Chemistry of Muscle Contraction

1. Chemistry of Muscle Contraction • _______ is the energy source for actin and myosin to contract. • Produced by the many _____________. • ATP that has become ADP can recharge back to ATP when creatine phosphate (CP) splits and donates a phosphate. • Glucose and oxygen are also needed for contraction. • Stored in form of glycogen and myoglobin for aerobic metabolism. • Anaerobic metabolism produces __________ acid Heat Production • Muscular activity is one of the major heat-generating mechanisms that the body uses to maintain its temperature. • Shivering (small spasms of contraction) helps to prevent hypothermia

2. Cardiac Muscle • Also known as ______________ due to lack of conscious control ________________ and _______________ due to microscopic appearance • Contain myofibrils • Only found within the heart (walls) • Much smaller than skeletal muscles cells and only contain one nuclei per cell • Are longer than wide and have multiple branches forming a network of cells. • Contain _________ _________- gap junctions where cells attach one to another. • Transmit impulses from cell to cell. • This allows entire groups of cells to contract together at the same time. • Dark, transverse

3. Physiology of Cardiac Muscle • No external nerve stimulation required to contract. • Rate and rhythm of contraction is due to (SA node) _______ ______ (pacemaker) of heart located in the wall of the right atrium. • Impulse follows a controlled path through the conduction system of the heart. • Groups of cardiac muscle cells that touch adopt the contraction rate of the most rapid cell. • Cardiac cells contract in rapid, wavelike fashion down a controlled path. • This helps to squeeze blood out of chambers of the heart

4. Nerve Supply of Heart • Heart rate is modifiedby Autonomic Nervous System • Sympathetic and Parasympathetic Nervous Systems • Sympathetic fibers stimulate heart to beat harder and faster as part of "fight or flight response” • Parasympathetic fibers inhibit cardiac function, causing heart to beat more slowly and with less force, part of “feed or breed” response.

5. Smooth Muscle • Also known as ______________ due to lack of conscious control ________________ and _______________ due to lack of striations. • Found in two forms: • _________________ smooth muscle • Large sheets of cells in the walls of some hollow organs • _________________ smooth muscle • Small, discrete groups of cells make delicate movements.

6. Smooth microscopic muscle anatomy • Small with single nucleus. • Actin and myosin are present, but are not arranged in parallel. • criss-cross cell and are attached to __________ bodies that are similar to Z lines of skeletal muscle. • Cell balls up as it contracts

7. Visceral Smooth Muscle • Found in walls of many soft internal organs that are known as viscera. • Instead of fine movements, work in waves of motion. • Does not need external stimulation. • If stretched, will contract more strongly. • __________ nervous system decreases activity, __________ nervous system increases activity

8. Multiunit Smooth Muscle • Individual cells or small groups of cells that produce fine and delicate movements • Ex: blood vessel walls, within the eye, small airways • Also under influence of the autonomic nervous system