Cardiovascular System

Cardiovascular SystemCardiovascular System

HeartHeart

Introduction of Cardiovascular Introduction of Cardiovascular SytemSytem

Consists of;Consists of;

1.1. BloodBlood

2.2. HeartHeart

3.3. Blood VesselsBlood Vessels

Location of HeartLocation of Heart

Heart lies between the lungs in the Heart lies between the lungs in the mediastinum.mediastinum.


Two-thirds of its mass is to the left of Two-thirds of its mass is to the left of the midlinethe midline


Precordium – The area of the chest Precordium – The area of the chest anterior to the heart anterior to the heart


Lies between the vertebral column Lies between the vertebral column and the sternumand the sternum

Structure and Function of Structure and Function of HeartHeart

1.1. PericardiumPericardium

2.2. Layers of the Heart Wall Layers of the Heart Wall

PericardiumPericardium

The heart is enclosed and held in The heart is enclosed and held in place by the pericardiumplace by the pericardium



1.1. Fibrous pericardium (outer)Fibrous pericardium (outer)

2.2. Serous pericardium (inner) Serous pericardium (inner)


Fibrous pericardium – anchors the Fibrous pericardium – anchors the heart in the mediastinumheart in the mediastinum


Serous pericardium composed of;Serous pericardium composed of;

1.1. Parietal layerParietal layer

2.2. Visceral layerVisceral layer


Pericardial cavity – a space between Pericardial cavity – a space between the parietal and visceral layers filled the parietal and visceral layers filled with pericardial fluid with pericardial fluid

Layer of the HeartLayer of the Heart

1.1. EpicardiumEpicardium

2.2. MyocardiumMyocardium

3.3. EndocardiumEndocardium

EpicardiumEpicardium

Consists of the visceral layer of Consists of the visceral layer of pericardium and connective tissue pericardium and connective tissue (adipose)(adipose)

MyocardiumMyocardium

Composed of cardiac muscleComposed of cardiac muscle


The cells are branched, involuntary, The cells are branched, involuntary, and have one nucleusand have one nucleus


The cells are connected by The cells are connected by intercalated discs, which have gap intercalated discs, which have gap junctions that allow ions to flow in junctions that allow ions to flow in between cells during depolarizationbetween cells during depolarization

EndocardiumEndocardium

Lines the chambers and covers the Lines the chambers and covers the connective tissue in the heart valvesconnective tissue in the heart valves

EndocardiumEndocardium

It consists of endotheliumIt consists of endothelium

Chambers of the HeartChambers of the Heart

1.1. Right AtriumRight Atrium

2.2. Right VentricleRight Ventricle

3.3. Left AtriumLeft Atrium

4.4. Left VentricleLeft Ventricle


On the surface of the heart are On the surface of the heart are auricles and sulciauricles and sulci


Auricles – small pouches on the Auricles – small pouches on the anterior surface of each atrium anterior surface of each atrium


Sulci – Are grooves that contain Sulci – Are grooves that contain coronary arteries and fat and coronary arteries and fat and separate the chambersseparate the chambers

Right AtriumRight Atrium

The right atrium receives systemic The right atrium receives systemic venous blood from;venous blood from;

1.1. Superior Vena CavaSuperior Vena Cava

2.2. Inferior Vena CavaInferior Vena Cava

3.3. Coronary sinusCoronary sinus


The atrium receives blood low in O2 The atrium receives blood low in O2 and high in CO2and high in CO2


Interatrial septum - separates the Interatrial septum - separates the right and left atriaright and left atria


Fossa ovalis – an oval depression in Fossa ovalis – an oval depression in the interatrial septum; it is a remnant the interatrial septum; it is a remnant of the foramen ovaleof the foramen ovale


Tricuspid Valve – Blood passes from Tricuspid Valve – Blood passes from the right atrium into the right the right atrium into the right ventricle through hereventricle through here

Right VentricleRight Ventricle

Forms most of the anterior surface of Forms most of the anterior surface of the heartthe heart

Right VentricleRight Ventricle

Pulmonary semilunar valve - Blood Pulmonary semilunar valve - Blood passes from the right ventricle to the passes from the right ventricle to the pulmonary trunk via this valvepulmonary trunk via this valve

Left AtriumLeft Atrium

Receives pulmonary venous blood Receives pulmonary venous blood from the pulmonary veins which is from the pulmonary veins which is rich in oxygen and low in CO2rich in oxygen and low in CO2

Left AtriumLeft Atrium

Mitral Valve – Blood passes from the Mitral Valve – Blood passes from the left atrium to the left ventricle via left atrium to the left ventricle via this valvethis valve

Left VentricleLeft Ventricle

Thickest and strongest chamberThickest and strongest chamber


Forms the apex of the heartForms the apex of the heart


Blood passes from the left ventricle Blood passes from the left ventricle through the aortic valve into the through the aortic valve into the aortaaorta


During fetal life the ductus arteriosus During fetal life the ductus arteriosus shunts blood from the pulmonary shunts blood from the pulmonary trunk into the aortatrunk into the aorta


At birth the ductus arteriosus closes At birth the ductus arteriosus closes and becomes the ligamentum and becomes the ligamentum arteriosumarteriosum


The left ventricle is separted from The left ventricle is separted from the right ventricle by the the right ventricle by the interventricular septuminterventricular septum

Myocardial Thickness and Myocardial Thickness and FunctionFunction

The atria walls are thin because they The atria walls are thin because they only pump blood to the nearby only pump blood to the nearby ventriclesventricles


The ventricle wall are thicker The ventricle wall are thicker because they pump blood greater because they pump blood greater distancesdistances


The right ventricle walls are thinner The right ventricle walls are thinner than the left because they pump than the left because they pump blood to the nearby lungs blood to the nearby lungs


The left ventricle walls are thicker The left ventricle walls are thicker because they pump blood through because they pump blood through the bodythe body

Function of Heart ValvesFunction of Heart Valves

Valves open and close in response to Valves open and close in response to pressure changes as the heart pressure changes as the heart contracts and relaxescontracts and relaxes


Two types of valves;Two types of valves;

1.1. Atrioventricular ValvesAtrioventricular Valves

2.2. SemilunarSemilunar

Atrioventricular ValvesAtrioventricular Valves

1.1. Tricuspid (right side)Tricuspid (right side)

2.2. Mitral or bicuspid (left side)Mitral or bicuspid (left side)


AV valves prevent blood flow from AV valves prevent blood flow from the ventricles back into the atriathe ventricles back into the atria


Back flow is prevented by the Back flow is prevented by the contraction of papillary muscles and contraction of papillary muscles and tightening the chordae tendinaetightening the chordae tendinae

Semilunar ValvesSemilunar Valves

SL valves allow ejection of blood SL valves allow ejection of blood from the heart into the pulmonary from the heart into the pulmonary arteries and aortaarteries and aorta

Semilunar ValvesSemilunar Valves

Prevent back flow into the ventriclesPrevent back flow into the ventricles

Circulation of BloodCirculation of Blood

1.1. Systemic Systemic

2.2. PulmonaryPulmonary

3.3. CoronaryCoronary

Systemic CirculationSystemic Circulation

The left side of the heart pumps The left side of the heart pumps oxygenated blood from the left oxygenated blood from the left ventricle into the ascending aorta.ventricle into the ascending aorta.

Systemic CirculationSystemic Circulation

The coronary arteries arise off of the The coronary arteries arise off of the ascending aortaascending aorta

Pulmonary CirculationPulmonary Circulation

The right side of the heart receives The right side of the heart receives deoxygenated blood from the body.deoxygenated blood from the body.

Pulmonary CirculationPulmonary Circulation

The right side of the heart pumps The right side of the heart pumps blood from the right ventricle and blood from the right ventricle and sends it into the lungs via the sends it into the lungs via the pulmonary arterypulmonary artery


Right atrium receives blood from the Right atrium receives blood from the superior and inferior vena cavasuperior and inferior vena cava


The Left atrium receives blood from The Left atrium receives blood from the pulmonary veinsthe pulmonary veins

Coronary CirculationCoronary Circulation

It delivers oxygenated blood and It delivers oxygenated blood and nutrients to and removes CO2 and nutrients to and removes CO2 and wastes from the myocardiumwastes from the myocardium


The The left and right coronary left and right coronary arteriesarteries branch from the ascending branch from the ascending aorta and carry oxygenated bloodaorta and carry oxygenated blood


Left coronary artery branches into Left coronary artery branches into the;the;

1.1. Left anterior descending arteryLeft anterior descending artery

2.2. Circumflex arteryCircumflex artery


Right coronary artery branches into;Right coronary artery branches into;

1.1. Marginal arteryMarginal artery

2.2. Posterior descending arteryPosterior descending artery


Deoxygenated blood returns to the Deoxygenated blood returns to the right atrium through the coronary right atrium through the coronary sinussinus

Histology of Cardiac MuscleHistology of Cardiac Muscle

In comparison to skeletal muscle In comparison to skeletal muscle fibers, cardiac muscle fibers are fibers, cardiac muscle fibers are involuntary, shorter in length, larger involuntary, shorter in length, larger in diameter, and squarish rather than in diameter, and squarish rather than circular in transverse section.circular in transverse section.


They also exhibit branchingThey also exhibit branching


Have same arrangement of actin and Have same arrangement of actin and myosin, and the same bands, zones, myosin, and the same bands, zones, and Z discs as skeletal musclesand Z discs as skeletal muscles

Cardiac Conduction SystemCardiac Conduction System

There is an atrial and ventricular There is an atrial and ventricular networknetwork


Fibers within the networks are Fibers within the networks are connected by intercalated discsconnected by intercalated discs


The intercalated discs allow the The intercalated discs allow the fibers to work together so that each fibers to work together so that each network serves as a functional unitnetwork serves as a functional unit


Cardiac muscle cells are Cardiac muscle cells are autorhythmic cells because they are autorhythmic cells because they are self-excitable.self-excitable.


They repeatedly generate They repeatedly generate spontaneous action potentials that spontaneous action potentials that then trigger heart contractionthen trigger heart contraction


The components of this system are;The components of this system are;

1.1. Sinoatrial node (SA)Sinoatrial node (SA)

2.2. Atrioventricular node (AV)Atrioventricular node (AV)

3.3. Bundle of HisBundle of His

4.4. Right and Left Bundle branchesRight and Left Bundle branches

5.5. Purkinje fibersPurkinje fibers


SA node is the pacemaker SA node is the pacemaker


From the SA node, a cardiac action From the SA node, a cardiac action potential travels throughout the potential travels throughout the atrial muscle and down to the AV atrial muscle and down to the AV nodenode


At the AV node the impulse is At the AV node the impulse is delayed (about 0.1sec)delayed (about 0.1sec)


This gives the atria time to This gives the atria time to completely contract before completely contract before ventricular contraction beginsventricular contraction begins


It then passes through the Bundle of It then passes through the Bundle of His, Right and Left Bundle Branches, His, Right and Left Bundle Branches, and the Purkinje fibers, resulting in and the Purkinje fibers, resulting in ventricular contractionventricular contraction

Cardiac CycleCardiac Cycle


1.1. Systole (contraction) and Diastole Systole (contraction) and Diastole (relaxation) of both atria(relaxation) of both atria

2.2. Systole and Diastole of both Systole and Diastole of both ventriclesventricles

Atrial DiastoleAtrial Diastole

The atria are relaxedThe atria are relaxed


They receive blood from three veinsThey receive blood from three veins


The A-V valves are open, allowing for The A-V valves are open, allowing for 70% of ventricular filling. The 70% of ventricular filling. The ventricles are therefore also in ventricles are therefore also in diastole.diastole.

Atrial SystoleAtrial Systole

The SA node then fires; after this The SA node then fires; after this electrical event, atrial systole begins electrical event, atrial systole begins (a mechanical event)(a mechanical event)

Atrial SystoleAtrial Systole

Atrial contraction accounts for 30% Atrial contraction accounts for 30% of ventricular fillingof ventricular filling

Ventricular SystoleVentricular Systole

Shortly after the beginning of Shortly after the beginning of ventricular depolarization, ventricular ventricular depolarization, ventricular systole beginssystole begins


The ventricles contract. The The ventricles contract. The ventricular pressure becomes higher ventricular pressure becomes higher than atrial pressures, causing the AV than atrial pressures, causing the AV valves to close.valves to close.


The SL valves open when the The SL valves open when the ventricular pressure becomes higher ventricular pressure becomes higher than aortic (pulmonary arterial) than aortic (pulmonary arterial) pressure.pressure.


Then blood is ejected into the aorta Then blood is ejected into the aorta and pulmonary trunk.and pulmonary trunk.

Ventricular DiastoleVentricular Diastole

Begins when the ventricles relaxBegins when the ventricles relax


Ventricular pressures drop below Ventricular pressures drop below arterial pressures, causing the SL arterial pressures, causing the SL valves to closevalves to close


The ventricular pressures continue to The ventricular pressures continue to drop below atrial pressures, causing drop below atrial pressures, causing the AV valves to openthe AV valves to open

AuscultationAuscultation

Listening to sounds within the body Listening to sounds within the body with a stethoscopewith a stethoscope


The first heart sound (lubb) is The first heart sound (lubb) is created by the closing of the AV created by the closing of the AV valves soon after ventricular systole valves soon after ventricular systole beginsbegins


The second heart sound (dupp) The second heart sound (dupp) represents the closing of the SL represents the closing of the SL valves close to the end of the valves close to the end of the ventricular systole.ventricular systole.

Cardiac OutputCardiac Output

The volume of blood ejected from the The volume of blood ejected from the left ventricle (or the right ventricle) left ventricle (or the right ventricle) into the aorta (or pulmonary trunk) into the aorta (or pulmonary trunk) each minute.each minute.


Cardiac Output = Stroke volume X Cardiac Output = Stroke volume X Heart RateHeart Rate


Stroke volume – the volume of blood Stroke volume – the volume of blood ejected by the ventricle with each ejected by the ventricle with each contractioncontraction


Stroke Volume = End Diastolic Stroke Volume = End Diastolic Volume (130ml) – End Systolic Volume (130ml) – End Systolic Volume (60ml)Volume (60ml)


Heart Rate – number of beats per Heart Rate – number of beats per minuteminute

Regulation of Heart RateRegulation of Heart Rate

Sympathetics impulses increase Sympathetics impulses increase heart rate and force of contractionheart rate and force of contraction

Regulation of Heart RateRegulation of Heart Rate

Parasympathetic impulses decrease Parasympathetic impulses decrease heart rateheart rate

TachycardiaTachycardia

Heart Rate over 100 beats/minHeart Rate over 100 beats/min

BradycardiaBradycardia

Heart Rate below 60 beats/minHeart Rate below 60 beats/min

FibrillationFibrillation

Prolonged tachycardiaProlonged tachycardia

Exercise And The HeartExercise And The Heart

Sustained exercise increases oxygen Sustained exercise increases oxygen demand in musclesdemand in muscles


Resting cardiac output 5.25 Resting cardiac output 5.25 Liters/minuteLiters/minute


In sedentary people CO may go up to In sedentary people CO may go up to 22 liters/minute22 liters/minute


In trained athletes CO may go up to In trained athletes CO may go up to 40 liters/minute40 liters/minute


Sedentary people increase their CO Sedentary people increase their CO during exercise by an increase in HR during exercise by an increase in HR and SVand SV


Sedentary peopleSedentary people Increase in HR more dramaticIncrease in HR more dramatic Stroke volume only goes up by 10-Stroke volume only goes up by 10-

35%35%


For a given activity, sedentary For a given activity, sedentary people’s maximum HR will be higher people’s maximum HR will be higher than in a trained athletethan in a trained athlete


Trained athletes increase their CO Trained athletes increase their CO during exercise by an increase in HR during exercise by an increase in HR and SVand SV


Trained AthletesTrained Athletes Increase in SV more dramatic than Increase in SV more dramatic than

HRHR Their SV goes up to 60%Their SV goes up to 60%


Athletes have larger stroke volumes Athletes have larger stroke volumes due to longer filling time due to longer filling time

Electrocardiogram (ECG or Electrocardiogram (ECG or EKG)EKG)

Records the electrical currents of the Records the electrical currents of the body generated by the heartbody generated by the heart


P= depolarization of the atriaP= depolarization of the atria


QRS= depolarization of the ventriclesQRS= depolarization of the ventricles

(repolarization of atria, but don’t see)(repolarization of atria, but don’t see)


T= ventricles repolarizationT= ventricles repolarization


PR interval= between beginning of PR interval= between beginning of atrial depolarization and ventrical atrial depolarization and ventrical depolarizationdepolarization


ST segment= ventricle contractionST segment= ventricle contraction


QT interval = ventricle depolarization QT interval = ventricle depolarization through ventricle repolarizationthrough ventricle repolarization

Cardiovascular System

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