The Cardiovascular System Chapter 11. The Cardiovascular System A closed system of the heart and...

The Cardiovascular System

Chapter 11

The Cardiovascular System• A closed system of the heart and blood

vessels• The heart pumps blood• Blood vessels allow blood to circulate to all

parts of the body• The function of the cardiovascular system is

to deliver oxygen and nutrients and to remove carbon dioxide and other waste products

The Heart• Location

• Thorax between the lungs in the inferior mediastinum

• Orientation• Pointed apex directed toward left hip• Base points toward right shoulder

• About the size of your fist

The Heart

The Heart

The Heart

The Heart: Coverings• Pericardium—a double-walled sac

• Fibrous pericardium is loose and superficial

• Serous membrane is deep to the fibrous pericardium and composed of two layers• Visceral pericardium

• Next to heart; also known as the epicardium

• Parietal pericardium • Outside layer that lines the inner

surface of the fibrous pericardium• Serous fluid fills the space between the

layers of pericardium

The Heart: Heart Wall• Three layers

• Epicardium• Outside layer• This layer is the visceral pericardium• Connective tissue layer

• Myocardium• Middle layer• Mostly cardiac muscle

• Endocardium• Inner layer• Endothelium

The Heart: Heart Wall



The Heart: Chambers

• Right and left side act as separate pumps• Four chambers

• Atria• Receiving chambers

• Right atrium• Left atrium

• Ventricles• Discharging chambers

• Right ventricle• Left ventricle

The Heart: Chambers

Differences in Right and Left Ventricles

The Heart: Septa • Interventricular septum

• Separates the two ventricles• Interatrial septum

• Separates the two atria

The Heart: Septa

Systemic and Pulmonary Circulations• Systemic circulation

• Blood flows from the left side of the heart through the body tissues and back to the right side of the heart

• Pulmonary circulation• Blood flows from the right side of the

heart to the lungs and back to the left side of the heart

Systemic and Pulmonary Circulations

Figure 11.3

The Heart: Associated Great Vessels• Arteries

• Aorta• Leaves left ventricle

• Pulmonary arteries• Leave right ventricle

The Heart: Associated Great Vessels• Veins

• Superior and inferior venae cavae• Enter right atrium

• Pulmonary veins (four)• Enter left atrium

The Heart: Associated Great Vessels

Blood Flow Through the Heart• Superior and inferior venae cavae dump

blood into the right atrium• From right atrium, through the tricuspid

valve, blood travels to the right ventricle• From the right ventricle, blood leaves the

heart as it passes through the pulmonary semilunar valve into the pulmonary trunk

• Pulmonary trunk splits into right and left pulmonary arteries that carry blood to the lungs

Blood Flow Through the Heart• Oxygen is picked up and carbon dioxide is

dropped off by blood in the lungs• Oxygen-rich blood returns to the heart

through the four pulmonary veins• Blood enters the left atrium and travels

through the bicuspid valve into the left ventricle

• From the left ventricle, blood leaves the heart via the aortic semilunar valve and aorta

Blood Flow Through the Heart• Pump Your Blood

http://www.youtube.com/watch?v=upctPUa6RhA

Systemic and Pulmonary Circulations

Figure 11.3

The Heart: Valves• Allow blood to flow in only one direction

to prevent backflow• Four valves

• Atrioventricular (AV) valves—between atria and ventricles• Bicuspid (mitral) valve (left side of

heart)• Tricuspid valve (right side of heart)

• Semilunar valves—between ventricle and artery• Pulmonary semilunar valve• Aortic semilunar valve

The Heart: Valves

The Heart: Valves• AV valves

• Anchored in place by chordae tendineae (“heart strings”)

• Open during heart relaxation and closed during ventricular contraction

• Semilunar valves• Closed during heart relaxation but open

during ventricular contraction• Notice these valves operate opposite of

one another to force a one-way path of blood through the heart

Figure 11.5a, step 1

Blood returning tothe atria, putspressure againstAV valves; the AVvalves are forcedopen

Ventricles

Operation of the AV valves

AV valves open

(a)



As the ventriclesfill, AV valve flapshang limply intoventricles

Ventricles


AV valves open

(a)



As the ventriclesfill, AV valve flapshang limply intoventriclesAtria contract,forcing additionalblood into ventricles

Ventricles


AV valves open

(a)


Ventricles contract,forcing bloodagainst AV valveflaps

(a)



AV valves close

AV valves closed(a)



AV valves close

Chordae tendineaetighten, preventingvalve flaps fromeverting into atria

AV valves closed(a)

Figure 11.5b, step 1

As ventriclescontract andintraventricularpressure rises,blood is pushedup againstsemilunarvalves, forcingthem open

Aorta

Pulmonarytrunk

Semilunar valveopen

Operation of the semilunar valves

(b)

Figure 11.5b, step 2

As ventriclescontract andintraventricularpressure rises,blood is pushedup againstsemilunarvalves, forcingthem open

Aorta

Pulmonarytrunk

Semilunar valveopen Semilunar valve

closed

As ventriclesrelax, andintraventricularpressure falls,blood flowsback fromarteries, fillingthe leaflets of semilunarvalves andforcing themto close

Operation of the semilunar valves

(b)

Coronary Circulation• Blood in the heart chambers

does not nourish the myocardium.

Coronary Circulation• The heart has its own nourishing

circulatory system consisting of• Coronary arteries—branch from the

aorta to supply the heart muscle with oxygenated blood

• Cardiac veins—drain the myocardium of blood

• Coronary sinus—a large vein on the posterior of the heart, receives blood from cardiac veins

• Blood empties into the right atrium via the coronary sinus

The Heart: Conduction System• Intrinsic conduction system (nodal system)

• Heart muscle cells contract, without nerve impulses, in a regular, continuous way

The Heart: Conduction System• Special tissue sets the pace

• Sinoatrial node = SA node (“pacemaker”), is in the right atrium

• Atrioventricular node = AV node, is at the junction of the atria and ventricles

• Atrioventricular bundle = AV bundle (bundle of His), is in the interventricular septum

• Bundle branches are in the interventricular septum

• Purkinje fibers spread within the ventricle wall muscles

Heart Contractions

Heart Contractions• Contraction is initiated by the sinoatrial

node (SA node)• Sequential stimulation occurs at other

autorhythmic cells• Force cardiac muscle depolarization in

one direction—from atria to ventricles

Heart Contractions• Once SA node starts the heartbeat

• Impulse spreads to the AV node • Then the atria contract

• At the AV node, the impulse passes through the AV bundle, bundle branches, and Purkinje fibers

• Blood is ejected from the ventricles to the aorta and pulmonary trunk as the ventricles contract

• Your Heart’s Electrical System

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html

Heart Contractions

Heart Contractions• Tachycardia—rapid heart rate over 100

beats per minute• Bradycardia—slow heart rate less than 60

beats per minutes

Heart Contractions

Heart Contractions• Contraction is initiated by the sinoatrial

node (SA node)• Sequential stimulation occurs at other

autorhythmic cells• Force cardiac muscle depolarization in

one direction—from atria to ventricles

Heart Contractions• Once SA node starts the heartbeat

• Impulse spreads to the AV node • Then the atria contract

• At the AV node, the impulse passes through the AV bundle, bundle branches, and Purkinje fibers

• Blood is ejected from the ventricles to the aorta and pulmonary trunk as the ventricles contract

• Your Heart’s Electrical System

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html

Heart Contractions

Heart Contractions• Tachycardia—rapid heart rate over 100

beats per minute• Bradycardia—slow heart rate less than 60

beats per minutes

Heart Diseases/Disorders

Stable angina• chest pain or discomfort that typically

occurs with activity or stress• caused by poor blood flow through the

blood vessels (coronary vessels) of the heart muscle (myocardium)



Unstable angina• may be a prelude to a heart attack• chest pain that is sudden and gets

increasingly worse• occurs without cause (for example, it

wakes you up from sleep)• lasts longer than 15 - 20 minutes• responds poorly to nitroglycerin• may occur along with a drop in blood

pressure or significant shortness of breath

Heart Diseases/Disorders• Coronary artery balloon angioplasty

http://www.nlm.nih.gov/medlineplus/ency/presentations/100160_1.htm


Aortic insufficiency• heart valve disease in which the aortic

valve weakens or balloons, preventing the valve from closing tightly

• leads to the backward flow of blood from the aorta into the left ventricle


Aortic stenosis• aortic valve does not open fully,

decreasing blood flow from the heart


Arrhythmias• disorder of the heart rate (pulse) or heart

rhythm, such as beating too fast (tachycardia), too slow (bradycardia), or irregularly

• Arrhythmia

http://www.nlm.nih.gov/medlineplus/ency/anatomyvideos/000005.htm


Cardiomyopathy• weakening of the heart muscle or a

change in heart muscle structure• often associated with inadequate heart

pumping or other heart function problems• Cardiomyopathy• implantable-cardioverter defibrillator (ICD)

may be needed to prevent sudden death


Heart Diseases/DisordersCardiomyopathy - Causes• Alcoholism and cocaine use• Chemotherapy drugs• Coronary artery disease• End-stage kidney disease• Genetic defects• High blood pressure (hypertension)• Infections due to viruses, HIV, Lyme

disease, Chagas disease• Nutritional deficiencies• Pregnancy• Systemic lupus erythematosus


Dilated cardiomyopathy• condition in which the heart becomes

weakened and enlarged, and it cannot pump blood efficiently

• decreased heart function can affect the lungs, liver, and other body systems


Hypertrophic cardiomyopathy• condition in which the heart muscle

becomes thick• thickening makes it harder for blood to

leave the heart, forcing the heart to work harder to pump blood


Hypertrophic cardiomyopathy – Causes• often asymmetrical, meaning one part of

the heart is thicker than the other parts• condition is usually passed down through

families• believed to be a result of several defects

with the genes that control heart muscle growth

• younger people are likely to have a more severe form of hypertrophic cardiomyopathy but the condition is seen in people of all ages



Ischemic cardiomyopathy• term that doctors use to describe patients

who have reduced heart pumping (squeezing) due to coronary artery disease

• these patients often have congestive heart failure

• "Ischemic" means that an organ (such as the heart) is not getting enough blood and oxygen. "Cardio" means heart and "myopathy" means muscle-related disease.


Restrictive cardiomyopathy• refers to a group of disorders in which the

heart chambers are unable to properly fill with blood because of stiffness in the heart


Congenital heart disease• refers to a problem with the heart's

structure and function due to abnormal heart development before birth


Congenital heart disease – Causes• most common type of birth defect• responsible for more deaths in the first

year of life than any other birth defects• some heal over time, others will require

treatment• divided into two types: cyanotic and non-

cyanotic


Cyanotic:• Tetralogy of Fallot• Transposition of the great vessels• Tricuspid atresia• Total anomalous pulmonary venous return• Truncus arteriosus• Hypoplastic left heart• Pulmonary atresia• Ebstein's anomaly


Non-cyanotic• Ventricular septal defect (VSD)• Atrial septal defect (ASD)• Patent ductus arteriosus (PDA)• Aortic stenosis• Pulmonic stenosis• Coarctation of the aorta• Atrioventricular canal (endocardial

cushion defect)

Heart Diseases/Disorders• problems may occur alone or together• majority of congenital heart diseases

occur as an isolated defect but they can also be a part of various genetic and chromosomal syndromes • Down syndrome• trisomy 13• Turner syndrome• Marfan syndrome• Noonan syndrome• DiGeorge syndrome.


Congestive Heart Failure• condition in which the heart can't pump

enough blood throughout the body - doesn’t mean that your heart has stopped or is about to stop working, just that your heart is not able to pump blood the way it should

Heart Diseases/DisordersCongestive Heart Failure• The weakening of the heart's pumping ability

causes:• blood and fluid to back up into the lungs• buildup of fluid in the feet, ankles and legs

- edema• tiredness, shortness of breath

• leading causes: • coronary artery disease• high blood pressure• diabetes


Congestive Heart Failure• Treatment:

• treat the underlying cause • medicine• heart transplantation (if other

treatments fail)• ~ 5 million people in the U.S. have heart

failure• contributes to 300,000 deaths each year


Coronary heart disease• narrowing of the small blood vessels that

supply blood and oxygen to the heart; also called coronary artery disease.

• Coronary Artery Disease



Causes of CHD• usually caused by atherosclerosis - fatty

material and other substances form a plaque build-up on artery walls, causing them to narrow

• blood flow to the heart can slow down or stop• stable angina• shortness of breath• heart attack


Endocarditis• inflammation of the inside lining of the

heart chambers and heart valves• risk factors

• injection drug use• prior valve surgery• recent dental surgery• weakened valves• bacterial/fungal infection


Heart attack (myocardial infarction)• blood vessels that supply blood to the

heart are blocked, preventing enough oxygen from getting to the heart

• heart muscle dies or becomes permanently damaged


Heart attack (myocardial infarction)• most are caused by a blood clot that

blocks one of the coronary arteries; if blood flow is blocked, heart starves for oxygen and heart cells die

• atherosclerosis: plaque (made up of cholesterol and other cells) builds up in the walls of your coronary arteries


Heart attack can occur as a result of the following:

• slow buildup of plaque may almost block one of your coronary arteries, preventing flow of oxygen-rich blood; more likely to happen when during exercise

• plaque itself develops cracks (fissures) or tears• platelets stick, form a blood clot

(thrombus) • blood clot may completely block te

passage of oxygen-rich blood to heart


Acute Myocardial Infarction


Progressive build-up of plaque in coronary artery


Heart attack symptoms• Symptoms of a possible heart attack

include chest pain and pain that radiates down the shoulder and arm. Some people (the elderly, people with diabetes, and women) may have little or no chest pain. Or, they may experience unusual symptoms (shortness of breath, fatigue, weakness).

• Women are more likely than men to have symptoms of nausea, vomiting, back or jaw pain, and shortness of breath with chest pain.


Heart attack symptoms


Atrial myxoma• An atrial myxoma is a noncancerous

tumor in the upper left or right side of the heart. It grows on the wall (atrial septum) that separates the two sides of the heart.

Causes• A myxoma is a primary heart (cardiac)

tumor. This means that the tumor started within the heart. Most heart tumors start somewhere else



Mitral regurgitation – acute• mitral valve suddenly does not close

properly, causing blood to flow backward (leak) into the upper heart chamber when the left lower heart chamber contracts

Mitral regurgitation – chronic• long-term disorder in which mitral valve

does not close properly, causing blood to flow backward (leak) into the upper heart chamber when the left lower heart chamber contracts; progressive condition


Mitral stenosis• mitral valve does not open fully, restricting

blood flow


Mitral valve prolapse• valve does not close properly

• Heart valve surgery - series

http://www.nlm.nih.gov/medlineplus/ency/presentations/100161_1.htm


Pulmonary valve stenosis• heart valve disorder that involves the

pulmonary valve• stenosis occurs when the valve cannot

open wide enough, resulting in less blood flow to the lungs


Tricuspid regurgitation• tricuspid valve does not close properly,

causing blood to flow backward (leak) into the right atrium when the right ventricle contracts

• most common cause of tricuspid regurgitation is not damage to the valve itself but enlargement of the right ventricle, which may be a complication of any disorder that causes right ventricular failure


The Heart: Cardiac Cycle• Atria contract simultaneously• Atria relax, then ventricles contract• Systole = contraction• Diastole = relaxation

generally refers to ventricles

The Heart: Cardiac Cycle• Atria contract simultaneously• Atria relax, then ventricles contract• Systole = contraction• Diastole = relaxation

Filling Heart Chambers: Cardiac Cycle

Figure 11.7, step 3

Atrialcontraction

Mid-to-late diastole(ventricular filling)

Ventricular systole(atria in diastole)

Early diastole

Isovolumetriccontraction phase

Ventricularejection phase

Isovolumetricrelaxation

Ventricularfilling

Left atriumRight atrium

Left ventricleRight ventricle

The Heart: Cardiac Cycle• Cardiac cycle—events of one complete

heart beat• Mid-to-late diastole—blood flows from

atria into ventricles; SL closed, AV open• Ventricular systole—blood pressure

builds before ventricle contracts, pushing out blood; AV close, SL open

• Early diastole—atria finish refilling, ventricular pressure is low; SL valves snap shut, AV open

The Heart: Cardiac Cycle• Heart Sounds

• “lub” – AV valves close• 1st sound; longer, louder• “dub” – SL valves close• 2nd sound; shorter due to snapping shut

• Heart Murmur• abnormal heart sounds• often indicates valve problem but might

be VSD, etc.• valve doesn’t close tightly lub-swish-

dub

The Heart: Cardiac Output• Cardiac output (CO)

• Amount of blood pumped by each side (ventricle) of the heart in one minute

• Stroke volume (SV)• Volume of blood pumped by each ventricle in one

contraction (each heartbeat)• Usually remains relatively constant • About 70 mL of blood is pumped out of the left

ventricle with each heartbeat• Heart rate (HR)

• Typically 75 beats per minute

The Heart: Cardiac Output• CO = HR SV • CO = HR (75 beats/min) SV (70

mL/beat)• CO = 5250 mL/min• Starling’s law of the heart—the more the

cardiac muscle is stretched, the stronger the contraction

• Changing heart rate is the most common way to change cardiac output

The Heart: Regulation of Heart Rate• Increased heart rate

• Sympathetic nervous system• Crisis• Low blood pressure

• Hormones• Epinephrine• Thyroxine

• Exercise• Decreased blood volume

The Heart: Regulation of Heart Rate• Decreased heart rate

• Parasympathetic nervous system• High blood pressure or blood volume• Decreased venous return

Cardiac Output Regulation

Figure 11.8

Blood Vessels: The Vascular System• Transport blood to the tissues and back

• Carry blood away from the heart• Arteries• Arterioles

• Exchanges between tissues and blood• Capillary beds

• Return blood toward the heart• Venules• Veins

Blood Vessels: The Vascular System

Figure 11.9a

Blood Vessels: Microscopic Anatomy• Three layers (tunics)

• Tunic intima• Endothelium

• Tunic media• Smooth muscle• Controlled by sympathetic nervous

system• Tunic externa

• Mostly fibrous connective tissue


Figure 11.9b

Differences Between Blood Vessels• Walls of arteries are the thickest• Lumens of veins are larger• Larger veins have valves to prevent

backflow• Skeletal muscle “milks” blood in veins

toward the heart• Walls of capillaries are only one cell layer

thick to allow for exchanges between blood and tissue


Figure 11.10

Movement of Blood Through Vessels• Most arterial blood is pumped by the

heart• Veins use the milking action of muscles to

help move blood

Capillary Beds• Capillary beds consist of two types of

vessels• Vascular shunt—vessel directly

connecting an arteriole to a venule• True capillaries—exchange vessels

• Oxygen and nutrients cross to cells• Carbon dioxide and metabolic

waste products cross into blood

Capillary Beds

Figure 11.11a

Capillary Beds

Figure 11.11b

Major Arteries of System Circulation• Aorta

• Largest artery in the body• Leaves from the left ventricle of the

heart• Regions

• Ascending aorta—leaves the left ventricle

• Aortic arch—arches to the left• Thoracic aorta—travels downward

through the thorax• Abdominal aorta—passes through

the diaphragm into the abdominopelvic cavity

Major Arteries of System Circulation• Arterial branches of the ascending aorta

• Right and left coronary arteries serve the heart

Blood Pressure• measurement of force applied to the walls

of the arteries as heart pumps blood through body• determined by the force and amount of

blood pumped• size and flexibility of arteries

• continually changing depending on activity, temperature, diet, emotional state, posture, physical state, and medication use

Blood Pressure – How the Test is Performed

• usually measured while you are seated with your arm resting on a table, arm should be slightly bent so that it is at the same level as your heart, upper arm should be bare

• readings are measured in mmHg, given as two numbers (EX: 110/70)• top #: systolic; maximum pressure

exerted when heart contracts• bottom #: diastolic; minimum pressure

in arteries the heart is at rest• Blood Pressure Video


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The Cardiovascular System Chapter 11. The Cardiovascular System A closed system of the heart and...

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