Question

Main parts of neurons are ............. and
A. Cell body, Axon
B. Axon hillock, synaptic knob
C. Cell body, synaptic knob
D. Myelin sheath, axon

Answer 1

Hint: Neurons, the longest cell of the body that are incapable of division, are the building blocks of the nervous system. Their body has three main parts : the dendrites, the perikaryon and a long myelinated or myelinated process called the nerve fibre.

Complete answer:
Neurons are the building blocks of the nervous system and these cells help in receiving and transmitting the information to the brain. They carry messages throughout the body.
There are mainly three parts of neurons:

Dendrites: These branches like extensions at the starting of neurons which helps to increase the surface area of the cell body. These dendrites receive the chemical signals from the other neurons and then these are converted into electrical impulses which are then transmitted toward the cell body.
Cell body: Cell body receives the signal from the dendrites. There is presence of nucleus in the cell body and both of these play important roles in transmission of neural signals. The cell nucleus produces RNA which directs the synthesis of proteins.
Axon: It is extended from the cell body to the terminal endings and it is the elongated fibre which transmits the neural signal. The transmission of information depends on the diameter of the axon. Larger the diameter of the axon, faster it will transmit the information.
If we look at options now, let start with option D which is Myelin sheath, axon. Both of these are part of neurons but the main parts are asked in the question and main parts are the cell body, axon and dendrites. This option is incorrect since myelin sheath is not one of the main parts of neurons.
Moving to option C which is Cell body, synaptic knob. Cell body is one of the main parts of neurons but synaptic knob is not one of the main parts of neurons, therefore this option is correct and it gets eliminated.
Moving to option B which is Axon hillock, synaptic knob. Both of these are not one of the main parts of neurons and therefore this option also gets eliminated.
First option A is the cell body, axon. This option is the correct one since both the cell body and axon are main parts of neurons. Therefore, this option is correct.

Thus, the correct option is A which is Cell body, Axon.

Note: Neurons have three main parts: the cyton or the cell body, the dendrites, and the axon. Axons can be myelinated or non myelinated. In myelinated neurons impulses travel faster. Neurons lack the centrosomes and are incapable of division.