Lecture 13: Muscle Flashcards
What are the three types of muscle in the body?
Smooth, skeletal, cardiac
What do skeletal muscle cells look like? What regulates them?
Very large cells, 3-5k nuclei, long and tubular, striated. Regulated by somatic nervous system.
What are gap junctions?
How smooth and cardiac cells communicate with each other.
What is skeletal muscle made of?
Muscle fibers (myocytes, muscle cells), peripheral nerves, vasculature.
_______ accounts for all voluntary body movement.
Contraction
What does endomysium do? Perimysuim? What types of tissue are they?
Endomysium surrounds each individual fiber. Perimysium surrounds a bundle of muscle fibers. Connective tissue.
What does fascicle do? Epimysium?
Fascicles are a bundle of fibers wrapped in perimysium. Epimysium surrounds the entire muscle.
Tendons are continuous with the _________ of bone. What does that term mean?
Periosteum. Means outside of bone.
Muscle fibers are made of _____________. These are made of ______________.
Myofibrils. Sarcomeres (basic contractile unit).
What is the difference between actin and myosin?
Actin = thin filament
Myosin = thick filament
What is viewed in the H zone?
Only myosin, nothing else.
Muscles enlarge with ________. More ______ and _________ are packed into the muscle cells.
Hypertrophy, actin, myosin.
Describe the sliding filament theory.
Actin and myosin filaments slide past each other during muscle contraction.
Which areas of a sarcomere shortens during contraction? What stays the same?
Sarcomere, H zone, I zone stays the same. A zone stays the same.
Describe myosin.
Thick filament = long tail region, power molecule. Many myosin in one thick filament.
Describe actin.
Acts as a regulator and decides when myosin can attach. Actin globules form 2 coiled chains.
What does tropomyosin do? Troponin?
Tropomyosin runs along actin and blocks binding sites. Troponin holds tropomyosin in place and regulates with calcium ions.
Why does rigor mortis happen?
The absence of ATP to release cross-bridge, causes semi-permanent tensing of muscles.
What is contraction coupling?
Electrical signal (excitation) from brain along motor neuron tells a muscle to move (contraction).
_______ ________ moves like a __ along muscle membrane. It is propagated down __-________.
Action potential, wave, T-tubules
Name the six steps of excitation contraction coupling.
Neurotrans, action potential, t-tubules, sarcoplasmic reticulum, release of calcium ions, contraction.
Relaxation occurs when _____ is ______________.
Calcium, re-sequestered.
What are the three factors that regulate muscle force production?
Muscle length, action potential frequency, number of fibers
If muscle length is too ________ or ________, force production is ___________.
Stretched, compression, decreased
What is a motor unit?
One motor neuron and all the muscle fibers it innervates
What are the three types of skeletal muscle fibers?
Slow oxidative, fast oxidative-glycolytic, fast-glycolytic
