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Chapter 6 Muscle
| Question | Answer |
|---|---|
| Four major functional characteristics of muscle | Contractility, excitability, extensibility, and elasticity |
| The ability pf skeletal muscle to shorten with force. | Contractility |
| The capacity of skeletal muscle to respond to a stimulus. | Excitability |
| The ability to be stretched. | Extensibility |
| Ability to recoil to their original resting length after they have been stretched. | Elasticity |
| What helps to produce heat essential or maintenance of normal body temperature. | Muscles |
| Each skeletal muscle is surrounded by a connective sheath called. | Epimysium |
| Another connective tissue located outside the epimysium. | Fascia |
| A muscle is composed of numerous visible bundles called | fasciculi |
| Fasiculi are surrounded by what? | Loose connective tissue |
| The fasciculi are composed of single muscle cells called? | Fibers |
| Each fiber is surrounded by a connective tissue sheath called the? | Endomysium |
| The cytoplasm of each fiber is filled with? | Myofibrils |
| Myofibrils | A threadlike structure that extends from one end of the fiber to the other. |
| Myofibrils consist of 2 major kinds of protein fibers called? | Actin myofilaments, and myosin myofilaments |
| Actin myofilaments | Thin myofilaments. They resemble 2 minute strands of pearls twisted together. |
| Myosin myofilaments | Thick myofilaments. They resemble bundles of minute golf clubs. |
| Actin and myosin myofilaments form highly ordered units called? | Sarcomeres |
| Sarcomeres are joined end to end to form the? | Myofibril |
| What is the basic structural and functional unit of the muscle? | Sarcomere |
| Each sarcomere extends from? | One z line to another z line |
| Each z line is an attachment site for what? | Actin |
| The arrangement of actin and myosin give a what type of appearance? | A banded appearance |
| The A band extends the length of what? | Myosin |
| In the center of each sarcomere is another light area called what? | H zone |
| What does the H zone only consist of? | Myosin |
| The myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called? | M line |
| The outside most cell membranes are what type of charged? | Positively charged |
| The inside of the cell membrane is what type of charged? | Negatively charged |
| The charge difference across the membrane is called the? | Resting membrane potential |
| The brief charge is called | Actin potential |
| Nerve cells that carry actin potentials to skeletal muscle fibers | Motor Neurons |
| Each branch that connects to the muscle forms a | Neuromuscular junction |
| Branch that connects to the muscle near the center of the cell | Synapse |
| A single motor neuron and all the skeletal muscle fibers it innervates are called a | Motor neuron |
| Many motor units form a | Single muscle |
| A neuromusclular junction is formed by an | Enlarged nerve terminal resting in an indentation of the muscle cell membrane |
| The enlarged terminal is the | Presynaptic terminal |
| The space between the presynaptic terminal and the muscle cell is the | Synaptic cleft |
| Muscle fiber is the | Postsynaptic terminal |
| Each presynaptic terminal contains | Synaptic vesicles |
| Synaptic vesicles that secrete a neurotransmitter called | Acetylcholine |
| When an action potential reaches the nerve terminal, it causes the synaptic vesicles to releases acetylcholine into the synaptic cleft by | Exocytosis |
| The combination of acetylcholine with its receptor causes an influx of what? | Sodium ions into the muscle fiber |
| The influx initiates an action potential in the muscle cell, which causes it to do what? | Contract |
| The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes what? | Acetylcholinesterase |
| When does the muscle contraction occur? | Occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten |
| When the sarcomeres shorten it causes the muscle too do what? | Shorten |
| The sliding of actin myofilaments past myosin myofilaments during contraction called the | Sliding filament mechanism |
| The H and I bands shorten, but A bands do not change in length. True or false | True |
| 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 |
| Point the muscle fiber will contract maximally is called what | all-or-none response |
| The time between application of a stimulus to a motor neuron and the beginning of a contraction is the | Lag phase |
| The time of contraction is the | Contraction phase |
| The time during which the muscle relaxes is the | Relaxation phase |
| Where the muscle remains contracted without relaxing | Tetany |
| The increase in number of motor units being activated is called what | Recruitment |
| Used for energy for muscle contraction | Adenosine triphosphate |
| ATP is produced in what | Mitochondrion |
| ATP is short-lived and unstable true or false | True |
| Plus phosphate | Adenosine dishosphate |
| It is necessary for muscle cells to constantly produce what | ATP |
| When at rest they cant stockpile ATP but they can store another high-energy molecule called | Creatine phosphate |
| Without oxygen | Anaerobic respiration |
| With oxygen | Aerobic respiration |
| The amount of oxygen needed in chemical reactions to covert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells | Oxygen debt |
| Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells | Muscle fatigue |
| (equal distance) the length of the muscle does not change, but the amount of tension increases during the contraction process | Isometric |
| (equal tension) the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes | Isotonic |
| Muscle tone refers to the constant tension produced by muscles of the body for long periods of time. Keeps head up straight | Muscle tone |
| Contract quickly and fatigue quickly. Well adapted to preform anaerobic metabolism | Fast-twitch fibers |
| Contract more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism | Slow-twitch fibers |
| The most stationary end of the muscle | Origin |
| The end of the muscle undergoing the greatest movement | Insertion |