Muscle 7 Flashcards
What surround the myofibrils?
The sarcoplasmic reticulum
What allows calcium to be released in close proximity to the contractile proteins?
The surrounding sarcoplasmic reticulum of myofibrils
Where does the Sarcoplasmic reticulum have their calcium release channels near?
The transverse tubules
What is another name for the Sarcoplasmic Reticulum Calcium Release channels?
Ryanodine receptors
What does each unit of the Ryanodine receptors have in skeletal muscle?
A foot like process
Where does the Sarcoplasmic Reticulum store large amounts of calcium?
In the terminal cisternae
What are Terminal Cisternae?
Enlarge regions of SR that store and release the majority of Ca2+
What is a Calsequestrin?
A calcium binding protein found in the SR that acts as a calcium buffer by holding calcium in the SR after a muscle contraction even though calcium conc. in the SR is higher than in the cytosol
How does the SR remove calcium from the cytoplasm and bring it back into the SR?
Using pumps (SERCA 1 and SERCA 2A)
Where do the calcium pumps of the SR get their energy?
From ATP
How does the SR speed up the contraction in skeletal muscle?
By creating a shorter distance for calcium to diffuse because it doesn’t need to come from outside the cell
What are the Transverse Tubules (T-tubules)?
A system of ducts that synchronize the release of Ca2+ from the terminal cisternae of the sarcoplasmic reticulum
What are T-tubules an extension of?
The surface membrane
Where do T-Tubules enter?
At the junction of A and I bands
What do the T-tubules carry and where?
Ions, nutrients and action potentials deep into the cell
