In a laboratory experiment you have treated a muscle cell with a calcium channel blocker. the membrane still depolarizes, but the concentration of calcium never increases in the cytosol. which of the following describes what will happen next?
a. only one cross-bridge cycle will occur but no second cycle.
b. binding of myosin to actin will take place.
c. tropomyosin will continue to cover the myosin binding sites on actin and no cross-bridges will form.
d. a single twitch in skeletal muscle but no sustained contraction.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

i think the answer is 95 hope this