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
How are T-tubules coupled to Ryanodine receptors on the SR?
Via DHP receptors (L-type Ca2+ channels)
How does an action potential travel from the outside of a muscle cell to the inside?
Through the T-tubule system
What brings an action potential in close proximity to the Sarcoplasmic reticulum?
The T-tubules
What physically are the T-tubules?
Invaginations of the plasma membrane of muscle that leads to the inside of muscle cells
How do action potential propagate into the interior of the muscle fiber?
Through the invaginations of the T-tubule system
How many Cisternae does each T-tubule associate with?
Two
What is a Triad composed of?
One transverse tubule adjacent to two sarcoplasmic reticulum cisternae
What varies in the Triad of Cardiac muscle tissue?
It is not a triad it is a dyad with only one cisternae associated with the T-tubule
What does Smooth muscle have instead of T-tubules?
Rudimentary invaginations called caveolae
What is the Triad important for?
The coupling of contraction and excitation of
