A&P 50B: Ch 14 (Autonomic)
Parasympathetic, sympathetic
Heart rate is normally controlled by [sympathetic or parasympathetic] tone? Blood pressure is normally under [sympathetic or parasympathetic] tone?
Adrenergic, muscarinic
* If norepinephrine is released by a sympathetic postganglionic neuron, it will bind to the a____________ receptors present on the target cell. * If ACh is released, it will bind to the m____________ receptors on the target cell.
Norepinephrine, acetylcholine
* Postganglionic sympathetic fibers release n_______________, with a minor exception. * Whereas postganglionic parasympathetic fibers release a________________. For any given target, the difference in which division of the ANS is exerting control is just in what chemical binds to its receptors. The target cells will have adrenergic and muscarinic receptors.
Prevertebral
*Collateral ganglia* are also called p________________ ganglia, which are named so because they are anterior to the vertebral column in the abdominal cavity.
Prevertebral ganglia
*Collateral ganglia* are called p______________ g__________, probaaaably because they are situated anterior to the vertebral column and receive inputs from splanchnic nerves as well as central sympathetic neurons. They are associated with controlling organs in the abdominal cavity, and are also considered part of the enteric nervous system (ENS).
Muscarinic agonist
A *parasympathomimetic drug* is also called a m___________ a________. Acts just like ACh released by the parasympathetic postganglionic fiber. Targets: Various organs, heart, smooth muscle and glands.
Amygdala
A good example of forebrain structures informing the hypothalamus of the state of the nervous system and influencing the regulatory processes of homeostasis is of the a____________. This structure is found beneath the cerebral cortex of the temporal lobe and plays a role in our ability to remember and feel emotions.
Postganglionic fiber
A p_________________ fiber (the axon from a ganglionic neuron that projects to the target effector) represents the output of a ganglion that directly influences the organ. Compared with the preganglionic fibers, they are long because of the relatively greater distance from the ganglion to the target effector. These fibers are unmyelinated.
Short reflex
A s_______ r________ is completely peripheral and only involves the local integration of sensory input with motor output. Involves the direct stimulation of a postganglionic fiber by the sensory neuron.
Sensory neuron
A s_________ n________ can project to the CNS or to an autonomic ganglion.
Visceral
ANS function is based on the [somatic or visceral?] reflex. Similar to the other reflex, but the efferent branch is composed of 2 neurons. 1. The central neuron projects from the spinal cord or brain stem to synapse on the ganglionic neuron that project to the effector.
Albuterol
A__________ is an example of a bronchodilator. Used for asthma?
Anticholinergic
A________________ drugs block muscarinic receptors, suppressing parasympathetic interaction with the organ.
Adrenergic
Acetylcholine can be considered a neurotransmitter because it is released by axons at synapses. The a__________ system, however, presents a challenge. * Postganglionic sympathetic fibers release norepinephrine, which can be considered a neurotransmitter. * BUT! the adrenal medulla releases epinephrine and norepinephrine into circulation, so they should be considered hormones.
Pupillary reflex
Activation of the p__________ r_______ comes from the amount of light activating the retinal ganglion cells, as sent along the optic nerve.
Splanchnic nerve
Additional branches from the ventral nerve root continue through the chain and on to one of the collateral ganglia as the greater or lesser s____________ n_______. For example, there is a greater one at the level of T5 with synapses with a collateral ganglion outside the chain before making the connection to the postganglionic nerves that innervate the stomach.
ACh
All preganglionic fibers, both sympathetic and parasympathetic, release _ _ _.
Pupillary size
An exception to dual innervation is in the control of p___________ s_______. The afferent branch responds to light hitting the retina. Photoreceptors are activated, and the signal is transferred to the retinal ganglion cells that send an action potential along the optic nerve into the diencephalon. * If light levels are low, the sympathetic system sends a signal out through the upper thoracic spinal cord to the superior cervical ganglion of the sympathetic chain. The postganglionic fiber then projects to the iris, where it releases norepinephrine onto the radial fibers of the iris (a smooth muscle). When those fibers contract, the pupil dilates (increasing the amount of light hitting the retina).
Dorsal motor nucleus
Another brain stem nucleus important for visceral control is the d________ m________ n_________ of the *vagus nerve*, which is the motor nucleus for the parasympathetic functions ascribed to the vagus nerve, including decreasing the heart rate, relaxing bronchial tubes in the lungs, and activating digestive function through the ENS system.
Nicotine
BC there is no parasympathetic influence on blood pressure for entire body, sympathetic input is *increased* by n_________, causing an increase in blood pressure.
Beta 2 receptors
B______ _ r_________ are located primarily on smooth muscle of bronchioles and blood vessels. -Bronchial and vascular smooth muscle -Affect bronchodilation, vasodilation. Ex. Albuterol
Efferent
Because the e_________ branch of a visceral reflex involves two neurons (the central neuron and the ganglionic neuron) a "short circuit" can be possible. If a sensory neuron projects directly to the ganglionic neuron and causes it to activate the effector target, then the CNS is not involved.
Parasympathetic
Bright light hitting the retina leads to the [sympathetic or parasympathetic] response. Through the oculomotor nerve, followed by the postganglionic fiber from the ciliary ganglion, which stimulates the circular fibers of the iris to contract and constrict the pupil.
Central control
C__________ c__________ of autonomic reflexes is different than for somatic reflexes.
Forebrain
Coordinating that balance requires integration that begins with f___________ structures like the hypothalamus and continues into the brain stem and spinal cord.
Postganglionic
Drugs that act on the parasympathetic system also work by either enhancing the p_________________ signal or blocking it.
Homeostasis
H_________________ is the balance between the sympathetic nervous system and the parasympathetic nervous system.
Strong
If a visceral sensation, such as cardiac pain, is s_______ enough, it will rise to the level of consciousness. However, the sensory homunculus does not provide a representation of the internal structures to the same degree as the surface of the body, so visceral sensations are often experienced as referred pain, such as feelings of pain in the left shoulder and arm in connection with a heart attack.
Muscarine
M_________ binds to the muscarinic receptors.
Vagus nerve
Neurons in the *dorsal nucleus* of the v________ n________ and the *nucleus ambiguous* project through CNX to the terminal ganglia of the thoracic and abdominal cavities.
White rami communicantes
Preganglionic sympathetic axons of T1-L2 spinal nerves are carried by the w______ r_______ c_________________, which are myelinated;
Sweat
S_______ glands have muscarinic receptors and produce and secrete sweat in response to the presence of ACh.
Ventral horn
Somatic reflexes, for instance, involve a direct connection from the v______ h______ of the spinal cord to the skeletal muscle.
Locally, distant
Some sensations of referred pain are felt l_________, whereas others are perceived as affecting areas that are quite d_______ from the involved organ.
ANS
The [somatic nervous system or ANS?] regulates activity of smooth muscle, cardiac muscle and certain glands.
Postganglionic fiber
The axon from the ganglionic neuron is called the p______________ f_______, which projects to a target effector where it wiill release *norepinephrine* to bind to an adrenergic receptor, causing a change in the physiology of the organ in keeping with the broad, divergent sympathetic response.
Baroreceptor apparatus
The b___________ a__________ is part of the ending of a unipolar neuron that has a cell body in a sensory ganglion. The ones from the carotid arteries have axons in the glossopharyngeal nerve, and those from the aorta have axons in the vagus nerve.
Dual innervation
The balance of homeostasis is attributable to the competing inputs from the sympathetic and parasympathetic divisions, called d_______ i_______________.
Varicosities
The synapses in the ANS are not always the typical type of connection first described in the neuromuscular junction. Instead of having synaptic end bulbs at the very end of an axonal fiber, they may have swellings (called v_____________) along the length of a fiber so that it makes a network of connections within the target tissue.
Terminal ganglia
The target of the preganglionic fibers of the parasympathetic division of the ANS are t________ g_______, which are located, near (or even within) the target effector. These ganglia are often referred to as "intramural ganglia" when they are found within the walls of the target organ.
Adrenaline
The term adrenergic should remind you of the word a_____________, which is associated with the fight-or-flight response.
Mesenteric
The word m___________ refers to the digestive system.
3
To continue with the analogy of the circuit diagram for the SNS, there are _ different types of "junctions" that operate within the sympathetic system
True
True or false: ACh binds to both nicotinic and muscarinic receptors.
True
True or false: Adrenaline and epinephrine are two names for the same molecule.
False
True or false: There is no preganglionic fiber that does not terminate in a ganglion.
False
True or false: Visceral senses are not primarily a part of conscious perception, and therefore those sensations can never make it to conscious awareness.
False
True or false:All axons from the central neurons terminate in the chain ganglia.
False
True or false: Norepinephrine and noradrenaline are not the same thing.
Adrenergic
An a___________ synapse is one where norepinephrine is released.
Epinephrine
An additional aspect of the adrenergic system is that there is a second signaling molecule called e____________.
Long reflex
A [long or short reflex?] has afferent branches that enter the spinal cord or brain and involve the efferent branches. Involves integration in the spinal cord or brain.
Branching
A b_________ pattern is exhibited by the preganglionic sympathetic neurons (a single preganglionic sympathetic neuron may have 10-20 targets).
Cholinergic
A c__________ synapse means that acetylcholine (ACh) is released.
ENS
A division of the nervous system that is related to the ANS is the _ _ _. Refers to the digestive organs, so this represents the nervous tissue that is part of the digestive system.
Nicotinic receptors
All ganglionic neurons (the targets of preganglionic fibers) have n__________ receptors in their cell membranes. These receptors are ligand-gated cation channels that results in depolarization of the postsynaptic membrane.
Sympathetic
An aspect of the cardiovascular system is primarily under [sympathetic or parasympathetic?] control. Blood pressure is partially determined by the contraction of smooth muscle in the walls of blood vessels. * These tissues have adrenergic receptors that respond to the release of norepinephrine from postganglionic sympathetic fibers by constricting and increasing blood pressure. * The hormones released from the adrenal medulla (epinephrine and norepinephrine) will also bind to these receptors. Those hormones travel through the bloodstream where they can easily interact with the receptors in the vessel walls. * There is no significant input of the other division of the ANS to the systemic blood vessels, so they are defined by autonomic tone.
Preganglionic fiber
An axon from the central neuron that projects to a sympathetic ganglion is referred to as a p________________ f______ [or neuron], and represents the output from the CNS to the ganglion. Because the sympathetic ganglia are adjacent to the vertebral column, these fibers are relatively short, and they are myelinated.
Thoracolumbar
An axon that leaves a central neuron of the lateral horn in the t________________ spinal cord will pass through the white ramus communicans and enter the sympathetic chain, where it will branch toward a variety of targets.
Dual innervation
At each target effector, d______ i____________ of both the sympathetic and parasympathetic systems determines activity. For example, the heart receives connections from both the sympathetic and parasympathetic divisions. One causes heart rate to increase, whereas the other causes heart rate to decrease.
Effector response
At most of the other targets of the autonomic system, the e________ r__________ is based on which neurotransmitter is released and what receptor is present. For example, regions of the heart that establish heart rate are contacted by postganglionic fibers from both systems. * If *norepinephrine* is released onto those cells, it binds to an adrenergic receptor that causes the cells to depolarize faster, and the heart rate increases. * If *ACh* is released onto those cells, it binds to a muscarinic receptor that causes the cells to hyperpolarize so that they cannot reach threshold as easily, and the heart rate slows.
Chain ganglion
At the level of the spinal cord at which the preganglionic sympathetic fiber exits the spinal cord, a branch will synapse on a neuron in the adjacent c________ g__________. Some branches will extend up or down to a different level of these. Other branches will pass through these and project through one of the splanchnic nerves to a collateral ganglion. Finally, some branches may project through the splanchnic nerves to the adrenal medulla.
Chemical
At the level of the target effector for autonomic reflex arcs, the signal of which system is sending the message is strictly [neural or chemical?] A signaling molecule binds to a receptor that causes changes in the target cell, which in turn causes the tissue or organ to respond to the changing conditions of the body.
Visceral reflexes
Autonomic control is based on the v__________ r__________, composed of the afferent and efferent branches. These homeostatic mechanisms are based on the balance between the two divisions of the autonomic system, which results in tone for various organs that is based on the predominant input from the sympathetic or parasympathetic systems.
Sympathetic, parasympathetic
Average heart rate: 100 bpm The [sympathetic or parasympathetic?] system speeds up the rate, like during exercise, to 120-140 bpm. The [sympathetic or parasympathetic?] system slows it down to a resting heart rate of 60-80 bpm.
Superior cervical, ciliary
For autonomic control of pupillary size, output of the *sympathetic* system projects through the s___________ c____________ ganglion. Whereas the *parasympathetic* sys. originates out of the midbrain and projects through the oculomotor nerve to the c_________ ganglion which then projects to the iris. The postganglionic fibers of either division release neurotransmitters onto the smooth muscles of the iris to cause changes in the pupillary size.
Autonomic tone
For each organ system, there may be more of a sympathetic or parasympathetic tendency to the resting state, which is known as the a_____________ t________ of the system. For example, the resting heart rate is the result of the parasympathetic system slowing the heart down from its intrinsic rate of 100 bpm, the heart can be said to be in parasympathetic tone.
Sympatholytic
If drugs are s___________________, they block adrenergic activity and cancel the sympathetic influence on the target organ.
Eddinger-Westphal nucleus
If light levels are too high to the eye, the parasympathetic system sends a signal out from the E_________-W__________ nucleus through the oculomotor nerve. This fiber synapses in the ciliary ganglion in the posterior orbit. The postganglionic fiber then projects to the iris, where it releases *ACh* onto the circular fibers of the iris (another smooth muscle). When those fibers contract, the pupil constricts to limit the amount of light hitting the retina.
Stretch receptors
If s________ r____________ in the stomach are activated by the filling and distension of the stomach, a *short reflex* will directly activate the smooth muscle fibers of the stomach wall to increase motility to digest the excessive food in the stomach. No CNS involvement is needed because the receptor is directly activating a neuron in the wall of the stomach that causes the smooth muscle to contract. That neuron, connected to the smooth muscle, is a postganglionic parasympathetic neuron that can be controlled by a fiber found in the vagus nerve.
Increase
In the context of avoiding a threat like the lioness on the savannah, the sympathetic response for fight or flight will [increase or decrease?] pupillary diameter so that more light hits the retina and more visual information is available for running away.
Photoreceptors
In the example of the pupillary reflex, the autonomic system is controlling how much light hits the retina. It is a homeostatic reflex mechanism that keeps the activation of p___________________ [what receptors?] within certain limits.
Eddinger-Westphal nucleus
In the midbrain, the E__________-W__________n_________ is part of the oculomotor complex, and axons from those neurons travel with the fibers in the oculomotor nerve (cranial nerve III) that innervate the majority of the extraocular muscles. The preganglionic parasympathetic fibers within cranial nerve III terminate in the *ciliary ganglion*, which is located in the posterior orbit The postganglionic parasympathetic fibers then project to the smooth muscle of the iris to control pupillary size.
Dilation, constriction
In the pupillary reflex, neurotransmitters are released from postganglionic fibers of the PNS and SNS to smooth muscles of the iris to cause changes in the pupil's size. Norepinephrine results in d________ and ACh results in c_________________.
Salivatory nuclei
In the upper medulla, the s___________ n________ contain neurons with axons that project through the facial and glossopharyngeal nerves to ganglia that control salivary glands.
Visual sensation
The pupillary light reflex begins when light hits the retina and causes a signal to travel along the optic nerve. This is v________ s_____________, because the afferent branch of this reflex is simply sharing the special sense pathway.
Baroreceptor
Many of the inputs to visceral reflexes are from special or somatic senses, but particular senses are associated with the viscera that are not part of the conscious perception of the environment through the SNS. For example, there is a specific type of mechanoreceptor, called a b______________, in the walls of the aorta and carotid sinuses that senses the stretch of those organs when blood volume or pressure increases. * You do not have a conscious perception of having high blood pressure, but that is an important afferent branch of the cardiovascular and, particularly, vasomotor reflexes. The sensory neuron is essentially the same as any other general sensory neuron.
Nicotine
N_________ is not a drug that is used therapeutically, except for smoking cessation. When it is introduced into the body via products, it has broad effects on the ANS. Carries a risk for cardiovascular disease because of these broad effects.
Cardiovascular
Nicotine stimulates both sympathetic and parasympathetic ganglia at the preganglionic fiber synapse. For most organ systems in the body, the competing input from the two postganglionic fibers will essentially cancel each other out. However, for the c______________ system, the results are different.
Solitary nucleus
One brain stem nucleus involved in cardiovascular function is the s________ n________. It receives sensory input about blood pressure and cardiac function from the glossopharyngeal and vagus nerves, and its output will activate sympathetic stimulation of the heart or blood vessels through the upper thoracic lateral horn.
Visceral reflex
One difference between a somatic reflex, such as the withdrawal reflex, and a v________ reflex, which is an autonomic reflex, is in the efferent branch.
Norepinephrine
Postganglionic sympathetic fibers release n_______________, except for fibers that project to sweat glands and to blood vessels associated with skeletal muscles, which release Ach.
Parasympathetic preganglionic fibers
P____________________ p________________ f________ primarily influence the heart, bronchi, and esophagus in the thoracic cavity and the stomach, liver, pancreas, gall bladder, and small intestine of the abdominal cavity.
Ganglionic
Preganglionic fibers of the SNS release *acetolycholine* (ACh), which excites the g__________ neuron through the *nicotinic receptor.*
Cervical
Projections from the medial and inferior divisions of the c________ ganglia do enter the spinal cord at the middle to lower levels, which is where the somatosensory fibers enter.
Reduces
Regarding vision, the PNS response of rest [increases or reduces?] the amount of light reaching the retina, allowing the photoreceptors to cycle through bleaching and is regenerated for further visual perception
Signaling molecules
S__________ m___________ can belong to two broad groups. Neurotransmitters are released at synapses, whereas hormones are released into the bloodstream.
Somatic reflexes, visceral reflexes
S__________ r__________ involve sensory neurons that connect sensory receptors to the CNS and motor neurons that project back out to the skeletal muscles. V_________ r___________ that involve the thoracolumbar or craniosacral systems share similar connections.
Brain stem
Several nuclei located in the b_______ s_______ are important for the visceral control of major organ systems.
Competing autonomic
The pupil is under c___________ a___________ control in response to light levels hitting the retina. The sympathetic system will dilate the pupil when the retina is not receiving enough light, and the parasympathetic system will constrict the pupil when too much light hits the retina.
Cardiac accelerator nerves
The *preganglionic sympathetic fibers* that are responsible for increasing heart rate are referred to as the c_________ a_____________ n________.
Lateral, thoracolumbar
The *sympathetic output* of the nervous system originates out of the ______l horn of the t______________ spinal cord regions (from T1 to L2). An axon from 1 of these central neurons projects by way of the ventral spinal nerve root and spinal nerve to a sympathetic ganglion.
Dorsal longitudinal fasciculus, medial forebrain bundle
The 2 main tracts of the hypothalamus are the d________ l_________________ f_______________ and the m________ f________________ b__________. Along these two tracts, the hypothalamus can influence the *Eddinger-Westphal nucleus* of the oculomotor complex or the lateral horns of the thoracic spinal cord.
2
The ANS is important for homeostasis because its _ [how many?] divisions compete at the target effector.
Sympathetic, parasympathetic
The ANS regulates many of the internal organs through a balance of two aspects, or divisions. In addition to the endocrine system, the ANS is instrumental in homeostatic mechanisms in the body. The two divisions of the ANS are the s____________ division and the p________________ division.
Reflex arc
The ANS regulates organ systems through circuits that resemble the reflexes described in the SNS. The main difference between the SNS and ANS is in what target tissues are effectors. SNS responses are solely based on skeletal muscle contraction. The ANS, however, targets cardiac and smooth muscle, as well as glandular tissue. Whereas the basic circuit is a r________ a____, there are differences in the structure of those reflexes for the SNS and ANS.
Voluntary, involuntary
The SNS is associated with v__________ responses (though many can happen without conscious awareness, like breathing), and the ANS is associated with i_____________ responses, such as those related to homeostasis.
Afferent
The [afferent or efferent?] branch of the *somatic* and *visceral* reflexes is very similar, as many somatic and special senses activate autonomic responses.
Sympathetic
The [parasympathetic or sympathetic] tone of blood vessels is caused by lack of parasympathetic input to the systemic circulatory system. Example: Sweat glands Only certain regions receive parasympathetic input that relaxes the smooth muscle wall of the blood vessels.
Parasympathetic
The [sympathetic or parasympathetic?] system constricts the pupils, stimulates flow of saliva, constricts bronchi, slows heartbeat, simulates peristalsis and secretion, stimulates bile release, and contracts bladder.
Sympathetic
The _______________ division of the ANS, in response to a threat, would increase heart rate and breathing rate and cause blood flow to the skeletal muscle to increase and blood flow to the digestive system to decrease. Sweat gland secretion should also increase as part of an integrated response. All of those physiological changes are going to be required to occur together to run away from the hunting lioness, or the modern equivalent.
Adrenal
The a________ gland secretes adrenaline. The ending "-ine" refers to the chemical being derived, or extracted, from this gland.
Amygdala
The a___________ is a structure within the limbic system that influences the hypothalamus in the regulation of the autonomic system, as well as the endocrine system.
Adrenergic
The a___________ system has 2 types of receptors called the alpha (α) receptor and beta (β) receptor. Unlike cholinergic receptors, these receptor types are not classified by which drugs can bind to them. All of them are G protein-coupled receptors. There are three types of α-adrenergic receptors, termed α1, α2, and α3, and there are two types of β-adrenergic receptors, termed β1 and β2
Limbic lobe
The amygdala is a group of nuclei in the medial region of the temporal lobe that is part of the l_________ l_______, which includes structures that are involved in emotional responses, as well as structures that contribute to memory function. [Involves the amygdala, hippocamus, and cingulate gyrus] Has strong connections with the hypothalamus and influences the state of its activity on the basis of emotional state.
Drugs
The autonomic system is affected by a number of d______, including some that are therapeutic and some that are illicit. * They affect the autonomic system by mimicking or interfering with the endogenous agents or their receptors. * Can be thought of as chemical tools to effect changes in the system with some precision, based on where they are effective.
Ganglionic neuron
The axon from the central neuron (the preganglionic fiber shown as a solid line) synapses with the g______________ n________ (with the postganglionic fiber shown as a dashed line). This neuron then projects to a target effector (in this case, the trachea) via gray rami communicantes
Parasympathetic
The blood vessels that have a [sympathetic or parasympathetic?] projection are limited to those in the erectile tissue of the reproductive organs. Acetylcholine released by these postganglionic parasympathetic fibers cause the vessels to dilate, leading to the engorgement of the erectile tissue.
Central neuron
The c________ n__________ is found in the lateral horn of any of any T1-L2 spinal regions and projects to ganglia adjacent to the vertebral column through the ventral spinal roots.
Cervical ganglia
The c_________ g________ are referred to as *paravertebral ganglia*, given their location adjacent to prevertebral ganglia in the sympathetic chain.
Cranial, sacral
The c__________ component of the parasympathetic system projects from the eye to part of the intestines. The s_________ component picks up with the majority of the large intestine and the pelvic organs of the urinary and reproductive systems.
Chromaffin cells
The cells in the adrenal medulla that are contacted by the preganglionic fibers are called c____________ c_____. These cells are neurosecretory cells that develop from the neural crest along with the sympathetic ganglia, reinforcing the idea that the gland is, functionally, a sympathetic ganglion.
Methyl
The chemical difference between norepinephrine and epinephrine is the addition of a m______ group (CH3) in epinephrine. The prefix "nor-" actually refers to this chemical difference, in which this CH3 group is missing.
Resting tone
The competing inputs can contribute to the r________ t____ of the organ system. [Not controlled more by sympathetic tone or parasympathetic tone].
Circuits
The connections, or "c__________", of the parasympathetic division are similar to the general layout of the sympathetic division with a few specific differences. The preganglionic fibers from the cranial region travel in cranial nerves, whereas preganglionic fibers from the sacral region travel in spinal nerves
Arrhythmias
The contradictory signals nicotine has (of stimulating both sympathetic and parasympathetic ganglia at preganglionic fiber synapse) do not cancel out for the heart. They alter its regularity and can cause a_______________. These, and hypertension, are risk factors for heart disease.
Nuclei
The cranial component of the parasympathetic system is based in particular n________ of the brain stem.
CNS
The difference between short and long reflexes is in the involvement of the _ _ _. Somatic reflexes always involve it, even in a monosynaptic reflex in which the sensory neuron directly activates the motor neuron. That synapse is in the spinal cord or brain stem.
Thoracolumbar output
The effector organs that are the targets of the autonomic system range from the iris and ciliary body of the eye to the urinary bladder and reproductive organs. The t___________________ o___________, through the various sympathetic ganglia, reaches all of these organs.
Preganglionic
The efferent branch of the visceral reflex arc begins with the projection from the central neuron along the p___________________ fiber. This fiber then makes a synapse on the ganglionic neuron that project to the target effector.
Target effector
The first type of "junction" in the circuit analogy of the sympathetic nervous system is most direct: the sympathetic nerve projects to the chain ganglion at the same level as the t_______ e__________ (the organ, tissue, or gland to be innervated). An example of this type is spinal nerve T1 that synapses with the T1 chain ganglion to innervate the trachea.
Gray rami communicantes
The g_____ r________ c_____________ are unmyelinated sympathetic postganglionic motor fibers.
Hypothalamus
The h________________ is the control center for many homeostatic mechanisms. * It regulates both autonomic function and endocrine function. * The role it plays in the pupillary reflexes demonstrates the importance of this control center. The optic nerve projects primarily to the thalamus, which is the necessary relay to the occipital cortex for conscious visual perception. Another projection of the optic nerve, however, goes here.
Hypothalamus
The h_________________, along with other CNS locations, controls the autonomic system. It receives input from cerebral structures and projects to brain stem and spinal cord structures to regulate the balance of sympathetic and parasympathetic input to the organ systems of the body.
Slowed, constriction
The heart rate is s__________ by the autonomic system at rest, whereas blood vessels retain a slight c________________ at rest.
Descending
The higher centers of the brain have [ascending or descending?] control of the autonomic system through *brain stem centers*, primarily in the medulla, such as the cardiovascular center.
Medial forebrain bundle
The hypothalamus receives input other areas of the forebrain through the m________ f___________ b_________. The olfactory cortex, the septal nuclei of the basal forebrain and the amygdala project into the hypothalamus through this tract. These *forebrain structures* inform the hypothalamus about the state of the nervous system and can influence the regulatory processes of homeostasis.
Parasympathetic, sympathetic
The hypothalamus then uses this visual system input to drive the pupillary reflexes. 1. If the retina is activated by high levels of light, the hypothalamus stimulates the [sympathetic or parasympathetic] response. 2. If the optic nerve message shows that low levels of light are falling on the retina, the hypothalamus activates the [sympathetic or parasympathetic] response.
Inferior mesenteric ganglion
The i___________ m_______________ g__________ innervates terminal portions of large intestine, the kidney, urinary bladder, and sex organs. [1/3 collateral ganglia]
Intrinsically
The influence that the autonomic system has on the heart is not the same as for other systems. Other organs have smooth muscle or glandular tissue that is activated or inhibited by the autonomic system. Cardiac muscle is i____________ active and is modulated by the autonomic system
Output
The key to understanding the ANS is to explore the response pathways, as the ANS is the o_______ of the nervous system.
Medial forebrain bundle
The m________ f_________ b________ is part of the hypothalamic output and connects the hypothalamus with higher centers of the limbic system where emotion can influence visceral responses.
Sympathetic chain ganglia
The majority of ganglia of the sympathetic system belong to a network of s______________ c______ ganglia that runs alongside the vertebral column. The ganglia appear as a series of clusters of neurons linked by axonal bridges. There are typically 23 ganglia in the chain on either side of the spinal column. * 3 for cervical region, 12 thoracic region, 4 lumbar region, 4 sacral region. * The cervical and sacral levels are not connected to the spinal cord directly through the spinal roots, but through ascending or descending connections through the bridges within the chain.
Hypothalamic output
The majority of h_______________ o________ travels through the medial forebrain bundle and the dorsal longitudinal fasciculus to influence brain stem and spinal components of the ANS.
Parasympathetic
Without [sympathetic or parasympathetic] input, the heart would would work at a rate of over 100 beats per minute (bpm). This input hyperpolarizes heart cells to not reach threshold as easily.
Cardiovascular center
The medulla contains nuclei referred to as the c___________________ c_______ which controls the smooth and cardiac muscle of the cardiovascular system through autonomic connections. * When the homeostasis of the "circulatory" system shifts, like when blood pressure changes, the coordination of the autonomic system can be accomplished within this region. * Furthermore, when descending inputs from the hypothalamus stimulate this area, the sympathetic system can increase activity in the circulatory system, such as in response to anxiety or stress.
Exogenous
The molecules defining nicotinic and muscarinic receptors are not crucial (they are simply tools for researchers to use in the laboratory). These molecules are e_________, meaning that they are made outside of the human body, so a researcher can use them without any confounding endogenous results (results caused by the molecules produced in the body).
Visceral, somatosensory
The most broadly accepted theory for the phenomenon of *referred pain* is that the v_________ sensory fibers enter into the same level of the spinal cord as the s____________________ fibers of the referred pain location. Ex: The sensory fibers of the organs from the mediastinal region, where the heart is located, would enter the spinal cord at the same level as the spinal nerves from the shoulder and arm, so the brain misinterprets the sensations from the mediastinal region as being from the axillary and brachial regions.
Nucleus ambiguus
The n_________ a__________ (named for its ambiguous histology), also contributes to the parasympathetic output of the vagus nerve and targets muscles in the pharynx and larynx for swallowing and speech, as well as contributing to the parasympathetic tone of the heart along with the dorsal motor nucleus of the vagus.
SNS, ANS
The nervous system can be divided into two functional parts: The somatic nervous system (SNS) and the ANS. The major differences between the two systems are evident in the responses that each produces. * The _ _ _ causes contraction of skeletal muscles. * The _ _ _ controls cardiac and smooth muscle, as well as glandular tissue.
Vagus
The nucleus ambiguus and the dorsal motor nucleus both contribute fibers to the [WHICH cranial nerve?]. This nerve then exerts parasympathetic control of the heart by decreasing heart rate.
Afferent branch
The other part of a reflex, the a_________ branch, is often the same between the two systems. Sensory neurons receiving input from the periphery (with cell bodies in the sensory ganglia, either of a cranial nerve or a dorsal root ganglion adjacent to the spinal cord) project into the CNS to initiate the reflex.
Lower motor
The output of a somatic reflex is the l_______ m_______ neuron in the ventral horn of the spinal cord that projects directly to a skeletal muscle to cause its contraction.
Preganglionic, cranial nucleus, ganglion
The output of a visceral reflex is a two-step pathway starting with the p_________________ fiber emerging from a lateral horn neuron in the spinal cord, or a c_________ n_________ neuron in the brain stem, to a g__________ (followed by the postganglionic fiber projecting to a target effector).
Parasympathetic
The p_____________________ division of the ANS is named because its central neurons are located on either side of the thoracolumbar region of the spinal cord.
Terminal ganglionic
The parasympathetic output is based in the brain stem and sacral spinal cord. Neurons from particular nuclei in the brain stem or from the lateral horn of the sacral spinal cord (preganglionic neurons) project to t_________ *(aka intramural)* ganglia located close to or within the wall of target effectors. These preganglionic fibers also release ACh onto nicotinic receptors to excite the g_________ neurons. The postganglionic fibers then contact target tissues w/in organ to release ACh, which binds to muscarinic receptors to induce *rest-and-digest responses.*
Craniosacral outflow
The parasympathetic system can also be referred to as the c________________ o_______ because the preganglionic neurons are located in nuclei of the brain stem and the lateral horn of the sacral spinal cord.
Muscarinic
The postganglionic connections to sweat glands in the skin and blood vessels supplying skeletal muscle are exceptions; those fibers release ACh onto m__________ receptors. [Stimulate smooth muscle and slow the heart rate]
Vagus nerve
The postganglionic fibers from the ganglia activated by the v_______ n_______ are often incorporated into the structure of the organ, such as the mesenteric plexus of the digestive tract organs and the intramural ganglia.
Neurotransmitters
The postganglionic fibers of the sympathetic and parasympathetic divisions both release n_______________________ that bind to receptors on their targets.
Short
The postganglionic parasympathetic fiber projects from the terminal ganglia a [long or short?] distance to the target effector, or to the specific target tissue within the organ.
Vasomotor nerves
The preganglionic sympathetic fibers responsible for constricting blood vessels compose the v_____________ n_________.
Organ systems
The role of visceral reflexes is to maintain a balance of function in the o_______ s___________ of the body. The two divisions of the autonomic system each play a role in effecting change, usually in competing directions.
Stress
The s_______ system, when activated by catecholamines of the adrenal medulla entering blood, increases heart rate, coverts glycogen to glucose [glycogenolysis] in the liver, decreases digestive system activity, raises blood pressure, and dilates bronchioles.
Solitary
The s_________ nucleus increases sympathetic tone of the cardiovascular system through the cardiac accelerator and vasomotor nerves.
Sensory homunculus
The s____________ h___________ is the representation of the body in the primary somatosensory cortexrepresentation of the body in the primary somatosensory cortex. It only has a small region allotted for the perception of internal stimuli.
Neurotransmitters, hormones
The signaling molecules utilized by the ANS are released from axons and can be considered as either n_____________ (when they directly interact with the *effector*) or as h__________ (when they are released into the bloodstream). The same molecule, such as norepinephrine, could be considered one or the other on the basis of whether it is released from: * A postganglionic sympathetic axon * The adrenal gland.
Varicosity
The structure of postganglionic connections are not the typical synaptic end bulb that is found at the neuromuscular junction, but rather are chains of swellings along the length of a postganglionic fiber called a v__________. Autonomic structures. Neurotransmitter is released from swellings along the length of a fiber that makes an extended network of connections in the target effector.
Thoracolumbar system
The sympathetic division of the ANS influences the various organ systems of the body through connections emerging from the thoracic and upper lumbar spinal cord. Thus, it is referred to as the t____________________ system to reflect this anatomical basis.
Bloodstream
The sympathetic system has a specialized preganglionic connection to the adrenal medulla that causes epinephrine and norepinephrine to be released into the b__________ rather than exciting a neuron that contacts an *organ* directly. This hormonal component means that the sympathetic chemical signal can spread throughout the body very quickly and affect many organ systems at once!
Sympathomimetic
The sympathetic system is affected by drugs that mimic the actions of *adrenergic molecules*, norepinephrine and epinephrine. Called s_______________________ drugs. Ex: Drugs like phenylephrine bind to adrenergic receptors and stimulate target organs.
2
The way we respond to the world around us, to manage the internal environment on the basis of the external environment, is divided between _ divisions of the ANS.
Celiac
The word c______ is derived from the Latin word "coelom," which refers to a body cavity (in this case, the abdominal cavity). [One of the 3 collateral ganglia]
2
There are _ [how many?] tracts that connect the hypothalamus with the major parasympathetic nuclei in the brain stem and the preganglionic (central) neurons of the thoracolumbar spinal cord.
3
There are _ collateral ganglia.
Myenteric plexuses
There are a few m_________ p_________ in which the nervous tissue in the wall of the digestive tract organs can directly influence digestive function. [ENS]
Dilate
There are a limited number of blood vessels that respond to sympathetic input in a different fashion. Blood vessels in skeletal muscle, particularly those in the lower limbs, are more likely to d______. It does not have an overall effect on blood pressure to alter the tone of the vessels, but rather allows for blood flow to increase for those skeletal muscles that will be active in the fight-or-flight response.
Ganglion
There are the axons from central sympathetic neurons that project to the adrenal medulla, the interior portion of the adrenal gland. These axons are still referred to as *preganglionic* fibers, but the target is not a g___________. The adrenal medulla releases signaling molecules into the bloodstream, rather than using axons to communicate with target structures.
Cardiovascular
There is a collection of medullary nuclei that regulate heart function and blood pressure, called the c_______________ center. Sensory input from the heart, aorta, and carotid sinuses projects to these regions of the medulla.
Ganglia
To coordinate all these responses, the connections in the sympathetic system diverge from a limited region of the CNS to a wide array of g_________ that project *to* the many effector organs simultaneously. The complex set of structures that compose the output of the sympathetic system make it possible for these disparate effectors to come together in a coordinated, systemic change
True
True or false: Because there are so many branches of the sympathetic division of the ANS, these branches mean that one preganglionic neuron can influence different regions of the sympathetic system very broadly, by acting on widely distributed organs.
False
True or false: Drugs other than nicotine can usually affect both divisions of the ANS. [Both parasympathetic and sympathetic]
True
True or false: In some cases, the target effectors are located superior or inferior to the spinal segment at which the preganglionic fiber emerges. With respect to the "wiring" involved, the synapse with the ganglionic neuron occurs at chain ganglia superior or inferior to the location of the central neuron. Ex: The spinal nerve T1 that innervates the eye. The spinal nerve tracks up through the chain until it reaches the superior cervical ganglion, where it synapses with the postganglionic neuron.
True
True or false: In the ANS, there is the possibility that the CNS is not involved.
True
True or false: In the sympathetic system, there are exceptions to this pattern of dual innervation. The postganglionic sympathetic fibers that contact the blood vessels within skeletal muscle and that contact sweat glands do not release norepinephrine, they release ACh.
False
True or false: It is problematic that the postganglionic sympathetic fibers that contact the blood vessels within skeletal muscle and that contact sweat glands do not release norepinephrine, they release ACh. This is because of the parasympathetic input to the sweat glands.
True
True or false: It is problematic to describe the projection from a sympathetic ganglion to a target as the "postganglionic neuron" because the cell body is also part of that "postganglionic" neuron. Typically, the term neuron applies to the entire cell.
False
True or false: Muscarine can bind to nicotinic receptors and nicotine can bind to muscarinic receptors. There is cross-reactivity between the receptors.
True
True or false: Nicotine stimulates both sympathetic and parasympathetic ganglia at the preganglionic fiber synapse.
True
True or false: Tear production is influenced by parasympathetic fibers in the facial nerve, which activate a ganglion, and ultimately the lacrimal (tear) gland.
True
True or false: The feeling of swallowing a large bolus of food that passes through your esophagus or distends your stomach, or the inhalation of especially cold air touching your larynx and trachea, are not the same sensations as high blood pressure or sugar levels.
False
True or false: The location of referred pain is random, as a definitive explanation of the mechanism has not been established.
True
True or false: The postganglionic parasympathetic fibers also release ACh, but the receptors on their targets are muscarinic receptors, which are G protein-coupled receptors and do not exclusively cause depolarization of the postsynaptic membrane.
True
True or false: There are reflexes that do not need to involve any CNS components.
False
True or false: When light hits the retina in one eye, only the pupil of that one eye contracts. When that light is removed, the pupil dilates again back to the resting position.
Neuroeffector junctions, neuromodulators
What are referred to here as synapses may not fit the strictest definition of synapse. Some sources will refer to the connection between a postganglionic fiber and a target effector as n_________________ j____________. Neurotransmitters, as defined above, would be called n_________________.
Unilateral
When a stimulus if u_____________, meaning it is presented to only one eye, the response is still *bilateral* (meaning both eyes). The same is not true for somatic reflexes. If you touch a hot radiator, you only pull that arm back, not both.
Referred pain
When particularly strong visceral sensations rise to the level of conscious perception, the sensations are often felt in unexpected places. For example, strong visceral sensations of the heart will be felt as pain in the left shoulder and left arm. This irregular pattern of projection of conscious perception of visceral sensations is called r__________ p________. Depending on the organ system affected, it will project to different areas of the body.
Amygdala
When you are anxious or scared, the a____________ will send signals to the hypothalamus along the medial forebrain bundle that will stimulate the sympathetic fight-or-flight response. The hypothalamus will also stimulate the release of stress hormones through its control of the endocrine system in response to input from this structure.
Synapse
Where an autonomic neuron connects with a target, there is a s_________. The electrical signal of the action potential causes the release of a signaling molecule, which will bind to receptor proteins on the target cell. They can be cholinergic or adrenergic in the ANS.
Muscarinic
Which ACh receptor, [nicotinic or muscarinic?] is a G protein-coupled receptor.
Nictonic
Which ACh receptor, [nicotinic or muscarinic?] is a ligand-gated cation channel.
Threat
You can respond to a t______ by the sympathetic nervous system actions of "fight" or "flight." Causes divergent effects as many different effector organs activated together for common purpose. * More oxygen needs to be inhaled and delivered to skeletal muscle. * Respiratory, cardiovascular, and musculoskeletal systems are all activated together. * Sweating keeps the excess heat that comes from muscle contraction from causing the body to overheat. * The digestive system shuts down so that blood is not absorbing nutrients when it should be delivering oxygen to skeletal muscles.
Circuit
this diagram that shows the connections of the sympathetic system is somewhat like a c_______ diagram that shows the electrical connections between different receptacles and devices. The "paths" of the sympathetic system are intentionally simplified.
