Muscular System Flashcards
a body tissue that functions for contraction or shortening
muscle
a body tissue that functions for contraction or shortening
muscle
they are responsible for essentially all body movement
muscle
they are a dominant tissue in the heart and in the walls of other hollow organs of the body
it makes up nearly half of the body mass
muscle
[muscle functions]
contraction of muscles attached to bones produces movements under voluntary control
producing movement
[muscle functions]
muscle attached to the bones keep the body upright despite the pull of gravity and stabilize the joints
maintaining posture
[muscle functions]
contraction of the skeletal muscles of the thorax and the diaphragm help us breathe
respiration
[muscle functions]
metabolic activity in the muscles generate abundant heat as by-product and is needed in maintaining body temperature
generating heat
[muscle functions]
skeletal muscles are involved in all aspects of __________, including speaking, writing, typing, gesturing, and smiling or frowning
communication
[muscle functions]
the contraction of smooth muscle within the walls of internal organs and vessels causes those structures to constrict
constriction of organs and vessels
[muscle functions]
the contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body
contraction of the heart
what are the three muscle types
skeletal muscles
cardiac muscles
smooth muscles
voluntary muscles attached to bones
skeletal muscles
locomotion, facial expressions, posture, respiratory functions, speech, and other body movements are due to __________ contraction
skeletal muscle
the __________ controls the voluntary aspects of skeletal muscle
nervous system
involuntary muscles found only in the heart
cardiac muscles
its contractions provide the major force for moving blood through the circulatory system
cardiac muscle
involuntary muscles widely distributed in the body such as in the walls of hollow visceral organs, stomach, intestines, uterus, blood vessels, ducts of glands, and respiratory passages
smooth muscles
__________ contraction propels urine through the urinary tract, mixes food in the stomach and small intestine, and regulates the flow of blood through blood vessels
smooth muscle
they are made up of single, very long and cylindrical cells with very obvious striations
skeletal muscle
they are made up of branching chains of cells with striations
cardiac muscles
they are made up of cells with no striations
smooth muscles
what are the four muscle properties
contractility
excitability
extensibility
elasticity
[muscle properties]
the ability of muscle to shorten forcefully
contractility
[muscle properties]
the capacity of the muscle to respond to an electrical stimulus
excitability
[muscle properties]
a muscle can be stretched beyond its normal resting length and still be able to contract
extensibility
[muscle properties]
the ability of muscle to spring back to its original resting length after it has been stretched
elasticity
individual muscle cell (with a length range from 1 to 40 mm) that contains multiple nuclei and other organelles
muscle fiber or myocyte
bundle of parallel skeletal muscle fibers
fasicle
layer of connective tissue that surrounds individual muscles and group of muscles
these outer layer keep the muscles separate from surrounding tissues and organs
muscle fascia
forms a connective tissue sheath that surrounds each skeletal muscle
its protein fibers gradually merge with the muscular fascia
epimysium
connective tissue sheath that surrounds fascicles, subdividing each whole muscle into numerous bundles of muscle fibers
perimysium
delicate layer of connective tissue that separates the individual muscle fibers within each fasicle
it serves as passageways for nerve fibers and blood vessels that supply each separate muscle fiber
endomysium
plasma membrane of muscle fibers
sarcolemma
tube-like inward folds of the sarcolemma
transverse tubules or T tubules
at regular intervals along the muscled fiber, the sarcolemma forms __________ by projecting and extending into the interior of the muscle fiber
T tubules
they carry electrical impulses into the center of the muscle fiber so that every contractile unit of the muscle fiber contracts in unison
T tubules
highly specialized smooth endoplasmic reticulum in skeletal muscle fibers that stores high levels of calcium
sarcoplasmic reticulum
enlarged portions of the sarcoplasmic reticulum
T tubules lie next to it
terminal cisternae
formed by two terminal cisternae and their associated T tubule
triad
bundle of parallel protein filaments running the length of the muscle fiber
hundreds to thousands of cylindrical __________ occupy the most of the cell’s volume
myofibril
structural and functional unit of the myofibril
the smallest portion of a muscle that can contract
sarcomere
individual thick and thin filaments that make up a myofibril
the interaction of these are the basis of muscle contraction
myofilaments
a thin filament of two entwined strands of proteins that makes up the sarcomere
actin
a long fibrous protein that lies in the groove along the fibrous actin strand
tropomyosin
in a relaxed muscle, __________ is covering the active sites of the actin where thick myosin filament binds
a muscle cannot contract until it moves to uncover the active sites
tropomyosin
attached to tropomyosin and lies within the groove between actin filaments in the muscle tissue
troponin
a thick filament of protein that also makes up the sarcomere
myosin
bind and pull on the actin filaments, causing actin to slide in between each myosin set, therefore shortening the entire contractile unit
when this process is duplicated across many sarcomere units, the entire muscle or group of mucles is enabled to contract, consequently causing a desired movement
myosin heads
made up of a motor neuron synapsed to the muscle fibers
motor unit
carry action potentials or electrical signals which stimulate muscles to contract
motor neurons
is the point of contact of motor neuron axon branches with the muscle fiber
neuromuscular junction or synapse
the neurotransmitter that stimulates the skeletal muscle fibers to contract
acetycholine
occurs when acetylcholine is no longer released at the neuromuscular junction
muscle relaxation
type of contractions where a muscle does not shorten
this type of contraction increases the tension in the muscle, but the length of the muscle stays the same
isometric contractions
type of contractions where the muscle shortens
this type of contraction increases the tension in the muscle and the length of the muscle decreases
isotonic contractions
isotonic contractions in which tension in the muscle is great enough to overcome the opposing resistance, and the muscle shortens
concentric contractions
isotonic contractions in which tension is maintained in a muscle, but the opposing resistance is great enough to cause the muscle to increase the length
eccentric contractions
[antagonistic muscle pairs]
prime mover muscles that causes a particular movement
agonist muscles
[antagonistic muscle pairs]
muscles that oppose or reverse a movement
antagonist muscles
[antagonistic muscle pairs]
help agonists by producing the same movement or by reducing undesirable movements
synergist muscles
[antagonistic muscle pairs]
are specialized synergists
they hold a bone still or stabilize the origin of the agonist muscles so all the tension can be used to move the insertion bone
fixator muscles
all muscles have at least two attachments: __________
origin or fixed end
insertion or mobile end
muscle is attached to the immovable or less movable bone in its proximal end
some muscles have more than one __________
origin or fixed end
muscle is attached to the movable bone in its distal end
the attached bone is being pulled toward the other bone of the joint
insertion or mobile end
muscles can only __________ and can never __________
can only pull
can never push
during contraction, the muscle insertion moves __________ the origin
moves toward
can greatly influence the degree to which it can contract and the amount of force it can generate
muscle shape
determines the type of movement it has and is determined by the arrangement of fasicles
muscle shape
[muscle shapes]
have their fasicles arranged in a circle around an opening and act as sphincters to close the opening
circular muscles
[muscle shapes]
have fasicles that join at one common tendon from a wide area, which created muscles that are triangular in shape
convergent muscles
[muscle shapes]
similar with convergent muscles, have fasicles that are organized parallel to the long axis of the muscle, but they terminate on a flat tendon that spans the width of the entire muscle
parallel muscles
[muscle shapes]
fasicles run the length of the entire muscle and taper at each end to terminate at tendons
these muscles have expanded midsection that the ends
fusiform muscles
[muscle shapes]
have fasicles that emerge like the barbs on a feather from a common tendon that runs the length of the entire muscle
pennate muscle
[muscle shapes]
fasicles are on one side of the tendon
unipennate muscles
[muscle shapes]
fasicles arranged on two sides of the tendon
bipennate muscles
[muscle shapes]
fasicles arranged at many places around the central tendon
multipennate muscles