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52 Cards in this Set

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  • Back
define sympathomimetic?
mimic effects of SNS on heart and circulation (Epi, NE, Dopamine, Isuprel)
Define sympatholytics?
Inhibit the function of the SNS . ( anti-adrenergics: Beta-blockers)
What higher center regulates the SNS?
Hypothalamus: the lateral and posterior nuclei are sympatheteic and stimulation results in discharge of the Sympatho-adrenal system
Where do the Sympathetic preganglionic nerves pass out of the spinal cord via which nerve roots?
Sympathetic preganglionic nerves originate in the lateral horns (INTERMEDIOLATERAL HORNS of the GRAY matter) of teh thoracolumbar segments (T1-L3) and pass out of the s.c nia the anterior roots.
where do the sympathetic preganglionic nerve fibers arise from what segments of the spinal cord?
T1-L2 in adults or T1- L3 neonate to adol.
What is the only organ innervated by sympathetic preganglionic neurons?
The adrenal (suprarenal) medulla is the only organ innervated by sympathetic preganglionic neurons
Identify four groups of sympathetic ganglia?
1. paravertebral ganglia(superior, middle and inferior)
2. Celiac ganglia
3. superior mesenteric ganglia
4. Inferior mesenteric ganglia
What is the hypogastric plexus and what pain is transmitted by it?
The hypogastric plexus is a retroperitoneal structure that is formed by confluence of the bilateral lumbar symp chains. ..situated between the bodies of L5 & S1.
Pelvic pain caused by inflammatory diseases or cancer is transmitted via this plexus and can be relieved by a superior hypogastric plexus block.
Postganglionic Symp neurons originate from where?
Postganglionic Symp neurons arise from the autonomic ganglia (paravertebral ganglia)
What two sympathetic ganglia form teh stellate ganglion?
The inferior cervical ganglion and the first toracic ganglion form the stellate ganglion. (In 80% of population, the inferior cervical and first thoracic ganglia are fused)
Are the effects of sympathetic stimulatiion of a motor or sensory nature?
Motor (efferent)
Sympathetic nerves arising from the T5-T12 innervate what organs? How about L1-L2?
Sympathetic nerves arising from T5-T12 innervate organs in the abdomin(intestine liver, kidneys, adrenal medula)
L1-2 innervate the bladder, colon, and rectum.
What are the two POSTganglionic sympathetic nervous transmitters?
Norepinephrine (released from symp. postganglionic ceurons to viscera, heart, lungs, sm musc, salivary glands)
Acetylcholine is released t sweat glands and piloerector muscles
Where do PREganglionic parasympathetic nerves originate?
CN 3,7, 9, 10 in the brainstem and from Sacral segments 2-4
(Craniosacral division)
Which nerve contains teh most parasympathetic fibers?
Vagus nerve (CN X) contains 75% of all parasympathetic nerve fibers
What autonomic nerves are cholinergic in nature?
The nerve fibers that release acetylcholine are cholinergic
--Sym & Parasym PREganglionic
--Parasym POSTganglionic
--Sympathetic POSTganglionic(sweatglands and piloerector muscles)
What is the only endogenous compound that causes simultaneous bradycardia and hypotension
Acetylcholine
Where are the muscarinic sites in the autonomic system?
Muscarinic receptors are found in tissues innervated by the parasympathetic postganglionic neurons.
What general classes of drugs interrupt muscarinic transmission peripherally?
Antimuscarinics (anticholinergics) such as atropine, scopolamine, and glycopyrrolate.
Where are the nicotinic sites in the peripheral nervous system?
Nicotinic receptors are found on cell bodies of sympathetic and parasympathetic postganglionic neurons , on chromaffin cells of the adrenal medulla and the motor end plate of the skelatel neuromuscular junct.
What general classes of drugs interrupt the nicotinic transmission periperally?
Nondepolarizing neuromuscular blockers interrupt nicotinic receptor transmission at the neuromuscular jx.
--the ganglionic blocker trimethaphan (Arfonad) and 2 NDMR (d-tubocurarine and metocurine) interrupt nicotinic receptor transmission at the ganglia
What causes Horner's syndrome?
blockade of teh stellate ganglion with local anesthetic produces horner's synfrome (also a SE of intersccalene or supraclavicular approaches to the brachial plexus)
What are 6 S/Sx of Horner's syndrome?
1. Miosis
2. anhydrosis
3. vasodilation
4. nasal congestion
5. increased facial temp
6. ptosis
(occur on ipsilateral side)
Norepi released from Sympat POSTganglionic nerve terminals has its actions terminated primarily by what mechanism normally?
reuptake!
Identify 2 forms of the enzyme MAO?
Type A (MAO-A) : metabolizes serotonin, dopamine, epinephrine, and norepinephrine
Type B (MAO-B): metabolizes tyramine and phenylethylamine and dopamine
whaere is Monoamine oxidase (MAO-A) type A found:
MAO-A is present in the CNS, adrenergic nerve endings, liver and gastrointestinal tract.
In addition to respiratory and cardiovascular, what other centers are found in the brainstem?
along with Resp and CV centers are the vomiting center, the cough center, and the swallow center.
What are the chemical steps in the synthesis of catecholamines beginning with Phenylalamine?
Phenylalamine
Tyrosine
Dopa
Dopamine
Norepinephrine
Epinephrine
What is the release of Ach from the vesicles of the nerve terminal dependent on?
Calcium influx.
What two properties of neuronal tissue enables them to respond to stimuli?
1. the presence of a resting membrane potential
2. the presence of voltage gated sodium channels permit neurons to respond to stimuli
What is the major cation of the neuron? and outside?
Inside: Potassium (140mM)
outside: sodium (142mM)
What is responsible for creating the resting membrane potential?
Potassium diffusing out of cells through potassium leak channels
when do voltage gated potassium channels snap open?
when the axon depolarizes to threshold
In what state are the voltage gated channels during the absolute refractory period?
they are closed and no additional action potential can be evoked no matter how intense the stimulus
Do rapidly conducting nerves have larger or smaller diameter? Are they myelinated or unmyelinated?
Large and myelinated
Wat ion deals with repolarization of the neuron?
potassium
what membrane ion channels play a role in cell repolarization
the voltage-gated sodium channel.
what neurotransmitter is the most common excitatory neurotransmitter in the CNS?
glutamate
List 3 ionotropic glutamate receptors in the central nervoous system?
NMDA, AMPA, kainate
What is the principle neurotransmitter of the efferent (motor) somatic nervous system?
Acetylcholine
What do efferent nerves of the somatic nervous system innervate?
skeletal muscle
How is neurotransmitter release affected by hypercalcemia, hypocalcemia, hypermagnesium, hypomagnesium?
release is increased with hypercalcemia and hypomagnesium. and is decreased with hypocalcemia, and hyper magnesium.
What enzyme catalyzes the synthesis of acetylcholine (ACh) ? Where does ACh synthesis occur?
Synthesis of ACh occurs in the cytoplasm of nerve terminals.
Choline acetyltransferase (ChAt) catalyzes the formation of ACh from the precursors choline and Acetyl-CoA .
The action of acetylcholine is terminated by what mechanism?
It is terminated by metabolism by acetylcholinesterase, located in the postsynaptic membranes nearbt cholinergic receptors.
What are the two types of cholinergic receptors, and where are they found peripherally?
MUSCARINIC and NICOTINIC receptors.
Muscarinic are cound on target tissue opposite the Parasympathetic postganglionic nerve endings. Nicotinic are located at autonomic ganglia at the neuromuscular jx.
what is up-regulation ?
Up-regulation is an increase in teh number of receptors when the prevailing concentration of agonist is decreased.
What causes upregulation of
ach receptos at the motor end plate of skeletal muscle?
Denervation or trauma to skeletal muscle
define down regulation?
A decrease in the number of receptors occuring in response to an increased concentration of agonists.
What is the first step in the termination of NE?
Diffusion away from the receptor
What are the three mechanisms that NE is terminated from the receptor?
1. Diffusion
2. metabolism(MAO in tissues & COMT in blood /liver)
3. reuptake (80% of the loss of efficacy )
In what proportion is NE and Epi normally released from the chromaffin cells in the adrenal medulla?
80% Epi (Eighty/Epi)
20% NE
what are the 7 ligand binding sites of teh
GABA receptor?
1. GABA
2. Barbituates
3. Benzodiazepines
4. Propofol
5. Alcohol/ anesthetic
6. steroids
7. Picrotoxin