Flashcards in Lecture 24: Autonomic Nervous System Deck (148):
True or False:
The autonomic nervous system can change visceral function rapidly and intensely.
How many seconds does it take for the ANS to increase heart rate to twice as normal?
How long does it take the ANS to double arterial pressure?
What are the two neurons in sequence in the ANS pathways?
- Preganglionic neuron
- Postganglionic neuron
Where are the cell bodies of preganglionic neurons located?
Do preganglionic neurons or postganglionic neurons have myelinated axons?
Preganglionic neurons - axons are myelinated.
Do preganglionic neurons or postganglionic neurons not have myelinated axons?
Postganglionic neurons - axons are NOT myelinated.
What is the neurotransmitter used by preganglionic neurons?
What is the neurotransmitter used by postganglionic neurons?
- Acetylcholine in parasympathetic system.
- Norepinephrine (usually) is sympathetic system.
What do postganglionic neurons in the parasympathetic system use as a neurotransmitter?
What do postganglionic neurons in the sympathetic system use as a neurotransmitter?
Where are cell bodies of postganglionic neurons located?
True or False:
Most parasympathetic and almost all sympathetic postganglionic fibers merely touch or pass near to the effector cells of the organs they innervate.
True or False:
Terminal ends of postganglionic fibers usually have enlarged varicosities where neurotransmitter and large numbers of mitochondria are stored.
Where does the cell body of each sympathetic preganglionic neuron lie?
In the intermediolateral horn of the spinal cord (T1-L2).
In the paravertebral chain, where can preganglionic fibers synapse?
- Can synapse with postganglionic neurons upward or downward in the paravertebral chain.
- Preganglionic fibers can pass for variable distances through the chain and then through one of the sympathetic nerves to synapse in a peripheral sympathetic ganglion.
Which communicating rami do postganglionic sympathetic fibers pass through?
What type of fibers are postganglionic sympathetic fibers classified as?
Type C Fibers
What percentage of fibers make up the fibers in the average nerve?
What do postganglionic sympathetic fibers control?
- blood vessels
- sweat glands
- piloerector muscles
Where does the thoracic sympathetic chain lie?
Against neck of ribs and constovertebral junctions.
How many thoracic ganglia pairs make up the sympathetic chain?
> 12 thoracic ganglia pairs:
- first one often fused with inferior cervical ganglion
- referred to as stellate ganglion collectively
What are the 3 cervical ganglia?
The preganglionic sympathetic supply to the thoracic viscera is from which vertebrae?
Where are the postganglionic fibers from that supply the thoracic viscera?
- superior, middle, and inferior cervical ganglia
- T1-T5 paravertebral ganglia
What do preganglionic sympathetic fibers exit the thoracic sympathetic chain as?
Exit the chain as direct fibers and travel downwards to enter the thorax as CARDIOPULMONARY SPLNACHNIC NERVES.
True or False:
The cardiopulmonary splanchnic nerves travel on their own and do not accompany other nerves or vessels.
What are the functions of the cardiopulmonary splanchnic nerves?
- coronary artery dilation
- increase heart rate
What are splanchnic nerves composed of?
- preganglionic fibers
- visceral sensory fibers
What do splanchnic nerves supply?
Where do splanchnic nerves synapse?
What are the 3 splanchnic nerves?
Where does the greater splanchnic nerve synapse?
Where does the lesser splanchnic nerve synapse?
superior mesenteric ganglion
Where does the least splanchnic nerve synapse?
From what vertebral level does the least splanchnic nerve preganglionic fiber arise?
From what vertebral levels does the lesser splanchnic nerve preganglionic fiber arise?
From what vertebral levels does the greater splanchnic nerve preganglionic fiber arise from?
Which nervous system stimulates the adrenal medullae to secrete epinephrine and norepinephrine?
What is secreted from the adrenal medulla upon stimulation by the sympathetic nervous system?
- 80% epinephrine
- 20% norepinephrine
How much longer do hormones last than neurotransmitter versions?
5-10 times longer
What effect does circulating norepinephrine have on most blood vessels of the body?
Constricts most of blood vessels of body.
**has greater effect on blood vessels in skeletal muscles so has greater effect on raising arterial pressure**
What effect does circulating norepinephrine have on heart activity?
Increases Heart Activity
What effect does circulating norepinephrine have on the GI tract?
Inhibits GI Tract
Does circulating norepinephrine constrict or dilate the pupil?
Dilates the Pupil
What effects do circulating norepinephrine have on the body?
- Constricts most of blood vessels of body.
> has greater effect on blood vessels in skeletal muscles so has greater effect on raising arterial pressure
- Increases heart activity.
- Inhibits GI tract.
- Dilates pupil.
Are secretory cells of the adrenal medulla preganglionic or postganglionic neurons?
What do secretory cells of the adrenal medulla, which are postganglionic neurons, have that secretes epinephrine and norepinephrine?
Have rudimentary fibers that secrete epinephrine and norepinephrine.
Does circulating epinephrine or norepinephrine have a greater effect on raising arterial pressure?
Norepinephrine raises arterial pressure more than epinephrine.
Does circulating epinephrine or norepinephrine increase cardiac output more?
Circulating epinephrine increases cardiac output more than norepinephrine.
Does circulating epinephrine or norepinephrine have a greater effect on metabolism?
Circulating epinephrine has a 5-10 times as great effect on metabolism as norepinephrine.
What percentage above normal can circulating epinephrine increase metabolic rate of the whole body?
As much as 100% above normal.
What is the effect of circulating epinephrine?
- Raises arterial pressure to a lesser extent than norepinephrine.
- Increases cardiac output more than norepinephrine.
- Has a 5-10 times as great effect on metabolism as norepinephrine.
- Can increase metabolic rate of whole body by as much as 100% above normal.
When does an alarm or stress response occur?
Occurs when there is a mass discharge of the entire sympathetic system (fright, fear, severe pain).
What happens when there is a mass discharge of the entire sympathetic system during an alarm or stress response to fright, fear, or severe pain?
- Increased arterial pressure.
- Rerouting of blood flow to active muscles.
- Increased rates in cellular metabolism.
- Increased blood glucose concentration.
- Increased glycolysis in liver and muscle.
- Increased muscle strength.
- Increased mental activity.
- Increased blood coagulation rate.
What percent of all parasympathetic fibers are in the vagus nerve (CN X)?
True or False:
Most preganglionic fibers pass all the way to the organ that is to be innervated.
In the parasympathetic system, where are post ganglionic parasympathetic fibers located?
In the wall of the organ.
What neurotransmitter is used by postganglionic parasympathetic fibers?
Of the 12 cranial nerves, which carry parasympathetic signals?
- Oculomotor (CN III)
- Facial (CN VII)
- Flossopharyngeal (CN IX)
- Vagus (CN X)
What is the function of the oculomotor nerve?
- Supplies 4 of the 6 extrinsic muscles of the eye and the levator palpebrae superioris.
What is the parasympathetic function of the oculomotor nerve?
- From Edinger-Westphal nucleus to the ciliary ganglion.
- From the ciliary ganglion to the sphincter pupillae muscle.
What nucleus do preganglionics from the oculomotor nerve come from and where are they going to synapse?
- From Edinger-Westphal nucleus.
- To the ciliary ganglion.
Where do the postganglionics of the oculomotor nerve come and go to?
- From the ciliary ganglion.
- To the sphincter pupillae muscle.
Which cranial nerve sends postganglionic fibers from the ciliary ganglion to the sphincter pupillae muscle?
Which cranial nerve sends preganglionic fibers from the Edinger-Westphal nucleus to the ciliary ganglion?
What is the function of the facial nerve?
- Primary motor nerve to muscles of facial expression.
- Carries sensation of taste from anterior 2/3 of the tongue.
Which cranial nerve carries sensation of taste from the 2/3 of the tongue?
Where do the preganglionic fibers of the facial nerve come from and travel to?
- From superior salivatory and lacrimal nuclei.
- To submandibular/sublingual ganglia.
Where do the postganglionic fibers of the facial nerve come from and travel to?
- From submandibular/sublingual ganglia.
> lacrimal gland
> submandibular gland
> sublingual gland
> mucous glands of mouth and nose
Look over slide 31.
Diagram of facial nerve innervation.
What is the function of the glossopharyngeal nerve?
Carries general sensation and sensation of taste from posterior 1/3 of the tongue.
Where do the preganglionic fibers arise from and travel to?
- From inferior salivatory nucleus.
- To otic ganglion.
Where do the postganglionics of the glossopharyngeal nerve come from and travel to?
- From otic ganglion.
- To parotid gland.
Which cranial nerve carries general sensation and sensation of taste from the 1/3 of the tongue?
Which cranial nerve innervates the parotid gland?
Which cranial nerve carries parasympathic innervation to the lacrimal gland, submandibular gland, sublingual gland, and mucous glands of mouth and nose?
What is the function of the vagus nerve?
Motor supply to muscles of the 4th and 5th pharyngeal arches and is important in swallowing and speaking.
Which cranial nerve provides major parasympathetic supply to thoracic and abdominal organs?
Where do preganglionic fibers from the vagus nerve arise from?
Dorsal Motor Nucleus
Where do postganglionic fibers of the vagus nerve travel to and provide innervation?
Myenteric plexus of wall of gut tube all the way to the left colic flexure.
What is the course of the vagus nerve in relationship to the esophagus?
Runs parallel to esophagus.
**vagus nerve innervates the esophagus**
What is the course of the vagus nerve in relationship to the root of the lung?
Passes posterior to root of lung on each side.
What is the course of the vagus nerve in relationship to the diaphragm?
Pierces diaphragm with esophagus.
Where does the esophagus and vagus nerve pass through the diaphragm?
T10 - esophageal hiatus.
What does the vagus nerve become once it passes through the esophageal hiatus at the vertebral level of T10?
Becomes gastric nerve.
What does the vagus nerve (gastric nerve) supply?
Viscera in thoracic cavity.
What are the branches of the vagus nerve?
- Cardiac branches to cardiac plexus.
- Pulmonary branches to pulmonary plexus.
- Esophageal branches to esophageal plexus.
- Left recurrent laryngeal nerve from left vagus.
- Right recurrent laryngeal nerve from right vagus.
What does the left recurrent laryngeal nerve from the left vagus nerve hook around?
Around arc of aorta to left of ligamentum arteriosum.
Where does the right recurrent laryngeal nerve from the right vagus arise from?
Arises in neck, not thorax.
True or False:
The right recurrent laryngeal nerve from the right vagus arises in the thorax.
False - arises in neck, not thorax.
What enzyme makes acetylcholine from acetyl-CoA + choline?
What enzyme breaks down acetylcholine -> choline + acetate ion?
What amino acid is norepinephrine derived from?
True or False:
In the adrenal medulla, 80% of the norepinephrine is methylated to form epinephrine.
What is the cascade of norepinephrine synthesis starting at tyrosine?
- hydroxylation of tyrosine to dopa
- decarboxylation of dopa to dopamine
- transport of dopamine into the vesicles
- hydroxylation of dopamine to norepinephrine
**note that in the adrenal medulla, 80% of the norepinephrine is methylated to form epinephrine**
What are the different ways in which norepinephrine is removed?
- destruction by monamine oxidase
> found in nerve endings
- destruction by catechol-O-methyl transferase (COMT)
> present in all tissues
Where is monamine oxidase, which destructs norepinephrine, found?
found in nerve endings
Where is catechol-O-methyl transferase (COMT), which destructs norepinephrine, found?
present in all tissues
True or False:
Norepinephrine/epinephrine is active for only a few seconds when secreted directly into the tissues but when secreted into the blood (via the adrenal medulla) it remains active until destroyed by COMT in surrounding tissues, especially the liver.
List the different types of acetylcholine receptors?
Where are muscarinic acetylcholine receptors found?
On all effector cells stimulated by postganglionic cholinergic neurons.
What type of receptors are found on all effector cells stimulated by postganglionic cholinergic neurons?
Muscarinic acetylcholine receptors.
Where are nicotinic acetylcholine receptors found?
> Found in autonomic ganglia at synapses between preganglionic and postganglionic neurons.
> Present in neuromuscular junctions in skeletal muscles.
What is muscarine a poison from?
Which acetylcholine receptor is present in neuromuscular junctions in skeletal muscles?
nicotinic acetylcholine receptors
List the different adrenergic receptors?
> alpha 1
> alpha 2
> beta 1
> beta 2
> beta 3
What type of adrenergic receptors are mainly excited by norepinephrine?
Excites mainly alpha receptors but also beta receptors to a lesser extent.
True or False:
Epinephrine excites both alpha and beta almost equally.
True or False:
Norepinephrine excites mainly alpha receptors but also beta receptors to a lesser extent.
What are the two different types of alpha, adrenergic receptors, besides alpha 1 and alpha 2?
Certain alpha receptors are excitatory; others are inhibitory.
What type of physiological functions are alpha, adrenergic, receptors associated with?
- Iris dilation
- Intestinal relaxation
- Intestinal sphincter contraction
- Pilomotor contraction
- Bladder sphincter contraction
- Inhibition of neurotransmitter release (alpha 2)
What physiological effects do beta1 adrenergic receptors signal?
- increased myocardial strength
What physiological effects do beta2 adrenergic receptors signal?
- intestinal relaxation
- uterus relaxation
- bladder wall relaxation
What physiological effects do beta3 adrenergic receptors signal?
Which subclass of beta adrenergic receptors control thermosgenesis?
Beta3 adrenergic receptors.
Which subclass of beta adrenergic receptors control vasodilation and uterus relaxation?
Beta2 adrenergic receptors.
Which subclass of beta adrenergic receptors control cardioacceleration, increased myocardial strength, and lipolysis?
Beta1 adrenergic receptors.
Which beta adrenergic receptor does Albuterol target, causing bronchodilation?
Beta2 adrenergic receptors.
Which beta adrenergic receptor does Isoproterenol target?
Beta adrenergic receptors.
Which beta adrenergic receptor does Phenylephrine target?
Alpha adrenergic receptors.
List the sympathomimetic drugs that we are covering in lecture.
- phenylephrine (alpha receptors)
- isoproterenol (beta receptors)
- albuterol (beta2 receptors)
List the 3 drugs that cause the release of norepinephrine?
Which drug blocks synthesis and storage of norepinephrine?
Which drug blocks the release of norepinephrine?
Which drug blocks sympathetic alpha adrenergic receptors?
Which drug blocks sympathetic beta1 and beta2 adrenergic receptors?
Which drug blocks mostly sympathetic beta1 adrenergic receptors?
Which drug blocks the transmission through autonomic ganglia?
List 3 drugs that block cholinergic activity.
List 3 drugs that inhibit acetylcholinesterase?
What are the characteristics of parasympathomimetic drugs?
- Not rapidly destroyed by cholinesterase.
- Include pilocarpine and methacholine.
- Act directly on muscarinic receptors.
Are parasympathomimetic drugs destroyed by cholinesterase?
Not rapidly destroyed by cholinesterase.
What type of adrenergic receptors do parasympathomimetic drugs act directly on?
Muscarinic Adrenergic Receptors
What is the effect of sympathetic stimulation on the eye?
What is the effect of parasympathetic stimulation on the eye?
- pupil constriction
- lens focusing
What is the effect of sympathetic stimulation on sweat glands?
Causes secretion of large amounts of sweat.
**cholinergic to most sweat glands (a few adrenergic fibers in palms and soles
**actually a parasympathetic function distributed via sympathetic fibers
What is the effect of parasympathetic stimulation on glands?
- Strongly stimulates lacrimal, nasal, salivary, and many GI glands.
- Strongly stimulates GI glands of upper tract.
** NOTE: glands of lower GI tract are mostly stimulated via the enteric system **
What is the effect of sympathetic stimulation on the GI tract?
- Strong stimulation inhibits peristalsis.
- GI tract is normally not dependent on sympathetic stimulation.
What is the effect of parasympathetic stimulation on the GI tract?
- Promotes peristalsis
- Relaxes sphincters
What is the effect of sympathetic stimulation on the heart?
Increases heart rate and strength of contraction.
What is the effect of parasympathetic stimulation of the heart?
Decreases heart rate and strength of contraction.
What is the effect of sympathetic stimulation on systemic blood vessels?
Constricts most blood vessels.
What is the effect of parasympathetic stimulation on systemic blood vessels?
Has almost no effect.
What is the effect of sympathetic stimulation on arterial pressure?
Results in acute increase in arterial pressure but little effect long term.
What is the effect of parasympathetic stimulation on arterial pressure?
Decreases pumping of heart but little effect on blood pressure.
What is the effect of sympathetic stimulation on general physiology?
Inhibits most of endodermal structures.