Muscles Flashcards
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
