The Cardiovascular System: The Cardiovascular System: The HeartThe Heart

A. Location and size of the heartA. Location and size of the heartB. PericardiumB. PericardiumC. Heart wallC. Heart wallD. Chambers of the heartD. Chambers of the heartE. Blood flow through the heartE. Blood flow through the heartF. Valves of the heartF. Valves of the heart

1. Atrioventricular valves1. Atrioventricular valves 2. Semilunar valves2. Semilunar valves

G. Heart blood supplyG. Heart blood supply 1. Coronary arteries1. Coronary arteries 2. Coronary veins2. Coronary veins

H. Conduction system and H. Conduction system and pacemakerpacemaker

1. Autorhythmic cells: the 1. Autorhythmic cells: the conduction systemconduction system

I. ElectrocardiogramI. ElectrocardiogramJ. Cardiac cycleJ. Cardiac cycle

1. Phases of the cardiac 1. Phases of the cardiac cyclecycle

2. Timing of systole and 2. Timing of systole and diastolediastole

K. Cardiac outputK. Cardiac output 1. Regulation of stroke 1. Regulation of stroke

volumevolume a. Preload: effect of a. Preload: effect of

stretchingstretching b. Contractilityb. Contractility c. Afterloadc. Afterload

2. Regulation of heart rate2. Regulation of heart rate a. Autonomic control of a. Autonomic control of

heart rateheart rate b. Chemical regulation of b. Chemical regulation of

heart rateheart rate

The heart is the center of The heart is the center of cardiovascular systemcardiovascular system..

1. double pump1. double pump

a. systemic circulationa. systemic circulation

b. pulmonary circulationb. pulmonary circulation

2. 1,800 gallons of blood per day through 2. 1,800 gallons of blood per day through about 60,000 miles of blood vesselsabout 60,000 miles of blood vessels

The Pulmonary and Systemic CircuitsThe Pulmonary and Systemic Circuits

Cardiac and Pulmonary CircuitsCardiac and Pulmonary Circuits

Heart Location and SizeHeart Location and Size

11. middle mediastinum. middle mediastinum

2. apex vs base2. apex vs base

Gross Anatomy of the Heart Gross Anatomy of the Heart (Anterior and Lateral View)(Anterior and Lateral View)

PericardiumPericardium

1. outer fibrous1. outer fibrous2. inner serous2. inner serous

a. parietal layera. parietal layer b. visceral layerb. visceral layer (epicardium)(epicardium)____________________________________

3. pericardial cavity3. pericardial cavity4. pericardial fluid4. pericardial fluid

Pericardium peeled backPericardium peeled back

Heart WallHeart Wall

1. epicardium1. epicardium2. myocardium2. myocardium

a. involuntarya. involuntary b. striatedb. striated c. branchedc. branched d. intercalated discsd. intercalated discs e. 2 muscle massese. 2 muscle masses3. endocardium3. endocardium (endothelium)(endothelium)

Epicardium

Fat and connective Tissue + simple squamous epithelium

Myocardium

Endocardium

Heart ChambersHeart Chambers

1. right and left atrium1. right and left atrium

2. atrial appendages2. atrial appendages

3. right and left ventricles 3. right and left ventricles ________________________________________

4. coronary sulcus4. coronary sulcus

5. interventricular sulci5. interventricular sulci

Septa of the HeartSepta of the Heart

1. interatrial septum1. interatrial septum

a. fossa ovalisa. fossa ovalis

b. foramen ovaleb. foramen ovale

2. interventricular septum2. interventricular septum

a. membranousa. membranous

b. muscularb. muscular

Heart ValvesHeart Valves

1. atrioventricular (AV) valves (2)1. atrioventricular (AV) valves (2) a. tricuspid & bicuspid (mitral)a. tricuspid & bicuspid (mitral) b. base vs apexb. base vs apex c. chordae tendineaec. chordae tendineae d. papillary musclesd. papillary muscles

2. semilunar (SL) valves (2)2. semilunar (SL) valves (2) a. pulmonary valve & aortic valvea. pulmonary valve & aortic valve

____________________________________________ b. 3 half-moon cuspsb. 3 half-moon cusps (pockets)(pockets)

The Heart Valves and Associated The Heart Valves and Associated StructuresStructures

Gross Anatomy of the Heart Gross Anatomy of the Heart ValvesValves

Blood Flow Through the HeartBlood Flow Through the Heart

Blood Flow Through the HeartBlood Flow Through the Heart

Coronary Circulation(Arteries)Coronary Circulation(Arteries)

1. left coronary artery1. left coronary artery a. anterior interventricular a.a. anterior interventricular a. b. circumflex a.b. circumflex a.2. right coronary artery2. right coronary artery a. marginal a.a. marginal a. b. posterior interventricular a.b. posterior interventricular a.__________________________________________________anastomosesanastomoses

Coronary Circulation(Veins)Coronary Circulation(Veins)

1. great cardiac v.1. great cardiac v.

2. middle cardiac v.2. middle cardiac v.

3. small cardiac v.3. small cardiac v.

4. coronary sinus4. coronary sinusSmall cardiac vein

Conduction System and Conduction System and PacemakerPacemaker

1. heart stimulates itself with autorhythmic cells1. heart stimulates itself with autorhythmic cells

2. ANS and hormones can only modify, not 2. ANS and hormones can only modify, not establish, the fundamental rhythmestablish, the fundamental rhythm

3. 1% of cardiac muscle cells lose the ability to 3. 1% of cardiac muscle cells lose the ability to contract during early development (specialized contract during early development (specialized autorhythmic cells)autorhythmic cells)

4. those cells that cannot contract form the 4. those cells that cannot contract form the pacemakers (primary and secondary) and the pacemakers (primary and secondary) and the conduction systemconduction system

Conduction System ComponentsConduction System Components

1. sinoatrial (SA) node1. sinoatrial (SA) node (90 - 100 action potentials/min)(90 - 100 action potentials/min) (primary pacemaker)(primary pacemaker)

2. atrioventricular (AV) node2. atrioventricular (AV) node (40 - 50 action potentials/min)(40 - 50 action potentials/min) (secondary pacemaker)(secondary pacemaker)

3. atrioventricular (AV) bundle3. atrioventricular (AV) bundle4. right and left bundle branches4. right and left bundle branches5. Purkinje fibers5. Purkinje fibers

Conduction System of the HeartConduction System of the Heart

Timing of Conduction Events

Times are in seconds

0.00

0.04

0.17

0.16 0.07

0.05

0.09

0.07

0.18

0.18

0.19

0.19 0.21

0.22

0.01

Where does the cardiac muscle contract first? Last?Why is there a 0.12 sec delay across the AV node?What separates the atrial muscle mass from the ventricular muscle mass?Why does the interventricular septum begin to contract before the apex?

Electrocardiogram (ECG)Electrocardiogram (ECG)1. P wave = atrial depolarization1. P wave = atrial depolarization

2. QRS complex = ventricular depolarization2. QRS complex = ventricular depolarization

3. T wave = ventricular repolarization3. T wave = ventricular repolarization

4. P-R interval4. P-R interval

5. S-T segment5. S-T segment

6. quiescent period6. quiescent period

Relationship of ECG to Electrical Relationship of ECG to Electrical Activity and ContractionActivity and Contraction

Normal and Pathological ECGsNormal and Pathological ECGs

Cardiac CycleCardiac Cycle

Two phenomena control blood flow Two phenomena control blood flow through the heart.through the heart.

1. contraction and relaxation1. contraction and relaxation

2. opening and closing of the AV and 2. opening and closing of the AV and SL valvesSL valves

The Cardiac Cycle PhenomenaThe Cardiac Cycle Phenomena

Operation of the Heart Valves Operation of the Heart Valves due to Pressure Changesdue to Pressure Changes

Blood flows from an area of higher pressure Blood flows from an area of higher pressure to an area of lower pressure.to an area of lower pressure.

The pressure developed within a heart The pressure developed within a heart chamber is related to two things.chamber is related to two things.

1. volume of blood within the chamber1. volume of blood within the chamber

2. size of the chamber2. size of the chamber

Pressures to Keep in MindPressures to Keep in Mind

1. venous pressure1. venous pressure

2. atrial pressure2. atrial pressure

3. ventricular pressure3. ventricular pressure

4. arterial pressure4. arterial pressure

In a normal cardiac cycle, the two atria contract In a normal cardiac cycle, the two atria contract while the two ventricles relax, then the two while the two ventricles relax, then the two

ventricles contract while the atria relax and then ventricles contract while the atria relax and then all chambers are relaxed until the next P waveall chambers are relaxed until the next P wave

1. systole vs. diastole1. systole vs. diastole

2. Four phases of the cardiac cycle:2. Four phases of the cardiac cycle:

a. Ventricular fillinga. Ventricular filling

b. Isovolumetric contractionb. Isovolumetric contraction

b. Ventricular ejectionb. Ventricular ejection

c. Isolvolumetric relaxationc. Isolvolumetric relaxation

Ventricular FillingVentricular Filling 1. In diastole, ventricles expand and pressure decreases.AV valves open when atrial pr. > ventricular pr.

2. Three phases of ventricular filling 2. Three phases of ventricular filling a. rapid ventricular fillinga. rapid ventricular filling b. diastasisb. diastasis c. atrial systole (30%)c. atrial systole (30%)

3. end-diastolic volume (EDV)3. end-diastolic volume (EDV) = 130 ml of blood= 130 ml of blood

70%

70% of filling occurs during quiescent period- time periodIn which all four chambers are in diastole

Isovolumetric ContractionIsovolumetric Contraction

1. Atrial diastole begins and

Ventricular systole begins

2. AV valves close when

ventricular pr. > atrial pr.

3. No blood is ejected because

arterial pr. > ventricular pr.

Ventricular EjectionVentricular Ejection

1. Ventricular pr. > arterial pr. 2. SL valves open when

ventricular pr. > arterial pr. 3. Rapid ejection, then

reduced ejection

Stroke volume (SV) = 70 ml Ejection fraction

= SV/EDV x 100 = 54% End-systolic volume

ESV = 60 ml

Isovolumetric RelaxationIsovolumetric Relaxation1. Early ventricular diastole2. Ventricles expand, pr. decreases3. SL valves close when

arterial pr. > ventricular pr.4. Isovolumetric because the

SL valves are closed and AV valves are still closed

The quiescent period begins when atrial pr. > ventricular pr.

AV valves open and the period of rapid ventricular filling begins for the next cycle.

Cardiac Cycle Events ContinuedCardiac Cycle Events Continued

Overview of Volume ChangesOverview of Volume ChangesEnd-systolic volume 60 ml

(left from previous heart beat)

Passively added during atrial diastole + 30 ml (rapid ventricular filling + diastasis)

Atrial systole + 40ml_____________________________________________________________

total = end-diastolic volume 130 ml

Stroke volume - 70 ml (ejected by ventricular systole)

Leaves the end-systolic volume 60 ml

Timing of the Cardiac CycleTiming of the Cardiac Cycle

1. resting heart rate = 75 beats/minute1. resting heart rate = 75 beats/minute

2. one cardiac cycle requires 0.8 sec.2. one cardiac cycle requires 0.8 sec.

3. first 0.4 sec. = quiescent period3. first 0.4 sec. = quiescent period

4. next 0.4 sec. = atrial and ventricular 4. next 0.4 sec. = atrial and ventricular systolesystole

Chamber Volume and Pressure Changes

0 sec.

pressure

8 sec.

volume

ECG

heart sounds

aortic valve opens

aortic valve closes

AV valve closes AV valve

opens

aortic pressure

atrial pressure

ventricular pressure

ventricular volume

SQ

R

PT

SQ

R

PT

lubb dupp lubb dupp

ventricular systole ventricular diastole

Cardiac output (CO) = amount of blood Cardiac output (CO) = amount of blood ejected from the left ventricle into the ejected from the left ventricle into the

aorta per minuteaorta per minuteCardiac output is determined by two factors:Cardiac output is determined by two factors:

1. stroke volume (SV)1. stroke volume (SV)2. heart rate (HR)2. heart rate (HR)

So how is cardiac output calculated?So how is cardiac output calculated?

CO = SV x HRCO = SV x HR = (70 ml/beat) x (75 beats/minute)= (70 ml/beat) x (75 beats/minute) = 5,250 ml/minute or 5.25 liters/minute (L/min)= 5,250 ml/minute or 5.25 liters/minute (L/min)

Cardiac ReserveCardiac Reserve

1. difference between maximum 1. difference between maximum cardiac output and resting cardiac cardiac output and resting cardiac outputoutput

2. expressed as percent of normal2. expressed as percent of normal

Normal cardiac reserve = 15-20L/min = Normal cardiac reserve = 15-20L/min = 200-300%200-300%

endurance athlete = 35L/min = 600%endurance athlete = 35L/min = 600%

Regulation of SV: Preload

increased venous pressure

increased venous return

increased ventricular filling increased preload

increased ventricular stretchFrank-Starling mechanism

increased force of contraction

increased stroke volume

increased cardiac output

Regulation of SV: Contractility

increased sympathetic activityincreased epinephrine

other factors

increased contractility

increased force of contraction

increased stroke volume

increased cardiac output

Regulation of SV: Afterload

increased arterial pressure

increased afterload

decreased blood volume ejected into artery

decreased stroke volume

decreased cardiac output

Autonomic Regulation of the Autonomic Regulation of the HeartHeart

1. CO = SV x HR1. CO = SV x HR2. sensory input2. sensory input a. baroreceptorsa. baroreceptors b. chemoreceptorsb. chemoreceptors3. cardiovascular center3. cardiovascular center4. motor output4. motor output a. cardioacceleratory nervesa. cardioacceleratory nerves (sympathetics)(sympathetics) b. cardioinhibitory nervesb. cardioinhibitory nerves (parasympathetics)(parasympathetics)

Chemical Regulation of the Heart Rate

Hormones- epinephrine, norepinephrine, throxine, and glucagon increase heart rate

Ions– Increased K+ decreases heart rate– Moderate increase in Ca2+ increases heart

rate

,