Chapter 23 CIRCULATION: CARDIOVASCULAR SYSTEM

1. Chapter 23 CIRCULATION: CARDIOVASCULAR SYSTEM

2. Functions of Cardiovascular System : 1. Transport and exchange of gases: • Carries oxygen for aerobic respiration from lungs to tissues. • Picks up carbondioxide from tissues and releases it in lungs. 2. Transport nutrients (from digestive system to cells) 3. Transport hormones (from glands to target cells). 4. Transport metabolic waste (to excretory organs) 5. Defense against infection by pathogens. 6. Regulates water and ion balance. 7. Distribution of metabolic heat and maintenance of body temperature.

3. Diffusion Between Blood and Tissue Cells

4. Cardiovascular System System of internal transport Components: 1. Blood (Fluid connective tissue) 2. Heart (Pumping device) 3. System of blood vessels: • Arteries and arterioles • Veins and venules • Capillaries

5. Cardiovascular Systems of Fish and Mammal Mammal: Double circuit Four chamber heart Fish: Single circuit Two chamber heart Right side pumps O2 poor blood Left side pumps O2 rich blood

6. 1. Blood Average Blood Volume: 4 to 6 liters. Blood composition: 55% Plasma (fluid matrix of water, salts, proteins, etc.) 45% Cellular elements: • Red Blood Cells (RBCs): 5-6 million RBCs/ml of blood. Contain hemoglobin which transport oxygen and CO2. • White Blood Cells (WBCs): 5,000-10,000 WBCs/ml of blood. Play an essential role in immunity and defense. Include: • Lymphocytes: T cells and B cells • Macrophages (phagocytes) • Granulocytes: Neutrophils, basophils, and eosinophils. • Platelets: Cellular fragments. 250,000- 400,000/ml of blood. Important in blood clotting.

7. Composition of Human Blood

8. Red Blood Cells Contain Hemoglobin and Transport Gases in Blood

9. Platelets are Essential for Blood Clotting

10. 2. Heart Anatomical Features: • Hollow muscular organ, about the size of a human fist. • Weighs less than one pound (10 ounces). • Rests on diaphragm, near middle of thoracic cavity. • Wall is composed of cardiac muscle covered by connective tissue. Pericardium: Membrane that surrounds entire heart and contains a fluid which protects heart and decreases friction.

11. Position of Heart in Thoracic Cavity

12. 2. Heart Heart Chambers: Heart is divided into four separate chambers. Both the left and the right side of the heart have a(an): • Atrium (Plural atria): Smaller, superior chambers. Receive blood from veins. • Ventricle: Larger, inferior chambers. Pump blood into arteries. Two sides of heart have different functions: • Right side: Pumps oxygen poor blood. • Left side: Pumps oxygen rich blood.

13. Structure of the Human Heart Right side pumps O2 poor blood. Left side pumps O2 rich blood

14. Pacemaker (Sinoatrial node): Specialized structure that sends electrical impulses that causes both atria and ventricles to contract.

15. 2. Heart Heart Valves: Heart has several valves made of connective tissue, that prevent backflow of blood as it circulates. • Atrioventricular (AV) Valves: Close between atria and ventricles • Right AV Valve: Connects right atrium to the right ventricle. • Left AV Valve: Connects left atrium to the left ventricle. • Semilunar Valves: Close as blood leaves the ventricles and enters the arteries. Heart murmur: Rushing, gurgling sound created by backflow of blood due to damaged or imperfect heart valves. Fairly common (10% of healthy population). Most are asymptomatic.

16. Internal Structure of the Human Heart

17. 3. Blood Vessels • Include arteries, arterioles, capillaries, venules, and veins. • Double circuit, closed system: 1. Pulmonary circuit: Delivers blood to lungs. Oxygenation of blood. 2. Systemic circuit: Delivers oxygenated blood to tissues and organs of body (brain, liver, heart, kidneys, etc). Picks up carbon dioxide produced by tissues.

18. Structure of Different Blood Vessels

19. Pulmonary and Systemic Circuits

20. 3. Types of Blood Vessels A. Arteries and Arterioles: • Carry blood awayfromheart to body. • Have high pressure. • Have thick muscular walls, which make them elastic and contractile. • Vasoconstriction: Arteries contract: • Reducing flow of blood into capillaries. • Increasing blood pressure. • Vasodilation: Arteries relax: • Increasing blood flow into capillaries. • Decreasing blood pressure.

21. Control of Capillary Blood Flow by Arteriole Constriction

22. 3. Types of Blood Vessels Capillaries: Only blood vessels whose walls are thin enough to permit gas exchange. Blood flows through capillaries relatively slowly, allowing sufficient time for diffusion or active transport of substances across walls. Only about 5 to 10% of capillaries have blood flowing through them. Only a few organs (brain and heart) always carry full load of blood. Blood flow to different organs is controlled by precapillary sphincters of smooth muscle.

23. Control of Capillary Blood Flow by Precapillary Sphincters

24. Movement of Fluid Across Capillary Walls 99% of fluid that leaves capillary at arteriole end, reenters at venous end. Remaining 1% is returned by lymphatic vessels.

25. 3. Types of Blood Vessels Veins and Venules: • Collect blood from all tissues and organs and carry it back towards heart. • Have low pressure and thin walls. • Veins have small valves that prevent backflow of blood towards capillaries, especially when standing. If the valves cease to work properly, may result in: • Varicose veins: Distended veins in thighs and legs. • Hemorroids: Distended veins and inflammation of the rectal and anal areas.

26. Veins Contain Valves to Prevent Backflow of Blood

27. Heart Beat • Average 70 beats per minute. • 100,000 beats every day. • Cardiac cycle about every 0.8 sec. • Diastole: Heart relaxes and blood flows into chambers (0.4 sec). • Systole: Heart contracts. • First atria (0.1 sec) • Then ventricles (0.3 sec) • Pumps about 8000 liters of blood/day. • Pacemaker (Sinoatrial node): Controls heart rate. • Regulated by nervous and endocrine systems. • Two heart beat sounds (“Lub-dupp”): • First sound: Ventricles contract, AV valves close. • Second sound: Heart relaxes, semilunar valves are closing. • Pulse: Arteries expand and contract with each heartbeat.

28. Stages of Cardiac Cycle Diastole: Heart Relaxes Systole: Heart contracts First Sound “Lub” Second Sound “Dupp”

29. Pacemaker Controls Cardiac Rhythm

30. Blood Pressure • Pressure is highest in arteries; lowest in veins. • “Blood pressure” usually refers to arterial pressure. • Usually measured at brachial artery in arm. • Two measurements: • Systolic Blood Pressure: During heart contraction. Normal systolic pressure is about 120 mm Hg. (Range: 110-140 mm Hg). • Diastolic Blood Pressure: During heart relaxation. Normal diastolic pressure is about 80 mm Hg. (Range: 70-90 mm Hg)

31. Measuring Systolic and Diastolic Blood Pressure

32. Blood Pressure and Velocity in Blood Vessels

33. Blood Pathway in Body • Right Side of Heart: • Right atrium receives oxygen poor blood from body. • Right ventricle pumps oxygen poor blood to lungs. • Left Side of Heart: • Left atrium receives oxygenated blood from lungs. • Left ventricle pumps oxygenated blood to body. Blood Pathway: Veins ---> Vena cava ---> Right atrium ---> Right ventricle ---> Pulmonary artery ---> Lungs ---> Left atrium ---> Left ventricle ---> Aorta ---> Arteries ---> Capillaries ---> Veins

34. Path of Blood Flow through Cardiovascular System

35. Cardiovascular Disease • Number one cause of death in the U.S. and industrialized nations. • Includes hypertension, strokes, heart attacks, and congestive heart failure. • Most often caused by complications of: Arteriosclerosis: A condition in which arteries become blocked by calcium and lipid deposits (plaque), losing their elasticity.

36. Heart Attack (Myocardial infarction-MI) • Sudden decrease in blood supply to the heart, due to a clot or plaque in arteries. • Death of cardiac muscle resulting in insufficient blood supply to rest of body. • Heart may stop beating altogether or suffer permanent damage. • Over 1.3 million heart attacks every year in U.S. • Leading cause of death and disability • 60% had no previous symptoms. • 25% are not recognized when they occur. • 25% die before receiving medical assistance. • In 1995 960,000 deaths in U.S.

37. Heart Attacks are Caused by Blocked Coronary Arteries

38. Heart Attack (Myocardial infarction) • Symptoms:Chest pain, pressure, or tightness, sweating, nausea, shortness of breath, dizziness, and fainting. • Risk factors: • Smoking • High blood pressure • High cholesterol • High LDLs (low density lipoproteins) • Diabetes • Male gender • Emotional stress • Obesity • Heredity • Sedentary lifestyle

39. Hypertension: High blood pressure. • Blood pressure over 140/90. • Over 20% of U.S. population suffers from blood pressures over 160/95. • Another 25% is borderline (above 140/90). • Heart must work harder to overcome resistance. • Silent killer: May have few or no symptoms. • May result in strokes, heart attacks, aneurysms, ischemia (insufficient blood supply to heart) and arteriosclerosis. • Risk factors: Heredity, obesity, high salt intake, black race (relative risk 2), smoking, stress, diet high in fat, and lack of exercise.

40. Ischemic Heart Disease: • Insufficient blood supply to the heart. • Especially during exercise or physical exertion. • May cause angina pectoris: sharp chest pain. Congestive Heart Failure: • Heart cannot pump enough blood to meet body’s needs. • Slow blood flow causes veins to back up causing edema in tissue (legs, tissues, or lungs). • Symptoms: Shortness of breath, edema, and fatigue. • Causes: Hypertension , arteriosclerosis, heart valve damage, heart attack, etc.

41. Stroke: • Third leading cause of death in U.S. after heart disease and cancer. • 5% of people over 65 have had a stroke. • 400,000 stroke victims discharged from hospitals every year. • Insufficient blood supply to the brain, caused by a blood clot or rupture of a blood vessel. • Depending on area affected may cause: • Paralysis (usually one side of body). • Loss of sensation or motor control. • Incontinence • Loss of speech, hearing, or sight. • Death

42. Relationship between major organ systems