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Chapter 6 Muscle


Contractility the ability of skeletal muscle to shorten with force
Excitability the capacity of skeletal muscle to respond to a stimulus
Extensibility the ability to be stretched
Elasticity ability to recoil to their original resting length after they have been stretched
What do muscles help? muscles help produce heat essential for maintenance of normal body temperature
Each skeletal is surrounded by a connective tissue sheath called the? epimysium
Another connective tissue located outside the epimysium fascia
A muscle is composed of numerous visible bundles called muscle fasciculi, 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 the? endomysium
The cytoplasm of each fiber is filled with? myofibrils
What are myofibrils? a threadlike structure that extends from one end of the fiber to the other
Myofibrils consist of what 2 kinds of protein fibers? actin myofilaments and myosin myofilaments
What are actin myofilaments? thin myofilaments. They resemble 2 minute strands of pearls twisted together
What are myosin myofilaments? thick myofilaments. They resemble bundles of minute golf clubs.
Actin and myosin myofilaments form highly ordered units called? sarcomeres
What is a sarcomere? the basic structural and functional unity of the muscle
Each sarcomere extends from what? from one Z line to another Z line
What do the arrangement of actin and myosin give? a banded appearance
On each side of the Z line is a light area called what? an I band
What does the I band consist of? actin
The A band extends what? the length of the myosin
In the center of each sarcomere is another light area called what? the H zone
What does the H zone consist of? myosin
The myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called what? the M line
The charge difference across the membrane is called what? the resting membrane potential
The brief reversal back of the charge is called what? action potential
Motor Neurons nerve cells that carry action potentials to skeletal muscle fibers
Each branch that connects to the muscle forms a? neuromuscular junction. or synapse near the center of the cell
A single motor neuron and all the skeletal muscle fibers it innervates are called? a motor unit
What do many motor units form? a single muscle
The enlarged nerve terminal is the? presynaptic terminal
The space between the presynaptic terminal and the muscle is the? synaptic cleft
Each presynaptic terminal contains? synaptic vesicles
Synaptic vesicles secrete a neurotransmitter called? acetylcholine
What does acetylcholine do? it diffuses across the synaptic cleft and binds to the postsynaptic terminal.
What does the combination of acetylcholine with its receptor cause? an influx of sodium ions into the muscle fiber
What does the enzymatic breakdown ensure? that one action potential in the neuron yields only one action potential in the skeletal muscle, and only one contraction of the muscle cell
The sliding of actin myofilaments past myosin myofilaments during contraction is called? sliding filament mechanism
Muscle twitch a contraction of an entire muscle in response to a stimulus.
The time between application of a stimulus until that stimulus reaches the level called? lag phase
What is the time of contraction called? contraction phase
What is the time during which the muscle relaxes called? relaxation phase
Tetany where the muscle remains contracted without relaxing
The increase in number of motor units being activated is called? recruitment
What is needed for energy for muscle contraction? ATP
What does ATP stand for? adenosine triphosphate
Where is ATP produced? in the mitochondria
What does ADP stand for? adenosine diphosphate
What does anaerobic respiration stand for? without oxygen
What does aerobic respiration stand for? with oxygen
What is oxygen debt? the amount of oxygen needed in chemical reactions
What are two types of muscle contractions? isometric and isotonic
Muscle tone Muscle tone refers to 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 resistant to fatigue
What is the origin? it is the most stationary end of the muscle
What is insertion? it is the end of the muscle undergoing the greatest movement
What is the portion of the muscle between the origin and the insertion? the belly
Muscles that work together to accomplish specific movements are called? synergists
Muscles that work in opposition to one another are called? antagonists
If someone winks at you they are using? the orbicularis oculi
The hip muscle commonly called the buttocks is also called what? the gluteus maximus
A muscle is composed of numerous bundles called? muscle fasicle
A muscle fiber will not respond to stimuli until the stimulus reaches a level called? threshold
Created by: alexismnelson



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