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chapter 6 flashcards
Anatomy
Term | Definition |
---|---|
The ability of skeletal muscle to shorten with force. | Contractility |
The capacity of skeletal muscle to respond to a stimulus. | Excitability |
The ability to be stretched. | Extensibility |
The ability to recoil to their original resting length after they have been stretched. | Elasticity |
They help to produce heat essential for maintenance of normal body temperature. | Mescles |
Each skeletal muscle is surrounded by a connective tissue sheath called... | Epimysium |
This is another connective tissue located outside the epimysium. It surrounds and separates muscles. | Fascia |
A muscle is composed of numerous visible bundles called... | Muscle Fasciculi (fascicle) |
Fascicle which are surrounded by loose connective tissue called... | Perimysium |
The fasciculi are composed of single muscle cells called... | Fibers |
Each fiber is surrounded by a connective tissue sheath called... | Endomysium |
The cytoplasm of each fiber is filled with... | Myofibrils |
A threadlike structure that extends from one end of the fiber to the other. | Myofibrils |
What are the four major functional characteristics of the skeletal muscle? | Contractility, Excitability, Extensibility, and Elasticity |
Myofibrils consist of 2 major kinds of protein fibers... | Actin Myofilaments, and Myosin Myofilaments |
Thin myofilaments | Actin Myofilaments |
Thick myofilaments | Myosin Myofilaments |
They resemble 2 minute strands of pearls twisted together. | Actin |
They resemble bundles of minute golf clubs. | Myosin |
Actin and myosin myofilaments form highly ordered units called... | Sarcomeres |
Sarcomeres | Which are joined end to end to form the myofibril. |
The arrangement of actin and myosin give... | Banded appearance |
On each side of the Z line is a light area called... | I band |
The A band extends the length of the... | Myosin |
In each sarcomere... | The center region is darker. |
In the center of each sarcomere is another light area called... | H zone |
The myosin myofilaments are anchored in center of the sarcomere at a dark staining band called... | M line |
The outside of most cell membranes is positively charged compared to the inside of... | Cell membrane |
The charged difference across the membrane is called... | Resting Membrane Potential |
When a muscle cell is stimulated the membrane characteristics... | Change briefly |
The brief reversal back of the charge is called... | Action Potential |
Nerve calls that carry action potentials to skeletal muscle fibers. | Motor Neurons |
Axons enter... | The muscles and branch. |
Each branch that connects to the muscle forms a... | Neuromuscular Junction |
Near the center of the cell. | Synapse |
A single motor neuron and all the skeletal muscle fibers it innervates are called... | Motor Unit |
Many motor unit form... | Single muscle |
A neuromuscular junction is formed by an enlarged nerve terminal resting in an indentation of the... | Muscle cell membrane |
The enlarged nerve terminal is the... | Presynaptic terminal |
The space between the presynaptic terminal and the muscle cell is the... | Synaptic cleft |
The muscle fiber is... | Postsynaptic terminal |
Each presynaptic terminal contains... | Synaptic vesicles |
Synaptic vesicles that secrete a neurotransmitter called... | Acetylcholine |
The diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a changed in the... | Postsynaptic cell |
When an action potential reaches the nerve terminal, is causes... | synaptic vesicles to release acetylcholine into synaptic cleft and exocytosis. |
The acetylcholine diffuses across the synaptic and binds to receptor molecules in the... | Sarcolemma |
The combination of acetylcholine with its receptor causes... | An influx of sodium ions into the muscle fiber. |
The influx initiates an action potential in the... | Muscle cell |
The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes... | Acetylcholinesterase |
Occurs as actin and myosin myofilaments slide past one another causing... | Sarcomeres to shorten |
When the sarcomeres shorten it causes the muscles to... | Shorten |
The sliding of actin myofilaments past myosin myofilaments during contraction is called... | Sliding filament mechanism of muscle contraction. |
Bands that do not change length... | A bands |
Bands that shorten... | H and I bands |
Is a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers. | Muscle twitch |
A muscle fiber will not respond to stimulus until that stimulus reaches a level called... | Threshold |
This phenomenon is called... | All-or-none response |
The time between application of a stimulus to a motor neuron and beginning of a contraction is the... | Leg phase |
The time of contraction is the... | Contraction phase |
The time during which the muscle relaxes is the... | Relaxation phase |
If successive stimuli are given you get successive twitches that occur so frequently the muscle doesn't have time to... | Fully relax |
Where the muscle remains contracted without relaxing. | Tetany |
The increase in number of motor units being activated is called... | Recruitment |
When at rest they can't stockpile ATP but they can store another high-energy molecule, called... | Creatine phosphate |
Without oxygen | Anaerobic respiration |
With oxygen | Aerobic respiration |
Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells. | Muscle fatigue |
2 types of muscle contractions. | Isometric, and Isotonic |
Equal distance this length of the muscle does not change, but the amount of tension increases during contraction process. | Isometric |
Equal tension the amount of produced by the muscle is constant during contraction, but the length of the muscle changes. | Isotonic |
Refers to constant tension produced by muscles of the body for long periods of time. | Muscle tone |
Contract quickly and fatigue quickly. | Fast-twitched fibers |
Contract more slowly and are more resistant to fatigue. | Slow-twitch fibers |
Is the most stationary end of the muscle. | Origin (head) |
Is the end of the muscle underdog the greatest movement. | Insertion |
The portion of the muscle between the origin and the insertion is the... | Belly |
Muscles that work together to accomplish specific movements are called... | Synergists |
Muscles that work in opposition to one another are called... | Antagonists |