Muscle Anatomy
This dense fibrous connective tissue sheath wraps around the entire muscle belly and anchors it to bones via tendons
What is Epimysium
Bounded by adjacent Z-lines, this repeating segment is the smallest functional contractile unit of a muscle fiber
What is the Sarcomere?
This specific neurotransmitter is stored in synaptic vesicles and released by alpha motor neurons to stimulate skeletal muscle fibers
What is Acetylcholine
In this variety of isotonic contraction, the tension developed by the muscle exceeds the opposing resistance, resulting in muscle shortening
What is a concentric contraction?
During the first 10 to 15 seconds of explosive exercise, ATP is rapidly regenerated by transferring a phosphate group from this stored molecule to ADP
What is creatine phosphate?
In musculoskeletal anatomy, this term designates a muscle's proximal attachment point, while the distal attachment is the insertion
What is Origin
According to the sliding filament model, this dark band representing the full span of the thick filaments does not change length during contraction
What is the A band?
Synaptic signaling at the neuromuscular junction is swiftly halted when this enzyme degrades acetylcholine within the synaptic cleft
What is acetylcholinesterase
Exemplified by an arm-wrestling stalemate, this type of muscle action generates tension without altering the muscle's length
What is an isometric contraction?
Possessing high myoglobin content, high capillary density, and slow contraction speeds, these red fibers are built for prolonged endurance
What are Type I fibers. (slow twitch oxidative fibers)
Described as resembling "pearls on a string," these thin myofilaments are formed by the polymerization of globular G-actin monomers into F-actin strands
What are actin filaments (or thin filaments)?
Located at the center of the A band, this lighter region contains only thick myosin filaments and shortens or disappears as thin filaments slide inward
What is the H-zone?
The most common form of exhaustion, this fatigue originates within the cerebral cortex when the psychological drive to continue work is lost
What is psychological fatigue (or central command fatigue)?
These continuous invaginations of the sarcolemma conduct action potentials rapidly from the cell surface deep into the interior of the muscle fiber
What are transverse tubules?
To expose myosin-binding sites on actin, calcium ions released into the sarcoplasm bind directly to this regulatory protein complex
What is troponin C?
This mechanism causes allows the release of Ca2+ from the terminal cisternae.
When stimulation frequency is so high that muscle fibers have no opportunity to relax between impulses, tension peaks in this smooth, sustained contraction
What is complete tetanus (or fused tetanus)
Lactic acid is converted back into this after being produced in the muscles after exercising.
What is pyruvate?
In skeletal muscle microstructure, this functional trio consists of a single central T-tubule flanked on both sides by the terminal cisternae of the sarcoplasmic reticulum
What is a triad?
Following death, cellular ATP depletion prevents myosin heads from detaching from actin filaments, causing this state of muscle rigidity
What is rigor mortis?
This receceptor accepts the neurotransmitter acetylcholine on the motor end plate to start an action potential on the skeletal muscle
What is a Nicotinic receptor?
Delayed-onset muscle soreness (DOMS), which typically lasts 3 to 4 days, is triggered most intensely by this type of contraction where the muscle lengthens under load
What are eccentric contractions?
While Type IIa fibers can adapt toward Type IIx or Type I profiles depending on training, this specific fiber-type transition does not occur
What is a transition from Type I to Type II?