Muscle Tissue Flashcards
Where are the nuclei of skeletal muscle cells located?
They are multinucleated with oval nuclei and located at the periphery of the muscle.
What type of filaments are found in the A band?
Thick and thin filaments.
What type of filaments are found in the I band?
Only thin filaments.
Which band is located in the middle?
H band (only thick filaments)
Describe the endomysium.
Composed of basal lamina and reticular fibers, covers each skeletal muscle fiber.
Describe the perimysium.
Dense irregular connective tissue that surrounds each skeletal muscle bundle of fibers.
Describe the epimysium.
Dense irregular connective tissue that covers the entire muscle.
What are satellite cells?
Spindle-shaped, inactive myoblasts that can be activated when the skeletal muscle is injured.
What is the difference between fast twitch and slow twitch skeletal muscle fibers?
Slow twitch (red) fibers are smaller with more myoglobin and mitochondria.
Fast twitch (white) fibers are larger with few mitochondria.
Is the sarcoplasmic reticulum of skeletal muscle cells basophilic or acidophilic?
Acidophilic (aka eosinophilic)
Is the sarcoplasmic reticulum of cardiac muscle cells basophilic or acidophilic?
Acidophilic (aka eosinophilic)
Describe cardiac muscle cells.
Centrally located, spherical nucleus. Contain glycogen-rich sarcoplasm. Cells branch and anastamose.
What transitions cardiac muscle cells? What does this form?
Intercalated disks create a syncitium because of the gap junctions within them
Describe smooth muscle cells.
Elongated, spindle-shaped cells with an elongated nucleus and acidophlic cytoplasm. Surrounded by reticular fibers produced by myocytes. Contain many thin myofilaments (actin + tropomyosin, no troponin) and few thick myofilaments (myosin).
What are dense bodies?
Anchor sites in smooth muscle cells that gather myofilaments and intermediate filaments so that there is a point of reference for contraction
