Neural Control and Coordination Test 10

Auditory nerve is a sensory nerve that transmits impulses from internal ear to central neural system.

4 pairs of cranial nerves are mixed nerves. These are trigeminal, facial, glossopharyngeal and vagus nerves.

Synapse is a junction found between the branches at the end of the axon of one neuron and the dendries or cell body of aother neuron. Through this junction nerve impulse transmits from one neuron to other.

Sympathetic neural system accelerates heart beat and inhibits secretion of digestive juices and saliva.

Vagus nerve is the mixed cranial nerve with maximum branches.

Autonomous neural system controls the given activities.This system controls and coordinates the involuntary activities of various organs. Involuntary activities are not under the will power of the animal.

Excessive stimulation of vagus nerve will lead to increased peristalsis which in turn will lead to more secretion of HCl from the stomach. This will cause erosion through protective barrier of mucus and muscular is mucosa into the submucosa leading to peptic ulcer.

Abducens nerve is a motor nerve that controls the movements of the eye ball.

During stress condition, stimulation of the sympathetic nerves to adrenal medulla causes large quantities of adrenaline to be released into the blood circulation and then this hormone is carried to the specific tissues of the body where it produces its effect e.g., increase in heart beat.

Somatic nerves innervate the skeletal muscles. Therefore, these nerves control the movements of the body by acting on the skeleta muscles.

Sympathetic neural system is also called the thoracolumbar division of autonomic neural system because nerves exit the spinal cord from first thoracic (T₁) to second lumbar (L₂) levels. Similarly, parasympathetic division is known as craniosacral division of autonomic neural system.

In a human being, the number of cranial nerves is 12 pairs. These are olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, auditory, glossopharyngeal, vagus, spinal accessory and hypglossal nerves.

The sensory nerves carrying impulses from the receptors to CNS are called afferent nerve fibres.

Hypoglossa nerve is a motor nerve that controls the movements of the tongue.

Each segment of myelin sheath is formed by one schwann cell. Myelin sheath is present in the melinated nerve fibres. It is made up of a substance of lipids, proteins and water called myelin and serves as an insulating layer, preventing loss of energy of the nerve impulse during its passage along the fibre.

Autonomic neural system is responsible for the control of involuntary functions of the body e.g., peristalsis digestion, excretion, sweating, beating of heart, etc. It is not concerned with memory and learning.

Vagus nerve innervates pharynx, larynx, oesophagus, stomach, lungs, heart and intestines. Thus, injury to vagus nerve will not affect tongue movements as it does not innervate tongue.

There are 31 pairs of spinal nerves. These are named and numbered according to the vertebrae with which they are associated. They include 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves and 1 pair of coccygeal nerves.

Abducens nerve is a motor nerve that controls the movement of the eyeball. Thus, if abducens nerve is injured, movement of the eyeball will be affected.