Muscle Histology Flashcards
What is the epimysium?
Dense connective tissue that surrounds the entire muscle; synonymous with the deep fascia
What is the perimysium?
Connective tissue that surrounds a group of fibers to form a fascicle; conveys the large blood vessels and nerves into the muscle
What is the endomysium?
Delicate connective tissue that surrounds individual muscle fibers
How do you differentiate between type I and type II skeletal muscle fibers in a histological section?
Stain for ATPase; type II will stain brown, type I will remain mostly white
Cards about organization of skeletal muscle
Cool
Histological slide of type I/II
Will do
What are the properties of type I skeletal muscle fibers?
Efficiency over long periods of time; used for postural maintenance or endurance exercise; high levels of myoglobin
How do type I skeletal muscle fibers generate ATP?
Oxidative phosphorylation
What is the difference in contraction speed between type I and type II skeletal muscle fibers?
Type I fibers have a low contraction speed, type II fibers have a high contraction speed
What is the difference in innervation between type I and type II skeletal muscle fibers?
Type I fibers have large motor units (large numbers of fibers innervated by a single neuron), type II fibers have small motor units (small number of fibers innervated by a single neuron)
What is the sarcolemma?
Plasma membrane of muscle cells
What are the properties of the sarcolemma?
Numerous ion transport proteins and receptors; surrounded by a basal lamina
What is the transverse tubule system (T-tubules)?
A network formed by finger-like projections from the sarcolemma that make contact with the sarcoplasmic reticulum and transmit the depolarization signal deep into the muscle cell
What is the sarcoplasmic reticulum (SR)?
Internal membrane network that makes junctional complexes with T-tubules (triads); site of intracellular Ca2+ storage and release
What two filaments are myofibrils composed of?
Actin and myosin
What is the function of desmin?
Anchors to the inside of the sarcolemma and extends between myofibrils to help organize the cytoplasm and facilitate coordinated contraction
What connective tissue layer is represented by 3?
Endomysium
What connective tissue layer is represented by 2?
Perimysium
What connective tissue layer is represented by 1?
Epimysium
What structure is represented by 9?
Fascicle
What structure is represented by 8?
Muscle cell or myofiber
What structure is represented by 10?
Total muscle
What is 1?
Sarcomere
What is 2 and what are its properties?
Z line; define the boundaries of each sarcomere; contains α actinin (actin binding protein)
What is 3 and what are its properties?
I band; composed exclusively of actin thin filaments; width decreases during contraction
What is 4 and what are its properties?
M line; middle of H band; overlapping tails of thick filaments
What is 5 and what are its properties?
H band; central region of the A band that contains only thick filaments; width decreases during contraction
What is 6 and what are its properties?
A band; composed of overlapping thick and thin filaments; width decrease during contraction
Which cells are type I skeletal muscle cells? Which are type II?
Type I are mostly white; type II are brown
What are the components of the troponin complex?
Troponin-I, troponin-T, troponin-C
What is the function of troponin-I?
Inhibits the binding of myosin to actin
What is the function of troponin-C?
Binds Ca2+
What is the function of troponin-T?
Binds tropomyosin
What is the composition of thin filaments?
A twisted, double stranded F-actin filament composed of G-actin monomers; nebulin (stabilizer of thin filament length)
What does F-actin complex with?
Tropomyosin and the troponin complex
What is the composition of thick filaments?
Myosin (two identical heavy chains and two pair of light chains); titin (controls assembly, provides elasticity)
What are the properties of the globular head of the myosin heavy chain?
Contains a binding site for actin; ATPase domain facilitates the hydrolysis of ATP; activity regulated by the myosin light chains
Not really sure how to make cards for the sliding filament model so have fun with that
…thanks
