module 6 autonomics Flashcards
sympathetic innervation
neurons arise in thoracic, lumbar regions
short preganglionic neurons, long post
parasympathetic innervation
neurons arise in cranial, sacral regions
long preganglionic neurons, short post
sympathetic neurotransmitters
preganglionic: acetylcholine: nicotinic receptors
postganglionic: norepi or acetylcholine: adrenergic or muscarinic receptors
parasympathetic neurotransmitters
preganglionic: acetylcholine: nicotinic receptors
postganglionic: acetylcholine: muscarinic receptors
nicotinic ACh receptors
stimulated by ACh
PSNS postganglionic neurons
SNS preganglionic and postganglionic sweat glands
neuromuscular junction
muscarinic receptors
sweat glands: stimulated by ACh
tissues innervated by PSNS: stimulated by ACh
adrenergic receptors
stimulated by norepi
a- and B- receptors on tissues (except sweat glands) innervated by SNS
Catecholamines
dopamine
norepinephrine
epinephrine
MAOI
sympathomimetic drugs: nonselective adrenoreceptor agonists
norepi
epinephrine
dobutamine
sympathomimetic
activate adrenergic receptors
adrenoreceptor
stimulated by epi or norepi
a1 selective agonist
work post-synaptic
a2 selective agonist
work on auto-receptor for negative feedback
sympatholytics
block activation of adrenergic receptors
a-agonist
a1 > a2»_space;» B
mixed a- and B agonists
Norepi - a1 = a2 - B1 >> B2 Epi - a1 = a2 - B1 = B2
a1 sympathomimietic effect vascular smooth muscle
contraction
a1 sympathomimetic effect pupillary dilator
contraction (dilates pupil)
a1 sympathomimetic effect pilomotor smooth muscle
erects hair
a1 sympathomimetic effect prostate
contraction
a1 sympathomimetic effect heart
inc. force of contraction
a2 sympathomimetic effect platelets
aggregation
a2 sympathomimetic effect adrenergic nerve terminals
inhibits transmitter release
a2 sympathomimetic effect vascular smooth muscle
vasodilation
a2 sympathomimetic effect fat cells
inhibits lipolysis
B1 sympathomimetic effect heart
inc. force and rate of contraction
B2 sympathomimetic respiratory, uterine, vascular smooth muscle
muscle relaxation
B2 sympathomimetic effect skeletal muscle
potassium uptake
B2 sympathomimetic effect liver
activates glycogenolysis
B3 sympathomimetic effect fat cells
activates lipolysis
dopamine agonists
dopamine: D1 = D2»_space; B»_space; a
D1 sympathomimetic effect smooth muscle
dilates renal blood vessels
D2 sympathomimetic effect nerve endings
modulates transmitter release
agonized cardiovascular effect
a1: vasoconstriction -> inc. BP
a2: vasodilation
B1: inc. CO -> inc. BP
B2: peripheral vasodilation -> dec. BP
agonized ocular effect
Vision accommodation - a1: mydriasis; pupil dilation Regulation of intraocular pressure - a1, a2: inc. humoral outflow - B1: inc. production of aqueous humor
agonized respiratory effect
B2: dilate bronchioles
a1: dec. mucosal secretion -> decongestion
agonized GI effects
a2, B2: smooth muscle relaxation -> dec. peristalsis
a2: dec. digestive secretions
agonized GU effects
a1: contraction of urethral sphincter -> urinary continence
B2: relaxation -> dec. urinary output
a1: facilitates ejaculation
B2: uterus relaxation -> inhibits labor
Epinephrine
direct-acting sympathomimetic: catecholamine
- a1: vasoconstriction
- B1: cardiac stimulation
- B2: vasodilation
Norepinephrine
direct-acting sympathomimetic: catecholamine
- a1: vasoconstriction
- B1: cardiac stimulation
isoproterenol
derict-acting sympathomimetic: catecholamine
B1: cardiac stimulation
dopamine
direct-acting sympathomimetic: catecholamine
- D1/D2: renal vasodilation (lower dose)
- B1: cardiac stimulation (middle dose)
- A1: vasoconstriction (high dose)
direct-acting sympathomimetics: non-catecholamine
not inactivated by COMT
longer duration of action
better access into brain
direct- acting sympathomimetic: non-catecholamine: A2 agonist
clonidine: CNS receptors: dec. BP
ciliary receptors: dec. intraocular pressure
indirect-active sympathomimetics
enhance release of catecholamines
