Autonomic System Flashcards
What is the purpose of the autonomic system?
Controls function of visceral system (smooth and cardiac muscles, and other glands)
What are the three parts of the autonomic system?
Parasympathetic, Sympathetic, and Enteric
Autonomic system does not have conscious control; however, what can it modulate?
Conscious drive
Where are the autonomic system fibers found?
Lateral horn
Where are fibers from the sympathetic system travel to and found?
Thoracolumbar Column (T1-L3) and found in the lateral horn
Where are fibers from parasympathetic system traveling to and found?
Start at brainstem (CN 3,7,9,10) and S2-S4
How are the somatic system and autonomic systems alike?
Their connection to reflex activity is the similar and their connection to higher function CNS are similar
How do the somatic and autonomic systems differ?
Structures that receive afferent information (thalamus - somatic) and (hypothalamus - autonomic). Descending pathways leave from (cerebral cortex - somatic) and (hypothalamus - autonomic).
Somatic systems only have ONE neuron pathway to innervate skeletal muscle; whereas, autonomic system has TWO neuron pathways to innervate target smooth muscles, cardiac muscles, and glands. Somatic muscle snaypse by way of chemical synapse; whereas, autonomic system synapses with electrical synapse
Explain the two neuron pathway for autonomic system?
Pregangolic fibers exit through the ventral root and synapse with gangiolic fibers in the postsynaptic neuron then innervate smooth and cardiac muscles, and glands
How do preganglionic fibers differ from postganglionic fibers?
Preganglionic are lightly myelinated
Postganglionic are not myelinated
How does the parasympathetic and sympathetic pathway differ in regards to the postganglionic and preganglionic fibers?
Parasympathetic have longer preganglionic fibers and their ganglion bodies are closer to target cells
Sympathetic have shorter preganglionic fibers and their ganglion bodies are closer to the spinal cord
What does the sympathetic system control?
Functions in response to emotional or physical stress
What are the 4 E’s that relate to the sympathetic system?
Exercise, Embarrassment, Excitement, Emergency
What is the function of the sympathetic nervous system?
Pupil dilation, Bronchodilation, Vasocontriction (reroutes blood to the muscles), Inhibition of lacriminal and salivation glands, stimulates sweat glands, stimulates piloerection, inhibits digestive system, and stimulates hormones (adrenal medulla: releases NE and Epinephrine; Pancreas: Glucagon)
Where does the sympathetic system start?
Lateral Column of Spinal Cord
Where do the preganglionic neurons of the sympathetic system extend?
T1-L3 (upper thoracolumbar region: head and thorax; lower lumbar regions: pelvic organs, abdominal organs, and LE targets)
Explain the three different routes in which efferent information take exiting the spinal cord through the ventral rami?
- Travel through the white communicating rami of the sympathetic trunk and synapse immediately to postganglionic neurons
- Travel through the white communicating rami of the sympathetic trunk and then synapse according on where it ascends and descends
- Travels through the white communicating rami of the sympathetic trunk without synapsing and then goes to synapse to the prevertebral ganglions
Explain where the three targets of the sympathetic nervous system exit to
- Preganglionic fibers that synapse directly in the sympathetic trunk exit directly to the targets of the LE
- Preganglionic fibers that synapse whether there are descending or ascending exit to blood vessels via the gray communicating matter
- Preganglionic fibers that travel through the sympathetic trunk without synapsing and then synapse at the prevertebral ganglion exit to the heart, lungs, gut, liver, kidney, bladder, and reproductive organs
What is the function of the parasympathetic system?
The function of the parasympathetic system is energy storage and conversation of energy
What are components of the parasympathetic?
Rest digest,
Contraction of bladder, constriction of pupils, vasodilation, bronchoconstriction, decrease of HR, Preganglionic nuclei of sacral nerve (s2-s4)
What are the four nuclei that are associated with efferent structures of the parasympathetic system?
EW Nuclei, Inferior and Superior Salivary Nuclei, Nucleus Ambigous, Dorsal Motor Nuclei of Vagus nerve
Where do the efferent structures of the parasympathetic exit to?
- EW nucleus –> cilliary muscles for pupil constriction
- Inferior and Superior Salivary Nuclei —> lacriminal and salivary glands
- Nucleus Ambigous –> Decreasing HR
- Dorsal Motor Nucleus of Vagus N. —> glandular secretion of abdominal, slow heart rate, broncho constriction of lungs, and increase gut motility
Preganglionic neurons from Sacral –> bladder contraction, vasodilation of rectum and colon, vasodilation of clitoral and penile
Parasympathetic and Sympathetic structures are usually innervate the same structures. What does the sympathetic system ONLY innervate
S: Sweat glands
A: Adrenal Medulla
M: more blood vessels
E: Erector pili muscles
What are some major differences between the parasympathetic and sympathetic system??
Sympathetic response are usually longer than parasympathetic due to: divergence of preganglionic neurons, unmyelinated post ganglionic neurons, presence of NE and epinephrine in the blood stream, slower inactivation of NE at the synapse
