Muscle Flashcards
______ muscle cells are multinucleated.
Skeletal
Muscles are composed of _____.
muscle fasciculi
Muscle fasciculi are made up of _____.
muscle fibers
Muscle fibers are made of ______.
myofibrils
What surrounds muscles?
Epimysium
What contains muscle fibers?
Perimysium
What separates muscle fibers?
Endomysium
During embryonic development, myoblasts fuse to become ______.
myotubes
Three smooth muscle cells come from ectoderm. What are they?
Pupillary, mammary, and sweat glands.
Actin filaments connect to the ____, a part of the I band.
Z line
The myosin thick filaments occupy the _____ section of the _____.
H band; A band
The ____ line is in the middle of the A band; it is where myosin attaches.
M
A myofibril is _____.
lots of sarcomeres placed end-to-end
A sarcomere is defined as the molecular area from _____.
one Z disc to the next Z disc
To stabilize the actin filaments, ____ proteins bind to the positive ends (at the ____ line).
CapZ; Z
At the negative end of the actin filaments, ___ proteins bind to stabilize the polymers.
tropomodulin
The nuclei of skeletal muscle cells are located on the _____ of the cells.
peripheries
The gap junctions of cardiac muscle cells are located in the ____.
intercalated discs
In smooth muscle, calcium binds to ____, instead of troponin. That complex then activates ____.
calmodulin; myosin light chain kinase
What is a myofilament, and how does it differ from myofibrils?
Myofilaments are the polymers of muscle action (actin, myosin, tropomyosin, and troponin), while myofibrils are collections of sarcomeres.
Titin connects _____.
myosin to the Z line
Nebulin connects ______.
actin to the Z line
_____ cross-links actin filaments.
Alpha-actinin
Triads allow the connection of ___ and ___.
transverse tubules; sarcoplasmic reticulum
A ______ is a group of muscle fibers innervated by a single neuron.
motor unit
_______ is the state in which calcium is being released constantly and muscles contract constantly.
Tetanus
The positive ends of actin are connected to the _____.
Z disc
Each myosin head contracts __ times per second in slow twitch muscles and ___ times per second in fast twitch muscles.
5; 20
In cardiac muscle, ____ is needed (from DHPR activation) to induce calcium release from the sarcoplasmic reticulum.
calcium (without extracellular Ca, the heart will not contract)
As a result of exercise, each ______ gets larger in diameter.
muscle fiber
_______ induces proliferation of satellite cells, a group of cells that repair skeletal muscle.
Leukemia Inhibitory Factor (LIF)
________ connects actin to the cell membrane.
Dystrophin
