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91 Cards in this Set

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What is the general role of the ANS?
Maintain homeostasis
What do cortical autonomic centers control in the ANS?
Initiating autonomic responses to emotion and pain
What is the role of brainstem centers in the ANS?
Receive visceral information, generate outputs through peripheral autonomic nerves
What are the roles of the hypothalamus in the ANS?
Control circadian rhythm, temperature regulation, hunger/thirst, serves as a relay center for all sympathetic autonomic information descending to the body
What are the 4 components of the ANS?
1. Neurohumoral
2. Intrinsic enteric
3. Sympathetic
4. Parasympathetic
What does the Nuerohumoral part of the ANS consist of and regulate?
Consists of hormones which regulate energy metabolism (pituitary-adrenal), blood volume (angiotensin), and other functions
What is the intrinsic enteric nervous system?

What does it regulate?
Interconnected neurons in the wall of the bowel from the esophagus to the anus

Regulates bowel motility, secretion, etc. --> bowel independent of extrinsic input
What are 5 characteristic sympathetic responses?
1. Pupils dilate
2. Muscle vasculature dilates
3. Heart rate and bp increases
4. Sweating
5. Digestive system put on hold
What are 4 situations in which the sympathetic system is activated?
1. emotional stress
2. exercise
3. dehydration
4. disease states
What are 4 characteristics of the parasympathetic system?
1. Pupils constrict
2. Heart rate slows
3. Secretion and digestion are stimulated (gut and salivary glands)
4. Bladder emptying and sexual function
Where do the preganglionic sympathetic neurons lie in the spinal cord?
Intermediolateral cell column of thoracic and upper lumbar cord (T1-L3)
Where do autonomic motor neurons sit in the spinal column, and how does this compare with where they exit the column?
Sit posterior and lateral to the anterior horn cells

Exit in the anterior root along with the somatic motor fibers
What is the pathway of sympathetic innervation to the head?
Myelinated preganglionic sympathetic axons ascend via white ramus --> paravertebral sympathetic chain --> sympathetic chain ganglia (superior cervical ganglia) --> head
What is Horner's syndrome?
Damage to the ascending sympathetic chain --> small pupil, loss of sweating, ptosis on one side of face
What do sympathetic fibers innervate in the head?

What happens in Horner's syndrome?
Innervate superior tarsal muscle --> open eyes wide in fight or flight

In Horner's, lose the innervation --> ptosis
What are 4 misplaced sympathetic ganglia (not in spine)?
Celiac
Superior mesenteric
Inferior mesenteric
Adrenal medulla
What are 3 unpaired prevertebral sympathetic ganglia? What do they do?
Celicac
Superior mesenteric
Inferior Mesenteric

Innervate the bowel and bladder
Adrenal chromaffin cells...
a. input?
b. output?
a. Preganglionic sympathetic fibers
b. Epinepherine into circulation
What are 2 similarities between autonomic and somatic motor nerves?

1 difference?
Both are cholinergic, both send axons out via the anterior spinal roots

Autonomics synapse outside the spinal cord in the autonomic ganglia before going to targets
What NT is used at the synapse in the sympathetic ganglia?

What type of receptor does the sympathetic ganglion neuron use
Ach

Ach receptor, nicotinic
What occurs to the signal between the sympathetic preganglionic nerve and the ganglionic neuron?
Signal integration (many inputs per ganglionic neuron)

Amplification (one input goes to many ganglionic neurons)
What types of fibers do Sympathetic ganglionic neurons send out to target organs?
Unmyelinated postganglionic fibers to target organs
Besides target organs, where might sympathetic postganglionic axons of the ANS go?
May rejoin spinal roots via gray (unmyelinated) communicating ramus
What NT fibers do sympathetic (postganglionic) fibers release at their target organs? What receptors are there?

What is one exception?
Release of NE to adrenergic receptors

Sympathetic fibers that innervate sweat glands release Ach
From where do preganglionic parasympathetic neurons arise?
Brainstem or sacral spinal cord
How do cranial parasympathetics travel?
Via CN 3, 7, 9, and 10
What is the function of the Vagus nerve?
Autonomic input to most of the viscera of the body (neck to distal 1/3 colon)
Where do sacral autonomic neurons sit in the spinal section?

What do they innervate?
Intermediolateral cell column

Innvervate the rectum, bladder, and reproductive organs
How does the placement of parasympathatic ganglia differ from sympathetic ganglia?
Parasympathetic ganglia are found very close to the target organ
How do preganglionic parasympathetic axons travel in comparison to their sympathetic counterparts?
Travel much further before synapsing with ganglia
What NT is used at parasympathetic ganglia?

What NT is released by postganglionic fibers and what type of receptors do target organs have?
Ach

Ach --> Ach muscarinic receptors (target organs)
What do all autonomic ganglia use as a NT?
Ach
What do postganglionic nerves release? (sympathetic/parasympathetic/exceptions)
Parasymp. = Ach

Sympathetic = NE

Exception = sympathetic fibers innervating sweat glands, piloerector muscles, and some blood vessels release Ach
What are 4 nuceli of the parasympathetic system?
Edinger Westphal
Salivatory
Dorsal Nucleus of X
Nucleus ambiguus
What does the EW nucleus send out?
Axons w/ CN 3 --> pupil constriction, lens accomodation
Where do axons from the salivatory nuclei go?
Salivary glands via CN 7 and 9
What fibers come from the dorsal nucleus of X?

What do they stimulate (3)?
Give rise to secretomotor fibers of the Vagus

Stimulate:
1. Gastric secretion
2. Gut motility
3. Respiratory secretions
Where do axons from the Nucleus ambiguus go?

What do they do? (2)
Via vagus --> heart, lungs, pharynx

1. Decrease heart rate
2. Bronchial constriction
Where do cells of the sympathetic system reside?
Intermediolateral column of T1-L3
What are 3 notable sympathetic ganglia?
Superior cervical
Celiac and mesenteric
Sympathetic chain
What does the superior cervical ganglion supply?

Functions (3)?
Supplies sympathetics to the head

1. pupillary dilation
2. facial sweating
3. elevation of the eyelid
What do the celiac and mesenteric ganglia supply?

Functions (2)?
Gut

1. Vasoconstriction
2. Inhibition of secretions
What does the sympathetic chain ganglia supply?

Functions (5)?
Thorax and periphery

1. Increase heart rate
2. Dilate bronchi
3. Selectively vasoconstrict
4. Vasodilate in active muscles
5. Stimulate sweating
What is the pathway for parasympathetic afferents?
Internal organs --> vagus --> nodose ganglion --> solitary tract (medulla) --> nucleus of solitary tract
What kind of information does the nucleus of the solitary tract receive?
Blood pressure, CO2 levels, gut distention
How do sympathetic afferents re-enter the spinal cord?

What is the effect of this?
Re-enter the dorsal horn along with sensory afferents from the skin

As a result, visceral pain is often perceived as originating from body surface (referred pain)
Heart
a. Parasympathetic
b. Sympathetic
a. Decrease heart rate, CO decreases
b. Increase heart rate, CO increases
Lung bronchioles
a. Parasympathetic
b. Sympathetic
a. constrict
b. dilate
LIver glycogen
a. Parasympathetic
b. Sympathetic
a. No effect
b. Glycogen breakdown, blood glucose increase
Basal metobolism
a. Parasympathetic
b. Sympathetic
a. No effect
b. Increases 2x
Fat tissue
a. Parasympathetic
b. Sympathetic
a. No effect
b. Breakdown of fat, blood FAs increase
Stomach
a. Parasympathetic
b. Sympathetic
a. Increased secretion of HCl and digestive enzymes, increased motility
b. Decreased secretion and motility
Intenstine
a. Parasympathetic
b. Sympathetic
a. increased secretion and motility
b. decreased secretion and motility
Urinary bladder
a. Parasympathetic
b. Sympathetic
a. Relaxes sphincter, detrusor contracts, urination promoted
b. Constricts sphincter, relaxes detrusor, urination inhibited
Rectum
a. Parasympathetic
b. Sympathetic
a. Relaxes sphincter, contracts wall muscles, defecation promoted
b. Constricts sphincter, relaxes wall muscles, defecation inhibited
Eye
a. Parasympathetic
b. Sympathetic
a. Iris constricts, adjust for near vision
b. Iris dilates, adjust for far vision
Male sex organ
a. Parasympathetic
b. Sympathetic
a. promote erection
b. promote ejaculation
What would be the effect of an impairment of both sympathetic and parasympathetic systems?
Person would be unable to respond to changes in activity or environment
What is the effect of high spinal cord injury (above T2)?

What remains, and what effect does it have?
Loss of entire sympathetic outflow, sacral parasympathetic function

Excess in vagus parasympathetic function --> bradycardia
What would be effected by a lesion to the conus medullaris?
Sacral parasympathetics
How is ANS tone maintained?
Parsympathetic reflexes
What is a simple reflex of the ANS?
Local axon reflex where the sensory afferent (nociceptor) sends a collateral axon to dilate local blood vessels at the site of injury
What are 3 examples of coordination in the autonomic ganglia?
1. Paravertebral chain ganglia connected --> fire concertedly in fight or flight
2. Prevertebral ganglia and intrinsic plexuses in gut are reflex centers for GI tract in digestion
3. In physical activity, sympathetic activity increases --> decreased motility in gut, vasoconstriction
What are three activities coordinated by the lumbar and sacral spinal cord?
Micturition, defecation, sexual reflexes
What are some events coordinated in the hypothalamus?
Temp regulation, homeostasis of bp, limbic system, etc.
What is the pathway of the baroreceptor reflex?
Increase in bp --> carotid baroreceptor sends signal to nucleus of solitary tract --> signal sent to nucleus ambiguus --> signal to heart --> Ach released --> slows down heart rate
What do inhibitory interneurons do in the baroreceptor reflex?
High bp -> inhibitory interneurons project to sympathetics in thoracic cord (descending sympathetics) --> inhibits their tonic firing --> bp drops, heart slows
What is a respiratory sinus arrhythmia?
Fluctuations in heart rate caused by baroreflex response to changes in intrathoracic pressure when breathing
What is vasovagal syncope?
When increasing pressure on carotid sinus (straining to lift something for example) --> baroreceptor response --> decrease in bp and heart rate --> fainting
What is the pathway of pupillary light reflexes?
Retina --> pretectal nuclei (which also receive input from contralateral pretectal nuclei via posterior commissure) --> ipsilat and contralat. EW nucleus --> ciliary muscle
What causes the consensual light reflex?
Bilateral connection of the pretectal nucleus to both EW nuclei of CN 3
What does the descending reticular formation control?

Ascending?
muscular tone

Arousal (sleep-wake)
What is affected by the rostral/lateral reticular formation?
Pressor - accelerates heart rate, increases heart contractions, increases peripheral resistance

Also expirations
What is affected by the medial and caudal reticular formation?
Depressor area - decreases heart rate, etc.

Also an inspiratory center
What is the pathway for the respiratory reflex?
Afferents --> nucleus solitarius and medullary reticular formation by CN X --> ventral horn of cervical spinal cord (C3-C5) --> motoneurons that supply axons to phrenic
What 2 factors does ventilation depend on?
Respiratory rate
Tidal volume
What do pulmonary stretch receptors sense and how do they participate in respiratory reflexes?
Sense degree of lung inflation--> CNX --> solitary nucleus --> inhibits inspiratory center, breathing rate and tidal volume (w/ pneumotaxic center)
What do chemoreceptors sense and how do they participate in respiratory reflexes?
owered oxygen, increased CO2, acidosis --> sensed by chemoreceptors in carotid and aortic bodies --> vagus --> excitatory to respiration centers

Also stimulated by hypotension
How does pain affect respiratory reflexes?

What if pain pathways are interrupted?
Pain --> induces arousal response, respiratory stimulation

Can cause hypoventilation, which, when added to lack of tonic arousal signal, may lead to complete apnea in sleep
How does irritation of the mucous membranes of the nose/respiratory passages lead to respiratory reflexes?
Irritation in nose --> CN 1 and 5 --> sneezing (increased respiration)

Irritation in respiratory passages --> CN 9 and 10 --> coughing
How do joint and muscle afferents participate in respiratory reflexes?
Respiratory excitation in exercise
Why can you consciously control your respiration rate?
Pressor and depressor areas played upon by many cerebral cortical areas
What is the effect of a bilateral diencephalon lesion or deep cerebral hemisphere lesion?
Cheyne-Stokes breathing -- hyperpnea (deep breathing) alternating with apnea
What is the affect of lesions to midbrain or rostral pons?
Sustained, rapid panting (polypnea)
What is the effect of lesions to the lower pontine tegmentum?
apneustic breathing (prolonged, end-inspiratory pauses occur)
What is the effect of lesions to the dorsal tegmentum of the medulla?
Ataxic breathing, irregular pauses and shallow breaths
What is the effect of large medullary lesions?
Complete cessation of all respiratory function
What 3 stimuli can elicit the vomiting response?
Excessive vestibular stimulation (CN 8)

Stimulation of receptors in pharynx (CN 9 and 10)

Activation by chemical agents in CTZ
Vomiting control region
a. input
b. output
a. CTZ, nucleus solitarius
b. CN 10 --> relax gastroesophageal sphincter, contract abdominals
What are some expected problems if deficit to sympathetic nervous system? (4)
Horner's Syndrome
Orthostatic Hypertension
Exercise intolerance
Heat intolerance - failure to sweat
What are some expected problems if deficit to parasympathetic nervous system? (3)
1. Dry mouth/dry eyes
2. Sexual impairment (erectile dysfunction)
3. Fixed pupils - unable to accomodate