69 terms

Muscular System

What are the three muscle types in the body?
skeletal, cardiac, smooth
What is the endomysium?
a thin layer of connective tissue that surrounds each muscle fiber
What is the perimysium?
connective tissue that surrounds groups of 10-100 individual muscle fibers separating them into bundles called fascicles.
What is the epimysium?
Connective tissue layer(outside muscle); an overcoat of dense irregular connective tissue that surrounds the whole muscle
Where are smooth muscles found in the body?
walls of hollow organs (except heart) in the digestive system, blood vessels, and urinary system
How is cardiac muscle contraction regulated?
involuntary contraction
What are the functions of muscle?
producing movement, maintaining posture, stabilizing joints and generating heat
What is the sarcolemma?
specialized plasma membrane of muscle cells
What is the function of the sarcoplasmic reticulum?
stores calcium
What is myosin?
Thick filament protein with a head and elongated tail, the heads form cross bridges with the thin filaments during muscle contraction
What is actin?
Thin filament protein. Twisted into a double helix and appears like a double-stranded chain of pearls. Contains the myosin-binding site.
What is the neurotransmitter for muscle contraction?
acetylcholine (ACh)
What is the energy needed for muscle contraction?
stored ATP
What types of muscles are involuntary?
smooth and cardiac
What types of muscle are striated?
skeletal and cardiac
What type of muscle is voluntary?
What type of muscle has intercalated discs?
Where is glycogen stored in the muscle cells?
in glycosomes
What is the cytoplasm of the muscle cell?
What is the light area of the sarcomere?
I Band
What structure attaches a bone to a muscle?
What proteins are on actin?
tropomysin and troponin (in skeletal muscle)
What is the H Band?
the center part of the sarcomere that gets smaller when a muscle contracts and appears when the muscle relaxes
What ion stimulates the contraction of muscle?
What is the function of skeletal muscle?
movement of bones
What type of muscle forms most of the heart?
What type of muscle exhibits autorhythmicity (beats with a steady rhythm)?
What type of muscle forms the walls of hollow internal structures?
What type of muscles have a striped appearance?
skeletal and cardiac
What is the contractile unit of muscle?
What is another name for a muscle cell?
muscle fiber
What is the ability of an electrical impulse to stimulate a muscle cell to contract?
What is the ability of muscle cells to shorten and generate a pulling force?
What is the muscles' ability to be stretched back to its original length by contraction of an opposing muscle?
What is a cross bridge?
The connection of a myosin head group to an actin filament during muscle contraction (the sliding filament theory)
What is the ability of a muscle to recoil after being stretched?
A sarcomere is the distance between two __ ?
Z discs
The thicker filaments are the ________filaments.
Both actin and myosin are found in the _______band.
What is troponin?
a regulatory protein that moves tropomyosin aside & exposes myosin binding sites when Ca+ is released during muscle contraction
What causes the striations of skeletal muscles?
Arrangements of myofilaments
What are striations?
the light and dark stripes in skeletal and cardiac muscles
True or False--The sliding filament model of contraction involves actin and myosin sliding past each other but not shortening.
What is tropomyosin?
It is a long, fibrous protein that winds around the actin polymer, blocking all the myosin-binding sites.
What is myoglobin?
A protein that holds a reserve supply of oxygen in muscle cells?
What is the sarcoplasmic reticulum?
an elaborate network of membranes in skeletal muscle cells that functions in calcium storage
What is sarcoplasm?
the cytoplasm of a striated muscle fiber
What is the neuromuscular junction?
point of contact between a motor neuron and a skeletal muscle cell
What is glycogen?
a complex carbohydrate consisting of stored glucose molecules in skeletal muscles; breaks down to release glucose when it is needed for energy.
List the structures in order from largest to smallest -sarcomere, myofibrils, muscle, actin & myosin, muscle fibers, fascicle
muscle, fascicles, muscle fibers, myofibrils, sarcomere, actin & myosin
What is a fascicle?
A bundle of skeletal muscle cells. Fascicles group together to form skeletal muscles.
What is the origin of a muscle?
less moveable of the two bones is considered to be the starting point of the muscle
What is the insertion of a muscle?
the end of a muscle attached to a movable part
What is an aponeurosis?
Broad, flat, sheet like connective tissue that connects muscles to a bone or another muscle
What is a myofilament?
threadlike structures found in myofibrils which aid in contraction, composed of myosin (thick) and actin (thin)
What is the M-line?
supporting proteins that hold the thick filaments together in the H zone
What is a cross bridge?
The connection of a myosin head group to an actin filament during muscle contraction (the sliding filament theory).
What is the sliding filament theory?
theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still
What is titin?
elastic protein, keeps thick and thin filaments aligned
What is acetylcholine?
neurotransmitter that diffuses across a synapse and produces an impulse in the cell membrane of a muscle cell
What is the function of calcium ions in muscle contraction?
when released from the SR, they stimulate the reaction leading to muscle contraction by attaching to regulatory proteins on actin.
What is an action potential?
Electrical impulse that travels down the axon triggering the release of neurotransmitters
sliding filament model
neuromuscular junction
muscle fiber
muscle attachments
Label the skeletal muscle