1. BIOLOGY OF HUMAN AGING CHAPTER 9 The Circulatory System

2. Functions of Cardiovascular System : 1. Transport and exchange of gases: u Carries oxygen for aerobic respiration from lungs to tissues. u Picks up carbon dioxide 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: u Arteries and arterioles u Veins and venules u Capillaries

5. Cardiovascular Systems of Fish and Mammal Right side pumps O 2 poor blood Left side pumps O 2 rich blood Mammal: Double circuit Four chamber heart

6. 1. Blood Average Blood Volume: 4 to 6 liters. Blood composition: 55% Plasma (fluid matrix of water, salts, proteins, etc.) 45% Cellular elements: F Red Blood Cells (RBCs) F White Blood Cells (WBCs) Play an essential role in immunity and defense. Include: Lymphocytes: T cells and B cellsLymphocytes: T cells and B cells Macrophages (phagocytes)Macrophages (phagocytes) Other types of WBCsOther types of WBCs F Platelets: Cellular fragments. Important in blood clotting.

7. 2. Heart Anatomical Features: u Hollow muscular organ, about the size of a human fist. u Weighs less than one pound (10 ounces). u Rests on diaphragm, near middle of thoracic cavity. u 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.

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

9. Structure of the Human Heart Right side pumps O 2 poor blood. Left side pumps O 2 rich blood

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

11. 2. Heart Heart Valves: Heart has several valves made of connective tissue, that prevent backflow of blood as it circulates. n Atrioventricular (AV) Valves: Close between atria and ventricles u Right AV Valve: Connects right atrium to the right ventricle. u Left AV Valve: Connects left atrium to the left ventricle. n Semilunar Valves: Close as blood leaves the ventricles and enters the arteries.

12. Internal Structure of the Human Heart

13. 3. Blood Vessels u Include arteries, arterioles, capillaries, venules, and veins. u 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.

14. Structure of Different Blood Vessels

15. Pulmonary and Systemic Circuits

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

17. Control of Capillary Blood Flow by Arteriole Constriction

18. 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.

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

20. Veins Contain Valves to Prevent Backflow of Blood

21. Heart Beat u Average 70 beats per minute. u 100,000 beats every day. u Cardiac cycle about every 0.8 sec. F Diastole: Heart relaxes and blood flows into chambers (0.4 sec). F Systole: Heart contracts. u Pacemaker (Sinoatrial node): Controls heart rate. F Regulated by nervous and endocrine systems. u Pulse: Arteries expand and contract with each heartbeat.

22. Pacemaker Controls Cardiac Rhythm

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

24. Measuring Systolic and Diastolic Blood Pressure

25. Blood Pathway in Body u Right Side of Heart: F Right atrium receives oxygen poor blood from body. F Right ventricle pumps oxygen poor blood to lungs. u Left Side of Heart: F Left atrium receives oxygenated blood from lungs. F 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

26. Path of Blood Flow through Cardiovascular System

27. Age-related changes Blood Total protein concentration decreases with aging The amount of red bone marrow diminishes with aging  replaced by yellow bone marrow Heart Decrease vs. increase in heart size increase of fat deposits Accumulation of lipofuscin pigment in cardiac muscle cells Endocardium tends to become thicker due to deposition of fat Scleroses (hard white patches may form Systolic and diastolic blood pressures tend to increase with aging Decrease in maximum oxygen consumption with aging Cardiac output decreases with aging (the volume of blood pumped/min by either ventricles)

28. Age-related changes n n Blood Vessels n n Reduction in elasticity. Reduction in ability to stretch. n n Reduction in elastin. Increase in collageneous CT. n n Tendency to bind with Ca and calcification of elastin. n n Gradual accumulation of lipids n n Increase in LDLs. Role of HDLs. Increase in systolic blood pressure with aging.

29. Age-related Dysfunction Atherosclerosis and Arteriosclerosis Hypertension Coronary Artery Disease Myocardial Infarction Angina Pectoris Cardiac Arrhythmias Congestive Heart Failure

30. Heart Attacks are Caused by Blocked Coronary Arteries

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