BIOLOGY OF HUMAN AGING

CHAPTER 9CHAPTER 9

The Circulatory SystemThe Circulatory System

Functions of Cardiovascular System :Functions of Cardiovascular System : 1. Transport and exchange of gases: 1. Transport and exchange of gases: Carries Carries oxygenoxygen for aerobic respiration from lungs to for aerobic respiration from lungs to

tissues.tissues. Picks up Picks up carboncarbon dioxidedioxide from tissues and releases it in from tissues and releases it in

lungs.lungs.

2. Transport nutrients (from digestive system to cells)2. Transport nutrients (from digestive system to cells)

3. Transport hormones (from glands to target cells).3. Transport hormones (from glands to target cells).

4. Transport metabolic waste (to excretory organs)4. Transport metabolic waste (to excretory organs)

5. Defense against infection by pathogens.5. Defense against infection by pathogens.

6. Regulates water and ion balance.6. Regulates water and ion balance.

7. Distribution of metabolic heat and maintenance of body 7. Distribution of metabolic heat and maintenance of body temperature.temperature.

Diffusion Between Blood and Tissue Cells

Cardiovascular SystemCardiovascular SystemSystem of internal transportSystem of internal transport

Components: Components:

1. 1. Blood (Fluid connective tissue)Blood (Fluid connective tissue)

2.2. Heart (Pumping device) Heart (Pumping device)

3.3. System of blood vessels: System of blood vessels: Arteries and arteriolesArteries and arterioles Veins and venulesVeins and venules CapillariesCapillaries

Cardiovascular Systems of Fish and Mammal

Right side pumps O2 poor bloodLeft side pumps O2 rich blood

Mammal: Double circuitFour chamber heart

1. Blood1. Blood

Average Blood Volume:Average Blood Volume: 4 to 6 liters. 4 to 6 liters.

Blood composition:Blood composition:55% Plasma (fluid matrix of water, salts, proteins, etc.)55% Plasma (fluid matrix of water, salts, proteins, etc.)

45% Cellular elements:45% Cellular elements: Red Blood Cells (RBCs)Red Blood Cells (RBCs)

White Blood Cells (WBCs)White Blood Cells (WBCs) Play an essential role in immunity Play an essential role in immunity

and defense. Include:and defense. Include:

• Lymphocytes:Lymphocytes: T cells and B cells T cells and B cells

• MacrophagesMacrophages (phagocytes) (phagocytes)

• Other types of WBCsOther types of WBCs

Platelets:Platelets: Cellular fragments. Important in blood clotting. Cellular fragments. Important in blood clotting.

2. Heart2. Heart

Anatomical Features:Anatomical Features: Hollow muscular organ, about the size of a human fist.Hollow muscular organ, about the size of a human fist. Weighs less than one pound (10 ounces).Weighs less than one pound (10 ounces). Rests on diaphragm, near middle of thoracic cavity.Rests on diaphragm, near middle of thoracic cavity. Wall is composed of cardiac muscle covered by Wall is composed of cardiac muscle covered by

connective tissue.connective tissue.

PericardiumPericardium: Membrane that surrounds entire : Membrane that surrounds entire heart and contains a fluid which protects heart heart and contains a fluid which protects heart and decreases friction.and decreases friction.

2. Heart2. Heart

Heart ChambersHeart Chambers: Heart is divided into four : Heart is divided into four separate chambers. Both the left and the separate chambers. Both the left and the right side of the heart have a(an):right side of the heart have a(an): Atrium (Plural atria)Atrium (Plural atria): Smaller, : Smaller, superiorsuperior

chambers. chambers. ReceiveReceive blood from veins. blood from veins. VentricleVentricle: Larger, : Larger, inferiorinferior chambers. chambers. PumpPump

blood into arteries.blood into arteries.

Two sides of heart have different functions:Two sides of heart have different functions: Right sideRight side: Pumps oxygen poor blood.: Pumps oxygen poor blood. Left sideLeft side: Pumps oxygen rich blood.: Pumps oxygen rich blood.

Structure of the Human Heart

Right side pumps O2 poor blood. Left side pumps O2 rich blood

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

2. Heart2. Heart

Heart ValvesHeart Valves: Heart has several valves made : Heart has several valves made of connective tissue, that prevent backflow of connective tissue, that prevent backflow of blood as it circulates.of blood as it circulates.

Atrioventricular (AV) ValvesAtrioventricular (AV) Valves: Close : Close between atria and ventriclesbetween atria and ventricles Right AV Valve:Right AV Valve: Connects right atrium to the right Connects right atrium to the right

ventricle.ventricle. Left AV Valve:Left AV Valve: Connects left atrium to the left Connects left atrium to the left

ventricle.ventricle.

Semilunar ValvesSemilunar Valves: Close as blood leaves : Close as blood leaves the ventricles and enters the arteries.the ventricles and enters the arteries.

Internal Structure of the Human Heart

3. Blood Vessels3. Blood Vessels

Include arteries, arterioles, capillaries, venules, Include arteries, arterioles, capillaries, venules,

and veins.and veins.

Double circuit, closed system:Double circuit, closed system:

1. Pulmonary circuit: 1. Pulmonary circuit: Delivers blood to lungs. Delivers blood to lungs.

Oxygenation of blood.Oxygenation of blood.

2. Systemic circuit: 2. Systemic circuit: Delivers oxygenated blood to Delivers oxygenated blood to

tissues and organs of body (brain, liver, heart, tissues and organs of body (brain, liver, heart,

kidneys, etc). Picks up carbon dioxide produced kidneys, etc). Picks up carbon dioxide produced

by tissues.by tissues.

Structure of Different Blood Vessels

Pulmonary and Systemic Circuits

3. Types of Blood Vessels3. Types of Blood Vessels

A. Arteries and Arterioles: A. Arteries and Arterioles: Carry blood Carry blood awayaway fromfrom heartheart to body. to body. Have high pressure.Have high pressure. Have thick muscular walls, which make them Have thick muscular walls, which make them

elastic and contractile.elastic and contractile. Vasoconstriction:Vasoconstriction: Arteries contract: Arteries contract:

Reducing flow of blood into capillaries.Reducing flow of blood into capillaries. Increasing blood pressure.Increasing blood pressure.

Vasodilation:Vasodilation: Arteries relax: Arteries relax: Increasing blood flow into capillaries.Increasing blood flow into capillaries. Decreasing blood pressure.Decreasing blood pressure.

Control of Capillary Blood Flow by Arteriole Constriction

3. Types of Blood Vessels3. Types of Blood Vessels

Capillaries: Capillaries: Only blood vessels whose Only blood vessels whose walls are thin enough to permit gas walls are thin enough to permit gas exchange.exchange.

Blood flows through capillaries Blood flows through capillaries relatively slowly, allowing sufficient relatively slowly, allowing sufficient time for diffusion or active transport time for diffusion or active transport of substances across walls.of substances across walls.

3. Types of Blood Vessels3. Types of Blood Vessels

Veins and Venules:Veins and Venules:

Collect blood from all tissues and organs Collect blood from all tissues and organs

and and carrycarry it back it back towardstowards heart. heart.

Have low pressure and thin walls.Have low pressure and thin walls.

Veins have small Veins have small valvesvalves that prevent that prevent

backflow of blood towards capillaries, backflow of blood towards capillaries,

especially when standing. If the valves especially when standing. If the valves

cease to work properly, may result in:cease to work properly, may result in: Varicose veinsVaricose veins: Distended veins in thighs and legs.: Distended veins in thighs and legs.

Veins Contain Valves to Prevent Backflow of Blood

Heart BeatHeart Beat Average 70 beats per minute. Average 70 beats per minute. 100,000 beats every day.100,000 beats every day. Cardiac cycleCardiac cycle about every 0.8 sec. about every 0.8 sec.

DiastoleDiastole: Heart relaxes and blood flows into chambers (0.4 sec).: Heart relaxes and blood flows into chambers (0.4 sec). SystoleSystole: Heart contracts. : Heart contracts.

Pacemaker (Sinoatrial node): Controls heart rate.Pacemaker (Sinoatrial node): Controls heart rate. Regulated by nervous and endocrine systems.Regulated by nervous and endocrine systems.

PulsePulse: Arteries expand and contract with each heartbeat.: Arteries expand and contract with each heartbeat.

Pacemaker Controls Cardiac Rhythm

Blood PressureBlood Pressure Pressure is highest in arteries; lowest in veins. Pressure is highest in arteries; lowest in veins.

““Blood pressureBlood pressure” usually refers to ” usually refers to arterialarterial pressure. pressure.

Usually measured at Usually measured at brachial arterybrachial artery in arm. in arm.

Two measurements:Two measurements:

Systolic Blood PressureSystolic Blood Pressure: During heart : During heart contractioncontraction. .

Normal systolic pressure is about 120 mm Hg.Normal systolic pressure is about 120 mm Hg.

(Range: 110-140 mm Hg).(Range: 110-140 mm Hg).

Diastolic Blood PressureDiastolic Blood Pressure: During heart : During heart relaxationrelaxation. .

Normal diastolic pressure is about 80 mm Hg.Normal diastolic pressure is about 80 mm Hg.

(Range: 70-90 mm Hg)(Range: 70-90 mm Hg)

Measuring Systolic and Diastolic Blood Pressure

Blood Pathway in BodyBlood Pathway in Body Right Side of HeartRight Side of Heart: :

Right atrium receives oxygen poor blood from body.Right atrium receives oxygen poor blood from body.

Right ventricle pumps oxygen poor blood to lungs. Right ventricle pumps oxygen poor blood to lungs.

Left Side of HeartLeft Side of Heart: :

Left atrium receives oxygenated blood from lungs.Left atrium receives oxygenated blood from lungs.

Left ventricle pumps oxygenated blood to body. Left ventricle pumps oxygenated blood to body.

Blood PathwayBlood Pathway::Veins ---> Vena cava ---> Veins ---> Vena cava ---> Right atriumRight atrium ---> ---> Right ventricleRight ventricle ---> --->

Pulmonary artery ---> Lungs ---> Pulmonary artery ---> Lungs ---> Left atriumLeft atrium ---> ---> Left ventricleLeft ventricle ---> --->

Aorta ---> Arteries ---> Aorta ---> Arteries ---> CapillariesCapillaries ---> Veins ---> Veins

Path of Blood Flow through Cardiovascular System

Age-related changesBlood

Total protein concentration decreases with agingThe amount of red bone marrow diminishes with aging replaced by yellow bone marrow HeartDecrease vs. increase in heart sizeincrease of fat depositsAccumulation of lipofuscin pigment in cardiac muscle cellsEndocardium tends to become thicker due to deposition of fatScleroses (hard white patches may formSystolic and diastolic blood pressures tend to increase with agingDecrease in maximum oxygen consumption with agingCardiac output decreases with aging (the volume of blood pumped/min by either ventricles)

Age-related changes Blood Vessels Reduction in elasticity. Reduction in ability to

stretch. Reduction in elastin. Increase in collageneous

CT. Tendency to bind with Ca and calcification of

elastin. Gradual accumulation of lipids Increase in LDLs. Role of HDLs. Increase in

systolic blood pressure with aging.

Age-related Dysfunction

Atherosclerosis and ArteriosclerosisAtherosclerosis and Arteriosclerosis

HypertensionHypertension

Coronary Artery DiseaseCoronary Artery Disease

Myocardial InfarctionMyocardial Infarction

Angina PectorisAngina Pectoris

Cardiac ArrhythmiasCardiac Arrhythmias

Congestive Heart FailureCongestive Heart Failure

Heart Attacks are Caused by Blocked Coronary Arteries

Heart Attack (Myocardial infarction)Heart Attack (Myocardial infarction) Symptoms:Symptoms: Chest pain, pressure, or tightness, sweating, Chest pain, pressure, or tightness, sweating,

nausea, shortness of breath, dizziness, and fainting.nausea, shortness of breath, dizziness, and fainting.

Risk factorsRisk factors:: SmokingSmoking High blood pressureHigh blood pressure High cholesterolHigh cholesterol High LDLs (low density lipoproteins)High LDLs (low density lipoproteins) DiabetesDiabetes Male genderMale gender Emotional stressEmotional stress ObesityObesity HeredityHeredity Sedentary lifestyleSedentary lifestyle