Types of Neurons
On the basis of the structure, the neurons are of three types:
- Unipolar neurons: They occur in the neural system of embryos.
- Bipolar neurons: They occur in the retina of the eye.
- Multipolar neurons: They occur in the neural system of adults.
Neurons can be classified according to their functions as follows:
- Sensory or afferent Neurons
- Motor or efferent Neurons
- Interneurons or Adjustor neurons. They are present in the central neural system (brain and spinal cord).
Neural Tissue
All living organisms are made of cells. A unicellular organism has a single cell in its body, i.e., a single cell performs all basic life activities. However, in multicellular organisms, there are millions of cells. Most of these cells are specialized to carry out only a few functions efficiently. These functions are taken up by a distinct group of cells. Thus, it can be said that there is a division of labor in multicellular organisms.
A tissue is a group of cells that are similar in structure, origin, and function. The term ’tissue’ was given by Bichat. The branch of science dealing with the tissues is called ‘histology’. Mayer introduced the term histology. Malpighi is considered the “founder of histology. Broadly animal tissues are classified into four types: epithelial, connective, muscular, and neural.