pharmaco - chapter 5 Flashcards
major involuntary, unconscious, autonomic portion of the nervous system
-contrasts in several ways with the somatic nervous system
ANS
– major pathway for information transmission from CNS to the involuntary effector tissues
Motor (efferent) portion of ANS
2 Major Subdivisions of ANS:
- PANS
2. SANS
– semiautonomic part of the ANS located in the GI tract
-consists of myenteric plexus or plexus of Auerbach and the submucous plexus of plexus of Meissner
ENS
SYMPATHETIC (SANS) Preganglionic fibers originate from:
- Thoracic (T1-T12) segments of the cord
* Lumbar (L1-L5) segments of the cord
PARASYMPATHETIC (PANS) Preganglionic motor fibers originate from
- Cranial nerve nuclei III, VII, IX and X
* Sacral segments (S2-S4)
Sympathetic or para
Most of the ganglia are located in 2 paravertebral chains that lie along the spinal cord
SYMPATHETIC
Sympathetic or para
Preganglionic fibers are short and the postganglionic fibers are long
SYMPATHETIC
• Most of the ganglia are located in the organs innervated, most distant from the spinal cord
PARASYMPATHETIC
• Preganglionic fibers are long and the postganglionic fibers are short
PARASYMPATHETIC
- A nerve ending that releases acetylcholine as the primary transmitter
- Also a synapse in which acetylcholine is the primary transmitter
CHOLINERGIC
primary transmitter in all autonomic ganglia and at the synapses between the parasympathetic ganglia and their effector cells
Ach
• All postganglionic parasympathetic fibers are
cholinergic
• A few postganglionic sympathetic fibers are
cholinergic
• All preganglionic fibers are
cholinergic
• Ach Synthesis Enzyme:
choline acetyltransferase
Ach is synthesized from
Acetyl-coA+choline
Rate-limiting step of Ach synthesis:
transport of choline into nerve terminal
• Inhibits transport/synthesis of ACh into the cell
HEMICHOLINIUM
• Inhibits storage of ACh into the vesicle
VESAMICOL
- Inhibits the release of Ach
* Prevents contraction of muscles
BOTULINUM TOXIN
• A nerve ending that releases norepinephrine as the primary transmitter
ADRENERGIC
• Also a synapse in which norepinephrine is the primary transmitter
ADRENERGIC
• Most postganglionic sympathetic fibers are
adrenergic
• Most postganglionic sympathetic fibers are adrenergic except for
sweat glands, thermoregulatory center, arrector pili
- Adrenal cortex and medulla
- Ductless gland that functions as a ganglion
- Postganglionic fibers are cholinergic
ADRENAL GLAND
• Inhibits the synthesis of NE
METYROSINE
- Inhibits the storage of NE
* Anti-hypertensive agent
RESERPINE
- Inhibits release of NE
* Used to lower blood pressure
GUANETHEDINE
- Inhibits metabolism of NE
* Vasoconstriction, higher BP
MAO I
Monoamine oxidase
what is the effect of reserpine to blood pressure
lowers it
what is the effect of guanethedine to blood pressure
lowers it
what is the effect of MAO to blood pressure
Raises it
- Other transmitter molecules in addition to the primary agents (ACh or NE)
- Contained in many autonomic nerves
- Localized in the same vesicle as the primary transmitter or in a separate population of vesicles
COTRANSMITTERS
function of COTRANSMITTERS
• Involved in the modulation of synaptic transmission
or balance
What are the 7 cotransmitters
Neuropeptide Y, Enkephalin, ATP, Neurotensin, VIP, Substance P, Somatostatin
- Also referred as cholinergic receptors
* Respond to ACh and its analogs
. CHOLINOCEPTORS
CHOLINOCEPTORS ARE Subdivided into
- MUSCARINIC receptors
2. NICOTINIC receptors
- Respond to muscarine (an alkaloid)
- Respond to ACh
- Mimics the effects of parasympathetic
MUSCARINIC receptors
SIGNALING MECHANISM OF MUSCARINIC RECEPTORS
• G-protein coupled
type of cholinoceptor located primary on effector cells
muscarinic
M1 location
nerve endings
M2 location
heart
M3 location
effector cells, smooth muscle, exocrine glands, endothelium
- Respond to ACh
- Respond to nicotine (another ACh mimic)
- Do not respond to muscarine
NICOTINIC receptors
SIGNALING MECHANISM OF NICOTINIC receptors
• Ligand-gated ion channel
• 2 major subtypes OF NICOTINIC receptors
o Nn-neuronal (ANS ganglia)
o Nm-neuromuscular endplate (skeletal muscle)
- Also referred as adrenergic receptors
* Respond to NE
ADRENOCEPTORS
SIGNALING MECHANISM OF ADRENOCEPTORS
• G-protein coupled
ADRENOCEPTORS subdivided into
o ALPHA receptors
o BETA receptors
alpha 1 receptor predom in
blood vessels
alpha 2 receptor predom in
presynaptic cleft
B1 receptor predom in
heart and kidney
B2 receptor predom in
heart, liver, uterus, pancreas, smooth muscle, lungs
B3 receptor predom in
fat or adipose tissue/cell
type of integration Predominant state in any situation
CENTRAL INTEGRATION
- Ergotrophic (energy expenditure)
* ”Fight or flight” response
SYMPATHETIC
- Tropotrophic (energy saving)
- Leading to growth
- ”Rest and digest”
PARASYMPATHETIC
Synaptic vesicles contain neurotransmitters.
With parasympathetic stimulation, — would be released.
Ach
Synaptic vesicles contain neurotransmitters.
With sympathetic stimulation, — would be released.
NE
ORGAN EFFECTS
EYE
sym and para
S: dilation of pupil
P: constriction of pupil
term that denotes dilation of pupil
Mydriasis –
term that denotes constriction of pupil
miosis
ORGAN EFFECTS
HEART
sym and para
S: increase HR
P: decrease HR
Most of the time, the effect of parasympathetic is opposite the effect of sympathetic because
most of the organs in the body are dually innervated.
ORGAN EFFECTS
LUNGS
sym and para
S: bronchodilation
NE + Beta 2 – bronchodilation
P: bronchoconstriction
What type of stimulation predominates in GIT
para
What type of stimulation predominates in glands
para
what happens to GIT when Overdose of parasympathetic drug =
diarrhea
parasympathetic effect in the GIT
increased motor and secretory activites
predominant receptor for uterus
Beta2
uterus has ____receptor only
sympathetic, NO PARA
If Uterus is β2, heart is also β2, what happens when NE binds to β2
Increase heart rate, relaxation of uterus
in uterus, NE + β2
RELAXATION
– known as the bladder muscle
Detrussor
-under parasympathetic stimulation,
it contracts
-under sympathetic stimulation, it will contract or relax
relax
when the detrussor muscle is relaxed, what happens to ureter
won’t open, urine can’t get out
type of stimulation in liver
sympathetic
-all glands under the influence of
parasympathetic
when parasympathetic increase in glands, what happens to amount of secretion
increases
