Lesson 25.3 - Peripheral Nervous System Flashcards
Peripheral Nervous System
this composed the nerves throughout the body. It has divisions, namely: Somatic Nervous System and Autonomic Nervous System.
Neurons
it comprises the PNS and is the basic unit of the nervous system.
Ganglia
are small sacs of clustured neurons that are found outside the spinal cord, which serves as the receiving point of nerve impulses.
Sensory Neurons or the Afferent Neurons
it detects outside stimuli with the diffent receptors on the skin, then it sends the signal to the spinal cord. (e.g. heat, pain, pressure.)
Motor Neurons or the Efferent Neurons
it controls the involuntary movement or contractions of the different muscle organs. (e.g heart, lungs, stomach)
Somatic Nervous System (SNS)
responsible for the voluntary and controlled movements of the muscle, organs, and the reflex movement. The components of this includes the cranial nerves and spinal nerves.
Cranial Nerves
carries information into and out of the brain stem. They are sensory in nature in terms of function, motor, or both. There are 12 known cranial nerves in the PNS.
Olfactory
olfactory really means the data of smells that a human intakes. They are responsible in transimitting those data to the brain.
Optic
it is associated with vision.
Oculomotor
these controls the eye’s pupil and its muscular functions.
Trochlear
they control the eye muscles.
Trigeminal
it controls the area around the eyes, mandibles, and the middle part of the face.
Abducens
it also controls the eye muscles.
Facial
it controls the movement of the face, taste, neck, and head.
Vestibulocochlear
it concerns with the body’s equilibrium, balance, and sound.
Glossopharyngeal
associated with the tongue and the throat.
Vagus
associated with the throat, ears and tongue
Spinal Accesory
controls neck muscles.
Hypoglossal
associated with tongue muscles.
Spinal Nerves
these are nerves in the spinal cord that were named based on which segment of the spine they are found in. There are 31 spinal cord segments
Functions of Somatic Nervous System (SNS)
Voluntary Movements, Reflex Arcs
Voluntary Movements
SNS cooperates with the skeletal system in order to provide voluntary movement and conscious control over these muscular movements.
Reflex Arcs
they are associated with reflex, which are involuntary but fast movements in response to stimuli that are detected.
How reflex arcs work:
receptors are excited by stimulus ~ sensory neurons will carry the signals to the spinal cord ~ pass it to a motor neuron ~ it generates a movement.
Autonomic Nervous System (ANS)
they control the involuntary movement of visceral muscle, smooth, muscle, cardiac muscle, and glandular muscle. They are composed of the symphathetic neurons and the parasympathetic neurons.
Sympathetic Division
they are responsible for the body’s “fight or flight” response of the body when encountering stress, danger, excitement and other emotions.
It increases the respiration and heart rate , releases adrenaline, and decreases digestion.
Sympathetic Division
Sympathetic Division
They are associated with the lumbar and thoracic spinal cord segments.
Parasympathetic Division
it initiates the “rest and digest” function of the body in response to rest, relaxation, and feeding.
It decreases respiration, increase digestion, and allows the elimination of wastes.
Parasympathetic Division
Parasympathetic Division
They are associated with the cranial and sacral segments of the spinal cord.
31 spinal segments
8 from cervical;
12 from thoracic;
5 from lumbar;
5 from sacral; and
1 caudal segment.
