Skeletal Muscle: Molecular Basis Flashcards
What are Transvers Tubules?
- Invaginations of sarcolemma into the center of the cell
- Contain voltage gated L type DHPR Ca channels
- Many other types of Na,K, and Ca channels and pumps.
What is the SR?
- system of tubular sacs
- stores high concentrations of Ca
- Contains DHPR activated channels (Ryanodine receptors)
- Release Ca to trigger muscle contraction and SERCA to pump Calcium back in
What is a sarcomere?
The Contractile Unit of muscle made of myofilament proteins
What is the role of nebulin Nd other Z disc proteins??
Anchor thin filaments in place
What is the role of Titian?
Large protein which spans entire sarcomere which helps to prevent pulling apart and in elastic recoil
What is the troponin complex, and what are its components?
Protein which regulates beginning and end of contraction based on calcium iron concentrations
Troponin C - Calcium binding unit
Troponin I - Inhibitory subunit which regulates actin-tropomysoin interaction
Troponin T: Tropomyosin binding subunit
What events follow Ca binding to troponin?
- Troponin-tropomyosin move and allow myosin to interact with actin
- Myosin produces contraction (shortening)
- Ca is pumped back into SR/out of cell
- Relaxation occurs when Ca unbind from troponin which results in troponin-tropomyosin preventing myosin from binding actin
What is the role ofATP in Muscle contraction?
During Contraction, ATP binds to myosin causing dissociation of myosin from actin
Describe the sliding filament model of muscle contraction.
- “swinging lover arm”
- Shortening occurs due to movement of actin filament over myosin
- Formation of crossbridges btwn actin and myosin makes power stroke