Question

In peripheral nervous system, the nerves are made up exclusively from the
A) Dendrons
B) Axons
C) Nodes of ranvier
D) Nissl body

Answer 1

Hint: The peripheral nervous system (PNS) is the division of the nervous system containing all the nerves that lie outside of the central system (CNS). The first role of the PNS is to attach the CNS to the organs, limbs, and skin. These nerves extend from the central system to the outermost areas of the body.

Complete answer:
The PNS consists of all the nerves branching out of the brain and funiculus (CNS). It allows the brain and funiculus to receive and send information to other areas of the body, which allows us to react to stimuli in the environment.

The nerves that structure the peripheral nervous system are literally the axons or bundles of axons from nerve cells or neurons. In some cases, these nerves are very small but some nerve bundles are so large that they'll be easily seen by the human eye.

The PNS is constructed almost entirely from nerves. There are two main types; spinal nerves and cranial nerves. It's divided into two parts: the somatic system and also the autonomic system. Each of those components plays a critical role in how the peripheral system operates.

The workhorse of the PNS are the peripheral nerves. Each nerve consists of a bundle of the many nerve fibers (axons) and their animal tissue coverings. Each fiber is an extension of a neuron whose cell body is held either within the nervous tissue of the CNS or within the ganglia of the PNS.

Peripheral nerves that carry information towards the CNS are called afferent or sensory neurons, while those transmitting impulses from the CNS are referred to as efferent or motor neurons.

Afferent neurons transmit a range of impulses from sensory receptors/sense organs. They carry general sensations like touch, pain, temperature. Efferent neurons bring general nervous information towards effector organs, like skeletal muscles, visceral organs and glands. They're chargeable for initiating voluntary and involuntary motor functions.

Nerves may be classified as ‘cranial’ or ‘spinal’ consistent with where they exit the CNS. Cranial nerves emerge from the cranium (brain/brainstem) whilst spinal nerves leave the CNS via the medulla spinalis. There are 12 pairs of cranial nerves and 31 nervus spinalis pairs, giving a complete of 43 paired nerves forming the premise of the peripheral system.

Note:The first set of peripheral nerves are the twelve cranial nerves: olfactory (cn i), optic (cn ii), oculomotor (cn iii), trochlear (cn iv), trigeminal (cn v1, cn v2, cn v3), abducens (cn vi), facial (cn vii), vestibulocochlear (cn viii), glossopharyngeal (cn ix), vagus (cn x), nervus accessorius (cn xi), and hypoglossal (cn xii) nerves. Cranial nerves are peripheral nerves that mainly innervate anatomical structures of the pinnacle and neck. The exception to the present is that the tenth cranial nerve, which also innervates various thoracic and abdominal organs. The second set of peripheral nerves are spinal nerves, of which there are 31 pairs: eight cervical, twelve thoracic, five lumbar, five sacral, and one coccygeal. Their numbering relates to the back exit level.