Anatomy & Physiology Unit 3

functions of the muscular system

movement and stability

what are the 3 types of muscle?

smooth, skeletal, cardiac

smooth muscle

organs and glands, 1 nucleus at center, not striated, involuntary movement

skeletal muscle

bones, many nuclei at periphery, striated, voluntary movement

cardiac muscle

heart, nucleus at center, striated w/ intercalated disks, involuntary movement

sarcoplasm

cytoplasm of skeletal muscle

sarcolemma

plasma membrane of skeletal muscle

myofibrils

bundles of contractile proteins

sarcoplasmic reticulum

smooth ER of skeletal muscle, reservoir of calcium ions for contraction

myofilaments

smaller units of protein within myofibril

actin

thin myofilament, shaped like beads, 2 intertwined strands

myosin

thick myofilament, shaped like golf clubs

sarcomere

contractile units of muscle fiber that shorten during a muscle contraction

what happens to z disks during a muscle contraction?

they move closer together as sarcomeres shorten

motor neuron

nerve cells that stimulate skeletal muscle fibers

synaptic knob

end of motor neuron that attaches to muscle fiber

motor unit

group of muscle fibers that motor neuron stimulates

neuromuscular junction

location where nerve cells and muscle fibers meet

synaptic cleft

space between motor neuron and muscle fiber

synaptic vesicle

store and release neurotransmitters