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Chapter 6 Muscle

muscle flashcards

QuestionAnswer
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 are four major functional characteristics of skeletal muscle? contractility, excitability, extensibility, and elasticity
What do muscles help produce? heat essential for maintenance of normal body temperature
Each skeletal muscle is surrounded by a connective tissue sheath called? epimysium
Is another connective tissue located outside the epimysium. fascia
A muscle is composed of numerous visible bundles called fasciculi(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 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 consists of what two major kinds of protein fibers? actin myofilaments and myosin myofilaments.
Actin and myosin myofilaments form highly ordered units called? sarcomeres
What are actin myofilaments? thin myofilaments
What do actin myofilaments resemble? they resemble 2 minute strands of pearls twisted together.
What are myosin myofilaments? thick myofilaments.
What do myosin myofilaments resemble? they resemble bundles of minute golf clubs
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
On each side of the Z line is a light area called what? I band
What does the I band consist of? actin
The A band extends what? the length of the myosin
What is the darker central region in each sarcomere? the A band
In the center of each sarcomere is another light area called what? the H zone
What does the H zone consist of? it consists of only myosin
The myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called the? M line
The charge difference across the membrane is called the? resting membrane potential
The brief reversal back of the charge is called? action potential
What are motor neurons? are nerve cells that carry action potentials to skeletal muscle fibers
What do axons enter? the muscles and branch
Each branch that connects to the muscle forms a? neuromuscular junction or synapse
A single motor neuron and all the skeletal muscle fibers it innervates are called a ? motor unit
What is a neuromuscular junction 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
Each presynaptic terminal contains what? synaptic vesicles
Synaptic vesicles secretes a neurotransmitter called what? acetylcholine
What diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell? acetylcholine
What occurs when actin and myosin myofilaments slide past one another causing the sarcomeres to shorten? muscle contraction
What is the sliding of actin myofilaments past myosin myofilaments during contraction called? sliding filament mechanism
What is muscle twitch? It is a contraction of an entire muscle in response to a stimulus that causes the actin potential in one or more muscle fibers.
A muscle fiber will not respond to stimulus until that stimulus reaches a level called what/ threshold
What is threshold? at which point the muscle fiber will contract maximally.
The time between application of a stimulus to a motor neuron and the beginning of a contraction is the? lag phase
What is a contraction phase? the time of contraction
What is the relaxation phase? the time during which the muscle relaxes.
What is tetany? where the muscle remains contracted without relaxing.
What is the increase in number of motor units being activated? recruitment
What is needed for energy for muscle contraction? ATP(adenosine triphosphate)
What is produced in the mitochondria? ATP( adenosine triphosphate)
What respiration is without oxygen? anaerobic
What respiration is with oxygen and (more efficient)? aerobic
What is the oxygen debt? the amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells.
What results when ATP is used during muscle contraction faster than it can be produced in muscle cells? muscle fatigue
What are the 2 types of muscle contractions? isometric and isotonic
The length of the muscle does not change, but the amount of tension increases during the contraction process. ( equal distance) Isometric
The amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes. ( equal tension) isotonic
What is muscle tone? it refers to constant tension produced by muscles of the body for long periods of time.
What contracts quickly and fatigue quickly? fast-twitch fibers
Is fast-twitch fibers more adapted to anaerobic metabolism or aerobic metabolism? anaerobic metabolism
What contracts more slowly and is more resistant to fatigue/ slow-twitch fibers
Is slow-twitch fibers more adapted to anaerobic metabolism or aerobic metabolism? aerobic metabolism
White meat is an example of which twitch fiber? fast- twitch fiber
Dark meat is an example of which twitch fiber? slow- twitch fiber
What is the most stationary end of the muscle? origin (head)
What is the end of the muscle that undergoes the greatest movement? insertion
The portion of the muscle between the origin and the insertion is the what? belly
Muscles that work together to accomplish specific movements are called what? synergists
Muscles that work in opposition to one another are called what? antagonists
If one muscle plays the major role in accomplishing the desired movement that muscle is called what? prime mover
Muscles are named according to their what? location, size, orientation of fibers, shape, origin, insertion, and function
What muscle raises the eyebrow? occipitofrontalis
What closes the eyelids and causes ''crows feet'' at the corners of the eyes? orbicularis oculi
What muscle puckers the lips? orbicularis oris
What muscle flattens the cheeks and is also known as the trumpeter's muscle? buccinator
What is the smiling muscle? zygomaticus
What is mastication? chewing
What are the 4 pairs of mastication muscles? 2 pairs of pterygoids, temporalis, and masseter
Which of the tongue muscles changes the shape of the tongue? Intrinsic tongue muscles
Which of the tongue muscles moves the tongue? extrinsic tongue muscles
Sternocleidomastoid is the what? lateral neck muscle and the prime mover of the neck
What are group of muscles on each side of the back called? erector spinae
What do external intercostals do? elevate the ribs during inspiration
What do internal intercostals do? contract during forced inspiration
What accomplishes quiet breathing? the diaphragm
Created by: alysongue