Flashcards in Muscle Deck (53)
3 types of muscle
Cardiac, smooth, skeletal
what are myofilaments made of?
What is the epimysium
Connective tissue that surrounds the entire muscle
What is the perimysium
Connective tissue that surrounds the fasicle
What is the endomysium
Connective tissue that surrounds each muscle fiber (muscle cell)
What is a synctium?
A multinucleated cell that was created through the fusion of unicellular cells
Characteristics of skeletal muscle
Each cell has multiple, peripherally located nuclei
How vascularized is skeletal muscle?
Extensive capillary network due to high energy requirement
What is a sarcomere?
Single contraction unit (Z dsk to Z disk)
What are thin filaments of the sarcomere
What are thick filaments of the sarcomere
What filament is most abundant in I band?
Actin, troponin, tropomyosin
What filament is most abunant in A band?
Myosin and Actin
What is the M line?
Where no actin filaments connect with myosin and two myosin filaments cross connect
Where are troponin and tropomyosin located?
What filament is in the H band?
Which bands shorten during contraction?
I and H bands
How is troponin and tropomyosin configured?
Tropomyosin is wrapped around actin covering myosin binding sites
Troponin is attached to tropomyosin
Is troponin present in smooth muscle?
What is troponin C
Troponin C binds the calcium to activate movement of tropomyosin
How are myosin filaments arranged?
Two heavy chain tails are connected together with cross bridge heads
These heads move back during contraction
What 2 structures are important for calcium and muscle contraction?
Sarcoplasmic reticulum and T-tubules
What does the sarcoplasmic reticulum do?
What do transverse tubules do?
Cell membrane invaginations that extend between the myofibrils and ensure high calcium inside every cell
What are terminal cisternae?
Expansions of sarcoplasmic reticulum
Located adjacent to T-tubules
What is a triad?
One T-tubule and its adjacent terminal cisternae
What happens at the neuromuscular junction?
ACh causes depolarization which spreads via T-tubules to triad junction to the dihydropyridine receptor activates the ryanodine receptor on the SR