Chapter 10: Muscle Tissue and Muscle Organization
postural muscles contract continuously when a person is awake to prevent collapse
maintenance of posture
specialized region of the sarcolemma and increases the surface for connection of the synaptic knob
motor end plate
neurons that stimulate muscle contraction
motor neurons
composed of a single motor neuron and all of the muscle fibers it controls
motor unit
the total force exerted by the muscle depends on the number of activates ______ _____
motor units
multiple fascicles housing many muscle fibers, connect tissue coverings, blood vessels, nerve fibers
muscle
what muscle level does the epimysium cover?
muscle
elongated, multinucleated cylindrical fiber (cell); contains myofibrils, separated from other fibers by delicate layer of areolar connective tissue; exhibits striations, involved
muscle fiber (muscle cell)
what muscle level does the endomysium cover?
muscle fiber (muscle cell)
equated with responsiveness, very responsive to input from stimuli
Excitability
double-stranded contractile protein, binding site for myosin to shorten a sarcomere
actin
what are the three components of a thin filament?
actin, tropomyosin, and troponin
what is a sarcomere?
functional contractile unit of skeletal muscle and is the distance between two adjacent Z discs, and it shortens when the muscle contracts
ensheaths the three connective tissue layers, extensive sheet of dense irregular connective tissue what separates individual muscles, binds together muscles with similar functions, and forms sheaths to help distribute nerves, blood vessels, and lymphatic vessels, and to fill spaces between muscles
deep fascia
triangular muscle with common attachment site, direction of pull of muscle can be changed, does not pull as hard as equal-sized parallel muscle
convergent (ex: pectoralis major)
increase in muscle fiber size, (increased by exercising) develops more myofibrils and contains a larger amount of myofibrils, increased ability to produce ATP
hypertrophy
the length of the muscle does not change because the tension produced by this contracting muscle never exceeds the resistance (load)
isometric contraction
the tension produced equals or is greater than the resistance and then the muscle fibers shorten, resulting in movement
isotonic contraction
areolar connective tissue layer surrounding a muscle fiber
endomysium
fibrous connective tissue envelope surrounding a skeletal muscle
epimysium
blood vessels and nerve fibers extend through which two of the connective tissue components
epimysium and perimysium
what are the connective tissue coverings of skeletal muscle?
epimysium, perimysium, endomysium
has a fulcrum in the middle, between the effort and the resistance
first-class lever
synergist can also be considered ___________ by assisting the agonist by preventing movement at a joint thereby stabilizing the origin of the agonist
fixators
resting tension in a skeletal muscle
muscle tone
what are the levels of organization of skeletal muscles?
muscles, fascicle, muscle fiber (muscle cell), myofibril, myofilaments
long, cylindrical contractile element within muscle fiber; as long as the muscle fiber itself; composed of myofilaments; exhibits striations
myofibril
short contractile proteins of two types: thick (composed of myosin) and thin (composed of actin, tropomyosin, and tropnin)
myofilaments
slow fibers are also called red fibers because they contain the red pigment ____________
myoglobin
The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a ______________
neuromuscular junction
the point where a motor neuron meets a skeletal muscle fiber
neuromuscular junction
a single motor neuron typically controls __________ muscle fibers in a muscle
numerous
the less mobile attachment of a muscle
origin
some motor units are always active, even when a muscle is at ______
rest
small in diameter and contract more slowly than fast fibers
slow fibers
what are the three types of skeletal muscle fibers?
slow, intermediate, fast
composed of short muscles cells that have a fusiform shape, single central nuclei, no visible striations/sarcomeres/z discs, involuntary control
smooth muscle
the voluntary muscles are controlled by what nervous system?
somatic nervous system
Skeletal muscle tissue formation is initiated during the fourth week of development from blocks of paraxial mesoderm that form structures called ______________
somites
store the material within an organ or to facilitate movement of materials
storage and movement of materials
protect organs and support their weight within the abdominopelvic cavity
support
a narrow space separating the synaptic knob and the motor end plate
synaptic cleft
expanded tip of an axon, nerve travels through the axon, exits at this tip to the sacrolemma
synaptic knob
these are within the synaptic knob and are filled with molecules of the neurotransmitter acetylcholine (ACh)
synaptic vesicles
muscle that assists the agonist in performing its actions by contributing to tension exerted close to the insertion of the muscle or stabilizes the point of origin
synergist
heat is always produced as a waste product of this energy usage, most of this heat maintains our normal body temperature
temperature regulation
attaches muscles to bone, skin or other muscle
tendon
expanded ends of the sarcoplasmic reticulum that contact the T-tubules, site of calcium ion release to promote muscle contraction
terminal cisternae
fine protein myofilament composed of bundles of myosin (11nm diameter), bind to thin filament and cause contraction
thick filament
what are the three types of myofilaments in myofibrils?
thick filament, thin filament, and titin
fine protein myofilament composed of actin, troponin, and tropomyosin (5-6nm diameter), thick filaments bind to it and cause contraction
thin filament
effort is applied between the resistance and the fulcrum, as when picking up a small object with a pair of forceps
third-class lever
filaments of an elastic protein, help return myofilaments to resting position after contraction; maintain positions of myofilaments in sarcomere
titin
narrow, tubular extensions of the sarcolemma into the sarcoplasm, contacting the terminal cisternae; wrapped around myofibrils, quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber
transverse tubule (T-tubule)
double-stranded regulatory protein, covers the sites on actin, preventing myosin from binding to actin when muscle fiber is at rest
tropomyosin
regulatory protein that holds tropomyosin in place and anchors to actin, when calcium ions bind to one of its subunits, troponin changes shape, causing the tropomyosin to move off the actin active site, and this permits myosin binding to actin
troponin
are skeletal muscles voluntary or involuntary
voluntary
wasting of a tissue that results in a reduction in muscle size, tome, and power, losses tone and mass, becomes flaccid, fibers decrease in size and become weaker (happens when one wears a cast)
atrophy
cardia muscle cells are _________ meaning that the individual cells can generate impulse without nervous stimulation
autorhythmic
each motor neuron has a long extension called a
axon
transmits a nerve impulse to a muscle fiber, travels through the epimysium and perimysium, delivers the nerve impulse to an individual muscle fiber in the endomysium
axon
delievers nutrients and oxygen to muscle fibers needed for the production of ATP and removes wastes products produced by muscles fibers
blood vessels
move when muscles contract and pull on the tendons by which the muscles are attached to the bones
body movement
what are the five functions of skeletal muscle tissue?
body movement, maintenance of posture, temperature regulation, storage and movement of materials, and support
individual muscle cells arranged in thick bundles, striated, shorter and thick, only one or two nuclei, intercalated discs, involuntary control
cardiac muscle cells
fibers arranged concentrically, functions as a sphincter to close a passage way or opening
circular (ex: orbicularis oris)
what are the four shape of skeletal muscles?
circular, parallel, convergent, pennate
the resistance is between the fulcrum and the applied effort
second-class lever
how many muscles are in the skeletal system?
100
dark band in the middle of a sarcomere and doesn't shorten when the muscle contracts
A band
what are the five components of a sarcomere?
A band, H zone, M line, I band, Z disc
found in the motor end plate and are activated by ACh
ACh receptors
tension within cell that causes cells to shorten, shortening results in either a pull on bones of the skeleton or the movement of specific body parts
Contractility
ability to return to its original length when tension is released
Elasticity
What are the four common properties of muscle tissue?
Excitability, Contractility, Elasticity, Extensibility
capable of extending in length in response to the contraction of opposing muscle cells
Extensibility
lighter region in the middle of the A band and shortens when the muscle contracts
H zone
light bank containing thin filaments only and titin proteins, shortens when the muscle contracts
I band
a thin transverse protein meshwork that appears as a dark protein disc in center of H zone where thick filaments attach, doesn't shorten when muscle contracts
M line
dark proteins called connectins in the center of the I band where thin filaments attach, doesn't shorten when muscles contracts
Z disc
neurotransmitter found in the synaptic vesicles
acetylcholine (ACh)
resides in the synaptic cleft and rapidly breaks down molecules of ACh that are released into the synaptic cleft, very important to prevent ACh from continuously stimulating the muscle
acetylcholinesterase (AChE)
also called a prime mover, a muscle that contracts to produce a particular movement
agonist
each muscle fiber obeys this principle which states that a muscle fiber either contracts completely or does not contract at all, when a muscle unit is stimulated, all its fibers contract at the same time
all-or-none principle
a muscle whose actions oppose those of the agonist
antagonist
occurs when the tendon forms a thin, flattened sheet
aponeurosis
if a muscle extends between a broad aponeurosis and a narrow tendon, the __________ is considered the origin and the __________ is the insertion
aponeurosis, tendon
a bundle of muscle fibers separated from other bundles of fibers by a dense irregular connective tissue covering
fascicle
what muscle level does the perimysium cover?
fascicle
what fibers do the majority of skeletal muscle fibers consist of?
fast fibers
large in diameter and they contain large glycogen reserves, densely packed myofibrils, and relatively few mitochondria
fast fibers also called white fibers because of lack of myoglobin
more mobile attachment of the muscle
insertion
resemble fast fibers; however, they have a greater resistance to fatigue
intermediate fibers
fascicles are parallel to the long axis of the muscles, body muscles increases in diameter with contraction, high endurance, not ver strong
parallel (ex: rectus abdominis)
muscle body has one or more tendons, fascicles at oblique angle to tendon, pull harder than a parallel muscle of equal size, three types: uni-, bi-, multi-)
pennat (unipennate: extensor digitorum) (bipennate: Rectus femoris) (multipennate: deltoid)
fibrous sheath enveloping each of the fascicles of skeletal muscle fibers
perimysium
plamsa membrane of a muscle fiber, regulates entry and exit of materials
sarcolemma
what are the five structures of a muscle fiber?
sarcolemma, sarcoplasm, sarcoplasmic reticulum, terminal cisternae, transverse tubule
cytoplasm of a muscle fiber, site of metabolic processes for normal muscle fiber activities
sarcoplasm
smooth endoplasmic reticulum in a muscle fiber, stores calcium ions needed for muscle contraction
sarcoplasmic reticulum