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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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