tissue is located in the brain, spinal cord, and nerves.
Muscle tissue is composed of long, excitable cells capable of considerable contraction. In the cytoplasm, there are a large number of a parallel arranged structure called microfilament. Three types of muscle are as follows.
Smooth Muscle Tissue:
These muscles lack cross striations and are spindle-shaped. they containing a single nucleus. They are involuntary in action. These cells are arranged closely to form sheets and mostly located in the walls of hollow organs like the gut, blood vessels, and excretory system. It helps in the movement of substances like food, urine, etc.
Skeletal Muscle Tissue:
The skeletal fiber is composed of striated muscle fibers that are long, cylindrical, and contain many peripheral nuclei. They are voluntary and attach with body bones through tendons. The contraction help in the bones to move and therefore is helping in the locomotion of animal.
Cardiac Muscle Tissue:
They consist of striated branched spindle-shaped cell and they are shorter than skeletal cells. They are located in the walls of the heart and it has involuntary control. As the walls of the heart contract so cardiac muscle tissue pump blood into the circulation.