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Chapter 6-Muscles
Anatomy/Physiology
| Question | Answer |
|---|---|
| What is contractility? | The ability of skeletal muscle to shorten with force. |
| What is excitability? | The capacity of skeletal muscle to respond to a stimulus. |
| what is extensibility? | The ability to be stretched. |
| What is elasticity? | The ability to recoil to their original resting length after they have been stretched. |
| What is the epimysium? | The sheath that surrounds eacch connective tissue. |
| What is the perimysium? | Loose coonective tissue that surrounds visible muscle fibers. |
| what is the fascia? | Another connective tissue that located outside the epimysium. |
| What are fibers? | Single muscle cells that composite fasciculi. |
| What are myofibrils? | A threadlike structure that extends from one end of the fiber to the other end of the fiber. |
| What are actin myofilaments? | Thin myofilament s that resemble 2 minute strands of pearls twisted together. |
| What are myosin filaments? | Thick myofilaments that resemble bundles of minute golf clubs. |
| What are sacromeres? | Actin and myosin myofilaments form highly ordered units. |
| What is resting membrane potential? | The charge difference across the membrane. |
| What is action potential? | The brief reversal back of the charge. |
| What are motor neurons? | Are nerve cells that carry action potentials to skeletal muscle fibers. |
| What is a neuoromuscular junction, or a synapse? | Axons enter the muscles and branch. Each branch that connects to the muscle. |
| What is a motor unit? | A single motor neuron and all the skeletal muscle fibers it innervates. |
| What is a presynaptic terminal? | The enlarged terminal. |
| What is the synaptic cleft? | The space between the presynaptic terminal and the muscle cell. |
| What is the postsynaptic terminal? | The muscle fiber. |
| Where are synaptic vesicles located? | In the presynaptic terminal. |
| What is acetylcholine? | A neurotransmitter that is secreted by synaptic vessels. |
| What is acetycholinesterase? | When the acetylcholine is released into the synaptic cleft between the neuron and muscle cell is broken down by enzymes. |
| What is a sliding filament mechanism? | The sliding of actin myofilaments past myosin myofilaments during contraction. |
| What is a muscle twitch? | A contraction of an entire muscle in respone to a stimulus that causes the action potential in one or more muscle fibers, |
| What is the treshold? | A level that is reached required to stimulate a muscle fiber. |
| What is the all or none response? | Whether or not a muscle fiber has been stimulated enough to operate fully or not at all. |
| What is the lag phase? | The time between application of a stimulus to a motor neuron and the beginning of a contraction. |
| What is the contraction phase? | The time of contraction. |
| What is the relaxation phase? | The time during which the muscle relaxes. |
| What is tetany? | Where the muscle remains contracted without relaxing. |
| What is recruitment? | The increase in the number of motor units being activated. |
| What is creatine phosphate? | A high-energy molecule. |
| What is anaerobic respiration? | Being without oxygen. |
| What is aerobic respiration? | Being with oxygen (more efficient). |
| What is oxygen debt? | The amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replinish the depleted stores of creatine phosphate stores in muscle cells. |
| What is muscle fatigue? | Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells. |
| What is the meaning of isometric? | When the length of the muscle does not change, but the amount of tension increases during the contraction process. |
| What is the meaning of isotonic? | The amount of tension produced by the muscle is constant during contraction, but the length if the muscle changes. |
| What is muscle tone? | Refers to constant tension produced by muscles of the body for long periods of time. Keeps heads up and backs straight. |
| What are fast-twitch fibers? | They contract quickly and fatigue quickly. Well adapted to performanaerobic metabolism. |
| What are slow-twitch fibers? | They contract more slowly and are more resistant to fatige. They are better suited for aerobic metabolism. |
| What is the origin? | The most stationary end of the muscle. |
| What is insertion? | The end of the muscle undergoing the greatest movement. |
| What is the belly? | The portion of the muscle between the origin and the insertion. |
| What are synergists? | Muscles that work together to accomplish specific movements. |
| What are antagonists? | Muscles that work in opposition to one another. |
| What is the prime mover? | The one muscle that plays a major role among a group of synergists. |
| Muscles help produce what that is essential for maintenance of normal body temperature? | Heat. |
| What does the fascia do? | It surrounds and seperates muscles. |
| What is a single cylindrical cell containing several nuclei? | A muscle fiber. |
| What is the cytoplasm of each fiber filled with? | Myofibrils. |
| Myofibrils consist of how mmany kinds of major proteins? | Two. |
| Sacromeres are joined end to end to form what? | The myofibril. |
| The sacromere is the basic structural and functional unity of what? | Muscle. |
| Each sacromere extens from one Z line to what other line? | A Z line. |
| Each Z line is an attachment site for what? | Actin. |
| The arrangement of actin and myosin give what kind of appearance? | Banded. |
| On each sid of the Z line there is a band that consists of actin called what? | An I band. |
| The A band extends the length of what? | The myosin. |
| What is darker than the central region in each sacromere? | The A band. |
| In the center of each sacromere is another light area which consists of only myosin called what? | The H zone. |
| The myosin myofilaments are anchored in the center of the sacromere at a dark staining band called what? | The M line. |
| The outside of most cell membranes is positively charged compared to the outside of the cell membrane which has what kind of a charge? | A negative charge. |
| When what is stimulated causes the membrane characteristics to briefly change? | The muscle cell. |
| Axons enter what? | The muscles and branch. |
| Many motor units form what? | A single muscle. |
| A neuromuscular junction if formed by what? | An enlarged nerve terminal restin in an indentation of the muscle membrane. |
| What diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell? | Acetylcholine. |
| When an action potential reaches the nerve terminal, what happens? | It causes the synaptic vessels to release acetylcholine into the synaptic cleft by exocytosis. |
| What diffuses across the synaptic cleft and binds to receptor molecules in the muscle membrane? | The acetylcholine. |
| What is the muscle cell membrane called? | Sarcolemma. |
| The combination of acetylcholine with its receptor causes an influx of what? | Sodium ions into the muscle fiber. |
| What causes the muscle to contract? | An influx of sodium ions which initiates the action potential. |
| What enzymatic breakdown ensures that one action potential in the neoron yields only one action potential in the skeletal muscle, and only one contraction of the muscle cell? | Acetycholinesterase. |
| Muscle contraction occurs when what happens? | When the actin and myofilaments slide past one another causing the sacromeres to shorten. |
| When the sacromeres shorten what else do they cause to shorten? | Muscle. |
| In muscle contraction, when the H and I bands shorten, which band does not change in length? | The A band. |
| If successive stimuli is given you get excessive what that occurs so frequently because the muscle doesn't have time to fully relax? | Twitches. |
| What is needed for energy for muscle contraction? | ATP |
| What does ATP stand for? | Adenosine Triphosphate. |
| Where is ATP produced? | In the mitochondria. |
| What is short-lived and unstable that eventually degenerates to more stable ADP plus phosphates? | ATP |
| What does ADP stand for? | Adenosine Diphosphate. |
| Constant ATP production isn't neccessary for the movement of what? | Muscles. |
| What high-energy molecule cannot be stockpiled while at rest? | ATP |
| During periods of inactivity as excess ATP is produced in the muscle cell, the energy contained in ATP is used to synthesize what? | Creatine Phosphate. |
| During perios of activity, the energy stored in creatine phosphate can be accessed quickly and used to produce ATP, which can then be used in what? | Muscle Contraction. |
| After intense exercise, what remains elevated for a period of time even though the muscles are no longer actively contracting? | Respiration Rate. |
| What provides the oxygen to payback the oxygen debt? | Increased respiration. |
| How many types of muscle contractions are there? | Two. |
| What are the two types of muscle contracitons called? | Isometric, and isotonic. |
| The points of attachment of each muscle are where? | It's origin and insertion. |
| At points of attachment muscle is connected to the bone by what? | Tendons. |
| What has multiple origins or heads? | Some muscles. |
| Most what have names that are descriptive? | Muscles. |
| What are muscles named according to? | Location, size, orientation of fibers, shape, origin, insertion, function, etc. |
| How many major functional characteristics are there to skeletal muscle? | Four. |
| What are the four major functional characteristics to skeletal muscle? | Conractility, Excitability, Extensibility, Elasticity. |
| Where is the I band located? | Between the Z band and the A band. |
| A sacromere consists of what? | One Z line to the left, and one to the right, while there is one I band accompanying each on the introverted side of each Z line, with an M line in btween the pair of A bands. |
| Where is the H zone located? | Around the perimeter of the M line. |
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davidpauley11
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