Muscle Structure
This is the basic functional unit of a muscle fiber
What is a sarcomere
This theory explains how muscles contract.
What is the sliding filament theory
The point where a motor neuron meets a muscle fiber.
What is the neuromuscular junction?
The molecule that provides immediate energy for contraction.
What is ATP
Muscle type that is voluntary.
What is skeletal muscle?
These two proteins slide past each other during contraction
What are actin and myosin
Cross-bridges form when this part of myosin attaches to actin
What is the myosin head
The neurotransmitter released at the NMJ.
What is acetylcholine (ACh)?
A sudden, involuntary muscle contraction.
What is a cramp or spasm
This muscle type is found only in the heart.
What is cardiac muscle?
This structure stores calcium inside the muscle cell
What is the sarcoplasmic reticulum
ATP binding to myosin causes it to do this.
What is detach from actin
A motor neuron and all the muscle fibers it controls.
What is a motor unit?
The “power stroke” occurs when myosin does this.
What is pull the actin filament?
This muscle type is non-striated.
What is smooth muscle?
Thick filaments are primarily made of this protein
What is myosin
This ion is required to expose binding sites on actin
What is calcium (Ca²⁺)
This enzyme breaks down ACh in the synaptic cleft.
What is acetylcholinesterase?
Exercise-induced increases in muscle size are called this.
What is hypertrophy?
Cardiac muscle cells are connected by these specialized junctions.
What are intercalated discs?
This connective tissue surrounds an entire muscle
What is the epimysium
This molecule blocks the binding site on actin when the muscle is relaxed
What is tropomyosin
This principle states that a motor unit contracts fully or not at all.
What is the all-or-none principle?
This organelle is more abundant in slow-twitch fibers.
What are mitochondria?
Fast twitch fibers are best suited for this type of activity.
What is explosive/anaerobic/high-intensity activity?