What is the function of the transverse tubules in a skeletal-muscle fiber?
A. They store the calcium ions that are the main source of activation for the cross-bridge cycle.
B. They form the Z lines that mark the end of each sarcomere.
C. They allow action potentials to propagate deep into the center of skeletal muscle cells.
D. They manufacture and store ATP.
E. They run in parallel with the myofibrils, and have abundant Ca2+-ATPase proteins for pumping Ca2+ back into the sarcoplasmic reticulum.
C
You might also like to view...
Clusters of ganglionic sympathetic neurons that innervate organs in the abdominopelvic region are called ________ ganglia
A) intramural B) collateral C) chain D) paravertebral E) adrenal
Voluntary urination involves
A) relaxing the abdominal and expiratory muscles. B) decreasing abdominal pressure. C) contracting the external sphincter. D) relaxing the external sphincter and compressing the urinary bladder. E) None of the answers are correct.
Marissa is an avid marathon runner, and she trains incessantly. She has slimmed down so that she is now underweight for her height and has very little fat tissue. One would expect Marissa to
A) have heavy menstrual flows. B) ovulate continuously. C) be amenorrheic (have no monthly menstrual flow). D) have painful menstrual cramps. E) show elevated levels of FSH.
What is one possible path of blood from the heart to the left hallux and back to the heart?
A. Aorta ? left common iliac artery ? left external iliac artery ? left great saphenous artery ? left anterior tibial artery ? dorsal artery of foot ? arcuate arteries ? dorsal venous arch ? left small saphenous vein ? left femoral vein ? left internal iliac vein ? left common iliac vein ? inferior vena cava B. Aorta ? left common iliac artery ? left internal iliac artery ? left small saphenous artery ? left popliteal artery ? left posterior tibial artery ? dorsal artery of foot ? arcuate arteries ? dorsal venous arch ? left femoral vein ? left internal iliac vein ? left common iliac vein ? inferior vena cava C. Aorta ? left common iliac artery ? left internal iliac artery ? left femoral artery ? left popliteal artery ? left posterior tibial artery ? dorsal artery of foot ? arcuate arteries ? dorsal venous arch ? left fibular vein ? left popliteal vein ? left internal iliac vein ? left common iliac vein ? inferior vena cava D. Aorta ? left common iliac artery ? left external iliac artery ? left femoral artery ? left popliteal artery ? left anterior tibial artery ? dorsal artery of foot ? arcuate arteries ? dorsal venous arch ? left great saphenous vein ? left femoral vein ? left external iliac vein ? left common iliac vein ? inferior vena cava