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Chapter 6- Muscles
| Four major functional characteristics | Contractility, excitability, extensibility, elasticity |
| Elasticity | Ability to recoil to their original resting length after being stretched |
| Extensibility | The ability to be stretched |
| Excitability | The capacity of skeletal muscle to respond to a stimulus |
| Contractility | The ability of skeletal muscle to shorten with force |
| Epimysium | Surrounds each skeletal muscle |
| Muscles help to produce what essential for maintenance of normal body temperature? | Heat |
| Fascia | Located outside of the emimysium and surrounds and seperates muscles |
| Perimysium | Surrounds the muscle fascicles, loose connective tissue |
| The fasciculi (fascicles) are composed of single muscle cells called what? | Fibers |
| Endomysium | Each fiber that is surrounded by connective tissue |
| The cytoplasm of each fiber is filled with ________. | myofibrils |
| What is a myofibril? | A threadlike structure that extends from one end of the fiber to the other. |
| Myofibrils consist of what 2 major kinds of protein fibers? | Actin and myosin myofilaments |
| Actin myofilaments | Thin, resemble 2 minute strands of pearls twisted together |
| Myosin myofilaments | Thick, resemble bundles of mini golf clubs |
| True/False: Actin myofilaments are thick | False |
| True/False: Myosin myofilaments are thick | True |
| Actin and myosin myofilaments form highly ordered units called _________. | Sarcomeres |
| Sarcomeres | Joined end to end to form the myofibril |
| Where does each sarcomere extend to? | From one Z line to another Z line |
| Each Z line is an attachment site for what? | Actin |
| On each side of the Z line is a light area called what? | I band |
| What does the I band consist of? | Actin |
| The A band extends the length of the _______. | Myosin |
| True or False: The A band is the darker central region in each sarcomere | True |
| In the center of each sarcomere is another area called the what? | H zone |
| Is the H zone light or dark? | Light |
| What does the H zone only consist of? | Myosin |
| Where is the M line located? | The Myosin myofilaments are anchored in the center of the sarcomere |
| Is the M line light or dark? | Dark |
| What is the charge difference across the membrane? | Resting membrane potential |
| What are Motor Neurons? | Nerve cells that carry action potentials to skeletal muscle fibers |
| Each branch that connects to the muscle forms a what? | neuromuscular junction |
| Motor unit | A single motor neuron and all the skeletal muscle fibers it innervates |
| Presynaptic terminal | The enlarged nerve terminal |
| What is the space between the presynaptic terminal and the muscle cell? | Synaptic cleft |
| Postsynaptic terminal | The muscle fiber in the nerve supply |
| Each presynaptic terminal contains what? | Synaptic vesicles |
| What do synaptic vesicles secrete that is a neurotransmitter? | Acetylcholine |
| Where is the acetylcholine? | It diffuses across the synaptic cleft and binds the postsynaptic terminal |
| Acetylcholinesterase | Rapidly breaks down acetylcholine by an enzyme |
| Muscle Contraction | Occurs as actin and myosin myofilaments |
| Sliding filament mechanism | The sliding of actin myofilaments past myosin myofilaments |
| Muscle twitch | A contraction of an entire muscle in response to a stimulus |
| The time between application of a stimulus to a motor neuron is called what? | Lag phase |
| The time of contraction is the what? | Contraction phase |
| The time during which the muscle relaxes is called the what? | Relaxation phase |
| Tetany | The muscle remains contracted without relaxing |
| The increase in number of motor units being activated is called what? | Recruitment |
| ATP means what? | Adenosine triphosphate |
| Where is ATP produced? | In the mitochondria |
| True/False: ATP is short-lived and unstable | True |
| ADP means what? | Adenosine diphosphate |
| What means without oxygen? | Anaerobic respiration |
| What means with oxygen? | Aerobic respiration |
| Oxygen debt | The amount of oxygen needed in chemical reactions |
| Muscle fatigue | When ATP is used during muscle contraction faster than it can be produced in the muscle cells |
| Isometric | Length does not change, amount of tension increases |
| Isotonic | Tension stays the same, length of the muscle changes |
| Muscle Tone | Constant tension produced by muscles of the body for long periods of time |
| Fast-twitch fibers | Contract quickly and fatigue quickly |
| Slow-twitch fibers | Contract more slowly and are more resistant to fatigue |
| True/False: Fast-twitch fibers are well adapted to preform anaerobic metabolism | True |
| True/False: Slow-twitch fibers are better suited for aerobic metabolism | True |
| Origin | The most stationary end of the muscle |
| Insertion | The end of the muscle |
| True/false: Insertion has the most movement in the muscle | True |
| What portion of the muscle is between the origin and the insertion? | The belly |
| Some muscles have multiple what? | Origins |
| Muscles that work together to accomplish specific movements are called what? | Synergists |
| Muscles that work in opposition are called what? | Antagonists |
| Prime mover | If one muscle plays a major role in accomplishing the desired movement |
| How are some muscles described? | Size, shape, origin... |
| When he sarcomeres shorten it causes the muscle to what? | Shorten |
Created by:
austinbryant
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