BIO 1314 - Chapter 15 - The Autonomic Nervous System
fibers of the sympathetic division
* Preganglionic Fibers - Are relatively short - Ganglia located near spinal cord - exits from spinal cord via TI-L2 spinal nerves - myelinated * Postganglionic Fibers - Are relatively long, except at adrenal medullae - unmyelinated
visceral reflex arc
- Receptors: nerve endings that detect stretch, tissue damage, blood chemicals, body temperature, and other internal stimuli - Afferent neurons: leading to the CNS - Interneurons: in the CNS - Efferent neurons: carry motor signals away from the CNS - Effectors: that make adjustments
parasympathetic division of ANS
-Calms many body functions reducing energy expenditure and assists in bodily maintenance -Digestion and waste elimination -"Resting and digesting" state
ANS contrasts to somatic motor pathway
-In somatic pathway: -a motor neuron from brainstem or spinal cord issues a myelinated axon that reaches all the way to skeletal muscle -In autonomic pathway: -signal must travel across two neurons to get to the target organ -must cross a synapse where these two neurons meet in an autonomic ganglion -presganglionic neuron: the first neuron has a soma in the brainstem or spinal cord -synapses with a postganglionic neuron whose axon extends the rest of the way to the target cell
parasympathetic tone
-Maintains smooth muscle tone in intestines -Holds resting heart rate down to about 70 to 80 beats per minute
spinal nerve route
-Some postganglionic fibers exit a ganglion by way of the gray ramus -Return to the spinal nerve and travel the rest of the way to the target organ -Most sweat glands, piloerector muscles, and blood vessels of the skin and skeletal muscles
sympathetic chain ganglia
-a series (or chain) of connected sympathetic postganglionic cell body clusters positioned along each side of the vertebral column adjacent to the major body wall branches of the aorta -each paravertebral ganglion is connected to a spinal nerve by two branches: communicating rami -preganglionic fibers are small myelinated fibers that travel from spinal nerve to the ganglion by way of the white communicating ramus (myelinated) -postganglionic fibers leave the ganglion by way of the gray communicating ramus (unmyelinated) -forms a bridge back to the spinal nerve -postganglionic fibers extend the rest of the way to the target organ
autonomic nervous system (ANS)
-a set of nerves that carries involuntary and automatic commands that control blood vessels, body organs, and glands; cardiac and smooth muscle -autonomic means "self-governed"- the ANS is independent of our will -it is part of the PNS -"fight or flight"
neural pathways through the sympathetic chain ganglia
-can take three routes: 1. through the spinal nerve route 2. the sympathetic nerve route 3. the splanchnic nerve route
solar plexus
-collective name for the celiac and superior mesenteric ganglia -nerves radiate from ganglia like rays of the sun
collateral ganglia
-contribute to a network called the abdominal aortic plexus -wraps around abdominal aorta -three major collateral ganglia in this plexus: 1. celiac 2. superior mesenteric 3. inferior mesenteric -postganglionic fibers accompany arteries of the same names and their branches to their target organs
facts about the parasympathetic division
-emanates from the brainstem (CN III, VII, XI, X) and S2-S4 spinal cord -long preganglionic fibers -short postganglionic fibers -synapse between pre and postganglionic neurons occurs in Terminal Ganglia -in or near target organ
sympathetic tone
-keeps most blood vessels partially constricted and maintains blood pressure
neurotransmitters overview
-preganglionic axons- are cholinergic (both use Acetylcholine) -postganglionic axons -sympathetic: mostly norepinephrine - parasympathetic: Acetylcholine
many synapses between pre and postganglionic neurons occur in autonomic ganglia located in:
-sympathetic chain of ganglia -this allows for the SNS to affect all areas of the body, not just the thoracolumbar region -allows SANS innervation to all areas of body, not just TL region
sympathetic adrenergic fiber
-the release of ACh but has a long postganglionic fiber -norepinephrine gets released
parasympathetic fiber
-the specific nerve that, when stimulated, causes a decrease in the cardiac rate -preganglionic neuron, acetylcholine gets released and the postganglionic neuron could have a nicotinic receptor that then stimulates the postganglionic neuron that then releases ACh again onto a muscarinic receptor that is on the target cell
Which are effects of the parasympathetic division on the digestive system? Multiple select question. Increased pancreatic enzyme secretion Increased glycogen breakdown by the liver Increased gastric motility Increased gastrointestinal secretion
1, 3, 4
Which activities are attributed to the parasympathetic division of the ANS? Multiple select question. Waste elimination Elevating heart rate Reduced energy expenditure Increasing blood-glucose levels Digestion
1, 3, 5
Parasympathetic fibers leave the brainstem through which cranial nerves? Select all that apply. Multiple select question. III VI IV X VII IX
1, 3-6
Which neurons secrete acetylcholine? Multiple select question. Most preganglionic sympathetic neurons Most postganglionic parasympathetic neurons Most postganglionic sympathetic neurons Most preganglionic parasympathetic neurons
1,2,4
Which are effects of the sympathetic division on the circulatory system? Multiple select question. Vasoconstriction of visceral blood vessels Increased blood clotting Increased heart rate Decreased heart rate Vasoconstriction of blood vessels in the skin Vasodilation of visceral blood vessels
1-3, 5
From which regions of the CNS do the nerves of the parasympathetic nervous system arise? Multiple select question. Lumbar division of spinal cord Sacral division of spinal cord Thoracic division of spinal cord Brainstem
2 & 4
What are the effects of the sympathetic division on the eye? Multiple select question. Pupillary constriction Pupillary dilation Secretion of tears from the lacrimal gland Relaxation of the ciliary muscle and lens for far vision Contraction of the ciliary muscle and lens for near vision
2,3
Parasympathetic fibers leave the brainstem through which cranial nerves? Select all that apply. Multiple select question. Hypoglossal Oculomotor Vagus Facial Glossopharyngeal Trochlear
2-5
What are two receptors that bind norepinephrine? Multiple select question. Nicotinic Muscarinic Alpha-adrenergic Beta-adrenergic
3 & 4
muscarinic receptors
Cholinergic receptors that are located postsynaptically in the effector organs such as smooth muscle, cardiac muscle, and glands supplied by parasympathetic fibers.
nicotinic receptors
On all ANS postganglionic neurons, in the adrenal medulla, and at neuromuscular junctions of skeletal muscle Excitatory when ACh binding occurs
sympathetic division of ANS
Prepares body for physical activity: exercise, trauma, arousal, competition, anger, or fear Increases heart rate, BP, airflow, blood glucose levels, etc. Reduces blood flow to the skin and digestive tract "Fight-or-flight" -excites heart but inhibits digestive and urinary function, while parasympathetic has the opposite effect
The ganglia of the sympathetic division are located ______. Multiple choice question. near the spinal column near or within the target organ near or within the brain
a
Vasomotor tone is produced by a baseline level of stimulation by which division of the ANS? Multiple choice question. Sympathetic Parasympathetic
a
What effect does the parasympathetic system have on the respiratory system? Multiple choice question. Bronchoconstriction Bronchodilation Decreased secretion by mucous glands via alpha-1 receptors Increased secretion by mucous glands via beta-2 receptors
a
Which division of the ANS causes a decrease in gastrointestinal secretions, pancreatic enzymes, and pancreatic insulin? Multiple choice question. Sympathetic Parasympathetic
a
Which division of the ANS causes a decreased heart rate, vasodilation of visceral blood vessels, and vasodilation of the skin's blood vessels? Multiple choice question. Parasympathetic Sympathetic
a
Which division of the ANS causes pupillary constriction and contraction of the ciliary muscle for near vision? Multiple choice question. Parasympathetic division Sympathetic division
a
Which ganglia extend from the cervical region to the coccygeal region along the vertebral column? Multiple choice question. Sympathetic chain Parasympathetic ganglia
a
Which of the following statements is true regarding parasympathetic tone? Select one: a.It holds the resting heart rate below its intrinsic rate. b.It accelerates the resting heart rate above its intrinsic rate. c.It might increase or decrease heart rate depending on the situation. d.It affects heart rate only after myocardial infarction. e.It does not affect heart rate.
a
Within the ANS, the effects of the ______ division are often general and widespread, while in the _______ division the effects are more specific and local. Multiple choice question. sympathetic, parasympathetic parasympathetic, sympathetic
a
______ receptors are cholinergic receptors that are found at the synapses of all autonomic ganglia, on cells of the adrenal medulla, and at neuromuscular junctions. Multiple choice question. Nicotinic Muscarinic
a
The sympathetic and parasympathetic systems exhibit a background rate of activity referred to as _____ tone
autonomic
postganglionic fibers
axons connecting the ganglion cells with the peripheral effectors
preganglionic fibers
axons extending from the CNS to a ganglion
The neurotransmitter ______ binds to cholinergic receptors. Multiple choice question. epinephrine acetylcholine norepinephrine
b
Which division of the ANS causes bronchodilation in the respiratory system? Multiple choice question. Parasympathetic Sympathetic
b
Which division of the ANS is responsible for increasing heart rate, alertness, blood pressure, pulmonary airflow, blood-glucose concentration, and blood flow to the heart and skeletal muscles? Multiple choice question. Parasympathetic division Sympathetic division
b
Which is the major control center of the visceral motor system? Multiple choice question. Epithalamus Hypothalamus Cerebellum Spinal cord Pons
b
Which nervous system division has skeletal muscles as effectors? Multiple choice question. Autonomic Somatic
b
Which neurotransmitter is most commonly secreted by postganglionic nerve fibers of the sympathetic division of the ANS? Multiple choice question. Acetylcholine Norepinephrine
b
The sympathetic fibers to a blood vessel have a ____________ sympathetic tone. This tone keeps the vessels in a state of partial ____________ , called vasomotor tone. An ___________ in firing rate constricts a vessel by increasing smooth muscle contraction. A drop in firing ____________ a vessel by allowing the muscle to relax. Thus, the sympathetic division alone exerts ____________ effects on the vessel.
baseline; constriction; increase; dilates; opposite
Atropine is sometimes used to dilate the pupil for an eye examination. Which receptor would atropine block? Select one: a.Alpha 1 adrenergic receptor b.Nicotinic receptor c.Muscarinic receptor d.Alpha 2 adrenergic receptor e.Beta receptor
c
From where do all preganglionic nerve fibers of the sympathetic nervous system arise? Multiple choice question. Brainstem and sacral region of spinal cord Cerebellum and brainstem Thoracic and lumbar regions of the spinal cord Cervical and thoracic regions of spinal cord
c
The motor pathway of the autonomic nervous system usually involves __________ neurons. Select one: a.no b.one c.two d.three e.four
c
What region of the brain is the primary regulator of the visceral motor system? Multiple choice question. Thalamus Cerebral cortex Hypothalamus
c
Which describes the sympathetic chain ganglia? Multiple choice question. A series of sympathetic ganglia located within the brain A longitudinal series of parasympathetic ganglia A longitudinal series of ganglia adjacent to both sides of the vertebral column A series of parasympathetic ganglia located within the spinal cord
c
Which nerve fibers secrete norepinephrine? Multiple choice question. Postganglionic nerve fibers of the parasympathetic division Preganglionic nerve fibers of the parasympathetic division Postganglionic nerve fibers of the sympathetic division Preganglionic nerve fibers of the sympathetic division
c
Which neurotransmitter is released by both preganglionic and postganglionic neurons of the parasympathetic division? Multiple choice question. Norepinephrine GABA Acetylcholine
c
Which type of receptor can either be inhibited or excited by the binding of acetylcholine? Multiple choice question. Adrenergic Nicotinic Muscarinic Sympathetic
c
communicating rami
carry visceral motor (sympathetic) and visceral sensory neurons to and from the sympathetic chain
Which receptors bind to ACh?
cholinergic
another name for the parasympathetic division
craniosacral division
Action potentials arriving at the sinoatrial and atrioventricular nodes of the heart cause ____________ to be released. Also known as the ____________ division, the parasympathetic nervous system has fibers exiting the CNS at the medulla oblongata. This parasympathetic neurotransmitter causes a ____________ in heart rate and contractility. The impulse arrives relatively quickly at the heart, as parasympathetic postganglionic fibers are ____________ compared to sympathetic postganglionic fibers. Action potentials travel down the preganglionic nerve fibers of the ____________ , towards the effector organs. These impulses arrive at the cardiac plexus where secretion of acetylcholine creates an action potential in the ____________ neuron.
craniosacral; vagus nerve; postganglionic; short; acetylcholine; decrease
Most preganglionic fibers in the sympathetic nervous system synapse with __________. Select one: a.no neurons b.somatic neurons c.parasympathetic neurons d.10-20 postganglionic neurons e.effectors directly
d
The neurotransmitter norepinephrine binds to ______ receptors. Multiple choice question. cholinergic muscarinic adrenergic
d
Which of the following is more effective in producing bronchodilation? Select one: a.Acetylcholine b.Nicotine c.Muscarine d.Norepinephrine e.Thyroxine
d
Which of the following is not a characteristic of the parasympathetic division of the ANS? Select one: a.Its effects are local. b.The terminal ganglia are very close to or within their target organs. c.It originates in the craniosacral regions of the CNS. d.It has short preganglionic fibers. e.It has short postganglionic fibers.
d
Baroreceptors
detect changes in blood pressure
Antagonistic effects of the two divisions of the autonomic nervous system are exemplified in the control of __________. Select one: a.blood clotting b.blood flow to the skeletal muscles c.sweating d.hair erection e.gastrointestinal motility
e
Autonomic nervous system fibers are involved in all of the following except __________. Select one: a.changing the diameter of the pupil b.adjusting heart rate and force c.altering salivary mucus secretion d.regulating gastrointestinal motility e.maintaining tonicity of the muscles of the neck
e
The background rate of sympathetic and parasympathetic activity is called ___________. Select one: a."fight-or-flight" activity b.visceral motor activity c.autonomic reflex arc activity d.visceral tone e.autonomic tone
e
The parasympathetic division arises from the __________ regions of the spinal cord. Select one: a.brain, thoracic, and lumbar b.brain, sacral, and coccygeal c.brain, lumbar, sacral, and coccygeal d.sacral and lumbar e.brain and sacral
e
The sympathetic chain of ganglia is found at the __________ levels of the spinal cord. Select one: a.cervical and thoracic b.thoracic and lumbar c.thoracic, lumbar and sacral d.sacral, lumbar and coccygeal e.cervical, thoracic, lumbar, sacral, and coccygeal
e
__________ nerve(s) pass(es) throughout sympathetic ganglia without synapsing. Select one: a.Facial b.Trigeminal c.Vagus d.Celiac e.Splanchnic
e
ANS is considered the
efferent pathway
Most autonomic efferent pathways involve one neuron. Select one: True False
false
The autonomic nervous system carries out many somatic reflexes that are crucial to homeostasis. Select one: True False
false. FALSE - carries out involuntary actions, visceral reflexes
Cell bodies of the sympathetic preganglionic fibers are found in the _____ horn of gray matter in the spinal cord.
lateral
Where are the cell bodies of sympathetic preganglionic fibers located in the spinal cord?
lateral gray horn
white communicating ramus
myelinated, where preganglionic fibers enter sympathetic chain of ganglia
The ganglia of the parasympathetic division are located
near or within the target organ
autonomic tone
normal background rate of activity that represents the balance of the two systems according to the body's changing needs
You shine a penlight into your patient's eyes. The right pupil constricts in response, but the left pupil remains dilated. In which branch of the nervous system does the problem lie - somatic, sympathetic, or parasympathetic?
parasympathetic because it mediates pupil constriction. Since the pupil didn't dilate, there must be some sort of pathological damage
The division of the ANS that has general and widespread effects is the _____ division
sympathetic
Which division of the ANS is associated with the "fight-or-flight" response?
sympathetic
does the neuronal divergence predominate in the sympathetic or parasympathetic division?
sympathetic -each preganglionic cell branches and synapses on 10 to 20 postganglionic cells -one preganglionic neuron can excite multiple postganglionic fibers leading to different target organs -has relatively widespread effects
two major divisions of the ans
sympathetic (fight-or-flight) and parasympathetic (rest-or-digest)
autonomic nervous system (ANS)
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms. controls the activity of glands, cardiac muscle, and smooht muscle
the sympathetic division is sometimes called the
thoracolumbar division (origin)
Also known as the ____________ division, the sympathetic nervous system exits the CNS via the spinal nerves from T1-L2. Action potentials travel along the preganglionic nerve fiber and enter the ____________ . Fibers exiting the sympathetic chain ganglia take one of three routes: the spinal nerve route, the sympathetic nerve route, or the ____________ nerve route. Arriving at target cells, ____________ nerve fibers release acetylcholine or norepinephrine into the synaptic cleft. The effect of norepinephrine binding to ____________ receptors stimulates cardiac muscle cells.
thoracolumbar; sympathetic chain ganglion; splanchnic; postganglionic; adrenergic
All autonomic output originates in the central nervous system.
true
Binding of norepinephrine (NE) to an alpha-adrenergic receptor is usually excitatory, and binding to a beta-adrenergic receptor is usually inhibitory. Select one: True False
true
In autonomic motor pathways, the nerve signal must travel along ____________ neurons to reach a target cell. The first neuron emerges from the CNS and synapses with a second neuron in a ____________ outside the CNS. The second neuron's axons extend to the ____________ from the ganglion. The first neurons are called ____________ and are myelinated. The second neurons are called ____________ and are unmyelinated.
two; ganglion; target cell; preganglionic; postganglionic
visceral reflexes
unconscious, automatic, stereotyped responses to stimulation involving visceral receptors and effectors
gray communicating ramus
unmyelinated, where postganglionic fibers exit the sympathetic chain
_____ tone describes the continual input from the sympathetic division to the smooth muscle of blood vessel walls, resulting in a partial and constant tension.
vasomotor
What is the other name for the autonomic nervous system?
visceral motor system
Atropine is a parasympatholytic (cholinergic blocking agent). If atropine is given as an intravenous injection, would you expect to see a change in heart rate? Explain.
yes, the heart rate would increase. The parasympathetic decreases heart rate, and atropine has the opposite effect
sympathetic nerve route
• Other nerves leave by way of sympathetic nerves that extend to the heart, lungs, esophagus, and thoracic blood vessels • These nerves form carotid plexus around each carotid artery of the neck • Issue fibers from there to the effectors in the head - Sweat, salivary, nasal glands; piloerector muscles; blood vessels; dilators of iris • Some fibers of superior and middle cervical ganglia form cardiac nerves to the heart
splanchnic nerve route
• Some fibers that arise from spinal nerves T5 to T12 pass through the sympathetic ganglia without synapsing - Continue on as the splanchnic nerves - Lead to second set of ganglia: collateral (prevertebral) ganglia and synapse there
