Circulation

1. Circulation Chapter 33

2. Circulatory System • Accepts oxygen, nutrients, and other substances from the respiratory and digestive systems and delivers them to cells • Accepts carbon dioxide and wastes from cells and delivers them to respiratory and urinary systems for disposal

3. Circulatory Systems Open System Closed System pump pump spaces or cavities in body tissues heart aorta

4. Vertebrate Systems • Fish • Two-chamber heart pumps blood through one circuit • Amphibians • Heart pumps blood through two partially separate circuits • Birds and mammals • Four-chamber heart pumps blood through two entirely separate circuits

5. Blood Flow in Fishes capillary beds of gills heart rest of body In fishes, a two-chambered heart (atrium, ventricle) pumps blood in one circuit. Blood picks up oxygen in gills, delivers it to rest of body. Oxygen-poor blood flows back to heart.

6. Blood Flow in Amphibians lungs right atrium left atrium heart rest of body In amphibians, a heart pumps blood through two partially separate circuits. Blood flows to lungs, picks up oxygen, returns to heart. But it mixes with oxygen-poor blood still in the heart, flows to rest of body, returns to heart.

7. Blood Flow in Birds and Mammals lungs right atrium left atrium right ventricle left ventricle rest of body In birds and mammals, the heart is fully partitioned into two halves. Blood circulates in two circuits: from the heart’s right half to lungs and back, then from the heart’s left half to oxygen-requiring tissues and back.

8. Velocity of Flow Varies • Volume of blood flowing through vessels always has to equal heart’s output • 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

9. Flow Analogy river in river out lake 1 2 3 1 2 3 1 2 3

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

11. Blood Volume and Composition • Plasma • 50-60 percent of volume • Water, plasma proteins, dissolved ions and molecules • Cellular portion • 40-50 percent of volume • Red cells, white cells, and platelets

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

13. Leukocytes (White Cells) • Function in housekeeping and defense • Cell types: Basophils Eosinophils B lymphocytes Neutrophils T lymphocytes Macrophages NK cells Dendritic cells Mast cells

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

15. Cellular Components of Blood B lymphocytes (mature in bone marrow) natural killer cells eosinophils neutrophils basophils mast cells T lymphocytes (mature in thymus) forerunners of the white blood cells (leukocytes) committed cell (proerythroblast) ? stem cells that multiply and differentiate in bone marrow monocytes (immature phagocytes) red blood cells (erythrocytes) dendritic cells mature macrophages megakaryocytes platelets

16. Blood Cell Development • 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 • Body must continually replace blood cells

17. Blood Disorders • Anemias - Too few white cells, or deformed ones • Polycythemias - Too many red cells • Mononucleosis - Too many monocytes and lymphocytes • Leukemias - Cancer suppresses white cell formation

18. Blood Type in Transfusions • Require that donor and recipient have same blood type • If bloods of incompatible types are mixed, recipient’s immune system will attack and destroy donor cells • This is an agglutination reaction

19. ABO and Transfusions

20. ABO Blood Type • Type A red cells have one type of marker at surface • Type B red cells have a different type of marker • Type AB cells have both markers • Type O cells have neither marker

21. Rh Blood Type • Based on presence or absence of Rh marker on red cells • Can cause problems during pregnancy • If mother is Rh negative, • has previously carried Rh positive child, • is carrying fetus that is Rh positive • Mother’s antibodies can attack fetal cells

22. Rh Markers in Pregnancy

23. Human Cardiovascular System

24. Human Heart Is a Double Pump • Partition separates heart into left and right sides • Each pumps blood through a different circuit

25. Location of the Heart • Heart is about size of a fist • Lies in thoracic cavity between the lungs • Enclosed in the pericardium • Pericardium is two layers thick with fluid between layers

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

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

28. Hepatic Portal System • Carries blood from capillaries in digestive organs to capillaries in the liver • Allows liver to detoxify substances from digestive tract before they are carried to the body

29. Functional Connections

30. Layers of Heart Wall • Inner layer of the pericardium is the outer layer of the heart wall • Beneath that is the myocardium, the thick cardiac muscle tissue • Thin endocardium lines the chambers of the heart and the blood vessels

31. Four Chambers • Each side has two chambers • Upper atrium • Lower ventricle • Valves between atria and ventricles

32. Direction of Blood Flow • Superior and inferior vena cava • Right atrium • Right ventricle • Pulmonary artery • Pulmonary veins • Left atrium • Left ventricle • Aorta

33. Cardiac Cycle • Contraction phase is systole • Relaxation phase is diastole Mid-to-late diastole . Early diastole Ventricular systole

34. SA node Conduction and Contraction abutting ends of cardiac muscle cells • SA node in right atrium is pacemaker • Electrical signals cause contraction of atria • Signal flows to AV node and down septum to ventricles

35. Blood Vessels • Arteries: main transporters of oxygenated blood • Arterioles: diameter is adjusted to regulate blood flow • Capillaries: diffusion occurs across thin walls • Veins: transport blood to the heart

36. Blood Pressure • Highest in arteries, lowest in veins • Systolic pressure is peak pressure (ventricular contraction) • Diastolic pressure is the lowest • Greatest pressure drop is in arterioles

37. Heart’s Output during a Nap

38. Controlling Blood Pressure • Cardiac output adjusted by controls over rate and strength of heartbeat • Total resistance is controlled by vasoconstriction of arterioles • Baroreceptor response is main short-term control of blood pressure

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

40. Bulk Flow • Movement of water and solutes in response to fluid pressure • Ultrafiltration - fluid moves out of capillary bed near arteriole end • Reabsorption - fluid moves into capillary bed near venous end

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

42. Net Bulk Flow • Normally, ultrafiltration only slightly exceeds reabsorption • Fluid enters interstitial fluid and is eventually returned to blood by way of the lymphatic system • High blood pressure causes excessive ultrafiltration and results in edema

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

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

45. Hypertension • Blood pressure above 140/90 • Tends to be genetic • May also be influenced by diet • Contributes to atherosclerosis • “Silent killer” - Few outward signs

46. Atherosclerosis • Arteries thicken, lose elasticity, and fill up with cholesterol and lipids • High LDL level increases risk of atherosclerosis coronary bypasses

47. Arrhythmias • Bradycardia - slow heart rate • Tachycardia - 100+ beats/minute • Atrial fibrillation - irregular heartbeat • Ventricular fibrillation - uncontrolled contraction of ventricles; quickly fatal

48. ECG Recordings

49. Risk Factors for Cardiovascular Disease • Smoking • Gender (maleness) • Genetic factors • Old age • High cholesterol • Obesity • Lack of exercise • Diabetes mellitus

50. Lymphatic System • The circulatory system is leaky • Some fluid is forced out of the smallest vessels and into the interstitial fluid • Vessels of the lymphatic system pick up this fluid, filter it, and return it to the circulatory system