Chapter 11.5 - Muscular System Flashcards
Where is smooth muscle found
walls of our organs, airways, blood vessels
Smooth muscle is not:
striated
smooth muscle contracts and relaxes:
involuntarily
What gives muscles a striated appearance?
sarcomeres
cardiac muscle contracts and relaxes:
involuntarily
cardiac muscle has __ nucleus/nuclei per cell
1 nucleus
Which muscles are striated?
skeletal and cardiac
Which muscle contains intercalated discs?
cardiac cells
Intercalated discs contain:
desmosome and gap junction
Gap junction allows for:
cells can pass ions quickly allowing heart to depolarize and contract in unison
skeletal muscle cells are:
long, multinucleated, striated
Smallest to largest unit of skeletal muscle
myofibril –> muscle fiber –> fascicles –> muscle
protective sheath encasing the muscle fiber:
sarcolemma
Cytoplasm of muscle fiber
sarcoplasm
Epimysium
The most superficial sheath. Covers the muscle itself
Perimysium
Covers the muscle fascicles
Endomysium
the deepest sheath, covers muscle fibers
Myofibril contain many repeating units called:
sarcomeres
Functional unit of muscle fibers
sarcomeres - shorten to faciliatte muscle contraction
Neuromuscular junction
space between the presynaptic motor neuron and postsynaptic muscle fiber
When a motor neuron sends an action potential, it releases ___ into the ___ ___
acetylcholine; neuromuscular junction
Steps to transfer action potential to muscle
- acetylcholine released at neuromuscular junction, binds to voltage gated Na+ channels
- graded potential created (small depolarization)
- opens more Na+ channels
- creates action potential in muscle
T-tubules
invaginations in the sarcolemma - allow the action potential initiated on the muscle fiber to spread throughout the cell very quickly, ensuring a coordinated contraction
Muscles contract across:
a joint
Muscles __ the bone they ___ upon closer to the bone they ____ from
pull; insert; originate
Muscle contraction is always:
a pull motion
The sarcolemma is:
muscle fiber’s cell membrane
sarcomeres contain:
array of long filament proteins (myofilaments)
Examples of myofilaments
thin actin filaments, thick myosin filaments
neuromuscular junction
space between the presynaptic motor neuron and postsynaptic muscle fiber