Muscular system Flashcards
There are over ______ skeletal muscles.
700
what are the 3 types of muscle tissues?
skeletal muscle (attach to bone)
cardiac muscle (makes up heart)
smooth muscle (functions of digestive system, beyond conscious control)
What are some characteristics of muscle?
muscle cells are long, narrow, elongated
muscle cell = muscle fiber
muscle is the only tissue capable of movement [through contraction- microfilament movement]
what are the 4 properties of muscle tissue?
1) excitability- responds to stimuli
2) contractibility- generates tension & shortens cell length
3) extensibility- returns to relaxed state
4) elasticity- resists stretching
The property of muscle cells that directly enables movement is:
contractibility
what are the functions of skeletal muscles tissue?
body movement
maintenece of posture
protection & support
guard openings
heat production
fascicle:
bundle of muscle fibers
-surrounded by perimysium CT [dense irregular CT]
Skeletal muscle connective tissue are composed of:
collagen, elastic fiber
Skeletal muscle connective tissue functions:
-protection
-blood vessel and nerve distribution
-attachment to skeleton
each individual muscle cell/fiber is surrounded by:
endomysium
myofibrils
make up muscle fibers
-made of myofilaments
what is the connective tissue over the entire muscle?
epimysium
what are the 4 patterns of skeletal muscle fiber organization?
1) parallel
2)convergent
3) pennate
4) circular/ sphincter
parallel muscles
muscle fascicles organized parallel to long axis of the muscle.
ex) biceps brachii; rectus abdominis
-allows the greatest distance of movement
-but relatively weak in proportion to their size
convergent muscles
triangular, has a broad base and narrow toward attachment site
-movement in different directions
ex) pectoralis major of chest
pennate muscles
feathered-like appearance, has central tendon to which vasicles are attached
-strongest muscle pattern
-don’t contract over much distance
ex) rectus femoris, extensor digitorum
circular muscles
concentric, around an opening
AKA sphincter muscle
-contracts, diameter of circle gets smaller
ex) orbicularis oris (eye)
direct VS indirect muscle attachment
direct
-periosteum and epimysium directly attached
indirect
-rope-like tendon attaches muscle to bone, skin, or other muscle
-thin flattened aponeurosis/tendon
which muscle pattern is widespread over a broad area and joined at a common attachment site?
convergent
The bundle of dense regular connective tissue that attaches a skeletal muscle to bone is called a(n):
tendon
The muscle that assists the agonist is called the:
synergist
A muscle attachment that is a thin, flat sheet is:
aponeurosis
The connective tissue that surrounds a fascicle is:
perimysium
A muscle that surrounds an opening is:
circular muscle (sphincter)
An individual muscle fiber (cell) is covered by a layer of connective tissue insulation called the:
endomysium
sarcolemma
muscle fibers’ plasma membrane
sarcoplasm
muscle fibers’ cytoplasm
sarcoplasmic reticulum
muscle fibers’ Smooth ER
what are the 2 main structures that are unique to muscle fibers?
1) transverse tubules (T-tubules)- carry impulses from sarcolemma to help stimulate contraction
2) sarcoplasmic reticulum [internal membrane complex]
-stores calcium used to initiate contraction
-includes terminal cisternae adjecent to T-Tubules
-triad= 2 terminal cisternae + 1 T-Tubule
Myofibrils
cylindrical structures within muscle fibers that run the length of the cell
-make up 80% of fiber volume
-can shorten, resulting in contraction of muscle fiber
-contain MYOFILAMENTS
Myofilaments & 2 types
strands of protein that allow for contraction
2 types
1) thick : made of hundreds of bundled myosin molecules
2) thin : made of 2 strands of filamentous actin (F-Actin) twisted around each other; also has 2 regulatory proteins- tropomyosin and troponin
Myosin
Each myosin molecule has 2 strands, 2 intertwined tails, each with a head
sarcomere
structural and functional units within a myofibril
-contains overlapping thick and thin filaments
-one sarcomere spans from one Z disc to the next
The plasma membrane of a skeletal muscle fiber is called the:
sarcolemma
In a skeletal muscle fiber, a triad is composed of:
one T-tubule and two terminal cisternae
The functional contractile unit of a skeletal muscle fiber is the:
sarcomere
The protein found in thick filaments is:
myosin
The sarcomere region with thin filaments only is the :
I band
the visible striations in skeletal muscle fibers are attributed to:
arrangement of thick and thin filaments in the myofibril
Doing the splits is what kind of movement?
abduction of the femur
what kind of movement is a butterfly stretch?
flexion at the knee
lateral rotation of femur
A back bend is what kind of movement?
extension of the back
sliding filament theory
during contraction, thin filaments slide past thick filaments
-Z discs move closer together, so sarcomeres shorten
-Width of A bands remain constant, but H zones dissapear
-I bands narrow
the M line contains:
thick filaments and accessory proteins
the H zone contains:
thick filaments
The A band contains:
thick and thin filaments
The Z disc contains:
thin filaments, connectin, accessory proteins
which event occurs during skeletal muscle contraction?
the area of actin and myosin overlap increases
globular myosin heads bind to :
actin filaments
neuromuscular junction
place where the motor neuron communicates with muscle fiber
skeletal muscle fibers are excited by:
axons of somatic motor neurons
motor unit
a single motor neuron and all of the muscle fiber it controls
in muscle contraction, a neurotransmitter:
diffuses across a synapse from a neuron to a muscle cell
what is the role of the sarcoplasmic reticulum in muscle contraction?
it stores CA2+ [calcium] ions for release during contraction
when animals die, the lack of ATP causes muscles to stiffen in rigor mortis because:
actin and myosin cannot separate without ATP
skeletal muscle
voluntary, striated
-moves and stabilizes skeleton
-made of myofibers>sarcomeres
-once mature, the skeletal muscle cells cannot divide or replace
cardiac muscle
involuntary, striated
-only found in heart
-extensive interconnections at intercalated discs>desmosomes>gap junctions
-pacemaker cells set contraction rate of heart
-.5-1% of cardiac tissue is replaced yearly
smooth (visceral) muscle
involuntary, non-striated
-remained of body’s muscle tissue after skeletal and cardiac
-all muscle tissue that are not consciously controlled and not apart of the heart
-digestive system, urinary structures, blood vessels, glands, reproductive tract..
-have actin and myosin fibers, but not arranged into sarcomeres, making it non-striated
-short fusiform cells
-1 central nucleus
-slow, efficient, fatigue resistant contractions
What is the connective tissue covering indicated by B in the above image?
perimysium
In the above image, the pre-synaptic cell would be found at:
A
What is indicated by #17 in the above image?
myofibril
The cellular structure responsible for storing calcium in the resting skeletal muscle cell is the:
sarcoplasmic reticulum
The repetitive unit of contractile proteins (composed of overlapping thin and thick protein filaments) that extends from Z line to Z line is called the:
sarcomere
Do neurons get in direct physical contact with the muscle cells they control?
No
What is the name of the structure covered by connective tissue covering A in the above image?
muscle
What is the name of #21, the three closely associated structures in the above picture?
triad
In skeletal muscle, another name for the synapse is:
“neuromuscular junction”.
Do skeletal muscle cells appear striated under the microscope?
yes
are muscle cells also called myofibrils?
NO
What type of action would be produced by a muscle anterior to the knee that is attached to bones proximal and distal to the knee?
extension of the leg at the knee
Is parallel or pennate muscle fiber stronger?
pennate
What is the connective tissue covering indicated by A in the above image?
epimysium
The connective tissue that surrounds each muscle cell is the:
endomysium.
What is indicated by #20 in the above image?
terminal cisternae of the sarcoplasmic reticulum
What is indicated by #18 in the above image?
mitochondria
The region above indicated by A is:
I band
The region indicated by B in the above image is:
H zone
Which structure in the above image represents the anchor for the thick filaments?
C
Muscle fascicles are composed of bundles of :
muscle cells.
The repetitive unit of contractile proteins (composed of overlapping thin and thick protein filaments) that extends from Z line to Z line is called the:
sarcomere
The end of a skeletal muscle that is moved when the muscle contracts is called the:
insertion
The connective tissue “sheath” that wraps around each muscle fascicle within a muscle is the:
perimysium
During the contraction of a sarcomere, calcium ions bind with the protein _____.
troponin
Which molecule directly supplies energy to myosin to allow the filaments to continue to contract?
ATP
Contractions called _____ occur whenever the forces applied to a muscle are increased, but the muscle does not appear to be moving.
isometric
The degeneration of muscle fibers caused by a lack of proper stimulation and usage is called _____.
atrophy
________________muscle fibers provide powerful contractions but fatigue quickly.
Fast-twitch
Which type of muscle is found in the wall of blood vessels?
multi-unit smooth muscle
transverse tubules (T-tubules)
carry impulses from sarcolemma to help stimulate contraction
what is the cellular structure responsible for rapid transmission of the action potential over a skeletal muscle cell?
transverse tubule
thin filaments are composed mainly of:
actin
the sarcoplasmic reticulum of a resting muscle cell contains large quantities of:
calcium ions
at the synapse, a neuron releases neurotransmitters into the:
synaptic cleft
what is the longest muscle in the body?
Sartorius
the microscopic functional unit of the muscle cells that extends from Z line to Z line is called:
Sarcomere
