A&P I Autonomic Nervous System
What are the 3 potential pathways from sympathetic trunk?
1. Synapse with postganglionic fibers in that trunk ganglion 2. Ascend/descend & synapse in another trunk ganglion 3. Pass through trunk w/o synapsing - will synapse with postganglionic neuron somewhere in pelvis or abdomen
How does the CNS regulate ANS activity?
1. starts in the hypothalamus 2. then things flow down to the lower CNS 3. cerebral cortex controls ANS at a subconscious level
All somatic motor neurons release _______________.
ACh
Preganglionic fibers of the ANS release ____________.
ACh
Active muscles require more oxygen and glucose (part of somatic nervous system). What is the ANS response to this?
ANS nerves speed up heart rate and open airways (they work with SNS)
________ plexus of ______ nerve innervate kidneys, small intestine, part of large intestine, gallbladder, stomach, liver, pancreas.
Abdominal aorta plexus; vagus
Which effectors are innervated only by sympathetic NS?
Adrenal gland, sweat glands, arrector pili muscles of skin, most blood vessels.
What type of neurons make up nicotinic receptors?
All postganglionic neurons
What is the role of neurotransmitters in the somatic nervous system? Which is released and what releases it? What is the effect?
All somatic motor neurons release acetylcholine (ACh) Effect of ACh release is always stimulatory
What is the exception to alpha adrenergic receptors' general excitatory response?
Alpha 2 on gut muscle are inhibitory
Two types of adrenergic receptors
Alpha and beta
Are nicotinic receptors stimulatory or inhibitory?
Always stimulatory
Because the hypothalamus is the "boss" of ANS control, what is the role of the anterior hypothalamic regions? The posterior hypothalamic regions?
Anterior- parasympathetic functions Posterior- sympathetic functions
Drug used by optometrists to dilate pupils
Atropine
What is the exception to beta adrenergic receptors' general inhibitory response?
Beta 1 on heart are stimulatory, more vigorous activity
Class of drugs used to decrease blood pressure, reduce/control migraines, treat abnormal heart rhythms
Beta-blockers
What part of the brain exerts the direct effects (from the hypothalamus' control of ANS)?
Brain stem
Are muscarinic receptors stimulatory or inhibitory?
Can be stimulatory or inhibitory based on which organ they innervate/ receptor subclass
What 3 plexus make up vagus nerves?
Cardiac plexus, pulmonary plexus, esophageal plexus
Describe the preganglionic neuron of ANS.
Cell body in CNS with thin, lightly myelinated preganglionic axon extending to ganglion
Describe the efferent pathways of the somatic nervous system.
Cell body is in CNS, and a single, thick myelinated group A axon extends in spinal or cranial nerves directly to skeletal muscle
What regulates autonomic nervous system activity?
Central nervous system
______________ receptors bind ACh.
Cholinergic
What is the role of the sympathetic NS in digestive tract smooth muscle? What receptor is in charge of this?
Decrease gut motility, alpha 2 and beta 2
Are adrenergic receptors stimulatory or inhibitory?
Depends on alpha/beta receptor and specific subclass
What is the effect of neurotransmitters in the autonomic nervous system?
Effect of ACh/norepinephrine release is either stimulatory or inhibitory, depending on type of receptors.
What type of neurons make up muscarinic receptors?
Effectors innervated by parasympathetic neurons
What type of neurons make up adrenergic receptors?
Effectors innervated by sympathetic neurons
_______________ plexus of vagus nerve forms anterior and posterior vagal trunks that sends branches to stomach, liver, gallbladder, pancreas, small intestine, and part of large intestine.
Esophageal
Example of cooperative interactions of autonomic NS
External genitalia - parasympathetic induces erections, sympathetic causes ejaculation.
_________ nerves stimulate large glands in head.
Facial (VII)
T/F: Neurotransmitters' effects are always the same- decrease for one, increase for another.
False- Depends on the receptor
__________________ nerves stimulate parotid salivary glands
Glossopharyngeal
Many autonomic ns effectors are doubly innervated by sympathetic and parasympathetic divisions that have opposing functions. Why is this?
Helps to maintain homeostasis
_____________________ regulate and control both the autonomic nervous system and the somatic nervous system.
Higher brain centers
What is the role of the parasympathetic NS to digestive tract smooth muscle? What receptor is in charge of this?
Increase gut motility, M3
Action of neostigmine
Inhibit acetylcholinesterase
How do the ANS and SNS overlap?
Most spinal and many cranial nerves contain both somatic and autonomic fibers Adaptations usually involve both skeletal muscles and visceral organs- Ex: heart rate speeds up (ANS) and increased glucose uptake to muscles (SNS) when faced with threat.
What part of the brain exerts direct control over ANS functions?
Motor centers in brain
Drug used to treat symptoms of myasthenia gravis (which occurs due to insufficient ACh stimulation to skeletal muscles).
Neostigmine
What is the type of cholinergic receptor found in sarcolemma of muscle cell at neuromuscular junction?
Nicotinic
What is the role of the parasympathetic NS in the liver? What receptor is in charge of this?
None; there are no innervations
Adrenergic receptors bind..
Norepinephrine and epinephrine
_________nerves control smooth muscle of eye, cause pupils to constrict and lenses to bulge for focusing.
Oculomotor (III)
Where are N2 (nicotinic 2) cholinergic receptors located?
On sarcolemma of skeletal muscle
Example of antagonistic interactions of autonomic NS
Opposite effects on target tissue- parasympathetic NS slows down breathing, sympathetic speeds it up
Describe the postganglionic/ganglionic neuron of ANS
Outside CNS cell body synapses with preganglionic axon in autonomic ganglion with nonmyelinated postganglionic axon that extends to effector organ
What neurons produce ACh?
Parasympathetic preganglionic neurons Parasympathetic postganglionic neurons Sympathetic preganglionic neurons
_______________ division has long preganglionic and short postganglionic fibers, while ______________ division has short preganglionic and long postganglionic fibers.
Parasympathetic, sympathetic
Drugs that are common in cold/allergy meds and constrict blood vessels in nasal mucosa to decrease mucus production.
Phenylephrine, pseudoephedrine (sympathomimetics)
Drug that mimics effects of ACh and binds to M receptors
Pilocarpine
Is the preganglionic neuron of ANS myelinated? the postganglionic?
Preganglionic= myelinated axon, postganglionic= nonmyelinated axon
What is the role of the parasympathetic NS in the eye? What receptor is in charge of this?
Pupil constriction via contraction of circular muscles in iris; M3
Function of pulmonary plexus of vagus nerve
Serve lungs and bronchi
How does the autonomic nervous system make adjustments to ensure optimal support for body activities?
Shunts blood to areas that need it and adjusts heart rate, blood pressure, digestive processes, etc.
During intense activity, what does the sympathetic nervous system do?
Shunts blood to skeletal muscles and heart Dilates bronchioles Causes liver to release glucose
Function of cardiac plexus of vagus nerve
Slow heart rate
What is the difference between the effectors of the somatic nervous system and the ANS?
Somatic nervous system innervates skeletal muscles ANS innervates cardiac muscle, smooth muscle, and glands
What is the role of the sympathetic NS in the liver? What receptor is in charge of this?
Stimulate glucose release into blood (beta 1, beta 2)
Rami communicantes is only present in which division?
Sympathetic nervous system
What neurons produce Norepinephrine?
Sympathetic postganglionic neurons
T/F: Most spinal and many cranial nerves contain both somatic and autonomic fibers.
True
T/F: Some effectors only innervated by sympathetic NS
True
Why is it important to study the autonomic nervous system?
Understanding the autonomic nervous system helps you to anticipate the effects and side effects of drugs on your patients
Describe the efferent pathways of the autonomic nervous system.
Uses a 2 neuron chain- preganglionic neuron and postganglionic neuron.
_________ nerve provide fibers to neck & nerve plexuses that innervate most thoracic & abdominal cavity organs.
Vagus
_____________ nerves account for ~ 90% of all preganglionic parasympathetic fibers in body.
Vagus (X)
_______________ nerves serve all thoracic and abdominal viscera
Vagus (X)
Neurotransmitter released at all ANS preganglionic fiber synapses and all parasympathetic postganglionic fiber synapses is _______________.
acetylcholine
What are the 2 major neurotransmitters of autonomic nervous system?
acetylcholine and norepinephrine
Fiber made up of neurons that release epinephrine or norepinephrine
adrenergic
How does dual innervation affect the autonomic nervous system?
all visceral organs are served by both divisions, but these divisions cause opposite effects
What are the 2 subclasses of adrenergic receptors?
alpha 1 and 2 beta 1 and 2
Nicotinic receptors stimulated by ACH results in...
always excitatory response
Action of nicotine
binds to Nicotine receptors (sympathetic NS effects- speeds HR, etc.)
Action of beta-blockers
block β receptors,
Cell bodies of parasympathetic division are located in the
brain stem
Role of medulla and pons in ANS control
breathing
Epinephrine causes ______________ when bound to beta 2 receptors.
bronchial relaxation
Fiber made up of neurons that release ACH
cholinergic
Sympathetic ganglia are located...
close to spinal cord
What is the function of the parasympathetic division of ANS?
conserves energy, promotes maintenance function "rest and digest"
What is the role of the parasympathetic NS in respiration? What receptor is in charge of this?
constriction of bronchiole smooth muscle M3
Role of midbrain in ANS control
controls eyes
Parasympathetic fibers are ______________; originate in __________ and ________________.
craniosacral; brain and sacral spinal cord
What is the role of the parasympathetic NS in the heart? What receptor is in charge of this?
decrease rate; M2
What is the role of the Sympathetic NS in the digestive system?
decrease secretory activity, Beta 2
Role of cortex in ANS control
defecation and micturition
Action of atropine
effectively blocks parasympathetic innervation of effectors by blocking Muscarine receptors
Sympathetic preganglionic also stimulates adrenal medulla (sits atop kidney) which secretes...
epinephrine and norepinephrine
Stimulating alpha adrenergic receptors generally results in
excitatory response of target cell
The axon of a postganglionic fiber...
extends to the effector organ
Degree of branching in preganglionic fibers of sympathetic division is...
extensive
Defecation
feces formation
Parasympathetic ganglia are located...
in or near visceral effector organ
What is the role of the sympathetic NS in the heart? What receptor is in charge of this?
increase rate; beta 1
What is the role of the Parasympathetic NS in the digestive system? What receptor is in charge of this?
increase secretory activity M3
The axons of sacral part of parasympathetic division synapsing with ganglia in pelvic floor forms...
inferior hypogastric [pelvic] plexus
Stimulating beta adrenergic receptors generally results in
inhibitory response of target cell
Two other names of the autonomic nervous system
involuntary nervous system or general visceral motor system
In ANS, the cell bodies of neurons are in ____________ horns of spinal cord.
lateral
Where are the postganglion cell bodies of oculomotor (III) nerves located?
located in ciliary ganglia within eye orbitals
Where are M1 (muscarinic 1) cholinergic receptors located? Inhibitory or excitatory?
located on neural tissue in the bran, excitatory response
Where are M3 (muscarinic 3) cholinergic receptors located? Inhibitory or excitatory?
located on smooth muscle and glands, gastrointestinal tract, excitatory
Where are M2 (muscarinic 2) cholinergic receptors located? Inhibitory or excitatory?
located on the heart, inhibitory response
Preganglionic fibers of vagus nerve arise from _____________ and synapse in _________________.
medulla; terminal ganglia/ intramural ganglia in walls of target organs
Degree of branching in preganglionic fibers of parasympathetic division is...
minimal
What is the function of the sympathetic division of ANS?
mobilizes body during activity, "fight or flight"
What is the role of the sympathetic NS in blood vessels? What receptor is in charge of this?
mostly vasoconstriction; alpha 1
The sacral part of the parasympathetic division originates from ________________ and serves pelvic organs and distal half of large intestine.
neurons in S2-S4
The adrenal medulla contains __________ receptors.
nicotinic
What are the 2 subclasses of cholinergic receptors?
nicotinic types 1 and 2 muscarinic types 1, 2 or 3
What is the role of the parasympathetic NS in blood vessels? What receptor is in charge of this?
no innervations (except those serving external genitalia)
Neurotransmitter released by most sympathetic postganglionic fibers is ___________.
norepinephrine
Postganglionic fibers of the ANS release _____________.
norepinephrine or ACh at effectors
Where are N1 (nicotinic 1) cholinergic receptors located (2 locations)?
on all post ganglion cell bodies (at all ganglia of the ANS) On adrenal medulla
Fibers of glossopharyngeal nerves synapse in ___________.
otic ganglia
Craniosacral nerves are associated with the ______________ division.
parasympathetic
In the _____________ division of the ANS, most ganglia located in the effector
parasympathetic
The _____________ division's neurons are characterized by long preganglionic axons and short postganglionic axons
parasympathetic
The _______________ division decrease heart rate, regulate activities like digestion, defecation, and urination.
parasympathetic
The axons of sacral part of parasympathetic division branch off to form
pelvic splanchnic nerves
A _________ is a second neuron whose cell body lies outside of CNS.
postganglionic fiber
A __________________ is a neuron whose cell body lies in the brain or spinal cord (CNS)
preganglionic fiber
What is the type of fiber that releases neurotransmitter that travels across a synapse and binds to a second neuron in brain or spinal cord (CNS) ?
preganglionic fiber
Fibers of facial nerves that activate nasal and lacrimal glands have synapse in _________________.
pterygopalatine ganglia
What is the role of the sympathetic NS in eye? What receptor is in charge of this?
pupil dilation via constriction of radial muscle in iris - alpha 1
Role of vagal center and vasomotor center in medulla in ANS control
regulate heart rate and blood vessel diameter
What is the role of the sympathetic NS in respiration? What receptor is in charge of this?
relaxation of bronchiole smooth muscle β2
What does the axonal terminus of postganglionic fiber do?
releases neurotransmitter that binds to receptors on effector cell
The motor neurons of the autonomic nervous system innervate...
smooth muscle, cardiac muscle, and glands
The autonomic nervous system operates via
subconscious control
Fibers of facial nerves that activate submandibular and sublingual salivary glands synapse in ____________.
submandibular ganglia
Exercise, excitement, emergency, embarrassment activates the ___________ division
sympathetic
Increased heart rate; dry mouth; cold, sweaty skin; dilated pupils characterize action of the ________________ division.
sympathetic
A chain of ganglia, extend from neck to pelvis but only sympathetic fibers only come from thoracic & lumbar segments, is _____________________.
sympathetic trunk
Action of phenylephrine, pseudoephedrine
sympathomimetics
Nicotinic and muscarinic receptors are named for...
the drugs they bind to, nicotinic= nicotine, muscarinic= muscarine (mushroom poison)
Sympathetic fibers are ______________; originate in _____________ and _____________.
thoracolumbar; thoracic and lumbar regions of spinal cord
Micturition
urine formation
In SNS, the cell bodies of neurons are in ____________ horns of spinal cord.
ventral
The axons of sacral part of parasympathetic division travel in ________________ of spinal nerves
ventral root