Question | Answer |
What does Origin mean? | The less moveable part where a muscle attaches to bone |
What does Insertion mean? | The more moveable end where a muscle attaches |
What is an aponeurosis? | A flattened, sheet like connective tissue attachment of muscle to bone |
What is a tendon? | A cord or stringlike connective tissue attachment of muscle to bone |
What are four unique characteristics of muscle? | excitability, elasticity, contractility, extensibility |
How do muscles and bones work like a lever system to move the body? | The bone is the rigid lever, a joint is usually the fulcrum and the muscle provides the force to move the resistance or load |
Distinguish between flexion and extension | flexion decreases the angle of a joint while extension increases the angle of a joint. |
Distinguish between abduction and adduction | Abduction is movement away from the body midline and adduction is movement toward the body midline. |
Distinguish between pronation and supination | Pronation is the rotation of a limb so that the palm or sole of the foot are facing downward or inward. Supination is the rotation of a limb so that the palm or sole are facing upward or outward. |
Name five functions of muscle | 1. generate heat 2. movement 3. posture 4. regulate openings 5. stabilize and support |
Name the 3 types of muscle tissue | cardiac, skeletal and smooth |
Distinguish between the SHAPES of the three types of muscle tissue | cardiac is branched, skeletal is cylindrical and smooth is short and elliptical. |
Distinguish between the CONTROL of the three types of muscle tissue | cardiac and smooth are involuntary and skeletal is voluntary |
Distinguish between the LOCATION of the three types of muscle tissue | Skeletal is attached to bone, cardiac is in the heart and smooth is in other organs besides the heart. |
Distinguish between the NUCLEI of the three types of muscle tissue | Skeletal has many nuclei, cardiac and smooth only have one per cell. |
What is a fascicle? | a bundle of muscle fibers (cells) |
What is a muscle fiber? | a single skeletal muscle cell. |
What is a sarcomere? | the functional unit of skeletal muscle (what is responsible for contraction). From one z-disk to another. |
What is the order of connective tissue wrappings from inside to outside of a muscle? | endomysium (around a fiber); perimysium (around a fascicle) and epimysium (around a muscle) |
What is the sarcoplasm? | the cytoplasm of a muscle cell |
What is a sarcolemma? | the cell membrane of a muscle cell |
What is a sarcoplasmic reticulum? | the endoplasmic reticulum of a muscle cell |
What is a myofibril? | The arrangement of actin and myosin (thin and thick) microfilaments in a muscle fiber. |
What is a thick filament made of? | myosin |
What is a thin filament made of? | actin, troponin and tropomyosin. Troponin and tropomyosin are regulatory proteins. Troponin binds calcium moving the tropomyosin off of the binding site so myosin can crossbridge with actin during a contraction |
What is the M line? | The mid line of a sarcomere |
What is a Z disc or Z line? | The ends of a sarcomere where the thin filaments (actin) are attached |
What is the I band? | The area of a sarcomere that contains thin filaments only. It shortens when a muscle contracts |
What is an H band or H zone? | The area of a sarcomere that contains thick filaments only. It shortens when a muscle contracts. |
What is an A band? | The area of a sarcomere that includes both thick and thin filaments--it is the length of a thick filament. |
What is a myosin head? | The part of a myosin (thick) filament that binds or attaches to a thin filament |
What happens when a muscle contracts? | The thick and thin filaments slide over each other shortening the sarcomere. (The sliding filament theory) |
What is the role of ATP in muscle contraction? | It is required for the myosin head to release from actin. It is then split to recock the myosin head. It is released as part of the power stroke. |
What is the role of calcium in a muscle contraction? | It is released from the Sarcoplasmic reticulum and binds to troponin. This shifts the tropomyosin off of the actin active site so that the myosin head can bind and form a cross bridge. |
What are the steps to a muscle contraction cycle (filaments only) | 1. Crossbridge formation (binding of myosin head to actin), 2. Power stroke (head pivots sliding actin), 3. Detachment of myosin head, 4 Reset (recock) |
What is acetylcholine? | A neurotransmitter released by the synaptic terminal and binding to the motor end plate to start a contraction |
What is the motor end plate? | The area of the sarcolemma with receptors to bind the acetylcholine (it is part of the neuromuscular junction) |
What is the synaptic terminal? | The end of the motor neuron that releases acetylcholine |
What are the steps to a muscle contraction starting with neuron? | An action potential reaches the synaptic terminal causing it to release Ach. The Ach binds to receptors on the motor end plate of the sarcolemma. This generates a new action potential in the muscle cell that travels along the sarcolemma and down T-tubules. The arrival of the Action potential at the triad (sarcoplasmic reticulum) causes the SR to release calcium. The calcium binds to troponin, revealing the active site on actin allowing a crossbridge to form. The contraction begins. |
What is the role of acetylcholine esterase? | It breaks down acetylcholine and leads to the end of a contraction. |
What is anaerobic respiration? | When muscle cells work continuously and run out of oxygen, they cannot make ATP in the mitochondria. Instead they switch to fermentation producing less ATP and also producing Lactic acid. This is a "plan B" to keep the contraction going. |
Distinguish between the STRIATIONS of the three types of muscle tissue | Cardiac and Skeletal are striated while smooth is not. (striated means striped) |