Autonomics Flashcards
divisions of ANS
sympathetic and parasympathetics
Autonomic plexus
sympathetisc, parasympathetics, and probaby some visceral afferents as well
GVE go to what?
cardiac muscle, smooth muscle and gland cells
ANS
is a visceral efferent system
nerve
collection of wires
nucleus
a collection of nerve cell bodies in the CNS
ganglion
collection of nerve cell bodies in the PNS
path from CNS to effector organ
takes 2 neurons, a pre-ganglionic and a post-ganglionic
parasympathetics
“rest and digest,” craniosacral system (conserve energy, replenish nutrient stores)
sympathetics
“fight or flight,” thoracolumbar system (reaction to emergencies. ALL pre-ganglionic nerve cell bodies are in spinal cord between T1 and L2.
sympathetic trunk
the location of some (not all) post-ganglionic sympathetic nerve cell bodies. Like a string of pearls.
Preganglionic sympathetic nerve cell processes
Preganglionic nerve cell bodies arise from the intermedio-lateral column of the spinal cord
Their nerve cell processes pass out the ventral root and join the spinal nerve.
They leave the spinal nerve as a white ramus communicans and go to the sympathetic chain ganglion
At this point they have 4 options
1) synapse at the chain ganglion, return to the spinal nerve via a gray ramus communicans and distribute with the spinal nerve
2) go up or down the chain ganglion, synapse, then go back to the spinal nerve via a gray ramus communicans at that higher or lower level to be distributed with the spinal nerve
3) synapse (at their initial level) and go to the heart, lungs and other organs directly from the chain ganglion as a cardiopulmonary splanchnic nerve. (nearly all other splanchnic nerves are PREganglionic)
4) Go through the chain ganglion WITHOUT synapsing as a splanchnic nerve and go to a ganglion near their effector organ (in a prevertebral ganglion)
Greater Splanchnic nerve cord levels
T5-T9
Lesser Splanchnic nerve cord levels
T10, T11
Least Splanchnic nerve cord level
T12
Parasympathetic nerves and segments
Preganglionic nerve cell bodies are in brainstem nuclei of cranial nerves III, VII, IX and X and S2,3,4, spinal cord segments
Parasympathetic Postganglionic nerve cell body location
wall of the effector organ (cardiac muscle smooth muscle or gland cells)
CN X (vagus)
Preganglionic nerve cell processes travel with X to the chest and abdominal viscera (to the level of the left colon) The postganglionic nerve cell bodies are located in the wall of the effector organ (cardiac muscle, smooth muscle and gland cell)
heart referred pain
Because afferent pain nerves follow sympathetic nerves to the T1-T4/T5 spinal segments, pain from the heart is referred to dermatomes supplied by these segments especially on the left side. Thus, pain from the heart often is referred to the chest and medial surface of the brachial area.
Cardiac Autonomic plexuses
- Postganglionic sympathetic and preganglionic parasympathetic nerve cell processes to the muscles and nodal tissues of the heart.
- Distribute via coronary arteries,
- Superficial plexus (located in the concavity of aortic arch).
- Deep plexus (located posterior to arch of aorta; anterior to tracheal bifurcation).
Preganglionic sympathetic nerve bodies (cardiac)
Preganglionic nerve cell bodies located in T1-T4 segments of spinal cord
(intermediolateral cell column of gray matter); their processes enter sympathetic chain.
Postganglionic sympathetic nerve cell bodies (cardiac)
Postganglionic nerve cell bodies located in upper thoracic and cervical sympathetic chain ganglia.
Postganglionic nerve cell processes from the sympathetic ganglia (cardiac)
form cardiac branches which are called cardiopulmonary splanchnic nerves. Note: these “splanchnic” nerves are POST ganglionic.
a. Superior cervical sympathetic cardiac nerve
b. Middle cervical sympathetic cardiac nerve
c. Inferior cervical sympathetic cardiac nerve
d. Thoracic (T1-4) sympathetic cardiac nerves
Functions of cardiac sympathetic nerves
a. Increase heart rate.
b. Dilate coronary vessels to increase blood flow to the heart.
c. Visceral afferents (acute pain fibers) piggyback sympatheic nerves to upper thoracic spinal segments. (nerve cell bodies are located in dorsal root ganglia)
Preganglionic neve cell bodies (parasympathetic nerves) (cardiac)
- Preganglionic nerve cell bodies located in the brain stem and processes travel with the vagus nerve.
- In the neck, the vagus gives off superior and inferior cervical cardiac parasympathetic branches and in the thorax, thoracic cardiac parasympathetic branches.
Postganglionic nerve cell bodies (parasympathetics)
bodies are found within the wall of the heart (especially around the SA and AV node).
parasympathetic nerve functions (re: cardiac)
a. Decrease heart rate
b. Constrict coronary vessels
c. Also may carry visceral afferents (stretch receptors; mainly in right atria)
