Lecture 1 Flashcards
What is our phrase for this class?
Form begets function
Muscles contain hundreds-thousands of individual contractile fibers made of what?
mostly collagen, some elastin. they are classified as connective tissue
what is the epimysium?
a tough coat of tightly wound collagen which surrounds an entire muscle. Separates from other muscles and structures.
What is a myotendinous junction (MTJ)?
MTJs are the ends of a muscle where the epimysium connects with the sarcolemma
what is the perimysium?
tough and thick barrier that divides muscle fibers into bundles. it provides pathways for arteries, veins, and nerves.
what is the endomysium?
surrounds each muscle fiber and connects to perimysium and basement membranes.
What kinds of arteries and veins run parallel along the surface of muscle?
conduit arteries and veins.
What kinds of arteries and veins periodically branch into the belly of the muscle in parallel, with multiple branchings?
Perforating arteries and veins.
do arterioles or veins lead into capillary networks which surround each fiber?
arterioles.
What advantages does the tortuosity of capillaries possess?
increased surface area for diffusion and greater elasticity of microcirculation during stretching and contraction.
in what direction do nerves run relative to a muscle fiber?
parallel. just like arteries and veins.
which type of nerve makes up 60% of nervous innervation in skeletal muscle?
Motor nerves
In which direction do nerve impulses travel during contraction of a muscle?
in an efferent direction (away from the CNS)
Explain the layout of a motoneuron and how it interacts with a muscle fiber.
the myelin sheath ends, splitting axons, which sends a terminal branch to each fiber.
what is a motor endplate?
the region of a motor neuron that directly interfaces with the fiber. It is located under the terminal axon.
what is the order of nervous innervation?
myelin sheath, terminal branches, and motor end plate
what kind of nerve represents 40% of the nerves in skeletal muscle?
sensory nerves
what is the direction of impulses from a sensory nerve?
afferent. (toward the CNS)
what is the sarcoplasmic reticulum?
a membranous network that surrounds each myofibril and stores/releases Ca++ to initiate the contraction process.
what are transverse (t) tubules?
t-tubules are extensions of the sarcolemma that extend inward from sarcolemma, surround each myofibril, and pass completely through the fiber. they pass between the cisternae.
approximately how many myofibrils are there per muscle fiber?
7000-8000
what is the function of a myofibril?
to act as the contractile component of a muscle fiber.
sarcomeres are columnar, contractile units within myofibrils that lie between where?
the z-discs
which of actin and myosin is thick which is thin?
actin=thin filament
myosin=thick filament
