Test: Animals Structural Organizations - September 26, 2022 - NEET MCQ

Neural coordination is not performed by unicellular organisms because neural coordination requires a complex set of cells and tissues to carry out the process which is not present in a single cell. It is coordination between different cells of the neural tissue.

The human body is composed of billions of cell to perform various functions. These cells aggregate to form tissues which in turn aggregate to form organs. Many organs coordinate with each other to form the organ system.

The group of similar or dissimilar cells that have a common origin and perform a similar function is called tissue. These tissues are organised in specific proportion and pattern to form an organ like stomach, lung, heart and kidney.

The structure of the cells varies according to their function. Therefore, the tissues are different and are broadly classified into four types –
i. Epithelial tissue
ii. Connective tissue
iii. Muscular tissue
iv. Neural tissue.

Epithelial tissue has the most regenerative power while neural tissue has the least regenerative power. We commonly refer to an epithelial tissue as epithelium.

Epithelial tissue is derived from Ectoderm, mesoderm and endoderm. Connective and Muscular tissues are derived from mesoderm. Nervous or neural tissue is derived from ectoderm.

Epithelial tissue performs the function of protection, secretion, absorption, excretion and diffusion. Conduction of stimulus is the function of neural tissue.

Epithelial tissue has a free surface, which faces either a body fluid or the outside environment and thus provides a covering or a lining for some part of the body. The cells of this tissue are compactly packed with a little intercellular matrix. There are two types of epithelial tissues namely simple epithelium and compound epithelium.

Based on structural modification of the cells, simple epithelium is further divided into three types. These are:
i. Squamous epithelium
ii. Cuboidal epithelium
iii. Columnar epithelium.

Squamous epithelium is made of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels, lymph vessels, air sacs of lung alveoli, Bowman’s capsule and Henle’s loop.