6 Flashcards
(38 cards)
Secretory Glands
Can self regulate, but affected by the
ANS
Sympathetic system:
epinephrine, norepinephrine
Parasympathetic system:
acetylcholine (muscarinic receptors)
Somatic system:
acetylcholine (nicotinic receptors)
Adrenergic transmission
Transmitter transported back into the
presynaptic terminus
Cholinergic transmission
Neurotransmitter hydrolyzed in
synapse
Sympathomimetic
Sympathetic PNS
Endogenous Adrenergic Amines made in
sympathetic nerve terminals and in the adrenal medulla
alpha1 receptors
Most important place - smooth muscle cells.
alpha 1 receptors all coupled to
Galphaq - leads to smooth muscle contraction
Alpha 1 receptors increase
Calcium, activity of yosin light chain kinase, myosin light chain phosphorylation, overall contractility.
a2 receptors
Most important at
presynaptic termini
a2 receptors inhibit
epinephrine and norepinephrine release (CNS and PNS)
b2 receptors on smooth muscle cells increase
PKA,
b2 receptors phosphorylate and inhibit
myosin light chain kinase,
b2 receptors diminish —— levels and inhibit
Ca++
myosin light chain kinase (next slide),
b2 receptors diminish phosphorylation of
myosin light chain and decrease muscle contractility
cAMP activates PKA which, in turn, inhibits
MLCK. Inhibition of MLCK diminishes myosin light chain phosphorylation and diminishes smooth muscle contraction (i.e. ‘causes’ dilation).
b1 receptors on cardiac muscle cells (mainly b1 but also b2) activate
PKA, activate L type Ca++ channels,
b1 receptors increase
Ca++ levels and increase muscle contractility
Cardiac effects Mainly
b1 effects. b2 effects contribute to epinephrine activity.
Non vascular smooth muscle
Usually relaxation mediated by
b2 receptors. GI decreased motility. Broncho dilation. However, a receptors mediate sphincter contraction
Salivary Glands
Net effect:
Modest secretion with a high concentration of protein.
Mainly a1 and b1 with some b2. b1 stimulates protein secretion
Intravenous administration of epi and norepi
you get anxiety, jitters, apprehension in spite of bbb not allowing it through.