3. Describe the structure and functions of following
tissues :
(a) Epithelial tissue
(b) Muscular tissue
(C) Nervous tissue
(d) Connective tissue
Answers
The term tissue is used to describe a group of cells found together in the body. The cells within a tissue share a common embryonic origin. Microscopic observation reveals that the cells in a tissue share morphological features and are arranged in an orderly pattern that achieves the tissue’s functions. From the evolutionary perspective, tissues appear in more complex organisms. For example, multicellular protists, ancient eukaryotes, do not have cells organized into tissues.
Although there are many types of cells in the human body, they are organized into four broad categories of tissues: epithelial, connective, muscle, and nervous. Each of these categories is characterized by specific functions that contribute to the overall health and maintenance of the body. A disruption of the structure is a sign of injury or disease. Such changes can be detected through histology, the microscopic study of tissue appearance, organization, and functions
Epithelial tissue, also referred to as epithelium, refers to the sheets of cells that cover exterior surfaces of the body, lines internal cavities and passageways, and forms certain glands. Connective tissue, as its name implies, binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body. Muscle tissue is excitable, responding to stimulation and contracting to provide movement, and occurs as three major types: skeletal (voluntary) muscle, smooth muscle, and cardiac muscle in the heart. Nervous tissue is also excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body
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Epithelial tissue-Epithelial tissue is scutoid shaped, tightly packed and form a continuous sheet. It has almost no intercellular spaces. All epithelia is usually separated from underlying tissues by an extracellular fibrous basement membrane. The lining of the mouth, lung alveoli and kidney tubules are all made of epithelial tissue.
Muscular tissue-Muscle tissue consists of elongated cells also called as muscle fibres. This tissue is responsible for movements in our body. Muscles contain special proteins called contractile protein which contract and relax to cause movement. Muscle tissues vary with function and location in the body.
Nervous tissue-Nervous tissue is composed of neurons, also called nerve cells, and neuroglial cells. ... Two types of neuroglia found in the PNS are satellite cells and Schwann cells. In the central nervous system (CNS), the tissue types found are grey matter and white matter.
Connective tissue- Connective tissues consist of three parts: cells suspended in a ground substance or matrix; and most have fibers running through it. ... It is composed of proteoglycans and cell adhesion proteins that allow the connective tissue to act as glue for the cells to attach to the matrix