Exam #3 Chapter 9 Muscular system (histology & physiology) part 1 Flashcards
though skeletal muscle fibers don’t divide what DO they do and what is that?
hypertrophy- increase in size
what are myofibrils composed of?
protein fibers (myofilaments)
where is smooth muscle located?
walls of hollow organs, blood vessels, eyes, glands and skin
what is the cell shape of smooth muscle?
spindle shaped
what is a neuromuscular junction?
a few enlarged presynaptic (axon terminals separated from the fiber by a small synaptic cleft
what do nerves do in a muscle fiber?
enter a muscle, branch and contract each muscle fiber near the middle.
what does the myosin heads do?
they bind the actin active site and are an ATPase enzyme
what is the endonysium?
a delicate structure that surrounds each muscle fiber
do skeletal muscles have special cell-to-cell attachments and if so what are they?
no
if you cut a nerve from skeletal muscle what will happen?
the muscle will never contract again
what type of tissue does skeletal muscle contain?
connective tissue
what is contractility?
the ability for the muscle to shorten forcefully or contract?
what is the knowledge of skeletal muscle fiber structure required to understand?
the muscle contraction
where is the muscular fascia located/
superficial to the epimysium
are any of the muscle tissues capable of spontaneous contraction?
yes, cardiac muscle and some smooth muscle tissue
what is the plasma membrane of a fiber called?
the sarcolemma
what are T Tubules continous with?
the sarcolemma
what are the tube-lie extensions of the sarcolemma into the cytoplasm of a fiber called?
transverse (T) tubules
what is the sarcomere?
the functional unit of a muscle (the smallest structure that can contract)
what type of nucleus does smooth muscle have and where?
single, centrally located
what are Z disk composed of?
proteins to which the thin filaments attach in an ordered way
what is extensibility?
when a muscle can be stretched beyond its normal resting length and still be able to contract.
what is another word for nerves?
somatic motor neuron axons
in muscle fibers what is the extensive smooth endoplasmic retiuculum called?
sarcoplasmic reticulum
what is the cell shape of skeletal muscle?
very long and cylindrical
which muscle tissues are voluntary and which are involuntary?
skeletal is both voluntary and involuntary (reflexes) and smooth and cardiac are involuntary
what are some function of smooth muscle? (6) (MERCCM)
1) moving food through the digestive system
2) emptying the urinary bladder
3) regulating blood vessel diameter
4) changing pupil size
5) contracting many gland ducts
6) moving hair
besides the mitochondria and glycogen granules what else does sarcoplasm contain?
many rod-like organelles called myofibrils
how many cells is a muscle fiber?
one cell
what do skeletal muscle look like?
1) long
2) cylindrical
3) multinucleate
4) striated cells
what is an example of contractility?
lifting a textbook requires certain muscles to contract.
which muscle tissue enables us to breath?
skeletal
in muscle fibers what is the postsynaptic membrane?
the muscle fiber sarcolemma
what do skeletal muscle fibers develop from?
the fusion of many myoblasts
what are myosin molecules composed of?
2 myosin protein chains
does cardiac muscle tissue have special cell-to-cell attachments and if so what are they?
yes, intercalated disks join cells to one another
what does thin filaments also contain besides titin?
two strands of tropomyosin molecules
what is the cell shape of cardiac muscle?
cylindrical and branched
which muscle tissue moves substances?
all of them
what is the muscular fascia?
separates individual muscles or group of muscles
what else is in the sacrcomere ?
other proteins to regulate the interaction between thick and thin filaments and others to stabilize the ordered structure of the sarcomere
what type of nucleus does skeletal muscle have and where?
multiple nuclei (peripherally located)
what does the rest of the A band contain?
thick and thin filaments
how do muscles function?
by forcefully shortening
how are the myofilaments organized?
into a highly organized and repeating structures called sarcomeres
besides titin and tropomyosin what else does thin filaments contain?
troponin molecules
what is the cytoplasm in a muscle cell called?
sarcoplasm
what are the thick myofilaments composed of?
mostly myosin
which muscle tissue produces body movement?
skeletal
what does titin do?
it keeps the ends of the thick filaments in position
what does the presynaptic terminals contain?
vessicles with the neurotransmitter acetylcholine (ACh)
when an action potential comes down the axon what does the axon terminals release?
aCh
what do Z lines (disks) do?
separate individual sarcomeres (boxcars filaments attach in an ordered way)
what is the function of skeletal muscle
body movement
what is the sarcoplasmic reticulum?
a compartment for calcium storage
what are the epimysium, perimysium and endomysium made of?
connective tissue
what is the perimysium?
surrounds a group of fiber muscles (fascicle) and is fibrous
where in the sarcomere are the thick filaments located?
in the center and positioned by proteins of the M line in an ordered array
what do all muscle tissues display? (4) (ECEE)
1) electrical excitability
2) contractility
3) extensibility
4) elasticity
what is elasticity?
the ability of a muscle to spring back to its original resting length after it has been stretched.
what functions does muscle tissue have? (5) (BSEGM)
1) body movements
2) stabilizes our body position
3) enables us to breath and to communicate
4) generates heat
5) moves substances in our body
what type of connective tissue is the epimysium?
dense irregular collagenous connective tissue
what does motor neuron axons carry?
action potential to muscle fibers at the neuromuscular junction to produce contraction
what are the 3 subunits of troponin do??
bind G actin, tropomyosin and calcium
what is excitablility?
the capacity of a muscle to respond to an electrical stimulus.
where is the H Zone located in the sarcomere?
in the center
what is caused when the ACh diffuses across the synaptic cleft and binds with ligand-gated channels?
causes an action potention in the sacrolemma
what do muscle only do when contracting?
shorten, they never lengthen
does the thin filaments reach the M line?
only part of the way
what are the thin myofilaments composed of?
mostly actin
what does the sarcoplasm contain?
the mitochondria and glycogen granules
what type of nucleus does cardiac muscle have and where?
single, centrally located
where does the light or I band extend from?
the ends of the thick filaments in one or more sarcomere to the ends of the thick filaments in the adjacent sarcomere (z disk in middle)
which muscle tissues are striated?
skeletal and cardiac
what does the thin and thick filaments produce?
they are aligned producing alternating dark and light bands (striations)
what is the entire skeletal muscle surrounded by?
the epimysium
what is the part of the sarcomere that contains the thick filament?
dark or A band
what does skeletal muscle fibers NOT do?
divide
what does the rod-like portion of mysoin form?
the thick filament with heads facing out
which muscle tissue stabilizes our body position (posture)?
skeletal
what do the 2 myosin protein chains composed from mysoin look like?
they have a rod-like portion and a hinged head
what does the H zone only contain?
thick filaments
what are thin filaments composed of?
two strands of G actin monomers
what does troponin and tropomyosin regulate?
the interaction between mysoin and actin
what does the ACh do when it’s released by the axon terminals?
it diffuses across the synaptic cleft, binds to the ligand-gated channels
what do blood vessels do in a muscle fiber?
branch and form capillaries around each fiber
which muscle tissue generates heat?
all of them
what are thick filaments composed of?
myosin molecules
does smooth muscle tissue have special cell-to-cell attachments and if so what are they?
yes, gap junctions join SOME visceral smooth muscle cells together
what does each G actin monomer each have?
an active site to which myosin binds
