Ch 14: Autonomic NS Flashcards
What does the ANS motor neuron do?
Innervate smooth and cardiac muscle, and glands.
Make adjustments to ensure optimal support for body activities.
Operate via subconscious control.
What are the differences between somatic and autonomic NS?
- Effectors.
- Efferent pathways and ganglia.
- Target organ responses to neurotransmitters.
What is the effector for Somatic NS?
Skeletal muscles
What are the effectors of the ANS?
- Cardiac Muscle
- Smooth Muscle
- Glands
What is the efferent pathways and ganglia of the Somatic NS?
- Cell body in CNS
2. Thick, myelinated, group A fiber extends in spinal or cranial nerve to skeletal muscle
What are the 2-neuron chains of the ANS?
- Preganglionic neuron (in CNS)
2. Postganglionic (ganglionic) neuron in autonomic ganglion
What are Postganglionic (ganglionic) neurons?
Outside CNS has nonmyelinated postganglionic axon that extends to effector organ
What are preganglionic (ganglionic) neurons?
thin, lightly myelinated preganglionic axon
What are the neurotransmitter effects of the somatic NS?
- Releases ACh
2. Always stimulatory
What are the neurotransmitter effects of the ANS?
- Preganglionic fibers release ACh.
- Postganglionic fibers release norepinephrine or ACh at effectors.
- Effect is either stimulatory or inhibitory, depending on type of receptors.
What are some of the overlaps of the somatic and autonomic functions?
- Most spinal and cranial nerves contain both
2. Adaptions involve skeletal muscles and visceral organs
What are the divisions of the ANS?
Sympathetic division
Parasympathetic division
What is dual innervation?
All visceral organs served by both divisions, but cause opposite effects.
What is Dynamic antagonism?
Two divisions that maintain homeostasis
What is the role of the parasympathetic division?
Promotes maintenance activities and conserves body energy.
What would occur when the Parasympathetic is activated?
- Blood pressure, heart rate, and respiratory rates are low
- Gastrointestinal tract activity high.
- Pupils constricted; lenses accommodated for close vision
What is the role of the sympathetic division?
Mobilizes body during activity; “fight-or-flight” system
When would Sympathetic activated?
vigorous physical activity
What would occur when the Sympathetic is activated?
- Shunts blood to skeletal muscles and heart.
- Dilates bronchioles.
- Causes liver to release glucose
What is SLUDD?
Occurs during the activation of Parasympathetic
Salivation, Lacrimation, Urination, Digestion and Defecation
What are the characteristics of long preganglionic fibers?
- Extend from CNS almost to target organs.
- Synapse with postganglionic neurons in terminal ganglia close to/within target organs.
- Short postganglionic fibers synapse with effectors
Where are cell bodies located?
Brain stem
What nerves targets smooth muscle of eye?
Oculomotor nerves (III)
What nerves stimulate large glands in head?
Facial nerves (VII)
What are the ganglia involved with Oculomotor nerves (III)?
Ciliary ganglia
What are the ganglia involved with Facial nerves (VII)?
pterygopalatine ganglia and submandibular ganglia
What nerves stimulate the parotid salivary glands?
Glossopharyngeal nerves (IX)
What ganglia is involved with Glossopharyngeal nerves (IX)?
Otic ganglia
What nerves stimulate the neck and nerve plexuses for ~ all thoracic and abdominal viscera?
Vagus nerves (X)
What are the ganglia involved with Vagus nerves (X)?
Cardiac, pulmonary and esophageal plexuses
What does the sacral part of the parasympathetic division stimulate?
Serves pelvic organs and distal half of large intestine (urinary bladder, ureters, reproductive organs)
Where are the Preganglionic neurons of the sympathetic located?
T1-L2
Where would Preganglionic fibers of the sympathetic division enter?
Sympathetic trunk (chain or paravertebral) ganglia
How many paravertebral ganglia are in the sympathetic trunk? Where are they located?
23 Cervical: 3 Thoracic: 11 Lumbar: 4 Sacral: 4 Coccygeal: 1
What does the ganglion short preganglionic fiber does when entering sympathetic trunk?
- Synapse with ganglionic neuron in same trunk ganglion.
- Ascend or descend sympathetic trunk to synapse in another trunk ganglion.
- Pass through trunk ganglion and emerge without synapsing (only in abdomen and pelvis).
Where is the location when preganglionic fibers pass without synapsing?
Adrenal medulla
What do medullary cells secrete in the blood?
Norepinephrine and epinephrine
What gland is “misplaced” sympathetic ganglion?
Adrenal medulla
What does visceral pain contribute to?
Referred pain
What is the process of the visceral reflex arcs?
- Stimulus
- Receptor in viscera
- Visceral sensory neuron
- Integration center
- Motor neuron
- Visceral effector
- Response
What fibers release ACh?
Cholinergic fibers
What are considered cholinergic fibers?
- All ANS pregonglionic axons
2. All parasympathetic postganglionic axons at effector synapse
What fibers release Norepinephrine?
Adrenergic
What are considered adrenergic fibers?
- Most sympathetic postganglionic axons
2. Exception: sympathetic postganglionic fibers secrete ACh at sweat glands
What are the receptors that bind to Ach?
- Nicotinic
2. Muscarinic
What are the classes of adrenergic receptors?
Alpha (a1-2)
Beta (B1-3)
Where are nicotinic receptors found?
- Sarcolemma of skeletal muscle cells at NMJ.
- All postganglionic neurons (sympathetic and parasympathetic).
- Hormone-producing cells of adrenal medulla.
What is the effect of ACh binding to nicotinic receptors?
Stimulatory
Opening ion channels
Depolarizing postsynaptic cell
Where are muscarinic receptors found?
All effector cells stimulated by postganglionic cholinergic fibers
What is the effect of ACh binding to muscarinic receptors?
Inhibitory or excitatory depending on target organ
What is the effect of atropine?
Anticholinergic; blocks muscarinic ACh receptors
What is the purpose for atropine?
Used to prevent salivation during surgery, and to dilate pupils for examination
What is the effect of neostigmine?
Inhibits acetylcholinesterase that breaks down Ach
What is the purpose of neostigmine?
Used to treat myasthenia gravis
What is the effect of Over-the-counter drugs for colds, allergies, and nasal congestion?
Stimulate a-adrenergic receptors
What is the effect of Beta-blockers?
Drugs that attach to B2 receptors to dilate lung bronchioles in asthmatics; other uses
Are most visceral organs dual innervated?
Yes
What is the purpose of sympathetic tone?
Keeps blood vessels in continual state of partial constriction
What division controls BP at rest?
Sympathetic
Why do sympathetic fibers fire more rapidly?
Constrict blood vessels and cause blood pressure to rise
Why do sympathetic fibers fire less rapidly?
To prompt vessels to dilate to decrease blood pressure
What does alpha-blocker drugs do?
Interfere with vasomotor fibers and used to treat hypertension
What does the parasympathetic division dominate?
- Heart
- Smooth muscle of digestive
- Urinary tract organs
- Most glands except for adrenal and sweat glands
What happens to the parasympathetic in times of stress?
Sympathetic division can override effects
What do the drugs that block parasympathetic responses do?
Increase heart rate and cause fecal and urinary retention
In regards to cooperative effects what do parasympathetic fibers do?
Vasodilation
Responsible for erection of penis or clitoris
In regards to cooperative effects what do sympathetic fibers do?
Ejaculation of semen in males
Reflex contraction of a female’s vagina
What parts of the body only receive sympathetic fibers?
- Adrenal medulla
- Sweat glands
- Arrector pili
- Muscles
- Kidneys
- Most blood vessels
What does the sympathetic division control?
- Thermoregulatory responses to heat.
2. Release of renin from kidneys.
What are the metabolic effects of the sympathetic?
- Increases metabolic rates of cells.
- Raises blood glucose levels.
- Mobilizes fats for use as fuels
What is the difference between parasympathetic and sympathetic in localization?
Para: short-lived, highly localized control over effectors
Sym: longer-lasting, bodywide effects
What destroys ACh?
Acetylcholinesterase
What is the hypothalamus?
Main integrative center of ANS activity
What is the subconscious cerebral?
Input via limbic system structures on hypothalamic centers
What aspects of the body does the hypothalamus control?
- Heart activity and blood pressure.
- Body temperature, water balance, and endocrine activity.
- Emotional stages (rage, pleasure) and biological drives (hunger, thirst, sex).
- Reactions to fear and “fight-or-flight” system
What does connections of the hypothalamus to limbic allow?
Cortical influence on ANS
What is biofeedback?
- Awareness of physiological conditions with goal of consciously influencing them.
- Biofeedback training allows some to control migraines and manage stress.
Can the cortical control be voluntary?
Yes
What is hypertension?
Overactive sympathetic vasoconstrictor response to stress
What treats hypertension?
adrenergic receptor - blocking drugs
What is Raynaud’s disease?
Exaggerated vasoconstriction in fingers and toes causing cyanotic and pain
How is Raynaud’s treated?
Vasodilators
What is autonomic dysreflexia?
Uncontrolled activation of autonomic neurons in quadriplegics and those with spinal cord injuries above T6 and blood pressure skyrockets, life threatening
What are the effects of age on ANS?
Constipation
Dry eyes
Frequent eye infections
Orthostatic hypotension
What a B1 receptors?
Increase heart rate and force contraction stimulating kidneys to release renin
What are B2 receptors?
Inhibitory: dilates blood vessels and bronchioles, relaxes the smooth muscle walls of digestive urinary and uterus
What are B3 receptors?
Stimulate lipolysis by fat cells
What are a1 receptors?
Constrict blood vessels and visceral organs, dilates pupils
What are a2 receptors?
Inhibit NE release from adrenergic terminals, inhibits insulin secretion, promotes blood clotting
