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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 |