describe the structure and function of following tissue: a) Epithelial tissue b) muscular tissue c) nervous tissue d) connective tissue.
Answers
a) Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.
The cells in epithelial tissue are tightly packed together with the very little intercellular matrix. Because the tissues form coverings and linings, the cells have one free surface that is not in contact with other cells. Opposite the free surface, the cells are attached to underlying connective tissue by a non-cellular basement membrane. This membrane is a mixture of carbohydrates and proteins secreted by the epithelial and connective tissue cells.
Epithelial cells may be squamous, cuboidal, or columnar and may be arranged in single or multiple layers.
b) Muscular tissue is a specialized tissue in animals that applies forces to different parts of the body by contraction. It is made up of thin and elongated cells called muscle fibres. It controls the movement of an organism.
Properties of Muscular Tissue
Contractibility– Muscle cells can shorten forcefully.
Extensibility– A muscle can be stretched.
Elasticity– The muscles can recoil back to their original length after being stretched.
Excitability– The muscle tissue responds to a stimulus delivered from a motor neuron or hormone.
Structure of Muscular Tissue
The muscular tissues are bundled together and surrounded by a tough connective tissue similar to cartilage known as epimysium.
The bundle of nerve cells that run in long fibres called fascicles are surrounded by the epimysium.
The fascicles are surrounded by a protective layer known as perimysium. It allows the flow of nerves and blood to the individual fibres.
Another protective layer, the endomysium surrounds the fibres.
These layers and muscles help in the contraction of different parts of the muscles. The different bundles slide past one another as they contract.
c) Structure Of Nervous Tissue
It is made of nerve cells or neurons, all of which consists of an axon. Axons are long stem-like projections emerging out of the cell, responsible for communicating with other cells called the Target cells, thereby passing impulses
The main part is the cell body which contains the nucleus, cytoplasm and cell organelles. Extensions of the cell membrane are referred to as processes.
The nervous tissue consists of the nerve cells or the neurons. Neurons are specialized cells that react to stimuli by generating signals through the axons, which are elongated structures arising from the cell body.
Characteristics Of Nervous Tissue
Nervous tissue makes up for the CNS and PNS of the nervous system
Contains two distinct cells – neurons and glial cells
It consists of the dendrites, cell body, axon and nerve endings.
Neurons secrete chemical neurotransmitters which are responsible for stimulating other neurons as a result of a stimuli
Presence of specialization at axonal terminals called synapsis
Nerve cells live long, cannot be divided and replaced(except memory cells)
Function Of Nervous Tissue
Neurons generate and carry out nerve impulses. They produce electrical signals that are transmitted across distances, they do so by secreting chemical neurotransmitters.
d) Connective tissue is the most abundant and widely distributed of the primary tissues. ... Major functions of connective tissue include: 1) binding and supporting, 2) protecting, 3) insulating, 4) storing reserve fuel, and 5) transporting substances within the body. Connective tissues can have various levels of vascularity.