1. CIRCULATION CHAPTER 22

2. Circulatory Systems Blood flows through blood vessels Blood flows through blood vessels Heart generates force to keep blood moving Heart generates force to keep blood moving Closed system Closed system –Blood is confined to vessels and heart Open system Open system –Blood mingles with fluid in tissues

3. Velocity of Flow Varies Volume of blood flow through vessels always has to equal heart’s output Volume of blood flow through vessels always has to equal heart’s output Flow velocity is highest in large-diameter transport vessels Flow velocity is highest in large-diameter transport vessels Flow velocity is slowest in capillary beds; blood spreads out into many vessels with greater total cross-sectional area Flow velocity is slowest in capillary beds; blood spreads out into many vessels with greater total cross-sectional area

4. Flow Analogy river inriver out lake 123123 123

5. Vertebrate Systems Fish Fish –Two-chambered heart pumps blood through one circuit Amphibians Amphibians –Heart pumps blood through two partially separate circuits Birds and mammals Birds and mammals –Four-chambered heart pumps blood through two entirely separate circuits

6. Functions of Blood Transports oxygen and nutrients to cells Transports oxygen and nutrients to cells Carries carbon dioxide and wastes away from cells Carries carbon dioxide and wastes away from cells Helps stabilize internal pH Helps stabilize internal pH Carries infection-fighting cells Carries infection-fighting cells Helps equalize temperature Helps equalize temperature

7. Blood Cell Development Stem cells in bone marrow are unspecialized cells that retain the capacity to divide Stem cells in bone marrow are unspecialized cells that retain the capacity to divide Some daughter cells of stem cells differentiate to form blood cells Some daughter cells of stem cells differentiate to form blood cells Body must continually replace blood cells Body must continually replace blood cells

8. Erythrocytes (Red Cells) Most numerous cells in the blood Most numerous cells in the blood Transport oxygen and carbon dioxide Transport oxygen and carbon dioxide Colored red by oxygen-binding pigment (hemoglobin) Colored red by oxygen-binding pigment (hemoglobin) Have no nucleus when mature Have no nucleus when mature

9. Leukocytes (White Cells) Function in housekeeping and defense Function in housekeeping and defense Cell types Cell types BasophilsDendritic cells EosinophilsB lymphocytes NeutrophilsT lymphocytes Macrophages NK cells Mast cells

10. Platelets Membrane-bound cell fragments Membrane-bound cell fragments Derived from megakaryocytes, which arise from stem cells Derived from megakaryocytes, which arise from stem cells Release substances that initiate blood clotting Release substances that initiate blood clotting

11. The Heart The heart is a cone-shaped, muscular organ located between the lungs behind the sternum. The heart is a cone-shaped, muscular organ located between the lungs behind the sternum. The heart muscle forms the myocardium, with tightly interconnected cells of cardiac muscle tissue. The heart muscle forms the myocardium, with tightly interconnected cells of cardiac muscle tissue. The pericardium is the outer membranous sac with lubricating fluid. The pericardium is the outer membranous sac with lubricating fluid.

12. The heart has four chambers: two upper, thin- walled atria, and two lower, thick-walled ventricles. The heart has four chambers: two upper, thin- walled atria, and two lower, thick-walled ventricles. The septum is a wall dividing the right and left sides. The septum is a wall dividing the right and left sides. Atrioventricular valves occur between the atria and ventricles – the tricuspid valve on the right and the bicuspid valve on the left; both valves are reinforced by chordae tendinae attached to muscular projections within the ventricles. Atrioventricular valves occur between the atria and ventricles – the tricuspid valve on the right and the bicuspid valve on the left; both valves are reinforced by chordae tendinae attached to muscular projections within the ventricles. Semilunar valves occur between the ventricles and the attached arteries Semilunar valves occur between the ventricles and the attached arteries

13. External heart anatomy

14. Coronary artery circulation

15. Passage of Blood Through the Heart Blood follows this sequence through the heart: superior and inferior vena cava → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk and arteries to the lungs → pulmonary veins leaving the lungs → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta → to the body. Blood follows this sequence through the heart: superior and inferior vena cava → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk and arteries to the lungs → pulmonary veins leaving the lungs → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta → to the body.

16. Internal view of the heart

17. Path of blood through the heart

18. The Heartbeat Each heartbeat is called a cardiac cycle. Each heartbeat is called a cardiac cycle. When the heart beats, the two atria contract together, then the two ventricles contract; then the whole heart relaxes. When the heart beats, the two atria contract together, then the two ventricles contract; then the whole heart relaxes. Systole is the contraction of heart chambers; diastole is their relaxation. Systole is the contraction of heart chambers; diastole is their relaxation. The heart sounds, lub-dup, are due to the closing of the atrioventricular valves, followed by the closing of the semilunar valves. The heart sounds, lub-dup, are due to the closing of the atrioventricular valves, followed by the closing of the semilunar valves.

19. Conduction system of the heart

20. Conduction and Contraction SA node in right atrium is pacemaker SA node in right atrium is pacemaker Electrical signals cause contraction of atria Electrical signals cause contraction of atria Signal flows to AV node and down septum to ventricles Signal flows to AV node and down septum to ventricles SA node

21. The Electrocardiogram An electrocardiogram (ECG) is a recording of the electrical changes that occur in the myocardium during a cardiac cycle. An electrocardiogram (ECG) is a recording of the electrical changes that occur in the myocardium during a cardiac cycle. Atrial depolarization creates the P wave, ventricle depolarization creates the QRS wave, and repolarization of the ventricles produces the T wave. Atrial depolarization creates the P wave, ventricle depolarization creates the QRS wave, and repolarization of the ventricles produces the T wave.

22. Electrocardiogram

23. The Vascular Pathways The cardiovascular system includes two circuits: The cardiovascular system includes two circuits: 1) Pulmonary circuit which circulates blood through the lungs, and 2) Systemic circuit which circulates blood to the rest of the body. 3) Both circuits are vital to homeostasis.

24. Pulmonary Circuit This loop oxygenates blood right pulmonary arteryleft pulmonary artery capillary bed of right lung pulmonary trunk capillary bed of left lung (to systemic circuit) pulmonary veins lungs (from systemic circuit) heart

25. Systemic Circuit Longer loop carries blood to and from body tissues capillary beds of head and upper extremities (to pulmonary circuit) aorta (from pulmonary circuit) heart capillary beds of other organs in thoracic cavity capillary bed of liver capillary beds of intestines capillary beds of other abdominal organs and lower extremities

26. Cardiovascular system diagram

27. The cardiovascular system has three types of blood vessels: The cardiovascular system has three types of blood vessels: Arteries (and arterioles) – carry blood away from the heart Arteries (and arterioles) – carry blood away from the heart Capillaries – where nutrient and gas exchange occur Capillaries – where nutrient and gas exchange occur Veins (and venules) – carry blood toward the heart. Veins (and venules) – carry blood toward the heart. The Blood Vessels

28. Blood vessels

29. The Arteries Arteries and arterioles take blood away from the heart. Arteries and arterioles take blood away from the heart. The largest artery is the aorta. The largest artery is the aorta. The middle layer of an artery wall consists of smooth muscle that can constrict to regulate blood flow and blood pressure. The middle layer of an artery wall consists of smooth muscle that can constrict to regulate blood flow and blood pressure. Arterioles can constrict or dilate, changing blood pressure. Arterioles can constrict or dilate, changing blood pressure.

30. Blood Flow The beating of the heart is necessary to homeostasis because it creates pressure that propels blood in arteries and the arterioles. The beating of the heart is necessary to homeostasis because it creates pressure that propels blood in arteries and the arterioles. Arterioles lead to the capillaries where nutrient and gas exchange with tissue fluid takes place. Arterioles lead to the capillaries where nutrient and gas exchange with tissue fluid takes place.

31. Blood Flow in Arteries Blood pressure due to the pumping of the heart accounts for the flow of blood in the arteries. Blood pressure due to the pumping of the heart accounts for the flow of blood in the arteries. Systolic pressure is high when the heart expels the blood. Systolic pressure is high when the heart expels the blood. Diastolic pressure occurs when the heart ventricles are relaxing. Diastolic pressure occurs when the heart ventricles are relaxing. Both pressures decrease with distance from the left ventricle because blood enters more and more arterioles and arteries. Both pressures decrease with distance from the left ventricle because blood enters more and more arterioles and arteries.

32. The Capillaries Capillaries have walls only one cell thick to allow exchange of gases and nutrients with tissue fluid. Capillaries have walls only one cell thick to allow exchange of gases and nutrients with tissue fluid. Capillary beds are present in all regions of the body but not all capillary beds are open at the same time. Capillary beds are present in all regions of the body but not all capillary beds are open at the same time.

33. Anatomy of a capillary bed

34. Blood Flow in Capillaries Blood moves slowly in capillaries because there are more capillaries than arterioles. Blood moves slowly in capillaries because there are more capillaries than arterioles. This allows time for substances to be exchanged between the blood and tissues. This allows time for substances to be exchanged between the blood and tissues.

35. Bulk Flow in Capillary Bed blood to venule inward-directed osmotic movement cells of tissue outward-directed bulk flow blood from arteriole

36. Diffusion Zone Capillary beds are the site of exchange between blood and interstitial fluid Capillary beds are the site of exchange between blood and interstitial fluid Capillary is a single sheet of epithelial cells Capillary is a single sheet of epithelial cells Flow is slow; allows gasses to diffuse across membranes of blood cells and across endothelium Flow is slow; allows gasses to diffuse across membranes of blood cells and across endothelium

37. The Veins Venules drain blood from capillaries, then join to form veins that take blood to the heart. Venules drain blood from capillaries, then join to form veins that take blood to the heart. Veins have much less smooth muscle and connective tissue than arteries. Veins have much less smooth muscle and connective tissue than arteries. Veins often have valves that prevent the backward flow of blood when closed. Veins often have valves that prevent the backward flow of blood when closed. Veins carry about 70% of the body’s blood and act as a reservoir during hemorrhage. Veins carry about 70% of the body’s blood and act as a reservoir during hemorrhage.

38. The Venous System The Venous System Blood flows from capillaries into venules, then on to veins Blood flows from capillaries into venules, then on to veins Veins are large-diameter vessels with some smooth muscle in wall Veins are large-diameter vessels with some smooth muscle in wall Valves in some veins prevent blood from flowing backward Valves in some veins prevent blood from flowing backward

39. Blood Flow in Veins Venous blood flow is dependent upon: Venous blood flow is dependent upon: 1) skeletal muscle contraction, 2) presence of valves in veins, and 3) respiratory movements. Compression of veins causes blood to move forward past a valve that then prevents it from returning backward. Compression of veins causes blood to move forward past a valve that then prevents it from returning backward.

40. Changes in thoracic and abdominal pressure that occur with breathing also assist in the return of blood. Changes in thoracic and abdominal pressure that occur with breathing also assist in the return of blood. Varicose veins develop when the valves of veins become weak. Varicose veins develop when the valves of veins become weak. Hemorrhoids (piles) are due to varicose veins in the rectum. Hemorrhoids (piles) are due to varicose veins in the rectum. Phlebitis is inflammation of a vein and can lead to a blood clot and possible death if the clot is dislodged and is carried to a pulmonary vessel. Phlebitis is inflammation of a vein and can lead to a blood clot and possible death if the clot is dislodged and is carried to a pulmonary vessel.

41. jugular veins superior vena cava pulmonary veins hepatic portal vein renal vein inferior vena cava iliac veins femoral vein carotid arteries ascending aorta pulmonary arteries coronary arteries renal artery brachial artery abdominal aorta iliac arteries femoral artery Major Vessels

42. Hemophilia Hemophilia is an inherited clotting disorder due to a deficiency in a clotting factor. Hemophilia is an inherited clotting disorder due to a deficiency in a clotting factor. Bumps and falls cause bleeding in the joints; cartilage degeneration and resorption of bone can follow. Bumps and falls cause bleeding in the joints; cartilage degeneration and resorption of bone can follow. The most frequent cause of death is bleeding into the brain with accompanying neurological damage. The most frequent cause of death is bleeding into the brain with accompanying neurological damage.

43. Cardiovascular Disorders Cardiovascular disease (CVD) is the leading cause of death in Western countries. Cardiovascular disease (CVD) is the leading cause of death in Western countries. Modern research efforts have improved diagnosis, treatment, and prevention. Modern research efforts have improved diagnosis, treatment, and prevention. Major cardiovascular disorders include atherosclerosis, stroke, heart attack, aneurysm, and hypertension. Major cardiovascular disorders include atherosclerosis, stroke, heart attack, aneurysm, and hypertension.

44. Atherosclerosis Atherosclerosis is due to a build-up of fatty material (plaque), mainly cholesterol, under the inner lining of arteries. Atherosclerosis is due to a build-up of fatty material (plaque), mainly cholesterol, under the inner lining of arteries. The plaque can cause a thrombus (blood clot) to form. The plaque can cause a thrombus (blood clot) to form. The thrombus can dislodge as an embolus and lead to thromboembolism. The thrombus can dislodge as an embolus and lead to thromboembolism.

45. Stroke, Heart Attack, and Aneurysm A cerebrovascular accident, or stroke, results when an embolus lodges in a cerebral blood vessel or a cerebral blood vessel bursts; a portion of the brain dies due to lack of oxygen. A cerebrovascular accident, or stroke, results when an embolus lodges in a cerebral blood vessel or a cerebral blood vessel bursts; a portion of the brain dies due to lack of oxygen. A myocardial infarction, or heart attack, occurs when a portion of heart muscle dies due to lack of oxygen. A myocardial infarction, or heart attack, occurs when a portion of heart muscle dies due to lack of oxygen.

46. Coronary bypass operation

47. Angioplasty

48. Hypertension About 20% of Americans suffer from hypertension (high blood pressure). About 20% of Americans suffer from hypertension (high blood pressure). Hypertension is present when systolic pressure is 140 or greater or diastolic pressure is 90 or greater; diastolic pressure is emphasized when medical treatment is considered. Hypertension is present when systolic pressure is 140 or greater or diastolic pressure is 90 or greater; diastolic pressure is emphasized when medical treatment is considered. A genetic predisposition for hypertension occurs in those who have a gene that codes for angiotensinogen, a powerful vasoconstrictor. A genetic predisposition for hypertension occurs in those who have a gene that codes for angiotensinogen, a powerful vasoconstrictor.

49. Blood Pressure Highest in arteries, lowest in veins Highest in arteries, lowest in veins Usually measured in the brachial artery Usually measured in the brachial artery Systolic pressure is peak pressure Systolic pressure is peak pressure –Ventricular contraction Diastolic pressure is the lowest pressure Diastolic pressure is the lowest pressure –Ventricular relaxation

50. Hemostasis Blood vessel spasm, platelet plug formation, blood coagulation Blood vessel spasm, platelet plug formation, blood coagulation Clotting mechanism Clotting mechanism –Prothrombin is converted to thrombin –Fibrinogen is converted to fibrin –Fibrin forms net that entangles cells and platelets

51. Hypertension Blood pressure above 140/90 Blood pressure above 140/90 Tends to be genetic Tends to be genetic May also be influenced by diet May also be influenced by diet Contributes to atherosclerosis Contributes to atherosclerosis “Silent killer”: few outward signs “Silent killer”: few outward signs

52. Atherosclerosis Arteries thicken, lose elasticity, and fill up with cholesterol and lipids Arteries thicken, lose elasticity, and fill up with cholesterol and lipids High LDL increases risk High LDL increases risk

53. Up in Smoke The vast majority of smokers picked up the habit before age 18 The vast majority of smokers picked up the habit before age 18 Smoking damages the circulatory and respiratory systems Smoking damages the circulatory and respiratory systems Smokers have increased risk of respiratory infections, cancers, high blood pressure, stroke, and heart attack Smokers have increased risk of respiratory infections, cancers, high blood pressure, stroke, and heart attack