Cellular Physiology of Skeletal, Cardiac, and Smooth Muscle Flashcards
What kind of muscles control breathing
skeletal, via contraction of the diaphragm and functions as a pump assisting return of the venous blood supply to the heart.
What is the smallest CONTRACTILE unit of skeletal muscle, and one or more nucleas?
multinucleated, elongated cell called a muscle fiber or myofiber
what is a fascicle?
bundle of linear aligned muscle fibers
what is the epimysium?
external sheet that contains the whole muscle.
what is the perimysium?
the sheath surrounding the fascicles
what is the endomysium?
the sheath surrounding muscle fibers.
what is the sarcolemma?
plasma membrane of the muscle cell under endomysium.
what are myofibrils?
densely arranged parallel array of cylindrical elements in skeletal muscle cell
what do myofibril consist of?
end-to-end chain of regular repeating units—or sarcomeres —that consist of smaller interdigitating filaments called myofilaments;
what do myofilaments consist of?
Thick and thin filaments.
where a the cell bodies of somatic neurons found
central nervous system ventral horn spinal cord.
what are motor neurons
the neurons that control skeletal mucle
what is the innervation ratio of whole skeletal muscle?
the number of muscle fibers innervated by a single motor neuron.
what do muscle control with a small innervation ratio
fine movements
large ratio= large force movements
Do skeletal muscles use chemcal or electrical activasion?
artifical both
otherwise always chemical and ACh
where to AP penetrate the muscle fibers?
at the T tubules
at what places do t tubules surround myofibril
junction of the A-I bands
what are terminal citsernae?
specialized regions of the sarcoplasmic reticulum. where the t tubule associates with (2x)
what is the triad junction
. The combination of the T-tubule membrane and its two neighboring cisternae (SR) is called a triad junction, or simply a triad.
The ultimate intracellular signal that triggers and sustains contraction of skeletal muscle cells is a rise in ?
[Ca 2+ ] i
what is Excitation-contraction coupling? EC coupling
he process by which electrical “excitation” of the surface membrane triggers an increase of [Ca 2+ ] i in muscle
how are L type Ca2+ channels activated
voltage gated, in the triad region t Tubule
what is the voltage sensor EC?
tetrads (groups of four) of L type Ca2+ channels
what is Cav1.1
a α 1 -subunit of the voltage-gated Ca 2+ channel