Question

Describe the peripheral nervous system and its anatomical and physiological components i.e. neurons, glial cells, etc. Discuss how the PNS is important in maintaining homeostasis. Describe the difference between motor and sensory neurons. Discuss a few import nerves in the body i.e. Radial, Medial, Sciatic, and more etc. Discuss the various conditions and diseases of the PNS.

Answer 1

PNS: The peripheral nervous system (PNS) is one of the two major divisions of the nervous system. ... The nerves in the peripheral nervous system (PNS) connect the central nervous system (CNS) to sensory organs (such as the eye and ear), other organs of the body, muscles, blood vessels and glands.

Anatomical & Physiological components:

The PNS is divided into the somatic nervous system and the autonomic nervous system. The somatic nervous system controls body movements that are under our control such as walking. The autonomic nervous system controls involuntary functions that the body does on its own such as breathing and digestion.

Neuron in PNS-  which consists of the neurons and parts of neurons found outside of the CNS, includes sensory neurons and motor neurons. Sensory neurons bring signals into the CNS, and motor neurons carry signals out of the CNS.

Neuroglia (glial cell): The PNS has two kinds of neuroglia: schwann cells and satellite cells. Schwann cells provide myelination to peripheral neurons. They also perform phagocytic functions and clear cellular debris, allowing for the regrowth of PNS neurons. Functionally, the schwann cells are similar to oligodendrocytes of the CNS.

Autonomic nervous system:

The autonomic nervous system (ANS) is the part of the peripheral nervous system that maintains homeostasis in the body. Your body carries out most of these maintenance activities without your conscious control, which is why the autonomic nervous system is also called the involuntary nervous system.

What is the difference between Sensory and Motor Neurons?

Sensory neurons bring sensory impulse from sensory organs to the central nervous system, whereas motor neurons carry motor impulses from the central nervous system to specific effectors. ... Sensory neuron has afferent fiber, whereas motor neuron has efferent fiber.

Radial nerve:The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.

Median nerve: The median nerve is the main nerve of the front of the forearm. It supplies the muscles of the front of the forearm and muscles of the thenar eminence, thus controlling the coarse movements of the hand.

Sciatic nerve: The sciatic nerve, also called the ischiadic or ischiadic nerve, is a large nerve in humans and other vertebrate animals which begins in the lower part of the sacral plexus and runs through the hip joint and down the lower limb. It is the longest and widest single nerve in the human body, going from the top of the leg to the foot on the posterior aspect.The sciatic nerve provides the connection to the nervous system for nearly the whole of the skin of the leg, the muscles of the back of the thigh, and those of the leg and foot. It is derived from spinal nerves L4 to S3. It contains fibers from both the anterior and posterior divisions of the lumbosacral plexus.

Disease of PNS:Some are quite common, for example, lepromatous neuropathy, diabetic neuropathy, Guillain-Barré syndrome and acute motor axonal neuropathy