16.4: Chapter Summary
This chapter focused on an introduction to the cardiovascular system and laid the foundation for cardiovascular pharmacology. The structure and anatomy of the cardiovascular system were described. The heart consists of four chambers: the two upper chambers (atria) and the two lower chambers (ventricles). The heart contains valves that direct blood flow and prevent backflow of blood through the heart. The heart is supplied with blood by the coronary arteries. Arteries carry oxygenated blood away from the heart to the body, and veins carry deoxygenated blood back to the heart from the body. Gas exchange occurs in the tissues via capillaries.
The pumping action of the heart and the cardiac cycle were also discussed. Systole is the contraction of the heart chamber for pumping, and diastole is relaxation of the heart chamber for filling. The venae cavae deliver deoxygenated blood from the tissues to the right atrium, then the blood moves to the right ventricle, which pumps the deoxygenated blood to the pulmonary circuit for oxygenation. Oxygenated blood then returns to the left atrium, and then the blood moves to the left ventricle. During systole, the left ventricle pumps the blood through the aorta to the tissues for use.
Finally, the conduction system of the heart was described. The conduction system is an electrochemical system that causes the heart to pump in a coordinated manner using movement of ions into and out of cells. The sinoatrial node acts as the pacemaker of the heart and spontaneously generates an impulse that moves through the conduction system, eventually reaching the muscle cells and causing them to contract during systole. The electrocardiogram allows clinicians to monitor the heart rate and rhythm in a noninvasive manner and can help diagnose dysrhythmias, or abnormal heart rhythms.