The three mechanisms which regulate the heart are endocrine, cardiovascular and Sinoatrial nodes.
The endocrine system consists of the glands and hormones of the human body. The cardiovascular system is the organ system which is responsible for the circulation of the blood around the body and the oxygenation of the body's tissues. The sinoatrial node (SA node) generates the electrical impulses and is considered the natural pacemaker of the heart.
The answer would be between b and d but i would go with d
16. Organelles can move around the cytoplasm and perform activities that are necessary for life. Each organelle has a different job.
17. The function of the nucleus is it's the main command of the cell which means that it controls most of the cell's activities.
18. It converts heat energy and turns it to food in which the cell can eat.
20. It helps control what enters and leaves the cell.
22. Cell Wall, Chloroplasts,
