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Flashcards from lecture notes.
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Smooth Muscle
Involuntary muscle; controlled unconsciously. Non-striated muscle, one nucleus per cell. In the walls of blood vessels and internal organs; Respiration, digestion, blood circulation.
Cardiac Muscle
Controls itself with help from nervous and endocrine systems. Striated muscle, one nucleus per cell. Only in the heart; Blood circulation
Skeletal Muscle
Voluntary muscle; controlled consciously. Striated muscle, multinucleate. Attached to the skeleton; Locomotion, posture, body temperature
Contractility
The ability to contract or shorten, allowing muscles to generate tension.
Extensibility
The property of muscles that allows them to be stretched or lengthened beyond their resting length.
Elasticity
The ability to return to its original shape after being stretched or contracted.
Excitability
The capacity to receive and respond to stimuli (from the motor neuron, neurotransmitters, hormone, etc).
Epimysium
A fascia (thin sheath) of fibrous connective tissue that surrounds the entire muscle.
Fascicle
A small bundle or cluster of muscle fibers
Perimysium
Connective tissue extensions from the epimysium that surround each fascicle.
Endomysium
Connective tissue extensions from the perimysium that surround the muscle fibers and are attached to the sarcolemma.
Myofibrils
Each muscle fiber contains several hundred to several thousands myofibrils. Each myofibril is composed by a linear series of repeating sarcomeres
Myofilaments
Are responsible for muscle contraction and composed of thin and thick filaments.
Sarcolemma
It is a thin cell membrane enclosing a skeletal muscle fiber (cell).
Sarcomere
Contain the myofilaments, basic contractile unit of striated muscle fibers (Found between Z LINES or Z discs)
Mitochondria
Power plant of a cell (generates ATP)
Sarcoplasmic Reticulum
Is a specialized endoplasmic reticulum and regulates calcium storage, release and reuptake
T-Tubules
Tubules arranged transversely to the myofibril which allows rapid transfer action potentials to the interior of the fiber.
Action Potential
Rapid change in voltage across a membrane caused by inflow of Na+ and outflow of K+
Agonist
Muscle responsible for the movement.
Antagonist
Oppose the agonists to prevent overstretching of them.
Synergist
Assist the agonists and sometimes fine-tune the direction of movement
Isometric contraction
Muscle fibers do not change in length
Concentric contraction
Muscle fibers shorten.
Eccentric contraction
Muscle fibers lengthen
Satellite cells
A type of stem cell located in skeletal muscles, involved in muscle growth and repair.
Myostatin
Produced and secreted by skeletal muscle cells, its primary function is to regulate muscle growth and development by inhibiting the proliferation and differentiation of muscle cells.
Neuromuscular Junction
The synapse between a motor neuron and a muscle fiber; where the motor neuron stimulates the muscle fiber to contract.
Sliding Filament Theory
The mechanism of muscle contraction based on the sliding of actin and myosin filaments past each other.
Motor Unit
A single motor neuron and all the muscle fibers it innervates.
Actin
A thin filament involved in muscle contraction; contains binding sites for myosin.
Myosin
A thick filament involved in muscle contraction; uses ATP to generate force.
Troponin
A protein complex that regulates muscle contraction by controlling the interaction of actin and myosin.
Tropomyosin
A protein that blocks the myosin-binding sites on actin molecules to prevent muscle contraction.
Z-disc
Serves as the attachment point for the actin thin filaments.
I-band
The region of the sarcomere that contains only actin thin filaments.
A-band
The region of the sarcomere that contains the myosin thick filaments and overlapping actin thin filaments.
M-line
The line in the center of the sarcomere; helps to physically align the myosin thick filaments.