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a&p chapter 10
| Question | Answer |
|---|---|
| made up of long muscle cells arranged parallel to one another | skeletal muscle tissue |
| skeletal muscle cells are known as _________ due to their length and appearance | fibers |
| skeletal muscle fibers are ___________ cells whose contractions are _______ | multinucleated, voluntary |
| striated muscle tissue are found attached by | connective tissue to the skeleton |
| cardiac muscle cells are found only in the | heart |
| each cardiac muscle cells is | short and highly branched; has one to two nuclei |
| joins adjacent cells | intercalated discs |
| intercalated discs contain | gap junctions and desmosomes (modified tight junctions) |
| cardiac muscle contraction is | involuntary |
| smooth muscle cells do not have | striations |
| where are smooth muscle cells found | lining most hollow organs in the eye, skin, and some glandular ducts |
| smooth muscle cells are linked to one another by | gap junctions |
| gap junctions allow for | synchronized contraction |
| ability to contract where proteins in the cell draw closer together | contractibility |
| ability of a cell to respond to a stimulus | excitability |
| ability of a cell to conduct electrical changes across the plasma membrane | conductivity |
| ability of a cell that allows it to be stretched without being ruptured | extensibility |
| ability of a cell that allows it to return to its original length after it has been stretched | elasticity |
| muscle cells that are described using specialized terminology | myocytes |
| the myocytes cytoplasm | sarcoplasm |
| the myocytes plasma membrane | sarcolemma |
| modified endoplasmic reticulum | sarcoplasmic reticulum |
| sarcoplasmic reticulum forms a weblike network surround the | myofibrils |
| found in great numbers in the myocyte | organelles |
| organelles are made up of bundles of ________ that allow for contraction | specialized proteins |
| smooth muscle cells myofibril arrangement is | different than cardiac and skeletal muscle cells |
| skeletal muscle tissue consists of | fibers and their surrounding endomysium |
| surrounds the myofibrils and stores and releases calcium ions | sarcoplasmic reticulum |
| deep inward extensions of sarcolemma that surround each myofibril | transverse tubules |
| t tubules are filled with | extracellular fluid |
| enlarged sections of SR found flanking each t tubule | terminal cisternae |
| two terminal cisternae and their corresponding t tubule form a | triad |
| each myofibril is made of hundreds to thousands | myofilaments |
| myofilaments consist of | contractile, regulatory, structural proteins |
| generate tension | contractile proteins |
| dictate when a fiber may contract | regulatory proteins |
| maintain proper myofilament alignment and fiber stability | structural proteins |
| three types of myofilaments | thick, thin, elastic |
| composed of the bundles of the contractile protein myosin | thick filaments |
| composed of the proteins actin, tropomyosin, and troponin | thin filaments |
| stablizes the myofibril structure and resists excessive stretching force | titin |
| composed of structural protein called titin | elastic filaments |
| composed of the contractile protein myosin | thick filaments |
| each myosin has | globular heads linked by intertwining tails |
| myosin heads are connected to the tails by | a hinge like neck |
| each myosin head has | an active site that binds with actin |
| subunits string together like beads on a necklace to form the two intertwining strands in the functional thin filament | multiple actin |
| long rope like regulatory protein that twists around actin | tropomyosin |
| small globular regulatory protein that holds tropomyosin in place and assists with turning contractions on and off | troponin |
| multiple muscle fibers form a | fascicle |
| each fascicle is surrounded by a later of connective tissue called | perimysium |
| come together at the end of the muscle to form a tendon that binds the muscle to its attaching structure | perimysium and epimysium |
| skeletal muscles are enclosed by a layer of thick connective tissue called | fascia |
| where only thin filaments are found | light bands |
| where both thin and thick filaments are found | dark bands |
| composed only of thin filaments | the I band |
| found in the middle of the I band | Z disc |
| contains the zone of overlap | the A band |
| where we find both thick and thin filaments | the zone of overlap |
| middle of the A band where only thick filaments exist | the H zone |
| dark line in the middle of the A band, made up of structural proteins that hold the thick filaments in place | M line |
| extends from one Z disc to the next | sacromere |
| where contraction occurs | functional unit |
| explains how tension is generated | sliding filament mechanism |
| what happens during contraction | both the I band and the H zone narrow while the A band remains unchanged |
| due to an unequal distribution of ions near the plasma membrane | membrane potentials |
| membrane potentials result in a | polarized resting state |
| a thin layer of negatively charged ions exists in the cytosol on the _______ of the cell while a thin layer of positively charged ions exists on the _________ of the cell | inside; outside |
| the separation of charges created an ____________ | electrical gradient |
| the electrical gradient represents a source of | potential energy |
| when the barrier separating the ions is removed, what happens? | they follow their gradients and the potential energy becomes kinetic energy |
| electrical gradient can be referred to as an | electrical potential |
| cytosol and extracellular fluid are always | electrically neutral |
| electrical potential exists where? | across the plasma membrane |
| a difference in charge between two points is called | a voltage |
| the phospholipid bilayer of any plasma membrane is | impermeable to charge particles |
| change only when the barrier to ion movement is removed from the plasma membrane | resting membrane potentials |
| sodium and potassium ions can then move through sarcolemma using | protein channels and carriers |
| the pump moves _____ Na+ ions out and ______ K+ ions into the cell | three, two |
| is necessary because this pump moves the ions against their concentration gradients | ATP hydrolysis |
| brief changes in the membrane potential of a cell from a resting negative value to a positive value, then back to its resting negative value | action potentials |
| contains gates that are normally closed and open only in response to a stimulus | gated channels |
| action potentials are generated by | ligand gated channels, voltage gated channels |
| open in response to the presence of a chemical or ligand | ligand gated channels |
| open and close in response to changes in the membrane potential of the plasma membrane | voltage gated channels |
| begins when voltage gated Na+ channels open | depolarization |
| begins after Na+ channels have closed and voltage gated K+ channels have opened | repolarization |
| action potentials dont stay in place but they are | conducted or popagated |
| all skeletal muscles are ________ meaning they are connected to a neuron | innervated |
| a single neuron that communicates with many muscle fibers | motor neuron |
| each connection in a motor neuron is referred to as | a synapse |
| synapse where a single motor neuron communicates with many muscle fibers | NMJ |
| function of the NMJ | transmit a signal called a nerve impulse |
| three components of NMJ | axon terminal, synaptic cleft, motor end plate |
| contains synaptic vesicles filled with the neurotransmitter ACh | axon terminal |
| space between axon terminal and muscle fiber, filled with collagen fibers and a gel that anchors the neuron in place | synaptic cleft |
| specialized region of the muscle fiber plasma membrane | motor end plate |
| ligand that opens these gates | ACh |
| three phases of muscle contraction | excitation phase, excitation contraction coupling, contraction phase |
| begins when an action potential signals the release of acetylcholine from the axon terminal into the synaptic cleft | excitation phase |
| link between the stimulus and the contraction | excitation and contraction coupling |
| begins when Ca++ ions bind to troponin | contraction phase |
| ligand gated channels open when they bind acetylcholine which allows Na+ ions to enter the muscle fiber generating _____________ | an end plate potential |
| occurs as a result of sodium ion influx | end plate potential |
| the end plate potential is generated by the influx of ___________ into the motor end plate | sodium |
| acetylcholine is released from the synaptic terminus in response to | an action potential arriving at the synaptic terminus |
| the term synaptic cleft refers to | the gap between the neuron and the muscle fiber |
| the sodium channels of the motor end plate are | ligand gated channels |
| the end plate potential is | a local depolarization |
| channels that open in the sarcolemma surrounding the motor endplate and generate an action potential are | voltage gated channels |
| the term propagate when referring to an action potential means | spread |
| in order to trigger a muscle contraction, an action potential must reach the | triads |
| a triad consists of | two terminal cisternae and a t tubule |
| ________ is released from the SR in response to arrival of an action potential | Ca++ |
| calcium ions released from the terminal cisternae bind to | troponin |
| tropomyosin | covers actin active sites |
| troponin has 3 subunits. which of the following does not bind to one of these subunits | myosin |
| when does the contraction phase begin | when the actin's active site is exposed |
| the crossbridge cycle may be repeated as long as | the stimulus to contract continues and ATP is available |
| hydrolysis of ATP is responsible for | recocking of the myosin heads |
| the binding of ATP to myosin is responsible for | release of myosin heads from the actin active sites |
| the release of ADP and Pi from myosin occurs during | the power stroke |
| the myosin heads return to their low energy state during | the power stroke |
| the power stroke | pulls the thin filaments toward the M lines |
| during muscle fiber relaxation, calcium channels in the SR close because | the resting membrane potential is restored |
| during muscle fiber relaxation | calcium is pumped back into the SR |
| acetylcholinesterase in the synaptic cleft degrades acetylcholine allowing | ligand gated sodium channels to close |
| sarcolemma repolarization during relaxation | restores the resting membrane potential |
| which aspect of muscle relation requires ATP? | pumping calcium ions back into the SR |
| in skeletal muscle, ATP is required to | power, release, and pump |
| ATP is generated by | immediate cytosolic reactions, gycolytic catabolism, oxidative catabolism |
| series of reactions that occurs in all cells cytosol to break glucose down into pyruvate | glycolysis |
| requires oxygen directly, allows for longer lasting muscle contractions | oxidative catabolism |
| muscle fibers prefer to use glucose but as it becomes unavailable, they will | catabolize fatty acids and amino acids |
| smallest muscle contraction | muscle twitch |
| three phases of a twitch on a myogram | latent period, contraction period, relaxation period |
| time it takes the action potential to propagate across the sarcolemma | latent period |
| begins as repeated crossbridge cycles generate tension | contraction period |
| begins as calcium ion levels are reduced int he cytosol by SR pumps and tension diminishes | relaxation period |
| begins at the onset of the latent period and ends at the beginning of the contraction period | refractory period |
| the increase in tension caused by repeated stimulation of the muscle fiber by a motor neuron is known as | wave summation |
| results when fibers are stimulated about 50 times per second and the fiber partially relaxes between stimuli | unfused tetanus |
| occurs when the fiber is stimulated at a rate of 80 -100 stimuli per second and the fiber does not relax between stimuli | fused tetanus |
| states that the optimal length of a sarcomere is about 100-120% of the natural length of the sarcomere | length tension relationship |
| two main classes of skeletal muscle fibers | type I slow and type II fast |
| small diameter, slow twitch fibers that contract slowly to produce less force for a longer period of time | Type I fibers |
| large diameter, fast twitch fibers that fatigue quickly | type II fibers |
| a single motor neuron and all the muscle fibers that it innervates | motor unit |
| as a greater force is required more motor units must be stimulated, known as | recruitment |
| baseline level of involuntary activation of motor units by brain and spinal cord | muscle tone |
| tension generated by the muscle constant | isotonic contractions |
| maintains constant tension while the muscle shortens | isotonic cocentric contractions |
| maintains constant tension but the muscle lengthens | isotonic eccentric contractions |
| where the muscle length remains unchanged because the external force applied equals that generated by the muscle | isometric contractions |
| describes the changes in muscle structure as a result of changes in function related to physical training | myoplasticity |
| meaning that they generally do not undergo mitosis | amitotic |
| small population of unspecialized cells that do retain mitotic ability | satellite cells |
| training with a large increase in the frequency of motor unit activation and a moderate increase in force production | endurance training |
| when both the number of myofibrils and the diameter of the muscle fibers increase | hypertrophy |
| decrease in the number of myofibrils and size of the fiber and a decrease in oxidative enzymes | atrophy |
| inability to maintain a given level of intensity during activity | fatigue |
| the time it takes after exercising to return to the pre exercise state | recovery period |
| the increased rate of breathing that occurs during this period supplies the necessary oxygen | excess postexercise oxygen consumption |
| propels materials through hollow organs | peristalsis |
| actin filaments are arranged obliquely in the sacroplasm and are anchored to proteins called | dense bodies |
| alternative to relaxation where the cell remains contracted in an energy efficient mode | latch state |
| link cells together both electrically by gap junctions and physically by desmosomes | intercalated discs |
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fosterwiygu