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PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

PART A 11

The Cardiovascular System


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 transportation - it delivers oxygen and nutrients and removes carbon dioxide and other waste products


The Heart §  Location – 2/3 to the left of the midline

§  Thorax between the lungs in the inferior mediastinum – medial cavity of the thorax

§  Orientation §  Pointed apex directed toward left hip – where

you would place a stethoscope

§  Base points toward right shoulder §  About the size of your fist and weighs less than a

pound


The Heart

Figure 11.1a–b


The Heart

Figure 11.1c


The Heart

Figure 11.2a


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

Figure 11.2b


The Heart: Heart Wall §  Three layers

§  Epicardium - Outside layer §  This layer is the visceral pericardium §  Connective tissue layer

§  Myocardium - Middle layer §  Mostly cardiac muscle twisted and whorled into

ringlike arrangement §  The layer that actually contracts §  Called the skeleton of the heart

§  Endocardium - Inner layer §  Endothelium that lines heart chambers §  Continuous with blood vessels leaving & entering the

heart


Homeostatic Imbalance: Pericarditis §  Inflammation of the pericardium §  Results in decrease of serous fluid §  Cause pericardial layers to stick together forming

painful adhesions

§  Interferes with heart movement



Figure 11.2b



Figure 11.2c


Review Questions 1 §  Where is the location of the heart in the thorax? §  What is the major function of the heart? §  What is the heart enclosed by? §  Name the two layers of the of the pericardial sac? §  Name the 3 layers of the heart wall §  What is and what causes pericarditis?


The Heart: Chambers §  Right and left side act as separate pumps §  Four hollow chambers

§  2 Atria §  Receiving chambers – not important in pumping activity of

heart §  Blood flows in from veins under low pressure §  Right atrium §  Left atrium

§  2 Ventricles §  Discharging chambers – actual pumps of the heart

§  Right ventricle §  Left ventricle


The Heart: Chambers

Figure 11.2c


Differences in Right and Left Ventricles

Figure 11.4


The Heart: Septa §  Septum divides the heart longitudinally

§  Interventricular septum - Separates the two ventricles

§  Interatrial septum - Separates the two atria


The Heart: Chambers

Figure 11.2c


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) §  Anchored in place by chordae tendinae

(“heart strings”) §  Open during heart relaxtion and closed

during ventricular contrations


Valves §  Semilunar valves—between ventricle and artery

§  Pulmonary semilunar valve §  Aortic semilunar valve §  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


**Homeostatic Imbalance §  Faulty Valves – heart can function with “leaky” valves as long as

damage is not too great

§  Incompetent valve – forces heart to pump and repump same blood because valves don’t close properly & blood backflows

§  Valvular stenosis – valve flaps become stiff often because of repeated endocarditis (bacterial infection of the endocardium)

§  Forces heart to contract more vigorously increasing workload

§  Faulty valve replaced with synthetic valve, cryopreserved human valve, or chemically treated porcine valve (pig heart valve)


The Heart: Valves

Figure 11.2c


Figure 11.5a, step 1

Blood returning to the atria, puts pressure against AV valves; the AV valves are forced open

Ventricles

Operation of the AV valves

AV valves open

(a)



Blood returning to the atria, puts pressure against AV valves; the AV valves are forced open As the ventricles fill, AV valve flaps hang limply into ventricles

Ventricles


AV valves open

(a)



Blood returning to the atria, puts pressure against AV valves; the AV valves are forced open As the ventricles fill, AV valve flaps hang limply into ventricles Atria contract, forcing additional blood into ventricles

Ventricles


AV valves open

(a)



Ventricles contract, forcing blood against AV valve flaps

(a)



Ventricles contract, forcing blood against AV valve flaps AV valves close

AV valves closed (a)



Ventricles contract, forcing blood against AV valve flaps AV valves close

Chordae tendineae tighten, preventing valve flaps from everting into atria

AV valves closed (a)


Figure 11.5b, step 1

As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open

Aorta

Pulmonary trunk

Semilunar valve open

Operation of the semilunar valves

(b)


Figure 11.5b, step 2

As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open

Aorta

Pulmonary trunk

Semilunar valve open Semilunar valve

closed

As ventricles relax, and intraventricular pressure falls, blood flows back from arteries, filling the leaflets of semilunar valves and forcing them to close

Operation of the semilunar valves

(b)


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

§  Veins §  Superior and inferior venae cavae - Enter right atrium §  Pulmonary veins (four) - Enter left atrium


The Heart: Associated Great Vessels

Figure 11.2c


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


Systemic and Pulmonary Circulations

Figure 11.3


Coronary Circulation §  Blood in the heart chambers does not nourish the

myocardium §  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


** Homeostatic Imbalance §  Angina Pectoris – crushing chest pain caused by

oxygen deprivation of the myocardium

§  Infarct – caused by prolonged oxygen deprivation where heart cells die

§  Myocardial infarction – “heart attack” or “coronary”


The Heart: Associated Great Vessels

Figure 11.2c


Review Questions 3 1.  Compare and contrast systemic versus pulmonary

circulation.

2.  Which side of the heart carries oxygenated blood? Deoxygenated blood?

3.  What is the major artery leaving the heart? The major veins returning blood to the heart?

4.  Where do the pulmonary vessels travel to & from? 5.  In linear fashion list flow of blood with arrows? 6.  How does the cardiac muscle tissue receive nourishment? 7.  Compare and contrast angina pectoris with an infarct.


II. Physiology of the Heart §  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 – similar to cross between

muscle & nervous tissue §  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

Figure 11.6


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


Heart Contractions

Figure 11.6


Heart Contractions §  Tachycardia—rapid heart rate over 100 beats per

minute

§  Bradycardia—slow heart rate less than 60 beats per minutes


**Homeostatic Imbalance §  Heart block – when the AV node is damaged

allowing the ventricles to beat at their own slower rate

§  Ischemia – lack of adequate blood supply which leads to fibrillation- rapid uncoordinated shudddering of heart muscles

§  Pacemaker will need to be inserted to correct this condition.


The Heart: Cardiac Cycle §  In a healthy heart, atria contract simultaneously §  Atria relax, then ventricles contract §  Systole = contraction §  Diastole = relaxation


Filling Heart Chambers: Cardiac Cycle

Figure 11.7

Atrial contraction

Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Early diastole

Isovolumetric contraction phase Ventricular ejection phase Isovolumetric relaxation Ventricular filling

Left atrium Right atrium Left ventricle Right ventricle



Figure 11.7, step 1a

Mid-to-late diastole (ventricular filling)

Ventricular filling




Figure 11.7, step 1b

Atrial contraction

Mid-to-late diastole (ventricular filling)

Ventricular filling




Figure 11.7, step 2a

Atrial contraction

Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole)

Isovolumetric contraction phase Ventricular filling




Figure 11.7, step 2b

Atrial contraction

Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole)

Isovolumetric contraction phase Ventricular ejection phase Ventricular filling




Figure 11.7, step 3

Atrial contraction

Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Early diastole

Isovolumetric contraction phase Ventricular ejection phase Isovolumetric relaxation Ventricular filling



The Heart: Cardiac Cycle §  Cardiac cycle—events of one complete heart beat

§  Mid-to-late diastole—blood flows from atria into ventricles

§  Ventricular systole—blood pressure builds before ventricle contracts, pushing out blood

§  Early diastole—atria finish refilling, ventricular pressure is low


Heart Sounds §  When using a stethoscope you hear two distinct

sounds in a cardiac cycle.

§  These heart sounds are described by two syllables “lub” and “dup”

§  The “lub” is caused by the closing of the AV valves (bicuspid and tricuspid)

§  The “dup” occurs when the semilunar valves close.


** Homeostatic Imbalance - Murmurs §  Murmur – abnormal or unusual heart sounds

§  Fairly common in young children (and some elderly people) with perfectly healthy hearts probably due to thin heart walls.

§  Outside of these groups a murmur may indicate a valve problem.


The Heart: Regulation of Heart Rate §  Increased heart rate

§  Sympathetic nervous system §  Crisis stressors (physical or emotional

trauma, high body temp.)

§  Low blood pressure §  Hormones can also increase heart rate

§  Epinephrine

§  Thyroxine §  Exercise – working muscles generate heat

which increases heart rate by boosting metabolism


The Heart: Regulation of Heart Rate §  Decreased heart rate

§  Parasympathetic nervous system slow and steady the heart giving it time to rest.


Cardiac Output Regulation

Figure 11.8


** Homeostatic Imbalance §  Congestive heart failure – when the pumping

efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs.

§  A progressive condition that may be caused by coronary atherosclerosis (blockage of coronary vessels with fatty buildup), persistent high blood pressure or multiple myocardial infarctions


Congestive Heart Failure (CHF) §  Each side can fail independently

§  If the left side fails it is pulmonary congestion because the right side continues to send blood to the lungs but the left side can not discharge blood into systemic circuclation

§  Lungs become swollen with blood, pressure increases and fluid leaks into lung tissue causing pulmonary edema

§  If untreated the patient suffocates


Congestive Heart Failure (CHF) §  If the right side fails peripheral

congestion occurs as blood backs up in the systemic circulation

§  Edema is most noticeable in distal parts of the body; feet, ankles, and fingers become swollen and puffy

§  Failure of one side puts a greater strain on the other side and eventually the whole heart fails


Heart Pop Quiz Word Bank Superior vena cava Inferior vena cava

Right atrium Bicuspid valve

Right ventricle Aortic Semilunar valve

Right Pulmonary artery Left Pulmonary artery

Right pulmonary vein Left pulmonary vein

Left atrium Tricuspid valve

Left ventricle Aorta

Septum Pulmonary semilunar valve

Pulmonary trunk

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