Muscle Physiology (skeletal) Flashcards
Muscle is classified as:
- Skeletal muscle
- Smooth muscle
- Cardiac muscle
- It is multinucleated
- It contains many mitochondria
- It has special structures called Transverse tubules (T tubules)
- It has myofibrils and sarcomeres
- It has specific terms for some of the intracellular
Skeletal Muscle Fiber
Skeletal Muscle Fiber
equivalent of Plasma membrane
Sarcolemma
Skeletal Muscle Fiber
equivalent of Cytoplasm
Sarcoplasm
Skeletal Muscle Fiber
equivalent of Smooth ER
Sarcoplasmic reticulum
are the structures that give skeletal and cardiac muscle their characteristic striated appearance
alternaring light and dark bands
Myofibrils
The term contraction does not necessarily mean shortening
true
Myofibrils are orderly arrangements of thick and thin filaments called
Actin (thin)
Myosin (thick)
It simply refers to activation of the force-generating sites within muscle fibers—the cross-bridges.
contraction
a type of muscle contraction where the muscle generates force without changing its length or causing movement of a joint
Isometric contraction
a type of muscle contraction where the muscle shortens while generating force, overcoming resistance, and causing movement, like lifting a weight.
concentric contraction
occurs when a muscle actively resists lengthening under a load, meaning the muscle contracts while simultaneously lengthening
eccentric contraction
what Regulatory protein binds to Ca2+ reversibly and once bound changes conformation to pull tropomyosin away from the myosin interaction sites
Troponin
Thin Filaments and Associated Proteins
Actin
Tropomyosin
Troponin
The ability of a muscle fiber to generate force and movement depends on the interaction of the contractile proteins actin and myosin.
produces shortening of a skeletal muscle fiber, the overlapping thick and thin filaments in each sarcomere move past each other, propelled by movements of the cross-bridges.
Sliding Filament Mechanism
- Contractile protein
- has a binding site for myosin.
- Think of pearls strung together on a string and then the strands of pearls are twisted together.
Actin
- Regulatory protein
- Forms a complex with the other proteins of the thin filament (actin and tropomyosin).
Troponin
- Regulatory protein
- Overlaps binding sites on actin for myosin and inhibits interaction when in the relaxed state.
Tropomyosin
regulates skeletal muscle contraction because it moves the tropomyosin away and allows myosin to interact with the actin.
Ca2+ binding to troponin
low amount og calcium in the muscles = relaxed state
true
defined as the motor neuron and the skeletal muscle fibers it innervates
Within a whole muscle there are many
Motor Unit
One motor neuron innervates many ______
muscle fibers
nerve cells whose axons innervate skeletal muscle fibers are known as ____________
motor neurons (or somatic efferent neurons),
muscle fiber is innervated by only one
motor neuron