Compound Epithelia Tissue
It consists of more than one layer of cells. Its function is to protect deeper structures and multiple layers of cells hamper the passage of materials. These cells are simple, they can be formed from Cuboidal cells, columnar cells, squamous cells or ciliated cells, or they might be keratinised. It can be found lining the urinary tract and keratinised cells form the outer layer of the skin.
Cilated cells
Connective Tissue
Connective tissue is widely distributed in the body and it lies beneath the epithelia tissue. Connective tissue has three main components: cells, matrix and fibers. Different types of cells are scattered throughout the matrix. The matrix fills the spaces between the cells and consists of protein-based fibers usually secreted by the connective tissue cells. The matrix can be liquid as in blood, jelly-like as in areolar tissue, firm in cartilage and hard in bones. The connective tissue functions are, to transport materials, to give support for the internal organs, it gives strengthen, it protects and stores energy, also it connects different parts of the internal structure.
There are five types of connective tissues:
Blood
It consists of straw- coloured plasma, in which several types of blood cells are carried. Blood delivers necessary substances as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. It consists of different types of blood cells:
Red blood cells (erythrocytes)
Is a very small cell with an elastic membrane, whose function is to transport Oxygen and Carbon dioxide in the blood. Red blood cells do not have a nucleus. It contains an iron-rich protein called haemoglobin which gives the cell the reddish colour.
White blood cells (leukocytes)
These cells are larger, nucleated and less numerous. They made up part of the immune system. These cells defend the body against infections assisting in the production of antibodies.
Platelets (thrombocytes)
They are products of much larger cells that have broken up. These cells have an important role in blood clotting.
Plasma (the matrix)
It consists of 90% water and contains nutrients, proteins, hormones and waste products.
Cartilage
Cartilage is an elastic, flexible, firm, tough and translucent substance. It is composed of closely packed collagenous fibers. No nerves or blood vessels occur in the cartilage. It can be found in the knee joint, between spinal vertebra, in the nose and in the ear flaps. The skeleton of humans is composed of cartilage. It provides strength and flexibility also protects the bones ends from friction during movement.
Bone
Bone is a harder substance that can be worn away by friction. Bone is a part of the skeletal system. It consists of calcium salts and collagen fibres. Bone can be either compact or spongy, it depends on how the cell and matrix are organised. A bone is made up of several types of connective tissue working together. Bones forms a supportive framework, giving shape and rigidity to the body, it serves to protect the soft and delicate organs of the body such as the skull protects the brain, red blood cells are manufactured in the red bone marrow, Bone plays a part in homeostasis because it helps to maintain a constant level of calcium in the blood.
Areolar Tissue
Areolar tissue consists of meshwork of collagen, elastic tissue and reticular fibres and many connective tissue cells in between the meshwork of fibres. It is found in the skin, around mucous membranes as well around blood vessels, nerves and many organs in the body. It lines joint cavities such as hip joints also the areolar tissue forms links between organs, it binds the skin to the muscle beneath. Areolar tissue enables a high degree of movement between connected parts, providing support, strength and elasticity.
Adipose Tissue
Adipose tissue is a loose connective tissue, packed with many cells. It can be found beneath the skin, around internal organs such as the kidney and the heart, in the bone marrow and in breast tissues. It stores fat which can be burned to meet the energy needs for the body. An adipose tissue act as an insulating layer, which reduces the heat loss through the skin, it helps to maintain body temperature in newborn babies, as well provides mechanical protection and support to major organs.
Muscle Tissue
Muscle tissue cells have the ability to contract and relax, which brings movement and mechanical work in various parts of the body. It cells are specialised for contraction. It contains numerous microfilaments composed of actin and myosin, which are contractile proteins. The main function of muscle tissue is to change chemical energy into mechanical energy in order to produce force, also to stabilise the body’s position, regulate organ volume, generate heat and push fluids through the various body systems.
There are three types of muscle tissues distinguished on the basis of structural, functional and location differences.
Skeletal Muscle Tissue – Striated
Skeletal muscle is called ‘striated due to alternating dark and light bands of fibres. A single skeletal muscle cell is long and cylindrical in shape, with many nuclei located at the edges of the cell. Skeletal Muscle tissues are attached to bones. Skeletal muscle tissues are voluntary, which means that can be made to contract or relax by conscious control. It roles include the movement of the skeleton, under conscious control, including movement of limbs, fingers, toes and neck also the movement of tissues of facial expression under conscious control e.g. the ability to smile and to frown.
Cardiac Muscle Tissue
Cardiac muscle tissues are striated, involuntary in action and branched. This tissue is found only in the wall of the heart. Cells are joined by one another via intercalated an disc, which allows the synchronization of the heart beat. Its main function is to pump blood to all parts of the body from the heart.
Smooth Muscle Tissue, Non-striated
Smooth muscle tissues are made up of thin-elongated muscle cells that have one centrally located nucleus. It forms the muscle layers in the walls of hallow organs such as digestive tract, the walls of the bladder, the uterus, various ducts of glands and the walls of blood vessels. Contractions of smooth muscle constrict they surround. This is particularly important in the digestive system in which the action of smooth muscle helps to move food along the gastrointestinal tract as well as breaking the food down further. Smooth muscle also contributes to moving fluids through the body and to the elimination of indigestible matter from the gastrointestinal system.
References:
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