capillaries, where blood loses O2 and gains CO2 -Superior/Inferior Vena Cava Physiology of Cardiac “Contraction” The action potential initiated by the SA Node travels along the cardiac conduction system and spreads out to excite the contractile fibers of the atria and ventricles. 1. Depolarization: When a contractile fiber is brought about by an action potential from the surrounding fibers, its Na+ channels open. Because the Na+ concentration is higher in the interstitial fluid this inflow
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allowing muscle contractions, and other actions, to be recorded and analyzed for the first time ever. Muscle cells, or muscle fibers, are defined as the basic unit of a muscle. Therefore, complete muscles are constructed from bundles of muscle fibers, but there are no gap junctions between adjacent cells so each fiber performs independently. Myofibrils establish an ordered structure for single muscle fibers. Every myofibril is comprised of actin and myosin. Actin and myosin are contractile proteins that
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which are large polymerized protein molecules that are responsible for the actual muscle contraction. (Textbook of Medical Physiology, Guyton & Hall, Elsevier 2006) Modified from: http://en.wikipedia.org/wiki/File:1022_Muscle_Fibers_(small).jpg From:http://users.rcn.com/jkimball.ma. ultranet/BiologyPages/S/sarcomere.png Interaction between these cross-bridges and actin filaments causes contraction. Myofibril is composed of about 1500 adjacent thick (myosin) filaments and 3000
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used for muscle contraction. The thin filaments consist of two strands of actin subunits twisted into a helix plus to types of regulatory proteins; troponin and tropomyosin. The sarcomere is the contractile unit, which is composed of myofilaments which also contain the A band, I band, H zone, Z disk and M line. Myofibrils are rod like contractile elements that occupy most if the muscle cell volume. Composed of saromeres arranged end to end they appear banded. The muscle fiber which is composed
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applying energy and power towards the vertical jump. 4. Which muscle fiber type is beneficial in anaerobic/explosive muscle power activities? Explain. Type IIa fast twitch fibers are beneficial for anaerobic/explosive muscle power activities as they have the ability to be able to rapidly transmit action potentials and generate a high cross bridge turnover rate which is responsible for quick muscle contractions. These fibers in the muscles also contain a high activity level of myosin ATPase and
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nervous system, which means that it is a voluntary muscle. When considering appearance, it is a striated muscle meaning to say that it has alternating light and dark bands (Sherwood, 2013, p. 259). Skeletal muscle is made up several muscle fibers in which each muscle fiber consists of myofibrils,
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Activity 2: The Effect of Stimulus Voltage on Skeletal Muscle Contraction Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Skeletal muscle fibers are innervated (stimulated) by You correctly answered: c. motor neurons. 2. A single action potential propagating down a motor axon results in You correctly answered: d. a single action potential and a single contractile event in the muscle fibers it innervates. 3. In resting skeletal muscle, calcium is stored
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types of muscle in the body (the other two being cardiac and smooth muscles) that allows movement by contraction of the muscles. When a motor unit, a single nerve that innervates all the muscle fibers, activates these muscles fiber, it causes a muscle contraction. These muscle contraction occurs when motor neurons from the spinal cord leaves and activates multiple muscle fibers, the number of muscle fibers depend on the type of muscle. According to the Hennemen size principle, muscles that react rapidly
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Dr. Robert P. Marino Review Questions 2 Question 1 Describe basic bone structure and classification. There are two basic types of Bone tissue, compact bone and spongy bone. 1. Compact bone is dense and homogeneous and forms the walls of bone. 2. Spongy bone is composed of slender intertwined pieces of bone enclosing a space filed with non-bone tissue. It is found in the interior of normal bone. Bones can also be classified according to shape: 1. Long bones are longer than they are
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All cells must contract in a specific sequence. This sequence is determined by the pathway known as the conduction system. 2. Cardiac cells are connective and autorhythmic. What does this mean? Connective cells, action potentials, (excitatory signals) can propagate from one cell to another via gap junctions. Autorhythmic cells can excite themselves spontaneously without stimulation of the nervous system and contract at a regular rhythm. 3.
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