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Chapter 6 Muscle

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
Created by: chybug2727



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