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Smooth muscle neurotransmitter enhance or disable smooth muscle contractility?
Can do either
What are the determining factors for and excitatory or inhibitory synapse?
- NOT THE NEUROTRANSMITTER
- The receptors
- The intracellular signaling pathway
The neurotransmitter defines whether a synapse is excitatory or inhibitory (T/F)?
- The receptors or the intracellular signaling pathway
What is norepinephrine's activity on alpha-adrenic receptors?
Excitatory (e.g. causes contraction of vascular smooth muscle)
What is norepinephrine's activity on beta-2-adrenergic receptors?
inhibitory, (e.g. relaxes bronchial smooth muscle)
Other than neurotransmitters, what else can impose local effects on smooth muscle tension?
- Extracellular ion concentration
- Paracrine signals
What type of effects do most local smooth muscle stimulants produce?
What is a paracrine relaxer of smooth muscle?
Mechanosenstive ion channels found in some smooth muscle are activated by what?
The resulting contraction due to smooth muscle stretch is of what relative tension?
Enough to oppose the forces acting to stretch the muscle.
What is pacemaker potential?
The membrane potential change occurring during the spontaneous depolarization to threshold sans neural input
Can some smooth muscle cells spontaneously depolarize?
What are "Slow waves"
Regular variations in ion flux that the cause the membrane potential of smooth muscle to drift up and down
What are the two ways that spontaneous contraction can occur in smooth muscle?
- Pacemaker potentials
- Slow waves due to ion flux
Gut smooth muscle tends to contract rhythmically without neural input?
True, due to pacemaker cells
Where are pacemaker cells of smooth muscle commonly found?
Other than the GI, where are pacemaker cells found?
How are smooth muscle cells connected?
What are the major components of varicosities?
Mitochondria and Synaptic vesicles
Large number of smooth muscle cells bind together in what conformation?