Peripheral nervous system
Peripheral Nervous System (PNS). Also known as the nervous system of relationship life, it is made up of nerves and neurons . The difference between this and the central nervous system (CNS) is that the peripheral nervous system is not protected by bones or the blood-brain barrier, which allows exposure to toxins and mechanical damage. The peripheral nervous system is what coordinates, regulates and integrates internal organs , through unconscious responses.
Summary
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- 1 Subdivision
- 1 Somatic nervous system
- 2 Autonomic nervous system
- 2 Functional components of the nervous system
- 3 Ganglia
- 4 Source
Subdivision
The SNP is subdivided into:
Somatic nervous system : Activates all organic functions (it is active).
Autonomous or vegetative nervous system : Protects and moderates energy expenditure. It is made up of billions of long neurons, many grouped into nerves. It serves to transmit nerve impulses between the CNS and other areas of the body .
Peripheral nerves : They have three layers: endoneurium, perineurium and epineurium.
somatic nervous system
Spinal nerves, which send sensory information (touch, pain) from the trunk and extremities to the central nervous system through the spinal cord . They also send information about the position and condition of the muscles and joints of the trunk and extremities through the spinal cord. They receive motor orders from the spinal cord to control skeletal muscles . There are a total of 31 pairs of nerves, each with two parts or roots: one sensory and the other motor.
The sensory part is what carries impulses from the receptors to the spinal cord.
The motor part is what carries impulses from the spinal cord to the corresponding effectors. The spinal nerves must always be taken into account . cranial nerves , which send sensory information from the neck and head to the central nervous system. They receive motor commands to control the skeletal muscles of the neck and head ; and there are 12 pairs of cranial nerves.
Estate
- Cervical roots
- Thoracic roots or dorsal roots
- lumbar roots
- sacral roots
Plexuses
The cervical plexus is the most superior nervous plexus in the system. It is formed by the anterior branches of the first four cervical nerves (from C1 to C4), branches that, with the exception of the first, are divided into ascending and descending branches, joining with the adjacent branches forming loops. It is located along the first 10 cervical vertebrae , anterolateral to the levator scapulae and middle scalene muscles , and deep to the scleidomastoid muscle. Brachial plexus and lumbosacral plexus.
Nerves
- cranial pairs
- Nerves of upper limbs
- Nerves of lower limbs
Autonomic nervous system
It regulates all bodily functions, controls the smooth muscles, the heart , the viscera and the glands by order of the central nervous system.
Sympathetic branch: involved in activities that require energy expenditure.
Parasympathetic branch: responsible for storing and conserving energy, as well as gastric mobility.
Enteric branch: regulates gastrointestinal activity and coordinates peristaltic reflexes. It is made up of roots, plexuses and nervous trunks.
Functional components of the nervous system
Sensory component (afferent), which receives and transmits impulses to the CNS for processing.
Motor (efferent) component, which originates in the central nervous system and transmits impulses to effector organs throughout the body , and this in turn is divided into: Somatic system, in which the impulses that originate in the nervous system central are transmitted directly through a neuron to a skeletal muscle Autonomous system, receives impulses from the CNS and is first transmitted to an autonomic ganglion through a neuron; A second neuron originating in the autonomic ganglion then carries the impulse to smooth muscle, cardiac muscle, or glands .
Ganglia
The sensory fibers contained in the cranial and spinal nerves are nothing more than extensions of certain nerve cells (T cells), grouped in small clusters located outside the neuroaxis: the cerebrospinal ganglia . The ganglia attached to the spinal nerves are equal to each other, in shape, dimensions and position. The posterior root of each nerve departs from them, always in the proximity of the intervertebral foramen that the nerve runs through to exit the spinal column . The ganglia of the cranial nerves, on the other hand, have a much more variable shape, dimensions and position. However, the functions and histological constitution are very similar for both types of lymph nodes.
