Week 5 Review Flashcards
Which neurotransmitter is used at the first autonomic nervous system synapse?
acetylcholine
Post-ganglionic autonomic neurotransmitters are diffusely sprinkled from numerous _______ along the axons.
swellings/varicosities
Which neurotransmitter is predominantly used at sympathetic postganglionic synapses? What is the one exception?
norepinephrine, except for sweat glands (ACh - muscarinic M3)
Which neurotransmitter is used at the postganglionic parasympathetic synapse? Which receptor class?
ACh - muscarinic
In which tissues are alpha1 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
smooth muscle (think blood vessels), binding causes vasoconstriction
In which tissues are alpha2 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
alpha2 receptors are found at the nerve terminals/varicosities of preganglionic sympathetic neurons. Receptor binding causes auto-inhibition - stops release of norepinephrine.
In which tissues are beta1 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
heart, kidneys
binding causes increased cardiac output and constriction of afferent arterioles
In which tissues are beta2 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
smooth muscle (think lungs)
binding causes bronchodilation
In which tissues are beta3 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
fat cells and bladder smooth muscle
binding causes lipolysis and bladder muscle relaxation
In which tissues are M3 receptors found and what is the normal physiologic effect of receptor binding?
glands, smooth muscle (bladder, GI), vasculature (endothelial cells)
binding causes contraction of glands and contraction of bladder and GI smooth muscle
in the vasculature, it causes NO release from endothelial cells –> vasodilation
In which tissues are M2 receptors found and what is the normal physiologic effect of receptor binding?
heart, presynaptic nerve terminals
binding causes decreased cardiac output in the heart, and auto-inhibition of ACh release from presynaptic nerves (similar to alpha2)
How are you going to remember the signaling pathways used by autonomic receptors?
QISSS IQ (G-protein types)
a1 = Q a2 = I B1 = S B2 = S B3 = S
M2 = I M3 = Q
Which tissues use ATP as a neurotransmitter? What is the effect of binding?
arterioles, vas defrens, and sweet, bitter, umami gustatory receptors
ATP binding to purinergic receptors –> opening of nonselective cation channel –> Ca2+ entry –> binds to calmodulin –> MLCK activation –> MLCK phosphorylates myosin heads –> cross bridging –> constriction of arterioles and vas defrens
How do M3 receptors in endothelial cells cause vasodilation?
ACh binding –> PLC cleaves PIP2 –> IP3 + DAG –> IP3 releases Ca2+ from SR –> stimulation of NO synthase –> NO stimulates smooth muscle relaxation
Mechanoreceptors in the aortic arch and carotid sinus monitor blood pressure via arterial wall ______.
stretch
If carotid sinus cells sense too much stretch, parasympathetic tone is ________ (increased/decreased).
increased –> decreased cardiac output
Name three histological identifying traits of skeletal muscle.
nuclei are 1) long and 2) squished to the side of the fiber
3) striations
Name three histological identifying traits of cardiac muscle.
1) intercalated discs
2) branched myocytes
3) central, round nuclei
Name three histological identifying traits of smooth muscle.
1) fusiform fibers
2) nonstriated
3) central nuclei
looks like a flowing river
How can you tell the difference between dense regular CT and smooth muscle?
Smooth muscle will be more acidophilic (pink/red) and have more densely-packed nuclei.
CT will have super long, fusiform nuclei of fibroblasts.
What is found in the I band of a sarcomere?
actin filaments
What’s up with the H zone?
In between the thin filaments - only includes thick filaments.
During contraction, which structures in the sarcomere shorten? Select all that apply.
a) A band
b) H zone
c) I band
d) Entire sarcomere
H zone, I band, and entire sarcomere shortens during contraction
Within which connective tissue structure surrounding muscle fibers do motor nerves give off unmyelinated terminal branches?
perimysium