Question | Answer |
What are the features of smooth muscle? | elongated nuclei, spindle shape of cells. Found in the walls of organs and in blood vessels. Myofilaments arranged randomly enable cells to stretch |
What are the features of skeletal muscle? | nuclei on the outer side of cells. Overlapping filaments create striation pattern. |
What are muscle spindles? | Fibers found in the belly of the muscle. They detect changes in length of the muscle. |
What is the A-band composed of in a skeletal muscle? | entire length of a single thick filament. |
What is the I-band of in a skeletal muscle? | zone of thin filaments that is not superimposed by thick filaments |
What are the Z-discs composed of in a skeletal muscle? | Series of dark lines between the I bands where two cells meet |
What are the features of cardiac muscle? | Found only in the heart, Y-shaped cells that are shorter than skeletal muscle cells, intercalated discs located between cells |
What are the features of cardiac myocyte nuclei? | Nuclei are larger than in skeletal muscle and centrally located |
What are intercalated discs? | Where two cardiac myocytes meet. Help muscle to contract as a unit |
What is the epicardium? | Outer CT layer of heart tissue. |
What is endocardium? | Lines chambers of the heart |
What are purkinje fibers? | Part of the heart's conductive system |
What do epimysium line? | Entire muscle |
What do perimysium line? | Groups of muscle fibers into fascicles |
What do endomysium line? | Individual muscle fiber |
What are the three types of cell junctions in intercalated discs? | fascia adherens, macula adherens, gap junctions |
What is the function of the fascia adherens? | Anchoring site for actin, connect to the closest sacromere |
What is the function of the macula adherens? | Stop separation during contraction by binding intermediate filaments. Also called desmosomes |
What is the function of the gap junctions? | Allow action potentials to spread between cardiac cells |
What is the structure of purkinje fibers in the heart? | Originates in the SA node. Fibers are split into left and right trees as well as atrial and ventricular contributions. Appear "fuzzy" |
What is the function of purkinje fibers in the heart? | Carry the contraction impulse from the left and right bundle branch to the myocardium of the ventricles |
What is the location of purkinje fibers in the heart? | just below the endocardium in the inner ventricular walls of the heart |