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Muscle, Contraction
| Question | Answer |
|---|---|
| skeletal muscle tissue functions | producing body movements, maintenance posture, generation of heat |
| cardiac muscle tissue functions | producing blood flow through heart and producing blood flow for pulmonary and systemic circuits |
| smooth muscle tissue functions | regulating diameter of hollow organs and regulation of movement of material through hollow organs |
| three types of muscle tissue | skeletal, smooth, and cardiac |
| characteristics of muscle tissue | excitability, contractility, extensibility, and elasticity |
| pulmonary circuit involves | blood flow thru lungs for gas exchange |
| ventricles | push blood and generate blood pressure that drive the blood into two primary circuits |
| systemic circuit involves | blood flow thru body |
| regulation of diameter of hollow organs involves | arterioles, which has a major impact on blood flow and BP |
| regulation of movement of materials thru hollow organs involves | mostly the digestive tract |
| excitability | ability of muscle fibers to be activated by and react to stimuli |
| muscle tissue is stimulated by | chemicals and electrical stimuli |
| excitation of muscle fibers lead to | contraction of the fiber |
| contractility | ability of muscle fibers to to draw together or shorten |
| contractility process | muscle fibers produce tension which is the force of the contraction |
| extensibility | ability of a muscle fiber to elongate or stretch |
| extensibility is apparent in | skeletal muscle flexion and extension |
| elasticity | ability of muscle fiber to return to its normal resting length after contraction or extension |
| generation of tension steps | muscle fibers, endomysium, perimysium, epimysium, tendon, periosteum, sharpeys fiber, matrix of bone |
| tendon | epimysium continues as a tendon which attaches muscle to bone |
| skeletal muscle is formed by | skeletal muscle fibers and connective tissue |
| blood vessels are essential for | delivery of nutrients, oxygen, etc and for removal of waste |
| nerves associated with muscle have | sensory and motor functions |
| sensory receptors function | monitor muscle contraction |
| motor fibers function | conduct action potential to the muscle fibers |
| acetylcholine | a neurotransmitter released at the neuromuscular junction |
| functional unit of skeletal muscles | muscle fibers |
| skeletal muscle fiber characteristics | long, cylindrical, striated, lies parallel to adjacent fibers |
| neuromuscular junction | a connection of a motor neuron at a nerve muscle site |
| fascicles | fibers and their associated sheaths of endomysium are arranged in groups and surround by connective tissue |
| endomysium | each muscle fiber is surrounded by and attached to a connective tissue covering called endomysium |
| perimysium | a layer of fibrous connective tissue that is continuous with the endomysium |
| epimysium | outer layer of dense irregular fibrous connective tissue that surrounds the entire muscle |
| thin and thick filament | striations are formed by the alternating patterns |
| myofibrils | long parallel elements that are composed of the proteins actin and myosin |
| A bands | dark crossed bands |
| 2 regions of A bands | zone of overlap and M line |
| I bands | light cross bands |
| Z lines | located at the center of I bands |
| sarcomere | region between two Z lines |
| indirect attachments occur when | epimysium continues as a tendon |
| direct attachment occurs when | epimysium directly attaches to the perimysium |
| insertion | site of attachment that moves when the muscle contracts |
| muscle origin | site of attachment that does not move when the muscle contracts |
| postsynaptic membrane | The region of the sarcolemma that is responsive to a neurotransmitter |
| action potential | begins at the postsynaptic membrane and spreads over the sarcolemma. |
| sarcolemma | the plasma membrane of the muscle fiber. excitable membrane |
| sarcoplasm | the cytoplasm of the muscle fiber. |
| T tubules | conduct action potentials from the sarcolemma into the inner of the fiber. |
| triad | is an association formed by a T tubule located between two associated terminal cisternae |
| sarcoplasmic reticulum | is a system of tubes and membranes. wraps around each myofibril and is in close association with the T tubules |
| The terminal cisternae are located | on each side of a T tubule |
| Calcium ion pumps of the sarcoplasmic reticulum remove | calcium ions from the sarcoplasm |
| The arrival of a/an ___________ at the terminal cisternae results in the opening of their _______ ion channels | action potential, calcium |
| Opening of channels in the terminal cisternae allows the _________ diffusion of __________ | outward, calcium ions |
| The ______ ions that diffuse into the sarcoplasm initiate ________ | calcium, contraction |
| myosin | The thick filaments are mostly composed of the contractile protein called myosin |
| H zone | The region of the A band where thin filaments are not located is called |
| I band components | F actin, G actin, Thin filaments, Tropomyosin, Z lines, Troponin |
| actin | The contractile protein of the I bands |
| troponin-tropomyosin complex | covers the myosin binding sites |
| In a resting muscle fiber, the subunit of troponin that binds calcium is _____ because calcium is stored in the __________ | open, sarcoplasmic reticulum |
| Calcium ions are released into the sarcoplasm when the terminal cisternae _______ | depolarizes |
| The troponin-tropomyosin complex moves ______ its blocking position when calcium ions bond to ________ | away from, troponin |
| Cross-bridge interaction | begins when myosin binds to actin |
| The functional unit of contraction | sarcomere |
| Proprioceptors | receptors that receive information from within the body. found located within muscle, joints, and their associated connective tissues. |
| In addition to monitoring muscle ________, muscle spindles respond to muscle stretch and function in _____ responses | contraction, reflex |
| ___________ binds to its receptors on the _______ membrane. | Acetylcholine, postsynaptic |
| not a common location of synapses? | neuron with tendon |
| sodium ions | The ions that move inward as a result of the binding of acetylcholine to its receptors on the postsynaptic membrane |
| The result of the movement of ______ ions into the fiber results in the ________ of the fiber. | sodium, depolarization |
| components of a chemical synapse | Synaptic cleft, Presynaptic neuron (membrane), Postsynaptic cell (membrane) |
| The two coupled events in the contraction of a muscle fiber are ________ and ________ | excitation, contraction |
| excitation begins | at the neuromuscular junction |
| The excitation of the fiber ends with the _________ of the terminal cisternae resulting in the release of ________ ions | depolarization, calcium |
| Contraction begins with the exposure of the myosin binding (active) sites of _______, the binding of myosin, and the movement of the (thin filaments) inward toward the centers of the ___ bands | actin, A |
| sliding filament theory | explains how the thin filaments move inward along the thick filaments |
| The arrival of an action potential at the ________ opens their calcium ion channels, which results in the _______ of acetylcholine | axon terminals, exocytosis, |
| Acetylcholine diffuses across the synaptic cleft and binds to its receptors located on the ________ | postsynaptic membrane |
| The binding of acetylcholine to its receptors results in the opening of ______ ion channels in the postsynaptic membrane | sodium |
| Sodium moves into the sarcoplasm resulting in the _______ of the postsynaptic membrane, and the generation of an __________ that spreads across the sarcolemma | depolarization, action potential |
| The depolarization of the sarcolemma spreads inward by ________ to the terminal cisternae which depolarize and release _____ ions | T tubules, calcium |
| Acetylcholine is rapidly degraded by the enzyme ___________, returning the synapse to its initial state, ready to respond to the arrival of another action potential | acetylcholinerase (AChE) |
| The depolarization of the T tubules stimulates the ________ to release calcium ions | terminal cisternae |
| Calcium ions bond to _______, and results in the movement of the troponin-tropomyosin complex away from its blocking position on ______ | troponin, actin |
| The interaction of myosin with actin allows the sliding of the thin filaments _______ | inward |
| factors that influences the tension produced by a contracting fiber? | number of active cross-bridges and position of the thin filaments within the A band |
| In the high energy state, the head of myosin faces _____ from the center of the A band | away |
| In the low energy state, myosin has reacted with ____ and its head is now positioned ______ the center of the A band | actin, toward |
| The ______ of the head is an expression of mechanical energy (derived from the chemical energy in the breakdown of ATP) | pivoting |
| Maximal tension is produced when the fiber is at its normal resting length, and it has maximal active _____ alignment | cross bridge |
| events of a twitch | Relaxation phase, Latent period, Contraction phase |
| The regulation of the ________ concentration of _______ ions is essential in the control of muscle contraction | sarcoplasm, calcium |
| A single brief stimulus produces a single brief _________ because calcium ions are continually being pumped _________ the sarcoplasmic reticulum | contraction, back into |
| twitch | A ______ is a single brief contraction-relaxation produced by a single stimulus |
| myogram | a recording of muscle activity |
| One factor that accounts for different velocities of twitches is the way the fiber _______ fuel molecules (glycolysis vs. aerobic metabolism) | catabolizes |
| Fibers that primary derive energy from _______ are fast twitch fibers. | glycolsis |
| Fibers that primary derive energy from ______ metabolism are slow twitch fibers | aerobic metabolism |
| The effect of increasing the number of contracting ______ is an increase in muscle tension | motor units |
| _______ stimulus for a muscle is the stimulus (voltage) required to produce an initial contraction | threshold |
| maximal stimulus | is the stimulus (voltage) that recruits all of the muscle’s fibers |
| Increasing voltage above the maximal stimulus does not increase muscle tension because all of the muscle’s fibers have already been _______ | recruited |
| factors that contributes to treppe | Increased heat, Increased efficiency of enzyme systems, Increased calcium ion availability |
| Treppe is a progressive series of _______ stronger contractions, where each contraction results from a stimulus of _______ intensity | increasing, the same |
| isotonic contraction | a contraction that results in a change in muscle length and movement of the load |
| Two types of isotonic contractions are ___________ | concentric and eccentric |
| concentric contraction | a contraction that results in the shortening of the muscle along with the movement of the load. |
| eccentric contraction | a contraction that occurs while a muscle lengthens |
| isometric contraction | a contraction where the muscle does not change length because it does not develop enough tension to overcome the resistance (load). |
| In addition to motor unit recruitment, another way muscle contraction can be graded (varied) is to change the ________ of muscle stimulation | frequency |
| One way to modify twitches to produce smooth sustained muscle contractions is to _______ the frequency of the stimulation | increase |
| wave summation | tension production due to the rapid succession of stimuli. |
| Incomplete tetanus is produced by | rapid successive contraction-relaxation phases of the muscle |
| Incomplete tetanus is characterized by a/an _______ contraction with the muscle quivering as it rapidly undergoes phases of contraction-relaxation | sustained |
| If the frequency of successive stimuli is increased, the phases of relaxation become _______. | shorter |
| Complete tetanus | a state of sustained contraction |
| Complete tetanus occurs because stimuli arrive so quickly the sarcoplasmic reticulum does not have time to ______ calcium ions | reabsorb |
| 2 common sources of glucose | delivered by the blood and derived from the breakdown of glycogen |
| The two primary sources of energy for resting muscles are | fatty acids and glucose |
| The energy source that supplies about 95% of the energy for the resting muscle | fatty acids |
| Fatty acids are catabolized in the | mitochondria |
| aerobic metabolism | catabolism of fuels, such as fatty acids and glucose, that requires molecular oxygen. |
| In the resting muscle, waste products from the catabolism of fatty acids are | carbon dioxide and water |
| In the resting muscle, waste products from the catabolism of fatty acids are | carbon dioxide and water |
| The chemical energy from the catabolism of fatty acids is captured in the formation of | ATP |
| In a resting muscle fiber, some ATP is “stored,” and some is used to create another energy rich molecule called | creatine phosphate |
| In the resting muscle fiber glucose is mostly stored as an energy rich polysaccharide | glycogen |
| glycogen | a branching polysaccharide produced by combining molecules of glucose |
| Glycogen is mostly used during a muscle’s ________ response and in ________ exercise | rapid, prolonged |
| As a muscle enters moderate activity, __________ is quickly metabolized. Metabolism then centers around the catabolism of ________ | creatine phosphate, glucose |
| The energy source that provides for prolonged ATP production is | glucose |
| aerobic pathway | The pathway that provides the most energy for each molecule of glucose |
| Glucose continues as the primary source of energy for a muscle in _____ activity. | peak |
| Muscles in both moderate and peak metabolize glucose ________. However, a muscle in peak activity increases the rate of ________ metabolism | aerobically, anaerobic |
| The rate of glycolysis can increase about 100x faster than in ______ metabolism | aerobic |
| Pyruvic acid that is not destined to enter the mitochondria for oxidation is converted to | lactic acid |
| Two general categories of skeketal muscle fibers | type I and II |
| glucose | The primary source of fuel in moderate and peak activity for both types of fibers |
| Type I fibers are also called | slow twitch red fibers |
| Type I fibers have abundant _______ and depend mostly upon the aerobic (mitochondrial) pathway of glucose oxidation. | mitochondria |
| Type I fibers are rich in the oxygen binding molecule, _________, and thus are also called _____ fibers. | myoglobin, red |
| Type II fibers are also called | fast twitch white fibers |
| Type II fibers have relatively few mitochondria and depend mostly upon the _________ (glycolytic) pathway of glucose oxidation. | mitochondria, anerobic |
| Type II fibers are rich in stored fuel called | glycogen |
| Type II fibers are low in oxygen binding _______, and are called ______ fibers | myoglobin, white |
| smooth muscle characteristics | lacks striations, cells have a single nucleus, cells are spindle shaped |
| Smooth muscle is contains both thin and thick _________. However, the filaments are not organized into _______. | filaments, myofibrils |
| dense bodies are found at | the association of intermediate filaments with the sarcolemma. |
| single unit smooth muscle is organized | in large groups of fibers that function as a single unit |
| single unit smooth muscle is found | in the internal organs (except the heart) |
| The outer layer of smooth muscle is called the ________ layer, and the inner layer is the _________ layer | longitudinal, circular |
| Contraction of the _____ layer lengthens the organ and constricts the internal cavity. | circular |
| Contraction of the _________ layer of smooth muscle shortens the organ and causes a dilation of its internal cavity | longitudinal |
| gap junctions | The cell junctions that allow the spread of action potentials from cell-to-cell |
| peristaltic waves | Wave-like contractions of single-unit smooth muscle in the digestive tract |
| similarities of contraction of smooth and skeletal muscle | Both have the contractile proteins actin and myosin, ATP provides the source of energy, Low levels of ionic calcium terminates contraction, Increased levels of ionic calcium initiates contraction |
| All initiators of muscle contraction lead to an _______ of ionic calcium | increase |
| Most of the calcium ions originate from the _________ environment | extracellular |
| The calcium ions bond to | calmodulin |
| The ________ complex activates an enzyme called myosin light chain kinase (MLCK). | calcium- calmodulin |
| Myosin light chain kinase (MLCK) catalyzes the transfer of phosphate from ATP to the light chain region of the myosin head, thus, producing ____________ | high energy myosin |
| Contraction begins when myosin binds with actin and results in the inward sliding of the __________. | thin filaments |
| Contraction of smooth muscle ends when the concentration of _______ is/are reduced to its original level | ionic calcium |
| The function of the _________ response of smooth muscle is to reduce tension in organs that are stretched by filling | stress relaxation |
| During stretch the contractile filaments are rearranged, thus, maintaining _________ interactions. | cross bridge |
| cardiac muscle characteristics | fibers are short, form branching chains, striated |
| Like skeletal and smooth muscle, contraction is dependent upon the presence of ________ | calcium ions |
| Like smooth muscle, most of the calcium ions are delivered from the __________ environment | extracellular |
| Gap junctions and desmosomes are found at the _________. | intercallated discs |
| ________ allow the transmission of small ions and function as a direct electrical connection | gap junction |
| Desmosomes provide _________ connections between adjacent cells | mechanical |
| _________ cells undergo spontaneous depolarization | pacemaker |
| The __________ cells of the heart are controlled by the autonomic nervous system | pacemaker |
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