Chapter 11

1. Chapter 11 Cardiovascular System

2. The major function of the cardiovascular system is transportation. • The blood is the transport vehicle. • It carries oxygen, nutrients, cell wastes, hormones, and many other substances vital for body homeostasis to and from cells.

3. The force to move the blood throughout the body is provided by the beating heart.

4. The Cardiovascular System consists of: • Blood (transport vehicle) • Heart (pump) • Blood vessels (network of tubes)

5. Location and Size of the Heart • The heart is the size of a fist • The heart is located between the two lungs • A double sac called the pericardium surrounds the heart.

6. Lubricating fluid is found in between the two layers of the sac. This fluid allows the heart to beat easily in a frictionless environment.

7. The walls of the heart are made of 3 layers: • Epicardium – outer layer • Myocardium – layer that contracts • Endocardium – lines the chambers and goes into the blood vessels

8. The heart has four chambers or cavities. • The two atria are located at the superior or top of the heart and the two ventricles are located at the inferior or bottom of the heart.

10. Blood flow through the heart

11. Pulmonary Circulation • Right side: pumps to lungs oxygen poor on its way to the lungs – picks up oxygen – becomes oxygen rich

13. The Steps: • Oxygen poor blood enter the superior and inferior vena cava • Blood goes into the right atrium then right ventricle • Blood is them pumped to the pulmonary trunk which branches into pulmonary arteries

14. Blood goes to the lungs and picks up oxygen • Blood leaves the lungs in the pulmonary veins and goes to the left atrium

17. Systemic Circulation • Left side: pumps blood with oxygen to the body cells and back to the heart

18. The Steps: • Blood enters the left atrium then goes to the left ventricle • Blood is then pumped to the body cells through the aorta

19. 3. Blood travels from the aorta to arteries, smaller arteries, capillaries (losses oxygen) then to the veins and then to the superior and inferior vena cava

22. Cardiac Circulation • The blood in the heart does not nourish the myocardium. The blood supply that nourishes the heart is provided by the right and left coronary arteries which branch from the aorta.

23. Physiology of the Heart • 6 quarts pushed through 1000X • Heart pumps 6000 quarts a day • Cardiac muscle cells can and do contract spontaneously and independently. These contractions occur in a regular and continuous way.

24. The muscles in the different parts of the heart have different rhythms. • The heart has a unifying control system that coordinates its movement.

25. The Two Controlling Systems 1. The autonomic nervous system (automatic) acts like: the brakes and accelerators to increase or decrease heart rate

26. Intrinsic conduction system or nodal system - causes the heart to depolarize in one direction (from atria to ventricle) - enforces a contraction rate of 75 beats/min

27. SA node starts each heartbeat and is known as the pacemaker.

28. Cardiac Cycle and Heart Sounds

29. In a healthy heart the atria contract simultaneously • Systole – heart contraction • Diastole – heart relaxation

30. The Cardiac Cycle refers to: • The events of one complete heart beat during which both atria and ventricles contract and then relax.

32. The average heart beats 75 beats/min. • The cardiac cycle lasts for .8 sec.

33. Heart Sounds • When using a stethoscope, you can hear 2 distinct sounds during each cardiac cycle. These heart sounds are often described as lub and dub.

34. The first heart sound is made when: the AV valve closes - Lub • The second heart sound is made when: the semilunar valves close at the end of systole - Dub

35. The average heart rate is faster in females than males. • Females – 72-80 beats per minute • Males – 64-72 bpm

36. Cardiovascular System: Blood Vessels

37. Blood circulates inside the blood vessels which is a closed transport system, the so called vascular system.

38. The Path of Blood: • Arteries carry blood away from the heart (oxygen) • Veins carry blood to the heart (no oxygen) • From the heart blood is propelled into: arteries smaller arteries  arterioles capillary beds venules  veins  great veins

40. Microscopic Anatomy of Blood Vessels

41. The walls of blood vessels have 3 coats or tunics • Tunica intima decreases friction • Tunica media changes diameter of blood vessels • Tunica externa  function: support and protect blood vessels

43. The walls of arteries are usually thicker than the walls of veins • Artery walls must be strong and stretchy enough to take these continuous changes in pressure

44. Veins have thinner walls because they do not have to take the pressure • However, they are modified: to ensure the amount returning to the heart equals what is being pumped

45. Modifications • Valves to prevent backflow • Muscles milk veins and move blood to the heart • Breathing also helps

46. Location of Arteries and Veins in the body

47. Arteries are generally located in deep, well protected body areas. • Many veins are more superficial and some are easily seen and palpated on the body surface. • Most deep veins follow the course of the major arteries.

48. Hepatic Portal Vein • Delivers blood to the liver from the digestive organs

49. Fetal Circulation • Since the lungs and digestive system are not yet functioning in a fetus, all nutrient, excretory and gas exchange occur through the placenta. • Nutrients and oxygen move from the mother’s blood into the fetal blood and fetal wastes move in the opposite direction.