The Muscular System
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What are the three types of muscle?
cardiac, smooth, skeletal
Which muscles are involuntary?
cardiac and smooth
Which muscle is self-excitatory, and what does this mean?
cardiac muscle can initiate its own contraction
What is skeletal muscle?
attached to bones, moves your body around, long and multinucleate, voluntary
What are the two proteins that make up muscle?
actin, myosin
What does actin form?
long, thin chains
What does myosin form?
bundle together to form thick fibers
What is a sarcomere?
basic unit of muscle
What is a myofibril?
many sarcomeres lined up end to end
What makes up a muscle cell?
many myofibril bundles + cytoplasm, organelles, nuclei, cell membrane
Muscle cells can be organized into groups called
fascicles
Fascicles are grouped together to form
whole muscle
Describe the hierarchy of substances that make up whole muscle.
actin/myosin > sarcomere > myofibril > muscle cell > fascicle > whole muscle
What is the name for the end of sarcomeres?
z-lines
Which muscles are striated?
skeletal and cardiac
How are skeletal muscles stimulated?
neurons that release neurotransmitters at special synapses
What are these special synapses?
motor end plates (also called neuromuscular junction)
Which neurotransmitter is used to stimulate skeletal muscle?
acetylcholine
Muscle contraction requires which mineral?
calcium