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Physiology Exam 1, Lecture 7-9: Autonomic Nervous System
Cell Physiology
118
Physiology
Graduate
08/29/2011

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Term
What are clusters of cell bodies in the CNS called?
Definition
Nuclei
Term
What are groups of axons in the CNS called?
Definition
Pathways, tracts, or commissures
Term
What are clusters of cell bodies in the PNS called?
Definition
Ganglia
Term
What are groups of axons in the PNS called?
Definition
Nerves
Term
Define vertebral column
Definition
Bone that surrounds the spinal cord
Term
What is a spinal tap?
Definition
A procedure to sample the CSF for diagnosis
Term
What is the function of gray matter?
Definition
Synaptic transmission and neural integration
Term
What is the function of white matter?
Definition
Propagate action potentials, it is white because of myelin
Term
Define subcortical nuclei
Definition
Small areas of gray matter within white matter
Term
How many spinal nerves are there?
Definition
31
Term
What is the cauda equina?
Definition
The bottom 1/3 of the column, individual nerves but no spinal cord bone surrounding them
Term
Which horn of the spinal cord is posterior?
Definition
Dorsal
Term
Which horn of the spinal cord is anterior?
Definition
Ventral horn
Term
What type of cell bodies are in the dorsal horn?
Definition
Interneurons on which afferent neurons terminate
Term
What type of cell bodies are in the lateral horn?
Definition
Autonomic efferent nerve fibers
Term
What type of cell bodies are in the ventral horn?
Definition
Somatic efferent neurons
Term
What are dorsal roots?
Definition
Bundles containing afferent neurons
Term
What are ventral roots?
Definition
Bundles containing efferent neurons
Term
Where do autonomic preganglions of the sympathetic nervous system originate?
Definition
The thoracic and lumbar positions of the spinal cord (T1-L3)
Term
What part of the spinal cord do preganglionic neurons originate?
Definition
Lateral horn
Term
What is another name for preganglionic neurons of the sympathetic nervous system?
Definition
The thoracolumbar sympathetic nerves
Term
Where do preganglionic neurons of the parasympathetic nervous system originate?
Definition
The brainstem or sacral spinal cord
Term
What is another name for the preganglionic neurons of the parasympathetic nervous system?
Definition
Craniosacral parasympathetic nerves
Term
What can the adrenal medulla be called?
Definition
A sympathetic effector
Term
What kind of receptors are on chromaffin cells?
Definition
Nicotinic cholinergic
Term
What is the effect of Ach binding to nicotinic cholinergic receptors on chromaffin cells?
Definition
Production of 80% epinephrine, 20% norepinephrie
Term
What effects does epinephrine have when released from the adrenal medulla?
Definition
It acts as a hormone, diffuses into the bloodstream, and increases blood glucose
Term
What neurotransmitter is released from all preganglionic neurons of the autonomic nervous system?
Definition
Ach
Term
What kind of receptor is on postganglionic neurons in the autonomic nervous system?
Definition
Nicotinic cholinergic
Term
What neurotransmitter is released primarily from parasympathetic postganglionic neurons?
Definition
Ach
Term
What kind of receptor is on parasympathetic effectors?
Definition
Muscarinic cholinergic
Term
What neurotransmitter is released from sympathetic postganglionic neurons?
Definition
Norepinephrine
Term
What kind of receptors do sympathetic effectors have?
Definition
Adrenergic
Term
Where do motor neurons originate?
Definition
The ventral horn of the spinal cord or the analogous brainstem nuclei
Term
What is the neurotransmitter for the neuromuscular junction?
Definition
Acetylcholine
Term
What kind of receptors are on the motor end plate?
Definition
Nicotinic cholinergic
Term
What can the PNS be divided into?
Definition
Somatic and Autonomic
Term
What can the autonomic nervous system be divided into?
Definition
Sympathetic and parasympathetic

Also, enteric (digestive system)
Term
Define sympathetic nervous system
Definition
Autonomic flight or fight response, expends energy
Term
Define the parasympathetic nervous system
Definition
Autonomic system for rest, digest, divest(eliminating), conserve/replenish energy
Term
How many neurons does the somatic nervous system have in a single pathway? How many does the autonomic?
Definition
1, 2
Term
What kind of receptor is on the effector in the somatic nervous system? For the autonomic nervous system?
Definition
Somatic: nicotinic

Autonomic: Muscarinic, adernergic
Term
Do preganglionic nerves have myelin? Do postganglionic?
Definition
Pre-ganglionic nerves do, post-ganglionic do not
Term
Compare and contrast sympathetic vs parasympathetic postganglionic nerves
Definition
Parasympathetic are very short, often on the organ

Sympathetic are longer

Both are unmyelinated
Term
Define intermediolateral nucleus
Definition
Small protrusion of gray matter in the spinal cord where preganglionic sympathetic neurons originate
Term
Define paravertebral ganglia and prevertebral ganglia
Definition
Paravetebral ganglia are higher up on the spinal cord

Prevertebral ganglia are lower on spinal cord

Both are where sympathetic ganglia originate from the chain
Term
What is the effect of nicotine on skeletal muscle?
Definition
A low dose contracts muscle, a high dose blocks
Term
Give an example of a nicotinic antagonist at the neuromuscular junction
Definition
Curare
Term
Give an example of a nicotinic antagonist at the autonomic ganglia
Definition
Trimethphan (Arfondad)
Term
Describe the drug Trimethphan (Arfondad)
Definition
A nicotinic antagonist at the autonomic ganglia

Previously used to lower emergency HBP, but not anymore because it removes the autonomic nervous sytem
Term
Give an example of an antagonist for muscarinic cholinergic receptors
Definition
Atropine
Term
What is the effect of atropine?
Definition
As an antagonist for muscarinic cholinergic receptors, it blocks the parasympathetic nervous system
Term
What is the primary neurotransmitter for sympathetic postganglionic neurons?
Definition
Norepinephrine
Term
What releases epinephrine?
Definition
The adrenal medulla, NOT sympathetic postganglionic nerves
Term
By what method does most NE deactivate?
Definition
Reuptake
Term
Do the sympathetic and parasympathetic nervous systems both have adrenergic and cholinergic receptors?
Definition
Adernergic are just in sympathetic,
cholinergic are in both
Term
Give an example of an Adrenergic α receptor agonist and describe it
Definition
Phenylephrine (Neosynephrine), the active ingredient in many decongestants
Term
Give an example of an Adrenergic α receptor antagonist
Definition
Phentolamine (Regitine)
Term
Give an example of an Adrenergic β receptor agonist and describe it
Definition
Isoproterenol (Isuprel), a drug not used too much because it stimulates all of the Beta receptors
Term
Give an example of an Adrenergic β receptor antagonist and describe it
Definition
Propanolol (Inderal), blocks β1 and β2
Term
Do α receptors produce excitatory or inhibitory responses?
Definition
α receptors produce excitatory effects everywhere except in GI, where they produce inhibitory effects
Term
Define α-2 receptors
Definition
α-2s are on presynaptic terminals and act as a negative feedback system

However, they are still on effector organs and tissues and have the same responses as α-1s
Term
Do β receptors produce excitatory or inhibitory responses?
Definition
β receptors produce inhibitory effects everywhere except in the heart, where they produce excitatory effects
Term
Where are β1 receptors?
Definition
Only on the heart, and therefore the only excitatory β receptors
Term
Where are β2 receptors found?
Definition
All over the body, they are the β receptors that produce inhibitory effects
Term
Where are β3 receptors found?
Definition
In fat, do lipolysis (we don't need to worry about those)
Term
Does NE excite or inhibit adrenergic receptors?
Definition
NE excites all α receptors and β1 receptors
Term
Does Epi excite or inhibit adrenergic receptors?
Definition
Epi excites all adrenergic receptors, but has a greater potency for β over α
Term
Describe α-1 receptors
Definition
The primary receptor on effector organs and tissues mediating alpha-aderenergic responses

(α-2 are for feedback on preganglion terminals, but are still on effector organs)
Term
Define dual innervation
Definition
Organs which receive innervation from both
the sympathetic and parasympathetic systems have dual innervation
Term
Define single innervation
Definition
When tissues receive innervation from only one autonomic system, such as the blood vessels that control peripheral resistance which receive only sympathetic innervation
Term
Define functional synergism
Definition
Functional synergism: This occurs in dual innervated organs when the sympathetic and parasympathetic systems work together to produce an effect. A good example is the control of heart rate.
Term
Define intrinsic heart rate
Definition
Once atropine and propanolol are given to the heart, no autonomic influence, just pacemaker rate
Term
If a heart was transplanted and did not have nerve endings, could HR still be raised?
Definition
Yes, by epinephrine from the chromaffin cells
Term
Define tonic/basal efferent activity
Definition

A continuous resting level of autonomic neural activity to an organ or tissue. This means that there is almost always some autonomic nerve activity from both the SNS and PNS under all types of conditions

Term
Define mydriasis
Definition
Contraction of the pupil radial muscle
Term
Define miosis
Definition
Contraction of the pupil circular muscle

Also, a symptom of Horner's syndrome, due to unopposed parasympathetic innervation to the iris.
Term
Is pupil dilation an excitatory or inhibitory response?
Definition
Inhibitory by definition- the pupil is overall relaxing and expanding in size; anologus to an arteriole, for example
Term
Describe autonomic control of blood vessels
Definition
Sympathetic innervation constricts with α-1 and α-2 and dilates with β-2 to direct blood flow to areas needed

No parasympathetic innervation
Term
In arterioles, how does the sympathetic nervous system distinguish between α-1 and α-2 (dilating) and β-2 (constricting) during a response?
Definition
β-receptors are more strongly stimulated by Epi than α, so there is a contest
Term
What is the most prominent inhibitory sympathetic response?
Definition
β-2 dilation in the lungs
Term
What do inhalers act on in asthmatics?
Definition
β-2 receptors in the lungs
Term
What sympathetic receptors decrease motility in the GI tract?
Definition
α1, α2, β2
Term
In the male reproductive tract, what does the parasympathetic system control and what does the sympathetic system control?
Definition
Parasympathetic: erection

Sympathetic: ejaculation
Term
What is the major exception of the sympathetic effector receptor?
Definition
Eccrine sweat glands have muscarinic receptors for thermoregulation, and therefore respond to Ach not NE
Term
Where are the stretch sensors that sense blood pressure located?
Definition
The carotid sinus and aortic arch
Term
Describe the neural pathway of the baroreflex from the carotid sinus to the nucleus of solitary tract
Definition
1. Carotid sinus mechanoreceptors
2. Carotid sinus nerve
3. Glossopharengeal nerve into brainstem
4. Nucleus of solitary tract (NTS) in brainstem
Term
Describe the neural pathway of the baroreflex immediately after the nucleus of solitary tract (NTS)
Definition
The nucleus of solitary tract goes to both

A. The nucleus ambiguss
B. The Caudal ventral lateral medulla (CVLM)
Term
Describe the neural pathway of the baroreflex after the nucleus ambiguss
Definition
The nucleus ambigus nerves act on postganglionic parasympathetic neurons to the heart, lowering blood pressure
Term
Describe the neural pathway of the baroreflex after the Caudal ventral lateral medulla (CVLM)
Definition
The CVLM acts on the Rostal ventral lateral medulla (RVLM) in the ONLY inhibitory reaction in the baroreflex

RVLM acts on the intermediolateral nucleus (IML)in the spinal cord

The IML uses parasympathetic ganglia to decreases constriction in arterioles and slow heart rate
Term
Define detrusor
Definition
Bladder muscle
Term
What produces bladder contraction?
Definition
Excitation of parasympathetic neurons via the Sacroparasympathetic nucleus
Term
Define pelvic plexus
Definition
An area near the bladder that contains a lot of parasympathetic and sympathetic nerves
Term
What senses how full the bladder is?
Definition
The mechanosensors on the bladder wall
Term
What nerves transmit sympathetic innervation to the bladder?
Definition
The hypogastric nerve and other preganglions from intermediolateral nucleus eventually transmit to bladder wall

Onuf's nucleus transmits to external urethral sphincter
Term
Is sympathetic input required for bladder filling?
Definition
Currently, the best evidence is that the sympathetic nervous system is not required for bladder filling, but can assist

This is indicated by people with diseases of the SNS that still can have bladder filling
Term
Where in the body do the (sympathetic) hypogastric nerve (and other preganglions from intermediolateral nucleus) transmit signals?
Definition
They transmit signals to bladder postganglionic neurons and also transmit inhibition to parasympathetic presynaptic terminals in the pelvic plexus
Term
Define Onuf's nucleus
Definition
A sympathetic sacral ganglion that constricts the external urethral sphincter
Term
Define supraspinal reflex
Definition
A reflex that needs to travel to the brain to function (ex. micturition)
Term
Where do bladder wall mechanoreceptors terminate?
Definition
All the way in the midbrain, the mechanoreceptors activate the periaqueductal gray

Also, to the intermediolateral nucleus in the spine
Term
Define the periaqueductal gray
Definition
The area in the dorsal midbrain that is activated by bladder mechanoreceptors

With enough innervation, it activates the pontine micturition center
Term
Define the Pontine micturition center
Definition
A region in the dorsal pons that, with sufficient innervation from the periaqueductral gray, will(via sacral neurons)contract the bladder wall and inhibit Onus nucleus
Term
Define the Pontine continence center
Definition
An area in the dorsal pons that is active during rest to excite the Onus nucleus to keep the sphincter closed
Term
What happens if the bladder gets too full?
Definition
The Pontine continence center is overriden by the Pontine micturition center

Then the Onus nucleus is overpowered and the bladder wall contracts
Term
Can the parasympathetic innervation of the micturition reflex be overidden?
Definition
Yes, by higher areas of the brain (Cerebral cortex)to a point
Term
Why do young babies lack control over their bladders?
Definition
The micturition reflex descending pathways have not developed
Term
Do we have control over the urethral sphincter?
Definition
Cerebral cortex control over the internal urinary sphincter (to a point), and skeletal muscle contol over the external urinary sphincter
Term
What causes hypertension?
Definition
While there are many causes, one
contributory mechanism is an increase in the tonic or basal level of sympathetic tone to
the heart and/or blood vessels.
Term
Define Pheochromocytoma
Definition
This is a tumor of the chromaffin cells in the adrenal gland, releasing more epinephrine.

This accounts for only 0.1% of hypertensive patients.
Term
Define Postural (orthostatic) hypotension
Definition
A drop in arterial pressure of 30
mmHg or more upon standing
Term
What causes Postural (orthostatic) hypotension?
Definition
Dizziness is felt upon standing due to an inadequate perfusion of the CNS.
Orthostatic hypotension is due to inadequate reflex control of blood pressure.
Term
Define Horner's syndrome
Definition
Loss of sympathetic innervation to the head

Can occur from damage in any part of the total pathway from hypothalamus to spinal cord and back up to the brain
Term
What are three signs of Horner's syndrome?
Definition
Miosis, Ptosis (eyelid drooping), and anyhydrois (loss of sweating in head and neck)

Ptosis and anhydrosis occur from loss of sympathetic innervation/tone
Term
In Horner's syndrome, will Miosis cause permanent damage to the iris?
Definition
Possibly, but miosis will subside (but not completely disappear) due to the development of increased
sensitivity to circulating catecholamines.
Term
Define Autonomic diabetic neuropathy
Definition
Degeneration of small nerve fibers in diabetics

Possibly due to inadequate blood perfusion or neuron metabolism problems
Term

What are some symptoms of Autonomic diabetic neuropathy?

Definition

Impaired swallowing, delayed gastric emptying, diarrhea, orthostatic hypotension, bladder dysfunction, and erectile dysfunction.

Term
What causes Autonomic dysreflexia (aka sympathetic hyperreflexia)
Definition
Some patients with a spinal
cord lesion at the T6 level or above may develop this condition, presumably due to the plasticity/"rewiring" that occurs after the injury
Term
What are some symptoms of Autonomic dysreflexia (aka sympathetic hyperreflexia)?
Definition
Extremely high blood pressure, activated by stimuli such as bladder/colon distention, pregnancy, or touching the lower abdomen
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