CHAPTER 32.2 The Muscular System

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Terms in this set (...)

Muscle fiber
long slender skeletal muscle cells; myocytes
Myofibril
tightly packed filament bundles found within fascicles
Myosin
thick filament of protein with heads found in skeletal muscle cells
Actin
thin filament of protein found in muscles with myosin head receptors
Sarcomere
the smallest unit of muscle contraction
Neuromuscular junction
the point of contact between a motor neuron and a skeletal muscle cell
Acetylcholine (ACh)
neurotransmitter that transmits an impulse in a muscle cell
Tendon
tough connective tissue that connects skeletal muscles to bones
Three types of muscle tissue
skeletal, cardiac, and smooth
Skeletal muscle
found attached to bones ,voluntary, appears to have striations of light and dark, controlled by the central nervous system, haven many nuclei
Smooth muscle
found throughout the organs, not voluntary, spindle shaped, single nucleus, contract on their own
Cardiac muscle
makes up most of the mass of the heart, not voluntary, striations of light and dark, one or two nuclei, contract on their own, intercalated disks
Muscle contraction
when myosin filaments form crossbridges with actin filaments. The cross bridges then change shape, pulling the actin filaments toward the center of the sarcomere.
Extensor muscle
a skeletal muscle whose contraction extends or stretches a body part and increases the angle between two bones
Flexor muscle
a muscle that bends a joint to decrease the angle between two bones.
Muscle pair contractions
when one muscle pair contracts, the other muscle in the pair relaxes (biceps- relaxes, triceps- contracted)
Two types of skeletal muscle fibers
red and white
Red muscle
slow-twitch muscle,contains many mitochondria, useful for endurance activities
Myoglobin
oxygen storing protein in blood within the red muscle
White muscle
fast-twitch muscle, contract more rapidly, contain only few mitochondria and tire quickly, useful for great strength or quick bursts of speed
Peristalsis
involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system.
Striations
alternate dark and light bands found on skeletal and cardiac muscle
Z disks
proteins anchoring thin filaments of adjacent sarcomeres
M line
supporting proteins that hold the thick myosin filaments together in the center of a sarcomere
Fascicle
a bundle of muscle fibers
Calcium ions
bind to the protein that blocks the myosin-binding sites on actin.
Troponin
a protein of muscle that together with tropomyosin forms a regulatory protein complex controlling the interaction of actin and myosin and that when combined with calcium ions permits muscular contraction
Tropomyosin
a protein that covers myosin binding sites on the actin molecules
ATP
(adenosine triphosphate) the main energy source that cells use for most of their work. In the case of muscles, ATP fuels myosin heads to attach to actin receptors to contract muscle
Sliding filament model
the system where the thick myosin and thin actin filaments slide past each other so that their degree of overlap increases to create a muscle contraction