Autonomic Nervous System Flashcards
Compare the structural and functional differences between the somatic efferent and the autonomic portions of the nervus system
- Somatic=skeletal muscle
- Autonomic nervous system= involves a preganglionic and postganglionic neuron to visceral-smooth muscle cardiac glamds
Identify the principal structural features of the autonomic nervous system
- preganglionic neuron begins CNS to ganglion- myelinated
- postganglionic begins at ganglion to effector- unmyolinated
Name three types of collateral or prevertebral autonomic ganglia in the sympathetic division
- These are sympathetic ganglia and the Celiac ganglion (solar plex) sends postganglionic fibers to upper abdominal structures such as stomach & liver
- the Superior Mesenteric ganglion sends postganglionic fibers to middle abdominal structures such as the small intestine
- the Inferior Mesenteric ganglion sends postganglionic fibers to lower abdominal/pelvic structures such as large intestine.
Define white ramus communicans and gray ramus communicans
- white ramus is the branching of the preganglionic neuron from the spinal nerve (leaving)
- synaps happens and can rejoin with the postganglionic
- gray ramus is the branching of the post ganglionic neuron to rejoin the spinal nerve.
-preganglionic neuron can also travel up or down the sympathetic trunk and have a synapse at any level with the postganglionic neuron.
Define splanchnic nerve
-pertaining to vicera
Name the 2 divisions of the ANS, Generally how do their functions differ?
- Sympathetic- fight or flight
- parasympathetic- rest and digest
Describe the anatomy of the sympathetic division. What is the sympathetic trunk= sympathetic chain ganglia
- The preganglionic neuron exits the spinal cord between T1-L2.
- Preganglionic neurons short & postganglionic neurons are long.
- The sympathetic trunk is a chain of interconnected ganglia so that the sympathetic response is widespread and shows divergence. (less control, but occurs in abundance and all over)
- It allows the stimulation that may have begun at L2 to have an effect at the level of your head.
Describe the anatomy of the parasympathetic division
- The preganglionic neurons exit the spinal cord in the S2-S4 region as well as from the brainstem along Cr. nerves III, VII, IX and X.
- There is no interconnection between these spinal cord segments and the individual cranial nerve segments.
- Isolated responses are the norm for parasympathetic.
- The preganglionic neurons long and the postganglionic neurons are quite short.
What structure does not have a postganglionic neuron?
-adrenal medulla which is a part of the sympathetic Division (releases norepinephrine and epinephrine to exaggerate f or f)
Compare the length of axons in the sympathetic and parasympathetic divisions. which division has more divergence?
- Sympathetic has much more divergence. It is rare to have and isolated sympathetic response such as increased heart rate without other sympathetic responses.
- isolated parasympathetic responses such as only a decreased heart rate.
Define cholinergic and adrenergic. Classify autonomic nerve fibers in each division as cholinergic or adrenergic
- Cholinergic- releases acetylcholine- both preganglionic PNS/postganglionic SNS
- Adrenergic- releases norepinephrine (postganglionic only) =SNS
Describe the various autonomic receptors
Acetylcholine
-Muscarine- located on the effector in the PNS
-will block salavary glands in R&D
-blocked by atropine
-Nicotinic- located on the postganglionic neuron in PNS and SNS
-Blocked by Curare
Norepinephrine/epinephrine SNS ONLY
-alpha (1&2’s, 1 more common)
-constricts muscle (why we are pale in F or F because of contraction of blood vessels)
-Beta 1 (cardiac only)
-Stimulatory effect (b1 blocker for cardiac arrest, decreasted need for o2)
-Beta 2 (airways)
- tend to be inhibitory
-Stimulation=relaxation= open airways
-responds only to epinephrine (epi pen in allergic reaction)
Explain the role of the hypothalamus and its relationship to the sympathetic and parasympathetic divisions
- control. produces response
The drug atropine causes what effects to the ANS?
-Atropine is antimuscarinic and thus blocks the PNS (like salivating gland)
Describe the effects of parasympathetic and sympathetic stimulations
- Heart rate-SNS increases PNS decreases
- lungs- SNS Open PNS narrow
- digestion- SNS Decrease secretions PNS -Increases
- pupil- SNS Dilate PNS constrict
- sweat glands-SNS only, turns on.
- adrenal medulla- SNS only. Causes release of -epinephrine and norepinephrine
- cutaneous blood vessels- SNS causes vasoconstriction (PNS no skin glands)
- abdominal blood vessels- SNS causes vasoconstriction
- skeletal muscle blood vessels-SNS causes dilation
- bladder-SNS causes contraction of sphincter (makes you feel like you have to urinate) and relaxation of bladder wall. PNS causes relaxation of sphincter (when you are voluntarily urinating this happens) and contraction of bladder wall.
