The nervous system is a controlling system of the body and is composed of nerve cells. It is further classified into central nervous system and peripheral nervous system.
The brain and spinal cord collectively form the central nervous system and the network of nerves found outside the brain and the spinal cord is the peripheral nervous system.
The nerves fibers are of two types – afferent fibers and efferent fibers. The afferent nerve fibers are responsible for transmission of impulses from the tissues to the central nervous system while the efferent nerve fibers are responsible for transmission of impulses from central nervous system to the concerned tissues or organs.
Let us study the peripheral nervous system, its definition, types, diagram and functions in detail.
Also Read: Central Nervous System
Peripheral Nervous System Definition
“Peripheral nervous system involves the parts of the nervous system outside the brain and the spinal cord.”
Peripheral Nervous System Divisions
The peripheral nervous system is divided into two parts:
- Somatic Nervous System
- Autonomic Nervous System
Peripheral Nervous System Parts
Following are the major parts of the peripheral nervous system:
Somatic Nervous System
The main function of the somatic nervous system is to transfer impulses from CNS to skeletal muscles.
It consists of
- Cranial Nerves
- Spinal Nerves
Cranial nerves emerge from the brain and there are twelve pairs of cranial nerves. Some of the examples may be the sensory nerves like optic, olfactory, etc.
Spinal nerves have their point of emergence as the spinal cords. There are thirty-one pairs of spinal nerves. They emerge from the spinal cords into dorsal and ventral roots. At the junction of these two roots, the sensory fibers continue into the dorsal root and the motor fibers into the ventral root.
Autonomic Nervous System
The autonomic nervous system relays impulses from the central nervous system to the involuntary organs and smooth muscles of the body.
It is further divided into two parts –
- Sympathetic Nervous System
- Parasympathetic Nervous System
The sympathetic nervous system consists of nerves arising from spinal cord between the neck and waist region.It prepares the body for violent actions against abnormal conditions and is generally stimulated by adrenaline.
The parasympathetic nervous system is located anterior in the head and neck and posterior in the sacral region. It is mainly involved in re-establishment of normal conditions when violent action is over.
Peripheral Nervous System Functions
Following are the important functions of the peripheral nervous system:
- The peripheral nervous system connects the brain and the spinal cord to the rest of the body and the external environment.
- It regulates the internal homeostasis.
- It can regulate the strength of the muscle contractility.
- It controls the release of secretions from most exocrine glands.
Also Read: Nervous System
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