Axon is a long fibre-like process of the cell body which is specialised to carry impulses away from the cell body. It is covered by one or two sheaths. The ensheathed axon is known as a nerve fibre. The single or the outer sheath is called neurilemma (neurolemma). It is made up of Schwann cells.

Given below are sets of five terms each. Rewrite the terms in correct order in a logical sequence beginning with the first word that is underlined: Stimulus , Response, Receptor, Effector, Spinal cord

A reflex action is a process for the body to automatically and immediately respond to a stimulus to reduce any further damage to the body. It follows this common sequence and does not involve the brain: S t i m u l u s → R e c e p t o r → S p i n a l c o r d → E f f e c t o r → R e s p o n s e The nerve pathway supported by a reflex action is called a reflex arc. For example, a simple reflex arc occurs if we accidentally touch something hot. A receptor in the skin detects a stimulus (the temperature change). The sensory neurone sends impulses to the relay neurone. The motor neurone sends impulses to the effector. Effector produces a response (muscle contracts to move the hand away).

Correct and rewrite the statements by changing the biological term that is underlined in the statement: Maintaining balance of the body and coordinating muscular activities is carried out by the cerebrum .

The cerebellum is the second-largest part of the brain. It consists of two deeply convoluted hemispheres. It helps in maintaining balance of the body and coordinating muscular activities helps keep the balance. It helps in our voluntary movements like walking, dancing, painting etc. It is known as small brain or little brain and is located below cerebrum. Maintaining balance of the body and coordinating muscular activities is carried out by the cerebellum .

Answer the following questions briefly: How are the cytons and axons placed in the brain and the spinal cord?

The brain and spinal cord are the two components of the central nervous system. The forebrain is a large part of the brain. It is also called the cerebrum. In the cerebrum, all the cytons of the neurons are present in the outer layer and axons are present in the inner portion. But in the spinal cord, axons are placed on the outer side and cell bodies/cytons are placed in the inner portions.

Correct the following statements by changing the underlined words: The outermost layer of Meninges is Pla mate r.

The brain is a very delicate organ well protected inside the brain box or cranium of the skull. Meninges: The brain is protected by 3 membranous coverings called meninges (meninx: membrane) which continue backwards on the spinal cord. Dura mater is the outermost tough fibrous membrane.

Mention the exact location of the following Corpus callosum

Corpus callosum is present between the two cerebral hemispheres, joining them together. It is a thick band of nerve fibres and carries information received in one hemisphere over to the other hemisphere.