Cardiac and Smooth Muscles

Cardiac Muscle Remember that intercalated disks contain gap junctions. When one cell is stimulated, all cells are stimulated. Cardiac myocytes each have one nucleus - they undergo spontaneous depolarization

EXCITATION-CONTRACTION COUPLING IN A CARDIAC MYOCYTE -- Excitation/contraction coupling is identical with skeletal muscle, but you don’t need a neurotransmitter. --Contains T-tubes

SMOOTH MUSCLE --No striations; contains actin and myosin but arrangement is not in sarcomeres. -- has extremely long thin filaments, which attach to the plasma membrane and to cytoplasmic proteins called dense bodies. --lines blood vessels, bronchioles, digestive tract (peristaltic waves), ureters, ductus deferentia (which transport sperm cells, uterine tubes (which transport ova)

Single-unit & Multi-unit smooth muscle Neurotransmitter is released along the length of an autonomic neuron from varicosities. Receptor proteins are on the entire surface of smooth muscle cells A number of smooth muscle cells are stimulated at once. Form synapses en passant (synapses in passing)

EXCITATION-CONTRACTION COUPLING: Smooth Muscle