1.2.3 Review of Skeletal Muscle Flashcards
The concentration of Ca++ in the T tubules is the same as what?
ECF
At high or low Ca++, does the troponin complex swing out of the way allowing for myosin to engage with actin?
High Ca++
How are myofibrils, the sarcoplasm, and nucleus arranged within a muscle cell?
What is the the biomechanical arrangement of most muscle?
Fusiform
What are four different types of frequency dependent forces?
Twitch, summation, incomplete tetanus, complete tetanus
What covers actin?
Tropomyosin and the troponin complex (I,C,T)
What protein (intermediate filament) connects myofibrils to the membrane?
Desmin
What is the H band?
Located in the midle of each A band. It’s the portion of the myosin tails without heads (the Headless zone)
What protein gives muscle its elastic properties?
Titin
Name the various levels of connective tissue and their corresponding muscle layers.
Endomysium - individual muscle cell
Perimysium - fasciculi
Epimysium - muscle body
What are the three different types of muscle fiber?
Type II - Fast twitch
Type I - Slow twitch
Intermediate fibers - combination of Type I and II
The type is determined by the properties of the myosin
What amount of energy and what substrate are required to unfold titin?
No energy and a water molecule
Fill in the chart
Type 1: the slow red ox
ID these four bands and lines
What type of muscle? Explain your reasoning
Skeletal muscle; striations and peripheral nuclei
What would happen to muscle if exposed to excessive calcium?
Constant contraction
Is energy required to refold titin?
No, it just has to kick out the water molecule
At high or low Ca++?
The troponin complex is engaging actin not allowing for myosin to bind.
Low Ca++
ID each of these bands, disks, and lines.
Draw the tension vs. length graph for any given muscle contraction
How does muscle contract?
Sliding filament - the A band and I band begin to overlap as muscle contracts
When can maximal tension be reached during muscle contraction?
When the A and I bands have overlapped to the point in which all the myosin heads are engaging with actin.
Depolarizing the T-tubule membrane results in what? What is the downstream result?
Depolarization of the t-tubule membrane results in the opening of the voltage-gated Ca++ channel causing an influx of Ca++ into the cytosol. That calcium then interacts with the sarcoplasmic reticulum allowing for it to release Ca++
What is the name of the finger-like processes of the sarcolemma?
Transverse tubules (T tubule) - these occur at the A-I Junction
What is different about the distribution of dystrophin and desmin?
Desmin starts at the membrane and penetrates down wrapping around myofibrils.
Dystrophin is only found along the membrane
