Autonomic NS Flashcards
Preganglionic (CNS) nerve fibers are
myelinated
Postganglionic (PNS) nerve fibers are
unmyelinated
Neurotransmitters of sympathetic NS (“thoracolumbar”) and ex of their action
Epinephrine - vasodilation
Norepinephrine - vasoconstriction
Difference w ganglia in symp vs parasymp NS
Sympathetic NS has Paravertebral “trunk” of ganglia
Parasympathetic NS has ganglia in the periphery, near the organ being innervated
Which nerve fiber travels from the CNS to the ganglia in Parasympathetic NS
PRESYNAPTIC nerve fiber travels from the CNS a lllllll the way to the local ganglia (near innervated organ). Post synaptic fiber is relatively short.
Through which two nerves do most parasympathetic nerve fibers travel to the periphery?
VAGUS and PELVIC nerves
Parasympathetics do NOT go to:
Heart (except pacemakers!)
Uterus
Sweat glands and Arrector Pilli
Skeletal Muscles
Adrenal gland (duh)
Only to select blood vessels (like coronary arteries)
Which part of the heart is the only little spot innervated by parasympathetic nerves?
Pacemaker cells
Which reproductive organ specifically is NOT innervated by parasympathetic nerves
Uterus
Are skeletal muscles innervated by parasympathetic nerves?
NO
Only a few select blood vessels are innervated by parasympathetic nerves - what is one example?
Coronary Arteries
A “modified sympathetic ganglion”
Adrenal Medulla
Preganglionic fibers»_space;»» ACh: Adrenal medulla»_space;
Postganglionic fibers»_space;> E, NE»_space; BLOODSTREAM
What is unique about the Adrenal Medulla?
The sympathetic preganglionic fibers travel alllll the way to the adrenal gland (like a ganglia)
Adrenal gland releases E, NE into the BLOODSTREAM, like an endocrine gland
Alpha adrenergic receptors in general are responsible for
Vasoconstriction > coronary arteries and veins
Decreased motility of GI smooth muscle cells
Key alpha 1 receptor actions
EXCITATION
Vasoconstriction of blood vessels in skin GI Kidney Brain
Contraction of
Pupils
Urethral sphincter
Gluconeogenesis
Glycogenolysis
Key alpha 2 receptor actions
INHIBITION
Glucose metabolism
- Inhibits insulin secretion
- stims glucagon release
- contraction of anal sphincter
Key beta 1 actions
Cardiac Increase: HR Contraction Conduction EF
INCREASES RENIN SECRETION
Key beta 2 actions
Smooth muscle relaxation of:
- Bronchus / bronchioles
- Detrusor / Uterine
Glucose metabolism
- inhibits insulin secretion
- stims gluconeogenesis and glycolysis
Of the alpha/beta receptors, which is the only one which is PRESYNAPTIC
alpha 2
These exist on the presynaptic neuron in a synapse and inhibit release of its neurotransmitter.
Which three receptors (of SNS) are responsible for glucose metabolism
alpha 1
alpha 2
beta 2
Most common adrenergic receptors
alpha 1
Where are nicotinic receptors found
POSTGANGLIONIC AcH receptors
Neuromuscular junctions
Where are muscarinic receptors found
CNS
Exocrine glands
Cardiac conduction
GI smooth muscle (help contraction)
Considering where nicotinic receptors are found, what might nicotinic receptor antagonists do?
Cause paralysis
receptors on skeletal muscles - neuromuscular junction
What other special “neurological” place are nicotinic receptors found - maybe especially affected by smoking ciagrettes/??
Brain - areas w Cognitive Function and Behavior
attention, learning, memory, reward
Unopposed sympathetic input to eyes cause
PUPIL DILATION
Myasthenia gravis - antibodies target nicotinic or muscarinic AcH receptors?
nicotinic! muscle!
Loss of sympathetic outflow - presynaptic neurons can not get to the postsynaptic sympathetic trunk to synapse. Usually due to injury / lesion in cervical / upper thoracic areas
Neurogenic shock
Is the complete loss of reflex function in all segments below the level of the lesion.
Manifestations include flaccid paralysis, sensory deficit, and loss of bladder and rectal control.
Spinal shock
Syndrome of sudden, massive RSD (reflex sympathetic discharge) with little to no opposing parasympathetic discharge to bring it down
Autonomic Dysreflexia
Autonomic Dysreflexia happens w lesions in what part of spine?
Above T 7
Symptoms of autonomic dysreflexia
Since message can’t make it up to the brain, SNS has to reflexively respond with:
Hypertension (up to 300)
Bradycardia (30-40)
Vasospasm
Shivering and goosebumps
