ANS anatomy & physiology 5 Flashcards
________________ is the neurotransmitter of most postganglionic sympathetic fibers
Norepinephrine
What are the nine types of adrenergic receptors
Alpha 1: a1A, a1B, a1D
Alpha 2: a2A, a2B, a2C
Beta: B1, B2, B3
Neurotransmitter release is modulated by activation of ______________________ at cholinergic and adrenergic synapses
prejunctional autoreceptors or heteroreceptors
Describe the sympathetic pathway of the adrenal medulla.
Preganglionic neurons release ACh onto chromaffin cell effectors (targets)- no postganglionic neurons
Postganglionic sympathetic neurons release _____________ at sweat glands
ACh
How many different chemical messengers can be co-released with NE or ACh?
over a dozen
The alpha 1 receptor as a whole has the following functional responses:
vasoconstriction
promotes cardiac growth and remodeling
The cellular response of activation of the alpha1 receptor is
couple to Gq to activate PLC: increased IP3/DAG, increased Ca2+, PKC
increased Na+/H+ exchanger
The cellular response of activation of the alpha 2 receptor is
coupled to Gi to inhibit adenylyl cyclase to decrease cAMP, decrease PKA activity
The functional response of alpha 2 activation is
vasoconstriction
decreased neurotransmitter release and release from adrenal medulla
The cellular response of activation of the beta receptors is
coupled to Gs to activate adenylyl cyclase= increased cAMP, increased PKA activity
activates L-type Ca2+ channels
Beta 1 blockers functional response include
positive chronotropic, dromotropic, & inotropic action on the heart
increased renin release
Beta 2 blockers functional response includes
relaxation of bronchial, gastrointestinal and uterine smooth muscle
decreased secretions from bronchial glands
vasodilation
Beta 3 blockers functional response includes
lipolysis & thermogenesis
One autoreceptor on each nerve terminal mediates _____________ neurotransmitter release, the positive feedback cycle.
increased
Two receptors on each nerve terminal, one autoreceptor and one heteroreceptor, mediate __________________ neurotransmitter release
decreased
Which receptor is responsible for decreased insulin release?
alpha 2 receptors
Which receptor is responsible for decreased preganglionic AcH release?
alpha 2 receptors
Which receptor is responsible for decreased preganglionic NE release?
alpha 2 receptors
Which receptor is responsible for skeletal muscle vasodilation?
beta 2 receptors
Which receptor is responsible for uterus smooth muscle relaxation?
beta 2 receptors
Which receptor is responsible for bronchodilation?
beta 2 receptors
Which receptor is responsible for increased heart rate?
beta 1 receptors
Which receptor is responsible for mydriasis?
alpha 1 receptors
Which receptor is responsible for increased renin release?
beta 1 receptors
Which receptor is responsible for pyloric sphincter contraction?
alpha 1 receptors
Which receptor is responsible for pilomotor muscle contraction?
alpha 1 receptors
Which receptor is responsible for increased dromotoropy?
beta 1 receptors
What is the rate limiting step in catecholamine synthesis?
tyrosine hydroxylase
Postganglionic sympathetic fibers to sweat glands are:
cholinergic
Contraction of this intraocular muscle causes mydriasis.
a. ciliary
b. radial
c. circular
d. orbitalis
b. radial
Control of pupil diameter in the eye is an example of the
SNS and PNS acting in a synergistic or cooperative manner
Contraction of the ____________ muscle of the iris causes mydriasis
dilator pupillae (radial)
Contraction of the ____________ muscle causes miosis
sphincter pupillae (circular)
The sympathetic division of the heart wields an overall
excitatory effect on the heart
The parasympathetic division of the heart produces an overall
inhibitory effect on the heart
The salivary glands are an example of ______________ elicited by sympathetic and parasympathetic innervation of the same target tissue
complementary physiologic responses
Activation of parasympathetic pathways of the salivary glands leads to
copious watery saliva via ACh acting at M3 receptors
Activation of postganglionic sympathetic fibers at the salivary glands leads to
thick, viscous secretion via the actions of NE at a1 & Beta receptors
Many organs or tissues receive input from only ________ of the ANS
one division- either sympathetic or parasympathetic
Organs or tissues that have parasympathetic innervation only include
lacrimal glands
ciliary muscle (for near vision accommodation)
nasopharyngeal glands
Organs or tissue that have sympathetic innervation only include:
adrenal medulla
most blood vessels
gallbladder
kidney
exocrine sweat glands
erector pili (pilomotor) muscles
The salivary glands are an example of ______________ physiologic responses elicited by sympathetic and parasympathetic innervation of the same target tissue.
Complementary
Which heart tissue shows little response to ACh?
ventricular muscle (myocytes)
