Autonomic Nervous System Flashcards
Distinguish between sympathetic and parasympathetic outflow with respect to:
Postganglionic transmission
Divergence
Parasympathetic synapses always use acetylcholine. Sympathetic is usually norepinephrine, but uses acetylcholine at sweat glands and vascular smooth muscle.
Sympathetic has greater divergence; it has broader and more general effect.
What are the primary parasympathetic nerves?
What may happen to a preganglionic sympathetic neuron as it enters the chain ganglia?
Cranial nerves III, VII, IX, X, and S2-S4.
It may synapse there, travel up or down to synapse, or travel through to reach the celiac/SMA/IMA ganglia or adrenal medulla.
What are the origin and peripheral ganglion for parasympathetic VII outflow?
What other cranial nerve innervates salivary glands?
What is the target of dorsal motor X PNS outflow?
Trace the path of the PNS outflow from the Edinger-Westphal nucleus.
VII PNS originates in the superior salivatory nucleus and synapses in the pterygopalatine and submandibular glands.
Cranial nerve IX (parotid gland via otic ganglion)
The muscles and glands of the GI tract.
Travels along cranial nerve III until reaching the ciliary ganglion. Targets the sphincter pupillae (miosis).
What causes vasovagal syncope?
What are its symptoms?
Vasovagal syncope is excess vagal stimulation in response to venous pooling.
Muscle weakness, warm sensation, nausea, sweating.
Which cranial nerves carry only visceral outflow (no somatic outflow or afferent signals of any type)?
None. While some nerves carry only somatic motor outflow, any that carry visceral or PNS outflow carry some sort of afferent (or in III’s case, somatic outflow).
What is the sensor for the baroreceptor reflex?
What is the effector?
Stretch receptors in the carotid sinus and aortic arch.
The vagus nerve, stimulated by the nucleus solitarius, inhibits the heart. Or, sympathetic outflow stimulates it and VSM.
What can cause horner’s syndrome?
How will such a patient present?
Pancoast tumors, Wallenberg syndrome, trauma, and about a hundred other things.
Ptosis, miosis, anhydrosis and enopthalmos, generally only affecting one eye.
What artery is typically involved in lateral medullary syndrome?
What symptoms does it present with?
The lateral medulla is mostly supplied by the vertebral arteries and PICA.
Horner’s syndrome, dysathria/dysphagia (CN X), contralateral loss of pain and temperature sensation of the body (ST), and ipsilateral loss of facial sensation (CN V).
Describe autonomic dysreflexia.
Spinal lesion at or above T5 is associated with discoordination of sympathetic outflow, generally too much of it. Patients present with hypertension (headaches), sweating, restlessness, skin blotching and piloerection.
Describe how the bladder detrusor, internal urethral sphincter, and external urethral sphincter muscles are controlled.
Detrusor is activated by PNS outflow (S2-4)
Internal urethral sphincter activated by SNS outflow (T11-L2)
External urethral sphincter under somatic control (Pudendal n)
What role does the ANS play in male reproduction?
What role does the ANS play in female reproduction?
“Point and Shoot”, Parasympathetic (filling of corpora cavernosum) and sympathetic (contraction of bulbospongiosus), respectively.
While the external genitalia are under somatic innervation, the internal receive autonomic and hormonal control.
What is Hirschprung’s disease?
Absence of the myenteric (auerbach’s) plexus, resulting in decreased gastric motility and colonic distension. Treatable with surgery.
