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Level 1: Remember/Understand

Connective Tissue Covering

  • The connective tissue covering that encloses the sarcolemma of an individual muscle fiber is called the (c) endomysium.

Fascicle

  • A fascicle is a (b) bundle of muscle fibers enclosed by a connective tissue sheath.

Thick and Thin Myofilaments

  1. (b) Thin - Contains actin

  2. (a) Thick - Contains ATPases

  3. (b) Thin - Attaches to the Z disc

  4. (a) Thick - Contains myosin

  5. (b) Thin - Contains troponin

  6. (a) Thick - Does not lie in the I band

T Tubules in Muscle Contraction

  • The function of the T tubules in muscle contraction is to (c) transmit the action potential deep into the muscle cells.

Motor Nerve Impulse Transmission

  • The sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal muscle cell membranes are the (a) neuromuscular junctions.

Muscle Contraction

  • Contraction elicited by a single brief stimulus is called (a) a twitch.

  • A smooth, sustained contraction resulting from very rapid stimulation of the muscle, in which no evidence of relaxation is seen, is called (d) fused tetanus.

Isometric Contractions

  • Characteristics of isometric contractions include all but (a) shortening.

ATP Production During Muscle Contraction

  1. (a) Coupled reaction of creatine phosphate with ADP - Provides ATP fastest

  2. (a) & (c) Creatine phosphate with ADP, anaerobic glycolysis - Do not require oxygen

  3. (b) Aerobic respiration of glucose - Provides the highest yield of ATP per glucose molecule

  4. (c) Anaerobic glycolysis - Results in the formation of lactic acid

  5. (b) Aerobic respiration - Produces carbon dioxide and water

  6. (b) Aerobic respiration - Most important in endurance sports

Neurotransmitter and Ion Involvement

  • The neurotransmitter released by somatic motor neurons is (a) acetylcholine.

  • The ions that enter the skeletal muscle cell during the generation of an action potential are (c) sodium ions.

Myoglobin Function

  • Myoglobin (c) holds a reserve supply of oxygen in the muscle.

Aerobic Exercise Effects

  • Aerobic exercise results in all of the following except (c) increased size and strength of existing muscle cells.

Smooth Muscle Types

  • The smooth muscle type found in the walls of digestive and urinary system organs and that exhibits gap junctions and pacemaker cells is (b) unitary.

Level 2: Apply/Analyze

  1. Four Special Functional Abilities of Muscle:

    • Excitability: Ability to receive and respond to stimuli

    • Contractility: Ability to shorten forcibly

    • Extensibility: Ability to stretch

    • Elasticity: Ability to recoil to resting length

  2. Muscle Attachments:

    • Direct attachment: Epimysium fuses directly with periosteum or perichondrium.

    • Indirect attachment: Connective tissue extends as a tendon or aponeurosis.

    • Tendon: Cord-like structure of dense regular connective tissue.

    • Aponeurosis: Sheet-like structure.

  3. Acetylcholinesterase Importance:

    • Breaks down acetylcholine to prevent continuous muscle contraction.

  4. Excitation-Contraction Coupling:

    • The process where an action potential leads to muscle contraction.

  5. Motor Unit Definition and Diagram:

    • A motor unit consists of a motor neuron and all the muscle fibers it controls.

  6. Muscle Fiber Types:

    • False: Most muscles contain a mix of fiber types (slow and fast-twitch).

  7. Muscle Fatigue:

    • Definition: The inability of muscle to contract despite stimulation.

    • Causes: Ionic imbalances, lactic acid accumulation, ATP depletion.

  8. Rigor Mortis Explanation:

    • ATP depletion prevents myosin heads from detaching from actin, causing stiffness. After 72 hours, proteolysis relaxes the muscles.

Level 3: Evaluate/Synthesize

  1. Sarcomere Structure & Sliding Filament Model:

    • Structure: Contains actin and myosin filaments between Z discs.

    • Sliding Filament Model: Myosin heads pull actin filaments, shortening the sarcomere.

  2. Smooth vs. Vigorous Contractions:

    • Small contractions recruit fewer motor units, while stronger contractions recruit more units.

  3. Smooth Muscle Properties and Function:

    • Uses less energy, sustains contractions, crucial for organ function.

  4. Muscle-Relaxing Drugs:

    • Chemical A (blocks ACh receptors) would be a good relaxant because it prevents muscle contraction.