Activity 4.3.1

1. Activity 4.3.1 The Heart of the Matter

2. Essential Question 1 • What types of muscles help move blood around the body? Cardiac Muscle Smooth Muscle Skeletal Muscle

3. Layers of the Heart Wall The wall of the heart consists of three layers: the epicardium (external layer), the myocardium (middle layer) and the endocardium (inner layer). The epicardium is the thin, transparent outer layer of the wall and is composed of delicate connective tissue. The myocardium, comprised of cardiac muscle tissue, makes up the majority of the cardiac wall and is responsible for its pumping action. The thickness of the myocardium mirrors the load to which each specific region of the heart is subjected. The endocardium is a thin layer of endothelium overlying a thin layer of connective tissue. It provides a smooth lining for the chambers of the heart and covers the valves. The endocardium is continuous with the endothelial lining of the large blood vessels attached Cardiac Muscle • Cardiac muscle fibers are shorter in length and larger in diameter than skeletal muscle fibers. • Cardiac muscle fibers have actin and myosin filaments arranged in the same way as skeletal muscle, but usually only one nuclei. • In contrast to skeletal muscle, cardiac muscle does not fatigue, cannot be repaired when damaged and is regulated by the autonomic nervous system. • Gap junctions between the fibers allow ions to travel between cells to permit the rapid fire of action potentials. • Excitement of a single fiber results in stimulation of all the other fibers in the network (ALL OR NONE) . As a result, each network contracts as a functional unit.

4. Cardiac Muscle

5. Smooth Muscle • Arteries have smooth muscle that functions to regulate the flow of blood through the artery. • Contraction of the smooth muscle decreases the internal diameter of the vessel in a process called vasoconstriction. • Relaxation of the smooth muscle increases the internal diameter in a process called vasodilation.

6. Smooth Muscle

7. Where else can you find Smooth Muscles • Walls of stomach • Uterus • Intestines • Iris of the eye • GI Tract • Respiratory Tract • Kidneys • Bladder • Ureters • Ciliary muscle • Sphincter • Trachea • Bile duct • .

8. Skeletal Muscle. • Veins pass between skeletal muscles. The contraction of skeletal muscle squeezes the vein. • Repeated cycles of contraction and relaxation of skeletal muscle, as occurs in the leg muscles while walking, helps facility blood back to the heart.

9. Skeletal Muscle

10. What do you remember from PBS about the heart?” • 1_______________ • 2____________ • 3___________ • 4___________ • 5___________ • 6___________ • 7___________ • 8___________ • 9__________

11. Position and Shape of the Heart. • The heart is located in the thoracic cavity in between the lungs, 60% of it lying to the left of the median plane. • The heart is cone-shaped, with a broad base at the top from which the large blood vessels enter and exit. • The tip, known as the apex, points downwards and lies close to the sternum.

12. Pericardium • A membrane that surrounds and protects the heart. It is composed of two layers containing a small volume of fluid which serves as a lubricant, facilitating the movement of the heart by minimizing friction. • The inner layer is firmly attached to the heart wall and is known as the visceral layer or epicardium. • The outer layer is composed of relatively inelastic connective tissue and is termed the parietal layer.

13. Layers of the Heart Wall • The wall of the heart consists of three layers: • epicardium (external layer), is the thin, transparent outer layer of the wall and is composed of delicate connective tissue. • myocardium (middle layer), comprised of cardiac muscle tissue, makes up the majority of the cardiac wall and is responsible for its pumping action. The specific regions dictates the thickness of the myocardium. • endocardium (inner layer). is a thin layer of endothelium. It provides a smooth lining for the chambers of the heart and covers the valves. It is continuous with the endothelial lining of the large blood vessels attached to the heart

14. Fibrous Skeleton • In addition to cardiac muscle tissue, the heart wall also contains dense connective tissues that: • forms the fibrous skeleton of the heart. • forms rings that surround the four heart orifices. • The skeleton performs several functions: • It serves as a point of attachment for the heart valves. • It prevents the valves from overstretching as blood passes through them. • It acts as an electrical insulator thereby preventing the direct spread of action potentials from the atria to the ventricles.

15. Chambers of the Heart • The heart contains four chambers where the thickness of the myocardium of the chambers varies according to its function. • The two upper chambers are the atria. The atria are thin-walled because they deliver blood into the adjacent ventricles. On the upper surface of each atrium is a pouch-like appendage which is thought to increase the capacity of the atrium slightly. • The two lower chambers are the ventricles. The ventricles are equipped with thick muscular walls because they pump blood over greater distances.

16. Ventricles • The right and left ventricles act as two separate pumps that simultaneously eject equal volumes of blood. The right ventricle only pumps blood into the lungs, which are close by and present little resistance to blood flow so work load is less. • On the other hand, the left ventricle pumps blood to the rest of the body, where the resistance to blood flow is considerably higher. Therefore, the left ventricle works harder than the right ventricle to maintain the same blood flow rate. Consequently, the left ventricle is significantly thicker than that of the right.

17. Right Atrium (RA) • The right atrium forms the section of the base of the heart and receives blood from the superior vena cava, inferior vena cava and coronary sinus. • Blood flows from the right atrium to the right ventricle through the tricuspid valve (also know as the right atrioventricular valve). • The right atrium also houses the sinoatrial node.

18. Right Ventricle (RV) • The right ventricle forms most of the anterior surface of the heart and is crescent-shaped in cross-section. • The tricuspid valve provides the means for blood to leave the RA and move into the RV • The right ventricle is separated from the left by a partition called the interventricular septum. • Deoxygenated blood passes from the right ventricle through the pulmonary semi-lunar valve to the pulmonary trunk, which conveys the blood to the lungs.

19. Left Atrium (LA) • The left atrium forms the section of the base of the heart and is similar to the right atrium in structure and shape. • It receives oxygenated blood from the lungs via the pulmonary veins. • Blood passes from the left atrium to the left ventricle through the bicuspid or mitral valve. • The left atrium lies under the tracheal bifurcation and enlargement of this area of the heart can cause breathing difficulties.

20. Left Ventricle (LV) • The left ventricle forms the apex of the heart and is conical in shape. • Blood passes from the left ventricle to the ascending aorta through the aortic valve. • From here some of the blood flows into the coronary arteries, which branch from the ascending aorta and carry blood to the heart wall. • The remainder of the blood travels throughout the body.

21. Coronary vasculature

22. Conduction system • Animation: Conducting System of the Heart

23. Think about blood supply to....

24. EKG

25. Electrical Conduction

26. Essential Question 2 & 3 • What is the relationship between the heart and the lungs? • What is the pathway of blood in and out of the heart in pulmonary and systemic circulation?

27. Activity 4.3.2 • Varicose Veins

28. Varicose Veins • Normally, one-way valves in the veins keep blood flowing from your legs up toward your heart. • Varicose veins are caused by weakened valves in the veins in your legs. • When these valves do not work as they should, blood collects in your legs, and pressure builds up.

29. Varicose Veins • As pressure builds in the veins, the walls of the veins become weak, dilated, and twisted. • Venous return is slowed, causing blood to become sluggish. www.sirweb.org/news/videoClips.shtml

30. Causes of Varicose Veins • Varicose veins often run in families. • Aging increases your risk. • Increased pressure on leg veins from • Being overweight • Pregnancy • Or having a job where you must stand for long periods of time.

31. The structure of blood vessels is in direct relationship to the function it performs Artery Vein Capillary

32. Cross section of an artery • Why don’t we get varicose arteries.

33. Essential Question 4. How do the structure of arteries, veins and capillaries relate to their function in the body? 5. What unique features of veins help move blood back to the heart? 6. What are varicose veins? 7. Why don’t we ever hear about varicose arteries?

34. View Vessel Slides • Draw in your journal what you saw in the slides • With team of 4 devise a way to explain how varicose veins form and why we done get varicose arteries. • Final product could be drawing, diagram, information brochure, clay model, or a letter to your grandmother to answer her questions about varicose veins. • Present your findings to the class

35. Activity 4.3.3 Go With the Flow

36. The Flow • Blood vessels move blood from the heart to the lungs to pick up oxygen and deliver this oxygen to all of the tissues of the body. • Arteries flow away from the heart and branch into smaller vessels called arterioles. • Arterioles lead into the capillary beds, thin nets of vessels where gas exchange occurs. • Blood then converges back into small veins called venules and eventually back into the major veins to be returned to the heart. • Vessel size varies dramatically along this path.

37. Make paper Flag for these vessels Ascending Aorta Renal artery/vein Descending Aorta Iliac artery/vein Brachiocephalic artery Femoral artery/vein Subclavian artery/vein Popliteal artery/vein Carotid artery vein Posterior Tibial artery/vein Radial artery/vein Superior Vena Cave Ulnar artery/vein Inferior Vena Cava Common Iliac Vein Internal Jugular vein Superficial palmar arch

38. Build this on Maniken

39. One Brachiocephalic Artery

40. The aorta is the largest artery in the body about the diameter of a garden hose. • The capillaries, on the other hand, are so tiny that about ten of them would be as thick as one of the hairs on our head. • The structure of blood vessels relates directly to their particular function and to the amount of pressure exerted on the vessel walls.

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42. Essential Question 8. What are the major arteries and veins in the body and which regions do they serve?

43. Arteries in the arm

44. Veins in the Arm

45. Veins more superficial

46. Activity 4.3.4 Cardiac Output

47. Cardiac Output • Cardiac Output is a measure of how much blood the heart can pump in one minute by the ventricles. • Cardiac Output (ml/min) = Stroke Volume (75ml/beat) X Heart Rate (BPM)

48. What are some diseases that affect CO if dependent on SV & HR • hypertension • heart failure • infection and sepsis • cardiomyopathy • rhythm disturbances • coronary artery disease

49. Essential Question 9. What is cardiac output? 10. How does cardiac output help assess overall heart health? 11. How does an increased or decreased cardiac output impact the body?

50. Changes in cardiac output • often signal diseases of the heart and these changes can impact the function of other body systems. • Increased blood pressure in vessels can indicate possible blockages, and these blockages can interrupt blood flow to an organ or limb • Increased BP decreases Cardiac Output in a diseased heart