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59 Cards in this Set

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What are the subdivisions of the peripheral nervous system?
1. Somatic nervous system (voluntary)
2. Autonomic nervous system
(involuntary)
Somatic innervations consists of _____ neuron(s) arising in the _________ and extending via the _________ to the skeletal muscles.
Single
Spinal Cord
Ventral Root
Somatic innervation neurons release what?
Acetylcholine
Autonomic innervations consist of how many neuron(s)?
2 sequential neurons - preganglionic and postganglionic.
Where do autonomic innvervations synapse at?
Autonomic ganglia
What are the divisions of autonomic nervous system?
Sympathetic and Parasympathetic
At what level does the preganglionic neurons exit the spinal cord?
Thoraco-lumbar
Preganglionic neurons synapse with postganglionic nerves at _______________ and _______________.
Para-vertebral ganglia (22 pairs on each side of spinal cord)

Prevertebral ganglia (celiac, mesentaric) in the abdomen.
What is considered to be a modified sympathetic ganglion?
Adrenal medulla
Describe the innvervation of sympathetic nerves.
One SHORT preganglionic fiber synapsing with several (one or more) LONG postganglionic fibers in the sympathetic ganglia.
What does the autonomic nervous system innervate?
Cardiac muscle, vascular/nonvascular smooth muscle, and exocrine glands.
In sympathetic nervous system, what is the ratio of pre to postganglionic fibers?
1:20
T/F - Sympathetic fibers have a ratio of pre to postganglionic fibers which allow for diffuse action.
True - Fight or flight responses.
T/F - Sympathetic nervous system is essential for life.
False.
T/F - Sympathetic nervous system is sometimes active and sometimes inactive.
False - It is normally active with degree of activity varying from moment to moment, and organ to organ.
T/F - Sympathetic nervous system does not adjust to changing environment.
False. It does adjust with changes in environment.
What does sympathetic nervous response do to:

Heart Rate
Blood Flow
Blood Glucose
Pupils
Heart rate increases
Blood flow shifts to muscles
Blood glucose levels increase
Pupils dilate
In the parasympathetic nervous system, where does the preganglionic neurons originate from?
Cranial nerves of the brain stem, and Sacral portion of the spinal cord.
In the parasympathetic nervous system, where would you expect the synapse to occur?
VERY CLOSE to the ganglia or IN the organs innervated.
Describe the innervation mechanism of parasympathetic nerves.
ONE LONG preganglionic fiber synapsing with ONE SHORT postganglionic fiber
For MOST (not always) cases, the ratio of pre to postganglionic in the parasympathetic nervous system.
1:1
Describe the discrete action of parasympathetic nervous system.
Conservation and restoration of energy, lo calized control of discrete functions.
T/F - Parasympathetic nervous system is essential for life.
True
Describe the Parasympathetic response to:

Heart Rate
Blood Pressure
Retina
Bladder
Heart rate decreases
Blood pressure decreases
Protects retina from light
Empties bladder
T/F - The sympathetic and parasympathetic systems usually function independently.
False - They are PHYSIOLOGICAL ANTAGONISTS
Acetylcholine (ACh or Cholinergic) synapses include? x 3
1. All PREganglionic fibers outside CNS (sympathetic & parasympathetic)

2. All parasympathetic POSTganglionic nerve endings
(Exception to this is sweat glands)

3. Somatic motor neurons innervating skeletal muscles
Noradrenergic (NE) synapses include? x 2
1. All POSTganglionic sympathetic fibers (except those to sweat glands)

2. Adrenal Medulla (Norepinephrine and epinephrine)
Acetylcholine is synthesized from what?
Acetyl CoA and Choline
Acetylcholine synthesis requires what enzyme?
Choline Acetyl transferase
What is the major means of INACTIVATION of acetylcholine?
Degradation in the synapse using the enzyme acetylcholinesterase.
What are the Acetylcholine (Cholinergic) receptors? x 2
Muscarinic
Nictonic
Muscarinic receptors are part of what fibers?
POSTganglionic parasympathetic fibers (except those innervating sweat glands)
Muscarinic receptors help innervate what?
Heart, smooth muscle, and exocrine glands.
What blocks muscarinic receptors?
Antimuscarinic agents
What does atropine do?
Block muscarinic receptors.
Describe the biphasic response of nicotinic receptors.
Stimulation at low doses.
Followed by inhibition at high doses.
Nicotinic receptors are part of what nervous system(s)?
Sympathetic and Parasympathetic autonomic ganglia.

Adrenal Medulla
Nictonic receptor effects can be blocked with what? x 2
1. Ganglionic blockers
2. Neuromuscular blockers
Nicotinic receptors can be found where?
At the neuromuscular junction.
Curare is an example of what?
Neuromuscular blocker of nicotinic receptor.
Trimethaphan and hexamethonium are examples of what?
Ganglionic blockers of the nicotinic receptors.
What is norepinephrine synthesized from?
Tyrosine
Tyrosine hydroxylase does what?
Converts Tyrosine to DOPA
Aromatic L-amino acid decarboxylase does what?
Converts DOPA to dopamine
Dopamine beta-hydroxylase does what?
Converts dopamine to norepinephrine.
What does phenylethanolamine N-methyl-transferase do?
Converts norepinephrine to epinephrine.
What is the major means of inactivation of norepinephrine?
REUPTAKE back into the presynaptic neuron form which it was released.
Alpha 1 NE (noradrenergic) receptors found where?
1. Vascular SM (contraction)
2. Genitourinary SM (contraction)
3. Liver (contraction)
4. Intestinal SM (hyperpolarization and relaxation)
5. Heart (increased contractile force, arrythmias)
Alpha 2 NE (noradrenergic) receptors found where?
1. Pancreatic islets (beta cells, decreased insulin secretion)
2. Platelets (aggregation)
3. Vascular SM (contraction)
Beta 1 NE (noradrenergic) receptors found where?
1. Heart (increased force and rate of contraction, AV nodal conduction velocity)
2. Juxtaglomerular cells (increased renin secretion)
Beta 2 NE (noradrenergic) receptors found where?
1. Smooth muscles (vascular/bronchial/GI/genitourinary) (relaxation)
2. Skeletal muscles (glycogenolysis; uptake of K+)
3. Liver (glycogenolysis; gluconeogenesis)
Potential ways to affect autonomic neurotransmission. x 5
1. Synthesis
2. Storage (vesicles)
3. Release (Ca2+ dependent exocytosis)
4. Receptor activation
5. Termination
How can you affect autonomic neurotransmission via synthesis? x 2
1. Availability of precursors for NT
2. Availability of synthesis enzymes
How can you affect the autonomic neurotransmission via storage (vesicles)? x 2
1. Protect the NT from degradation
2. Provide for the quantal release of NT
How can you affect the autonomic neurotransmission via release (Ca2+ dependent exocytosis)?
Interfere or enhance release of NT.
How can you affect the autonomic neurotransmission via receptor activation?
Use agonists vs antagonists
Describe agonists in terms of affinity and intrinsic activity.
High affinity (binds well to receptor)

High intrinsic activity (good biological response)
Describe antagonists in terms of affinity and intrinsic activity.
High affinity (binds well to receptor)

NO intrinsic value (no biological response, but causes effects by simply preventing agonists to bind)
How can you affect the autonomic neurotransmission via termination?
METABOLISM of ACh in synaptic cleft via Acetylcholinesterase.

REUPTAKE of norepinephrine into presynaptic neuron.