BIOL 202 Lecture Notes - Lecture 1: Skeletal Muscle, Cardiac Muscle, Smooth Muscle Tissue
Muscles:
Skeletal muscle:
• Long, cylindrical, and unbranched.
• Multiple nuclei.
• Unable to divide but repaired by satellite cells
• Straited
• Voluntary movement.
• Intracellular Ca+2
Cardiac muscle:
• Only in the heart
• Long cylindrical, branched cells
• Straited
• Single nucleus
• Interacted discs between cells for communication
• Involuntary
• Intercellular and extracellular Ca+2
Smooth muscle:
• Found in blood vessels walls, around organs, respiratory, digestive, and reproductive tract.
• Cells are short and spindle-shaped.
• Single nucleus
• Not straited
• Involuntary
• Extracellular Ca+2
Basic features of skeletal muscle:
Epimysium:
• Dense outer layer of collagen fibers.
• Continuous with collagen fibers of the tendon (those in turn are continuous with collagen fibers
of bone)
• Surrounds the entire muscle and keeps it separate from different tissues and organs.
• Connected to deep fascia.
Perimysium:
• Inside the muscle, spindle fibers
• Divides the muscle into different compartments, bundles of spindle fibers called fascicles. Blood
vessels and nerves included.
Endomysium:
• Covers each individual muscle fiber cell, collagen fibers.
• Includes capillaries, satellite cells and nerves (axons of motor neurons)
• No pain receptors, nociceptors, in muscles are on connective tissue coverings.
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Document Summary
Long, cylindrical, and unbranched: multiple nuclei, unable to divide but repaired by satellite cells, straited, voluntary movement. Long cylindrical, branched cells: only in the heart, straited, single nucleus. Smooth muscle: found in blood vessels walls, around organs, respiratory, digestive, and reproductive tract, cells are short and spindle-shaped, single nucleus, not straited. Inside the muscle, spindle fibers: divides the muscle into different compartments, bundles of spindle fibers called fascicles. Endomysium: covers each individual muscle fiber cell, collagen fibers, no pain receptors, nociceptors, in muscles are on connective tissue coverings. Includes capillaries, satellite cells and nerves (axons of motor neurons) Collagen: does not contract, not electrically excitable, stretchy and elastic. Macroscopic anatomy of a skeletal muscle cell (fibers) Sarcolemma (cell membrane: cell membrane of skeletal muscle cell (fibers), below endomysium, has a transmembrane potential and voltage gated na+ channel, neuromuscular junction (nmj) Sarcoplasm (cytoplasm: cytoplasm of the skeletal cell, contains glycogen (energy) and myoglobin (oxygen bonds)
