Chapter 5: Lesson 4 Flashcards
Skeletal muscle
The type of muscle tissue that connects to bones and generates the forces that create movement.
Fascia
Connective tissue that surrounds muscles and bones.
Epimysium
Inner layer of fascia that directly surrounds an entire muscle, commonly referred to as the “deep fascia.”
Fascicles
Largest bundles of fibers within a muscle. Fascicles are surrounded by perimysium.
Perimysium
Connective tissue surrounding a muscle fascicle.
Endomysium
Connective tissue that wraps around individual muscle fibers within a fascicle.
Glycogen
Glucose that is deposited and stored in bodily tissues, such as the liver and muscle cells; the storage form of carbohydrate.
Myoglobin
Protein-based molecule that carries oxygen molecules into the muscles.
Myofibrils
The contractile components of a muscle cell; the myofilaments (actin and myosin) are contained within a myofibril.
Myofilaments
The filaments of a myofibril; include actin and myosin.
Actin
The thin, stringlike, myofilament that acts along with myosin to produce muscular contraction.
Myosin
The thick myofilament that acts along with actin to produce muscular contraction.
Sarcomere
The structural unit of a myofibril composed of actin and myosin filaments between two Z-lines.
Z-line
The meeting point of each sarcomere.
Neural activation
The nervous system’s signal that tells a muscle to contract.
Neuromuscular junction
The specialized site where the nervous system communicates directly with muscle fibers.
Synapse
A junction or small gap between the motor neuron and muscle cells.
Motor unit
A motor neuron and all of the muscle fibers that it innervates.
Action potential
Nerve impulse that is relayed from the central nervous system, through the peripheral nervous system, and into the muscle across the neuromuscular junction.
Neurotransmitters
Chemical messengers that cross the synapse between neuron and muscle and assist with nerve transmission.
Acetylcholine (ACh)
A neurotransmitter that helps the action potential cross the synapse into the muscle, which initiates the steps in a muscle contraction.
Sliding filament theory
The series of steps in muscle contraction involving how myosin (thick) and actin (thin) filaments slide past one another to produce a muscle contraction, shortening the entire length of the sarcomere
Excitation-contraction coupling
The physiological process of converting an electrical stimulus to a muscle contraction.
Power stroke
The myosin heads bind to actin and pull them toward the sarcomere center, which slides the filaments past each other, shortening the muscle.
Adenosine triphosphate (ATP)
A high-energy molecule that serves as the main form of energy in the human body; known as the energy currency of the body.
Resting length
The length of a muscle when it is not actively contracting or being stretched.
Type I muscle fibers
Muscle fibers that are small in size, generate lower amounts of force, and are more resistant to fatigue.
Type II muscle fibers
Muscle fibers that are larger in size, generate higher amounts of force, and are faster to fatigue.
All-or-nothing principle
Motor units cannot vary the amount of force they generate; they either contract maximally or not at all.
Capillaries
The smallest blood vessels and the site of exchange of elements between the blood and the tissues.
