alcium is released and sequestered differently in Skeletal and Cardiac muscles. Why are the differences important physiologically in relation to the purpose of those types of muscles

Calcium is an essential ion as it required in the contraction of both cardiac and skeletal muscles. The sarcoplasmic reticulum stores these ions that are pumped by calcium pumps and released when contraction and functioning of these muscles. It binds to troponin and altered the change of shape and prevents tropomyosin from the site of the binding.

In case of cardiac muscle, the coupling Ca2+ is from its contact with extracellular concentration of Ca2+. When the calcium is released in the skeletal muscle it leads to the interaction between the actin and myosin. The binding sites of the myosin is exposed that bind and forms cross bridges with actin and hence helps in the contraction of the muscle. With the calcium induced calcium release, it helps in the contraction of the cardiac muscle. As the calcium is released it leads to initiation of the smooth muscle contraction in the cardiac muscle through binding of calmodulin and leads to activation of the myosin light chain kinase enzyme. There are receptors for the Calcium induced calcium release within the cardiac cells called as cardiomyocyte that binds to the calcium during depolarization and hence releases more calcium ions within the cells.

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.