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54 Cards in this Set
- Front
- Back
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What is meant by tissue excitability?
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The potential ability of a cell or a tissue to receive and to respond to stimuli.
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Contraction is defined as the ability of a tissue to.....
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forcefully shorten.
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Regarding fatigue, how does cardiac muscle differ from skeletal and smooth?
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It is the most fatigue resistant of muscle cells.
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Differentiate between muscle cell and muscle fiber.
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They are the same.
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Explain why striations are visible in both cardiac and skeletal muscle.
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This is due to the myofibrils which are neatly aligned.
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How does skeletal muscle control blood pressure?
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It doesn't. Smooth muscle controls blood pressure.
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What is the name of the connective tissue membrane found within a skeletal muscle that surrounds each fascicle?
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Perimysium
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What structure does the epimysium surround?
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It is a dense irregular connective tissue that surrounds an entire skeletal muscle.
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`When a muscle attaches directly to a bone, instead of a tendon which is attached to a bone, the ________________ of the muscle fuses with the_______________ of the bone.
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Epimysium;Periostium
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This is considered the smallest contractile unit of skeletal muscle.
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Sarcomere. It extends from one Z disc to the next Z disc.
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Actin and myosin are considered two types of.........
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Myofilament.
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What is another name for a thin myofilament?
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Actin.
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What is another name for myosin?
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Thick myofilament.
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Why are skeletal muscle fibers multinucleated?
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Aside from the high metabolic requirement of this tissue, skeletalmuscle fibers are formed when several stem cells merge.
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Why are skeletal muscle fibers often called syncytiums/
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Because they are formed by the fusion of several cells.
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What is the function of myoglobin?
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Myoglobin is found in muscle cells. It is similar to hemoglobin and its function is to store oxygen for the muscle cell.
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Can muscle cells store carbohydrates?
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Yes. They store CHO for use as a fuel in the form of glycogen(glycosomes).
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What is Sarcoplasm?
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It is the cytoplasm of a muscle cell.
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In between the sarcomeres, these structures often form channels that run transversely through the skeletal muscle cell. What are they?
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T tubules.
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What exactly is a triad?
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This is represented by the terminal cisternae of two proximal sarcomeres, and the T tubules that separate them.
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A bands are dark striations. Where are they formed?
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They are formed where actin and myosin overlap.
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Dark striations called I bands are formed where only myosin is present. Is this a true statement?
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No. The statement should read:
Light striations called I bands are formed where only actin is present. |
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Is there a functional relationship between actin, myosin and Z discs?
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Yes. Both Actin and Myosin need some structure to pull against. Actin at each end of a sarcomere is attached to a structure referred to as a Z disc,
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Action potentials that are carried deep into the cell by______________: signal the sarcoplasmic reticulum to________________.
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T tubules; release calcium
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The signal for a skeletal muscle to contract is calcium. This in turn binds to troponin causing what to happen?
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This will cause tropomyosin, to move out of myosin's way.
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Within the skeletal muscle fiber, after tropomyosin changes or shifts in its response to calcium, what substance binds to actin?
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Myosin.
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As actin and myosin slide past each other, what is released from the myosin?
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ADP and inorganic phosphate.
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All fibers in a motor unit contract simultaneously. is this a true statement?
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Yes. It is true.
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After a nerve releases the chemical signal, the receptors on the muscle fiber, at the NMJ open to admit what?
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Sodium ions.
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What process must occur to fully restore ion balance?
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To restore ion balance, the sodium -potassium pump, must utilize energy to bring potassium into the cell, and push the sodium out.
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During the period of contraction, _________________ crossbridges form and the muscle fiber shortens.
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Actin myosin crossbridges.
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With respect to calcium, why is it that a motor unit cannot partially contract?
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Since calcium is either released by the SR within the innervated cells , or it is not, it is for this reason that a motor unit does not partially contract.
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Define tetanus.
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Tetanus refers to a single, elongated constant muscle contraction.
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What is the name of the process , in which an ever increasing quantity of motor units are stimulated to create a combined force?
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This is called recruitment.
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What is meant by maximal stimulus for a muscle?
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The maximal stimulus for a muscle is when it causes all motor units to reach and achieve tetanus.
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What is an isometric contraction?
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Regarding muscle length, the distance between the origin of the muscle and insertion does not really change.
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In an isotonic contraction, the force muscular generation does not change. True/False
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True.
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What is the following process referring to?
When a small amount of the energy in glucose is captured, rather quickly, in ATP, the remainder is taken up in lactic acid. |
Anaerobic respiration. It is also called glycolysis.
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What causes muscle fatigue?
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When the ATP production in a muscle does not, or cannot parallel with ATP usage, the result is muscle fatigue.
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What exactly is rigor mortis?
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When the supply of ATP in a muscle becomes rather scarce or limited, there will be muscle contracture. This muscle is unable to decontract or relax. rigor mortis is when this happens after death.
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What is another cause of muscle fatigue?
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When levels of potassium or calcium are too low in a muscle, or conversely if sodium is too high, the result is muscle fatigue.
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What is Oxygen debt?
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The need or requirement of oxygen to restore the body to its original resting state, after muscle activity has been terminated.
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if the quantity of muscle cells in each fascicle is high, the force that is exerted by the fiber will also be high. Is this a true statement?
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No. The question as posed is not logical.
It should read: If the quantity of myofilaments in each fiber is high, the force exerted by the fiber will be high. |
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What must a muscle contain for its contractions to be rapid?
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When the muscle contains primarily glycolytic muscle fibers, its contractions will be rapid.
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The duration of muscular effort is usually increased if the majority of fibers rely on what for the generation of ATP?
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Aerobic respiration.
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These particular fibers can contract continuously for a very long time(100 mile bicycle race).
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Slow oxidative fibers
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What type of fibers are more usually employed for a 100 yard dash race?
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Fast oxidative fibers.
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Why are oxidative fibers generally red in color?
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They are red due to the presence of myoglobin, which contains a small quantity of reserve oxygen.
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In smooth muscle where is calcium stored?
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It is stored in the sarcoplasmic reticulum, as well as outside the cell.
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What are dense bodies?
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Myofilaments in smooth muscle, pull gainst dense bodies, instead of Z discs as is the case with skeletal muscle.
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Only smooth muscle fibers are able to divide. True/False
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True.
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Regarding smooth muscle, action potentials may be transferred from cell to cell through________________ permitting the entire sheets of cells to contract in response to a single unit.
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Gap junctions.
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Does calcium in smooth muscle interact with troponin?
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No. Calcium in smooth muscle does not interact with troponin, but may indirectly trigger the phosphorylation of myosin.
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In aging and with continued disuse of muscle, muscle fibers will be replaced with........
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Connective tissue
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