Smooth muscle doesn't have t-tubules and has small sarcoplasmic reticulum. Calcium enters from the ECF bia Ca+2 channels.
1. Verapamil 2. Nifedipine 3. Norvasc
antagonists to dihydropyradines -> block receptors *last line of protection
unitary smooth muscle
function independently from eachother each smooth muscle innervated independently neurogenic (from the neuron) no AP in this type of muscle found in vessels, airways, eye, erector pili
single unit smooth muscle
most abundant "visceral" contracts as a single unit electrically linked by gap junctions forms functional synctium self excitable rather than requiring nervous stimulation pacemaker cells can depolarize on their own do not have resting membrane potential myogenic (from the muscle) innervated - metabotrophic receptors respond to Ca from 2nd messenger systems symp and parasymp don't intitiate contraction, but rate and force
two types: pacemaker potential (reproductive, urinary tract) slow wave potential (only found in gut, peristalisis)
smooth muscle innervation
Norepi and ACh can be excitatory or inhibitory. They are usually antagonistic to eachother and is the case for multiunit smooth muscle. Can be Norepi, ACh, oxytocin, serotonin, angiotensin, histamine that alter Ca+2 levels.
2 categories: V sensitive (dihydropyradine receptors) Receptor mediated (g-proteins)