In your OWN words, describe the cardiac cycle

The cardiac cycle is defined as a sequence of alternating contraction and relaxation of the atria and ventricles in order to pump blood throughout the body. ... In other words, when the atria are in diastole, the ventricles are in systole and vice versa.The cardiac cycle describes all the activities of the heart through one complete heartbeat—that is, through one contraction and relaxation of both the atria and ventricles. ... The volume of the ventricles remains unchanged (isovolumetric) during this period.

Explanation:

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.

a physical change is being made.