CBSE Questions for Class 11 Medical Biology Neural Control And Coordination Quiz 8 - MCQExams.com

The periodic gap in the insulating sheath (myelin) on the axon of certain neurons serves to facilitate the rapid conduction of nerve impulses is known as node Ranvier.
So, the correct answer is 'Node of Ranvier'.

• Neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system. 
• They maintain homeostasis, form myelin, and provide support and protection for neurons. Hence, neuroglial cells are non-sensory supporting cells.

A. Above piamater

Reason: In humans, the brain is covered by three membranes or meninges. The innermost membrane, the piamater is thin, very delicate. The next is the arachnoid membrane. The outermost membrane, the duramater. Between the arachnoid membrane and pia-mater is a space known as subarachnoid space. Space that is present between the arachnoid and duramater is called subdural space. The subarachnoid space is filled with cerebrospinal fluid. 

• Medulla oblongata encloses a cavity called fourth ventricle. 
• The medulla contains centres for controlling the functions of important organs e.g., cardiac centre (heart), respiratory centre, vasomotor centre (for regulating the diameter of blood vessels) and reflex centres (for swallowing, vomiting, peristalsis, salivation etc.)

C. $$O_2$$ and glucose

Reason: Brain is dependent on blood the supply for oxygen and glucose. It produces energy for the physiological reactions of brain.

A. Heart beat

Reason: Medulla of brain consists two regions affecting heart rate, cardiac inhibitory centre and cardiac accelerator centre. Sensory nerves originating from the accelerator centre and enter the SA node. Stimulation by these nerves which are part of sympathetic nervous system causes an increase in heartbeat.

• Medulla oblongata extends from the Pons Varolii above and is continuous with the spinal cord below. 
• Medulla oblongata receives and integrates signals from the spinal cord and sends resulting signals to the cerebellum and thalamus. 
• It contains centres that regulate heart rate, blood pressure, breathing, salivation, sneezing, vomiting and coughing.

C. Brain

Reason: The brain is the anterior-most part of the central neural system which is lodged in the cranial cavity of the skull. The brain covered by three membranes or meninges. The innermost membrane, the piamater. The next is the arachnoid membrane and the outermost membrane, the duramater.

• Uvea is a pigmented layer of eye which is present beneath sclera and cornea. It comprises iris, choroid and ciliary body.
• Cornea is the anterior portion of eye which absorbs oxygen from the air. It is the only part of human body which is devoid of blood supply and absorbs oxygen directly from the air.
• Conjunctiva is a thin transparent membrane lining the eyelids and protects the delicate cornea and front portion of the eye.
• Sclera (the external layer of eye) and cornea together constitute the fibrous layer or fibrous coat of eye.