The Cardiovascular System

1. The Cardiovascular System Unit 3 (Ch.15)

2. Structure of the Heart • About as big as your fist. • Located within your thoracic cavity. • In the mediastinum • Sits on the diaphragm • 14 cm long by 9 cm wide.

3. Coverings of the Heart • Pericardium encloses the heart • Layers: 1.fibrous 2.visceral 3.parietal pericardium

4. Wall of the Heart • The epicardium protects the heart by reducing friction. • The myocardium pumps blood out of the heart chambers. • The endocardium is continuous with the inner linings of blood vessels attached to the heart.

5. Heart Chambers and Valves • The upper chambers, atria, receive blood returning to the heart. • The lower chambers, ventricles, receive blood from the atria and contract to force blood out of the heart in the arteries.

6. The triscuspid valve permits blood to move from the right atrium to the right ventricle. • The pulmonary valve allows blood to leave the right ventricle and prevents backflow into the ventricular chamber. • The mitral valve permits blood to move from the left atrium to the left ventricle. • The aortic valve allows blood to move from the left ventricle into the aorta.

7. Path of Blood Through the Heart (fig.15.40 on pg. 591) • Blood enters the right atrium from the venae cavae and coronary sinus. • passes though the tricuspid valve • enters the chamber of the right ventricle, though the pulmonary valve, • into the pulmonary arteries, • then the capillaries, • back to the pulmonary veins, • Out the left ventricle into the aorta

8. Coronary arteries • Supply blood to the tissues of the heart.

9. Systol and a Diastole • Systol- when atria contract (atrial systol) • Diastole-when ventricle relaxes. (ventricular diastole) • = Cardiac cycle – complete heartbeat.

10. Heart Sounds • Lubb-dupp or lubb-dubb

11. Electrocardiogram (ECG) • Records electrical changes in the myocardium during a cardiac cycle. • Pattern contains several waves • P wave • QRS wave • T waves *Physical exercise, body temperature, and concentration of various ions affect heartbeat.

12. Arteries and Arterioles • Arteries – adapted to carry blood under high pressure away from the heart. • A small branch of an artery that communicates with a capillary network = arteriole.

13. Vasoconstriction and Vasodilation • Vasoconstriction = a decrease in the diameter of a blood vessel. • Vasodilation = an increase in the diameter of a blood vessel.

14. Capillaries • A small blood vessel that connects an arteriole and a venule. (linchpin between arteries and veins)

15. Veins and Venules • Veins are vessels that carry blood toward the heart. • Venules are vessels that carries blood from capillaries to a vein.

16. Systolic and Diastolic Pressure • Systolic pressure-arterial blood pressure during the systolic phase of the cardiac cycle. • Diastolic pressure- lowest arterial blood pressure reaching during diastolic phase of cardiac phase.

17. Hypertension • High blood pressure.

18. Next Time • Paths of Circulation • Pulmonary circuit • Systemic circuit • Arterial System • Venous System • Life Span Changes