What makes Cardiac muscle unique?
Involuntary, striated, branched, with intercalated discs and gap junctions, Myogenic or autonomous, single nucleus, prolonged action potential, does not experience fatigue under normal circumstances, Ca+ induced, Ca+ release.
What is a desmosomes?
Holds the cell tightly together.
What are the two types of cardiac cell?
Conductive 1% - Automaticity (generate their own signal), Greater # of ion channels allowing for rapid transmission of action potentials. (SA Node, AV Node, Bundle of His, Purkinje Fibers.
Contractile Cells 99% - similar to skeletal Ca+ is released into the cytoplasm for Actin-myosin.
Explain the Starling Curve
Stroke Volume vs. Ventricular End-Diastolic Volume. Optimal length of stretch needed for optimal CO.
Describe Smooth Muscle?
Spindle shaped cells with solitary nucleus, non-straiated(lack sarcomeres) Lack T-tubules, Lack Troponin(Calmodulin) Involuntary(ANS) slow-wave like contractions, lines the hollow organs. Very prolonged contractions, little energy expenditure, Plasma Membrane has dense bodies (gets pulled on). Myofilaments criss-cross the cell.
What is Calmodulin?
Ca2+ binds to calmodulin and activates the myosin light chain kinase (tropomysin) with allows the myosin to move its head.
What is a single unit smooth muscle ?
Cells are joined by gap junctions which allow the muscle to contract contiguously as a single unit. Intestinal Tract, blood vessels, bladder etc…
What is a smooth muscle multi-unit?
Each cell has it’s own innervation from the ANS. Each cell behaves as a separate motor unit. Ex. pupillary muscle (iris), ciliary muscle.
What is myoglobin?
Oxygen binding protein, contains a heme moiety, binds O2 with high-affinity/higher than hemoglobin. Releases into the muscle with injury, toxic to renal tubules in high amounts
What is Rhabdomyolysis?
Severely elevated myoglobin … toxic to the renal tubules.
What is Creatine Kinase?
Enzyme involved in conversion of
ATP -> ADP + P. There are high amounts in Muscle. Requires Mg as a cofactor. Can be measured in the serum, can be fractionated. Skeletal has a different CK than Cardiac.
What is Dystrophin?
Responsible for anchoring muscle to the sarcolemma. Structural protein
