ANS Flashcards
What are the 2 divisions of the PNS?
Sensory afferent
Motor efferent
What are the 2 divisions of the sensory afferent?
Somatic, visceral
What are the 2 divisions of the motor efferent PNS?
Somatic Nervous System
Autonomic Nervous System
The ANS is a branch of which nervous system?
Visceral motor efferent of the PNS
Somatic sensory afferent receives signals from what?
Skin
Bones
Skeletal muscle
Visceral sensory afferent receives signals from?
Organs
Glands
Vessels
Somatic nervous system sends efferent signals to what?
Skeletal muscle
What are the 2 branches of the ANS?
Sympathetic
Parasympathetic
What do the visceral efferent neurons of ANS innervate?
Smooth muscle
Cardiac muscle
Glands
Where is smooth muscle innervated by ANS located?
Walls of organs
Walls of vessels
Hair follicles
Eye
What is the entire structure of a nerve? Smallest to largest
Axon –> endoneurium –> fascicle –> perineurium –> nerve –> epineurium
What is an axon?
Part of a neuron
What is the endoneurium?
Surrounds individual axons
What is a fascicle?
Groups of axons
What is a perineurium?
Surrounds fascicle
What is a nerve?
Cluster of fascicles and blood vessels
What is an epineurium?
Surrounds entire nerve
What are the 4 types of neurons?
Somatic efferent
Somatic afferent
Visceral efferent
Visceral afferent
What is unique about visceral efferent neurons?
They are actually a 2-neuron chain
What type of neuron is a visceral efferent neuron?
Multipolar
What is a preganglionic fiber?
Part of the first neuron in the CNS before the synapse in the PNS at the ganglia
Where in general does the synapse occur?
Ganglia of PNS
What is a postganglionic fiber?
Part of second neuron after the synapse in the PNS that goes to target organ
Where are the cell bodies of preganglionic sympathetic neurons?
Lateral horns of T1-L2/L3 in CNS
Preganglionic sympathetic neurons leave the CNS via what structure?
Ventral root
Where do sympathetic preganglionic fibers synapse?
Sympathetic chain
Prevertebral ganglia
What are the effects of the sympathetic nervous system?
Increase HR Dilate pupils Increase sweating Dilate bronchi Divert blood to muscles
What is the thoracolumbar division?
Sympathetic nervous system location of preganglionic cell bodies
Where are the cell bodies of preganglionic parasympathetic neurons?
Brainstem
S2-S4
Which has longer postganglionic fibers, sympathetic or parasympathetic?
Sympathetic
Parasympathetic has short postganglionic fibers since synapse is CLOSE to target organ
What are the effects of the parasympathetic nervous system?
Increase digestion Increase excretion Conserve energy Decrease HR Constrict pupils Constrict bronchi Increase peristalsis Increase secretion of digestive enzymes
Where are the preganglionic cell bodies of the parasympathetic located in the brainstem?
CN3, CN7, CN9, CN10
Where are the parasympathetic preganglionic cell bodies of the sacral spinal cord located?
Lateral horns of S2-S4
What is the craniosacral division?
Parasympathetic preganglionic cell bodies
Where is the sympathetic chain?
Lateral to vertebral column
Base of skull to coccyx
What connects spinal nerves to sympathetic chain?
Rami communicantes
What is the difference between the WRC and GRC?
WRC- where neurons ENTER the sympathetic chain
GRC- where neurons EXIT the sympathetic chain
Where do preganglionic neurons synapse in cervical region?
Superior, middle and inferior cervical ganglia
What is the path of a preganglionic sympathetic neuron?
Lateral horn –> ventral horn –> ventral root –> spinal nerve –> WRC –> sympathetic chain
Once in the sympathetic chain, where can the preganglionic neuron travel?
Limbs/body wall
Head
Thoracic cavity
Abdominopelvic cavity
If the visceral efferent structure is located in the limbs/body wall, where does the sympathetic pre and post ganglionic neurons travel?
Preganglionic travels from T1-L2/L3 and synapses at the level of the organ in the sympathetic chain and postganglionic fiber travels to limbs/body wall
If the visceral efferent structure is located in the head, where does the sympathetic pre and post ganglionic neurons travel?
Preganglionic fibers travel from T1-L2/L3 to sympathetic chain and go UP toward cervical region where they synapse at superior cervical ganglion
How do postganglionic sympathetic neurons travel to innervate head structures?
Through internal and external carotid nerves
How do postganglionic sympathetic neurons travel to innervate structures in the thoracic cavity?
Through cardiac nerves
How do postganglionic sympathetic neurons travel to innervate the abdominopelvic cavity?
Through splanchnic nerves
If the target organ is within the abdominopelvic cavity, where does the synapse occur?
Preganglionic fibers DO NOT synapse in the sympathetic chain but synapse in prevertebral ganglia of plexuses and postganglionic fibers travel via splanchnic nerves to target
After the synapse, how do postganglionic sympathetic fibers get to target organ?
Leave via GRC from sympathetic trunk to target organ
Where do parasympathetic preganglionic neurons travel?
Cranial and splanchnic nerves to target organs directly
Where do parasympathetic preganglionic neurons synapse?
In ganglia close to target organ
What are the 2 branches of the nervous system?
Peripheral and Central