Cells and Tissues
The smallest, basic, and structural component of the body is a cell. It is the basic functional unit of life. No organism can exist on this Earth without a cell. Thus, it is the fundamental unit. These cells perform the major functions of the body. The term cell was given by Robert Hooke, who stated that all organisms’ bodies, whether unicellular or multicellular, are made of cells. In single-celled organisms such as amoeba and protozoa, all the body functions are performed by a single cell. The multicellular organisms have collective cells which perform a specific function in the body.
Types of Tissues
The smallest, basic, and structural component of the body is the cell. It is the functional unit of life. No organism can exist on this Earth without a cell. An organism's body, whether unicellular or multicellular, is made of cells. In unicellular organisms such as amoeba and protozoa, all the body functions are performed by a single cell. The multicellular organisms have collective cells which perform a specific function in the body. Tissues are a group of cells that work together to perform a particular function in the body. They make a series of networks or a system to coordinate with the different tissues in the body, forming a tissue system. The word tissue is derived from the Latin word 'weave.' Plants and animals have various kinds of tissue systems that differ in their work and composition according to the different requirements.
Tissue System
The smallest, basic, and structural component of the body is the cell. It is the functional unit of life. No organism can exist on this Earth without a cell. An organism's body, whether unicellular or multicellular, is made of cells. In unicellular organisms such as amoeba and protozoa, all the body functions are performed by a single cell. The multicellular organisms have collective cells which perform a specific function in the body. Tissues are a group of cells that work together to perform a particular function in the body. They make a series of networks or a system to coordinate with the different tissues in the body, forming a tissue system. The word tissue is derived from the Latin word 'weave.' Plants and animals have various kinds of tissue systems that differ in their work and composition according to the different requirements.
differentiate between the fibrous (loose, dense, elastic, reticular) and special connective tissues
Connective tissue is a type of tissue that are involved in connecting,separating and supporting all other types of tissues in the body. They consists of cells loosely packed surrounded by the compartment of fluid called extracellular matrix. There are two types of connective tissues: connective tissue proper and specialized connective tissue.
Loose connective tissue has almost equal amounts of cells, fibers and ground substance and is also called areolar connective tissue. Chief cells are fibroblasts and principal fibers in ECM is the collagen fibers which are sparsely distributed. Examples: lamina propria of alimentary and respirator canals , dermis of skin etc.
Dense connective tissues has fewer cells than loose connective tissue and ECM is densely packed with collagen fibers. It is further divided into dense regular and dense irregular connective tissue based on the orientation of the collagen fibers. Examples of dense regular connective tissue includes tendons and ligaments and that of dense irregular connective tissue includes walls of the organs,dermis of skin etc.
Modified fibroblasts known as reticular cells produces reticular connective tissue which produce reticular fibers arranged in network known as reticulum which is more or less similar to dense irregular connective tissue. The mesh is thinner and delicate. It is present in bone marrow,lymph nodes and spleen.
Elastic connective tissue comprises of fibers made up of protein known as elastin which gives stretching and bending properties to tissues and are mostly found in blood vessels,elastic cartilages,lungs and skin.
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