Which isare) true statements about Sarcomeres? 1. The A band includes the entire length of the thin filaments. 2. The H zone increases in size during contraction. 3. The I band decreases during contraction. 4. The A band remains the same length with contraction. A. 1, 2, 3 and 4 B. 3 and 4 only C. 2, 3 and 4 only D. I and 2 only 41. The ion responsible for the rapid depolarization phase of contractile (myocardial) cells in the heart is The plateau phase of the action potential in these cells functions to A. Calcium; prevent tetanus B. Calcium; prevent the heart from filling with too much blood C. Sodium; prevent tetanus D. Sodium; prevent the heart from filling with too much blood E. Sodium; prevent high afterload inntion of the nacemaker cells
