Chapter 9 & 10 Flashcards
Action potential
A rapid change in a cell’s electrical charge that reverses the plasma membrane’s electrical polarity.
Muscle fiber
Muscle cell
neuromuscular junction
The junction between nerve endings and muscle fibers.
Axon
A nerve fiber that sends nerve impulses.
Synaptic knob
The enlargement at the end of an axon that secretes a neurotransmitter.
Neurotransmitter
A chemical in the neuromuscular junction that aids in stimulating or inhibiting muscle contraction.
Protein
An organic substance composed of linked amino acid molecules.
Ligand gated ion channel
A channel that opens or closes when a ligand is bound to the receptor site.
Resting Membrane Potential
The difference between the electric charge inside the membrane and just outside the membrane.
End Plate Potential
A rapid change in membrane voltage.
Sarcolemma
The cell membrane of a muscle fiber.
T Tubules
Tube-like canals in the sarcolemma that deliver action potentials into the muscle fiber.
Cytosol
The fluid matrix of the cytoplasm.
Troponin
The protein component of the actin filament that helps block myosin from binding until calcium is present.
Tropomyosin
The protein of the actin filament that blocks myosin from binding until calcium is present.
Myosin
A thick myofilament in the sarcomere that acts with actin to contract and relax muscles.
Actin
A thin myofilament in the sarcomere that is responsible for contraction and relaxation.
Cross-bridge
The connection between the actin and myosin filaments where myosin heads bind.
Myosin head
Globular protrusions on a myosin filament that bind to actin filaments to form cross-bridges.
Ligand
A molecule that binds to a receptor site or enzyme.
Cisternae
The interior space of the sarcoplasmic reticulum where calcium is stored.
Antagonistic muscles
The other force is an opposite muscle that is paired with the first. This opposing muscle contracts to relieve the first muscle.
Sliding filament theory
A theory that explains that muscles contract when thick and thin filaments slide past each other.
H zones and I bands of skeletal muscle fibers get narrower because of overlap and the Z lines compress closer to one another.
contractility
(shortens forcefully),
Myasthenia gravis
is a common disorder that inhibits action potentials that occur at the neuromuscular junction.
excitability
(responds to stimuli),
extensibility
(can be stretched and still contract),
elasticity
(recoils to resting length).
Myofibrils
are composed of two major protein fibers: actin and myosin.
Depolarization
results from an increase in the permeability of the plasma membrane to Na+.
The repolarization phase
of the action potential occurs when the Na+ channels close and the K+ channels open briefly.
Isometric contractions
cause a change in muscle tension but no change in muscle length.
Isotonic contractions
cause a change in muscle length but no change in muscle tension.
Treppe
is an increase in the force of contraction during the first few contractions of a rested muscle.
Incomplete tetanus
is partial relaxation between contractions;
complete tetanus
is no relaxation between contractions.
Multiple-motor-unit recruitment
Muscle tone is the maintenance of steady tension for long periods.
results in more motor units responding to greater stimuli.
Concentric contractions
cause muscles to shorten and tension to increase.
Eccentric contractions
cause muscles to lengthen and tension to decrease gradually.
Asynchronous contractions of motor units
produce smooth, steady muscle contractions.
Slow twitch muscle fibers
Slow-twitch muscle fibers break down ATP slowly and have a well-developed blood supply, many mitochondria, and myoglobin. Long distance runners. Slow-twitch muscle fibers contract slowly and can remain contracted for longer amounts of time without becoming fatigued.
Fast-Twitch Muscle Fibers
Fast-twitch muscle fibers break down ATP rapidly. Sprinters. Human muscle fibers that contract rapidly; become tired quickly when contracted.
Visceral smooth muscle fibers - Smooth muscle
contract slowly, have gap junctions (and thus function as a single unit), and can be autorhythmic. More common in the body; works throughout the entire body
Multiunit smooth muscle fibers - Smooth muscle
contract rapidly in response to stimulation by neurons and function independently. Contracts only when told to by nerves and hormones
Smooth muscles
Fine and randomly organized, smooth muscles are short and have only one nucleus per fiber. Like cardiac muscles, smooth muscle movement is involuntary. They assist with digestion.
Cardiac muscle
Your heart contains powerful cardiac muscles composed of cylindrical cells that branch. They pump involuntarily to send blood to every cell in your body.
Skeletal
This muscle usually connects two bones, spanning between the bones to hold a joint together. When you contract skeletal muscle, it moves one bone in relation to another. Its fibers are long and thin.
Electrical signal
A signal sent by the nervous system when there is a change in electrical charge between two points.
Aerobic exercise
Aerobic exercise (like running) helps increase strength in slow-twitch muscles. It can also help convert fast-twitch fatigable muscle fibers into fast-twitch-fatigue-resistant fibers, allowing the muscle to become stronger and work longer.
Anaerobic exercise
Anaerobic exercise (like weight-lifting) increases muscle mass and strength and also strengthens fast-twitch muscles.
origin
The less movable end of a muscle attachment
insertion
the more movable end is the
An agonist
causes a certain movement
Antagonist
acts in opposition to the agonist.
Synergists
are muscles that function together to produce movement.
Prime movers
are mainly responsible for a movement.
Fixators
stabilize the action of prime movers.
fulcrum
is located between the pull and the weight.
weight
is located between the fulcrum and the pull.
pull
is located between the fulcrum and the weight.
