Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
5 Cards in this Set
- Front
- Back
|
What are the 6 steps of the contraction of muscle cells? (macroscopic picture)
|
1. AP depolarizes surface of muscle fiber (via neuromuscular junction)
2. AP travels deep via T-tubules 3. Depolarization of T-tubule membrane induce dihydropyridine receptors to undergo conf. change -> pulls up ryanodine receptors of SR to release Ca2+ 4. Myoplasm [Ca2+] rises from 10-7 M to 10-5 M 5. higher [Ca2+] causes Ca2+ to bind to troponin, unwinding tropomyosin off actin to allow myosin crossbridges to bind and cause contraction 6. Ca2+ actively pumped back into SR; tropomyosin rebinds to actin |
|
|
What is the resting muscle Ca2+ concentration and active muscle Ca2+ concentration?
|
Resting = 10^-7 M
Active = 10^-5 M (or greater than 10^-6 M) |
|
|
What are calsequestrin proteins and their purpose?
|
Bind to free Ca2+ ions in SR to lower free [Ca2+] by 99% (from 10^-2 M to 10^-4 M), easing concentration gradient that Ca2+ pumps must work against to pump Ca2+ back into SR
|
|
|
What is the importance of T-tubules and SR?
|
To uniformly and simultaneously spread AP across all of muscle fiber; also, minimize diffusion distance of Ca2+ to get to sarcomeres
|
|
|
How does SR get its Ca2+ ions?
|
By actively pumping it in from its surroundings
|
