Download - The Cardiovascular System: The Heart
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
,