Anatomy and Physiology

• The muscular system includes the muscle terminology such as origin or head, which is a muscle end attached to a more stationary of two bones.
• The muscular system also includes the termination point of a muscle, known as the insertion, which is attached to a bone with the greatest movement.
• The belly is the largest portion of the muscle between the origin and the insertion.
• Tendons attach muscles to bones.
• Aponeurosis is a very broad tendon.
• Agonist is a muscle that, when it contracts, causes an action.
• Antagonist is a muscle working in opposition to the agonist.
• The action potentials of cardiac muscle cells are of longer duration and have a longer refractory period.
• Cardiac muscle has intercalated disks and gap junctions.
• Calcium regulates contraction in cardiac muscle.
• Aging results in reduced muscle mass, increased time for muscle to contract in response to nervous stimuli, reduced stamina, increased recovery time, loss of muscle fibers, and decreased density of capillaries in muscle.
• Cardiac muscle is found only in the heart and is striated, with each cell usually having one nucleus.
• Cardiac muscle is autorhythmic.
• Synergists are muscles that work together to cause a movement.
• Prime mover plays a major role in accomplishing movement.
• Fixators stabilize joints crossed by the prime mover; prevent movement of the origin of the prime mover.
• Muscles are named according to location, size, shape, orientation, and number of heads.
• Muscles and their tendons and bones act together as lever systems to move either parts of the body or the whole body.
• Muscle contractions are a pull or force by relative positions of lever, fulcrum, and weight or resistance.
• Human diet must supply chemical energy, organic building blocks, and essential nutrients.
• Human diet must provide chemical energy for cellular processes and organic building blocks for macromolecules.
• Essential nutrients are required materials that an animal cannot assemble from simpler organic molecules and must be obtained from an animal’s diet.
• There are four classes of essential nutrients: essential amino acids, essential fatty acids, vitamins, and minerals.
• Vitamin B3 is an example of a vitamin (coenzyme).
• Actin is composed of G actin monomers each of which has an active site.
• Myosin is composed of many elongated myosin molecules shaped like golf clubs.
• Myosin molecules consist of myosin heavy chains wound together to form a rod portion lying parallel to the myosin myofilament and two heads that extend laterally.
• The tropomyosin/troponin complex regulates the interaction between active sites on G actin and myosin.
• The Sliding Filament Model states that actin myofilaments sliding over myosin to shorten sarcomeres, with no change in length, is responsible for skeletal muscle contraction.
• Tropomyosin is an elongated protein that winds along the groove of the F actin double helix.
• When all the sarcomeres in a muscle fiber shorten, the fiber contracts.
• Part of the energy used to bend the hinge region of the myosin molecule during contraction.
• Troponin is composed of three subunits: one that binds to actin, a second that binds to tropomyosin, and a third that binds to calcium ions.
• Titin filaments are elastic chains of amino acids that make muscles extensible and elastic.
• Myosin heads can bind to active sites on the actin molecules to form cross-bridges.
• During relaxation, sarcomeres lengthen because of some external force, like contraction of antagonistic muscles.
• The Z disk is a filamentous network of protein that serves as an attachment for actin myofilaments.
• The sarcomere is the basic functional unit of muscle fiber.
• In muscle fibers, A and I bands of parallel myofibrils are aligned.
• Iron is an example of a mineral (cofactor).