Series of membranous channels (modified ER) that surround each myofibril
Rod-like contractile elements within a muscle fiber
Functional unit of a skeletal muscle fiber
Area of the sarcomere with overlapping thick and thin filaments
Area of the sarcomere containing only thin filaments
Area in the center of the A band containing only thick filaments
Contains vesicles filled with acetylcholine
Space between the neuron and the muscle
Contains receptors for acetylcholine
motor end plate
Type of contraction represented by a single stimulus/contraction/relaxation sequence
A muscle producing peak tensions with visible relaxation during rapid cycles of contraction and relaxation
A muscle that is stimulated so frequently that the relaxation phase is completely eliminated
When a muscle is stimulated repeatedly for several seconds with a constant stimulus, the amount of tensions gradually increases to a maximum.
skeletal, striated, voluntary
skeletal muscle tissue
heart, striated, involuntary
cardiac muscle tissue
visceral, nonstriated, voluntary
smooth muscle tissue
Ability to receive and respond to a stimulus
Ability to shorten forcibly when adequately stimulated
Ability to be stretched or extended
Ability of a muscle to resume its resting length after being stretched
Contraction of muscle during which the muscle changes in length and the tension remains constant through most of the contractile period
Contraction of muscle during which the tension continues to increase but the muscle neither shortens nor lengthens
Contraction of the muscle in which the muscle shortens and does work
Contraction of muscle in which the muscle contracts as it lengthens
Neurotransmitter at the neuromuscular junction
stored in muscles and tapped to regenerate ATP while metabolic pathways are adjusting to the higher demands for ATP
red pigment that stores oxygen
Product of anaerobic glycolysis
Type of muscle fibers that contract quickly and rely on aerobic respiration for ATP
fast oxidative fibers
Type of muscle fibers that are most resistant to fatigue
slow oxidative fibers
Type of fibers that have few mitochondria
fast glycolitic fibers
Sustained spasm, or tetanic contraction
Inflammation of a muscle, its connective tissue coverings and tendons, and capsules of nearby joints
Muscle pain resulting from any muscle disorder
Excessive stretching and possible tearing of a muscle caused by muscle overuse or abuse
period of time between stimulation and the onset of muscle contraction
The time during which the muscle is shortening
The time during which the muscle is returning to its original length
The very brief time after one stimulus during which the muscle is unresponsive to a second stimulus
Propagation of an electrical current along the sarcolemma
The initial polarized state
Restoration of membrane potential to resting potential
The time when fiber cannot be stimulated until repolarization is complete
Electrical event occurring only at neuromuscular junction
end plate potential
Neurotransmitter released into the neuromuscular junction
Enzyme released into neuromuscular junction to break down acetylcholine
Released by terminal cisternae into the sarcoplasm to bind with troponin
Cytoplasmic, calcium-binding protein
Changes shape during the contraction cycle
Slides toward the M line during a contraction
Covers the binding site
Binds Ca2+ and starts the contraction cycle
An entire skeletal muscle is surrounded by
As an axon enters a muscle, it branches into a number of axonal terminals, each of which forms a neuromuscular junction with a single muscle fiber. A motor neuron and all the muscle fibers it supplies is called a:
What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in the formation of cross bridges?
Each skeletal muscle fiber is controlled by a neuron at a single:
best describes the composition of the structure known as a triad in a skeletal muscle fiber
Terminal cisterna, transverse tubule, and terminal cistern
In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and _________.
The dense layer of collagen fibers that surround an entire skeletal muscle is the
The functional unit of a skeletal muscle fiber is the:
The space between the neuron and the muscle is the
The term that means a continued mild or partial contraction of an entire muscle is muscle:
The type of muscle contraction in which the muscle fibers produce increased tension, but the muscle neither shortens nor lengthens, is called:
increases in quantity during repetitive muscle contraction
The sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated is known as the:
allows recoil of the muscle fiber when contraction ends
Which one of the following binds calcium ions in a smooth muscle, causing contraction?
A sarcomere is part of a
Cross bridges that link between the thick and thin filaments are formed by the:
globular head of thick filaments
Which of the following is thought to be an autoimmune disease of acetylcholine receptors?
The refractory period in which the muscle will not contract if stimulated occurs during __________ of the muscle cell.
What is the cause of rigor mortis?
calcium influc into the cell after death
Where does 95% of the energy needed for contraction come from during moderate exercise?
The alternating contraction and relaxation of opposing layers of smooth muscle is referred to as:
characteristic that is unique to smooth muscle?
absence of striations
Which of the following muscle types is both voluntary and striated?
Muscle cells initiate nerve impulses.
Which of the following is a special adaptation present in muscle cells, but absent in most other cells?
presence of myoglobin
The final "go" signal for skeletal muscle contraction is
increase in intracellular calcium ion levels
The ___________ serve as a communication network that coordinates the contraction of each myofibril that makes up the muscle fiber
Thin myofilaments are composed chiefly of:
Acetylcholinesterase breaks down
Myofibrils are composed of repeating contractile elements called:
When an action potential arrives at the neuromuscular junction, the most immediate result is:
the release of acetylcholine
If a muscle is applied to a load that exceeds the muscle's maximum tension
the muscle length will not change during contraction (isometric contraction)
The variation of stimulation needed in skeletal muscle contraction in order to have controlled movement is called a:
graded muscle response
The most efficient means of producing ATP is:
What would occur if a muscle became totally depleted of ATP?
The muscle would remain in a contracted state due to an inability to break actin-myosin cross bridges.
Duchenne muscular dystrophy is more common in females than in males.