Muscular 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