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divisions of nervous system (for descriptive
purposes)
-Structurally: Central nervous system vs. Peripheral nervous system;-Functionally: Somatic nervous system vs. Autonomic nervous system TERM 2
neurons
DEFINITION 2 structural & functional units of the nervous system specialized for rapid communication TERM 3
dendrites
DEFINITION 3 carry impulses to the cell body TERM 4
axon
DEFINITION 4 carries impulses away from the cell body. TERM 5
myelin sheath
DEFINITION 5 surrounds some axons, increasing the velocity of impulse conductions.
synapses
points of contact between neurons, with communication occurring through the release of neurotransmitters. TERM 7
Central Nervous System (CNS)
DEFINITION 7 consists of brain & spinal cord TERM 8
CNS: function
DEFINITION 8 integrate & coordinate incoming/outgoing neural signals and to carryout higher mental functions TERM 9
gray matter
DEFINITION 9 -centrally located in CNS, butterfly shape on transverse section; -Largely consists of neuron cell bodies;-Divided into an anterior horn, posterior horn, and lateral horn (between T1-L2(3)) TERM 10
white matter
DEFINITION 10 -peripherally located in CNS;-Largely consists of nerve fibers (axons) & myelin; color due to whiteness of myelin
general sensory (afferent)
fibers
Transmit sensations (e.g., pain, temperature, touch, pressure, and proprioception) from the body to the CNS TERM 17
what do afferent fibers consist of?
DEFINITION 17 pseudounipolar neurons TERM 18
pseudounipolar neurons
DEFINITION 18 -Cell bodies located outside of the CNS, either in spinal ganglia or sensoryganglia of cranial nerves; -Appear to have a single process, which almost immediately divides into aperipheral process to the sensory end organ and a central process to the CNS (via the posterior root of spinal nerves) TERM 19
shingles
DEFINITION 19 common name for painful condition resulting from reactivation of the varicella zoster virus. virus typically lies dormant in ganglia of the sensory nervous system but can reactivate and spread to skin through sensory neurons and cause a painful rash that occurs in a well defined dermatomal distribution TERM 20
general motor (efferent) fibers
DEFINITION 20 Transmit impulses to skeletal (voluntary) muscles & part of somatic nervous system
what do efferent fibers consist of?
1 neuron between spinal cord & target;Cell bodies located in gray matter (anterior horn) of the spinal cord; Axons exit the CNS via anterior roots of spinal nerves or via cranial nerves TERM 22
autonomic nervous system
DEFINITION 22 involuntary system consisting of 2 neurons between CNS & target (presynaptic neuron & postsynaptic neuron) TERM 23
autonomic nervous system: function
DEFINITION 23 Stimulate smooth (involuntary) muscle in the walls of blood vessels & organs, modifiedcardiac muscle (SA & AV nodes), and glands (sweat, salivary, & lacrimal) TERM 24
presynaptic neuron
DEFINITION 24 cell body located w/in the gray matter of the CNS; axon terminateswithin an autonomic ganglion upon the postsynaptic neuron TERM 25
postsynaptic neuron
DEFINITION 25 cell body located w/in autonomic ganglion; axon terminates on target
4 possible courses of the presynaptic
sympathetic neurons within the sympathetic
trunk
synapse at level of entryascend to higher ganglion to synapsedescend to lower ganglion to synapseOR pass through without synapsing to enter anabdominopelvic splanchnic nerve TERM 32
postsynaptic sympathetic neurons for
innervation of abdominopelvic vicera
DEFINITION 32 fibers pass out of collateral ganglia located around the major branches of the abdominal aorta via sympathetic postsynaptic nerve fibers that follow blood vessels (periarterial plexuses) to reach their target structures. TERM 33
postsynaptic sympathetic neurons for
innervation of thoracic viscera
DEFINITION 33 postsynaptic fibers pass via cardiopulmonary splanchnic nerves to their target structures. TERM 34
postsynaptic sympathetic neurons for
innervation of the head
DEFINITION 34 fibers synapse in the superior cervical ganglia in the sympathetic trunk and post synaptic fibers pass to carotid periarterial nerve plexuses, which follow the arteries. TERM 35
postsynaptic sympathetic neurons for
innervation of the body wall or limbs
DEFINITION 35 fibers pass out of the sympathetictrunk at the level of the synapse via gray rami communicans to anterior rami of all 31 pairs of spinal nerves. Postsynaptic fibers enter both posterior & anterior rami of each spinal nerve, and all branches of all spinal nerves will include some sympathetic postsynaptic fibers.
parasympathetic nervous system
promotes normal function, rest & digest TERM 37
parasympathetic nervous system: functions
DEFINITION 37 Constricts pupils (protecting the retina) Adjusts the lens for near vision (accommodation) Decreases rate & strength of cardiac contractions to normal levels, decreasing blood pressure & conserving energy Constricts bronchioles (returns dilated bronchioles to normal) Promotes peristalsis for digestion Responsible for the autonomic phase of emptying the urinary bladder and rectum Erection TERM 38
Presynaptic parasympathetic neuron cell
bodies:
DEFINITION 38 -Located within the gray matter of the brain in the nuclei of CN III, VII, IX, X;-Located within S2-S4 spinal cord segments TERM 39
Path of presynaptic parasympathetic neurons:
cranial outflow
DEFINITION 39 exit CNS via CN III, VII, IX (to head/neck) & X (extends to left colicflexure of the large intestine) TERM 40
Path of presynaptic parasympathetic neurons:
sacral outflow
DEFINITION 40 exit CNS via pelvic splanchnic nerves (to pelvic viscera & descendingcolon from left colic flexure)
referred pain
pain perceived at a location other than the site of the painful stimulus TERM 47
why does referred pain happen?
DEFINITION 47 it is thought that when nerve fibers from regions of high sensory input (e.g., skin) and nerve fibers from regions of normally low sensory input (e.g., internal organs) converge on the same levels of the spinal cord. However, the brain isn't used to receiving such strong signals from the viscera, so it interprets them as pain coming from a different location. TERM 48
routes to CNS of most visceral pain impulses
DEFINITION 48 travel in visceralafferent fibers that accompany sympathetic fibers retrogradeToward cell bodies located in the spinal (dorsal root) ganglia of T1-L2(3) and to the posterior horn of the spinal cord. TERM 49
routes to CNS of most visceral reflex
sensation and some pain below the pelvic
pain line
DEFINITION 49 travel in visceral afferent fibers that accompany parasympathetic fibers retrograde;-Toward cell bodies in the sensory nuclei in the brain of the Vagus nerve (CN X).-Toward cell bodies in the spinal (dorsal root) ganglia of S2-S4 and to the posterior horn ofthe spinal cord (sensations distal to the left colic flexure of the large intestine).
