Gross Anatomy of the Heart Cardiac Conduction System and Cardiac Muscle Electrical and Contractile Activity of Heart Chapter 19 Part 1 Lecture 3 The Heart The Circulatory System Heart ID: 775494
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Slide1
The Circulatory
System
Overview of Cardiovascular System Gross Anatomy of the HeartCardiac Conduction System and Cardiac MuscleElectrical and Contractile Activity of Heart
(Chapter
19)
(Part 1)
Lecture # 3
The Heart
Slide2The Circulatory System
Heart
Blood vessels
-Blood
It transports substances from place to place in the
body.
It is the liquid medium in which these substance travel.
They ensure the proper routing of blood to its destination.
It is the pump that keeps the blood flowing.
-Cardiovascular System
Slide3Arteries
Veins
Capillaries
They carry blood
away from the heart.
They carry blood back to (toward) the heart.
They connect the arteries with the veins.
Blood Vessels
Veins (4)
Pulmonary
Arteries (2)
Cardiovascular System
Pulmonary Circuit
Systemic Circuit
It carries blood to the lungs for gas exchange and returns it to the heart.
It supplies blood to every organ of the body, including the heart itself.
Vena cava
Aorta
Pulmonary
Slide4Gas exchange
Systemic Circuit
It supplies blood to every organ of the body, including the heart itself.
O
2
rich blood through
ARTERIES
O
2
poor blood through
VEINS
O
2
poor blood through ARTERIES
O
2 rich blood through VEINS
Pulmonary Circuit
It carries blood to the lungs for gas exchange and returns it to the heart.
Slide5Tissue
Arteriole
Venule
Capillary
Lung
CO
2
Wastes
O
2
Nutrients
Venule
Arteriole
O
2
rich,
CO
2
poor blood
O
2
poor,
CO
2
rich blood
Gas
Exchange
Capillary
CO
2
O
2
Venae cavae
Aorta
Pulmonary
arteries (2)
Pulmonary
veins (4)
Pulmonary
Circuit
Systemic
Circuit
Slide6Position, Size, and Shape of the Heart
The heart is located in the thoracic cavity, in the mediastinum, between the lungs.
The base is the wide, superior portion of the heart, the great blood vessels attach here.
The apex is the inferior end, tilts to the left.
The heart is enclosed in the pericardium.
Slide7The Pericardium
The pericardium is a double-walled sac (pericardial sac) that encloses the heart.
Parietal pericardium
Superficial fibrous layer of connective tissue
Deep, thin serous layer.
Visceral pericardium or epicardium
Pericardial cavity
It is the space inside the pericardial sac filled with 5-30 mL of pericardial fluid.
1- It allows the heart to beat without friction.
2- It provides room to expand, yet resists excessive expansion.
Functions of the Pericardium:
Pericarditis
: It is the inflammation of the membranes. It produces a painful friction rub with each heartbeat.
Slide8The Heart Wall
Epicardium
(visceral pericardium)
It is a serous membrane covering heart. Also includes a thick layer of adipose tissue in some places. The coronary blood vessels travel through this layer.
Epicardium (visceral pericardium)
Myocardium
It is a layer of cardiac muscle proportional to work load.
It also contains a framework of collagen and elastic fibers, which:
- Provides structural support and attachment for cardiac muscle and anchor for valve tissue.
- Is an electrical insulation between atria and ventricles, so the atria can not stimulate the ventricles directly.
Myocardium
Endocardium
Endocardium
It is the smooth inner lining of heart and blood vessels. It covers the valve surfaces and is continuous with the endothelium of blood vessels.
Slide9Endocarditis
is
the inflammation of the inside lining of the heart chambers and heart valves (endocardium). Most people who develop endocarditis have heart disease of the valves.
The Heart Wall
Mesothelium
Fibrous tissue
Areolar tissue
Pericardial cavity
Parietal pericardium
EPICARDIUM
MYOCARDIUM
(cardiac muscle tissue)
ENDOCARDIUM
Mesothelium
Areolar tissue
Visceral pericardium
Endothelium
Areolar tissue
Slide10RIGHT ATRIUM
LEFT ATRIUM
RIGHT VENTRICLE
LEFT VENTRICLE
Aorta
To the rest of the body
Poor oxygen blood
Reach oxygen blood
Gas exchange
Superior vena cava
Inferior vena cava
Coronary sinus
Pulmonary arteries
Pulmonary veins
The Heart
TISSUES
Slide11It drains oxygen-poor blood from tissues and organs
superior
to the diaphragm to the right atrium.
It drains oxygen-poor blood from tissues and organs inferior to the diaphragm to the right atrium.
Coronary sinus (no shown)
It drains oxygen-poor blood from the heart tissues to the right atrium.
It carries oxygen-poor blood from the right ventricle to the lungs.
Superior vena cava
Pulmonary trunk
They carry oxygen-rich blood from the lungs to the left atrium.
Aorta
It carries oxygen-rich blood from the left ventricle to the whole body.
Pulmonary veins (4)
Inferior vena cava
Slide12Right atrium
Right ventricle
Left atrium
Left ventricle
Anterior view
Posterior view
Left auricle
Coronary or atrioventricular sulcus
Coronary or atrioventricular sulcus
Anterior interventricular sulcus
Posterior interventricular sulcus
Interventricular septum
Interatrial septum
Trabeculae
carneae
Pectinate
muscles
The Chambers of the Heart
Slide13Right atrium
It receives O
2
poor blood returning to the heart through the superior and inferior vena cava and the coronary sinus (no shown).
Right ventricle
It pumps
O
2
poor blood to the lungs through the pulmonary arteries.
Superior vena cava
Inferior vena cava
Left atrium
It receives blood returning from the lungs through the pulmonary veins (4).
Pulmonary veins
Left ventricle
It pumps
O
2
rich blood
through the aorta artery to every organ of the body.
Pulmonary trunk
Aorta
Pulmonary
arteries
Pulmonary veins
Blood Flow Through Heart Chambers
Slide14Slide15Slide16The Valves
Left AV
(bicuspid) valve
Left
AV
(bicuspid or mitral)
valve
Right AV
(tricuspid) valve
It prevents back flow of blood from the LV to the LA
Pulmonary semilunar valve
Right AV
(tricuspid) valve
It prevents back flow of blood from the RV to the RA
It prevents back flow of blood from the pulmonary trunk to the RV
Pulmonary semilunar valve
Aortic semilunar valve
It prevents back flow of blood from the aorta to the LV
Aortic semilunar valve
Chordae tendineae
Papillary muscles
The valves ensure a one-way flow, by
preventing back flow
of the blood.
Slide17Blood Flow Through Heart Chambers
Slide18Endoscopic photo of the aortic valve, viewed from above.
Papillary muscles and tendinous cords seen from within the right ventricle.
Slide19The Coronary Circulation
If you heart lasts 80 years and beats an average of 75 times a minute, it will be beat more than 3 000 000 000 times and pump more than 200 000 000 liters of blood.
The heart is a remarkable hardworking organ and needs an abundant supply of O
2.
The blood vessels of the heart wall constitute the coronary circulation.
A polymer cast of the coronary circulation.
The coronary circulation supplies the myocardium with about 250 mL of blood per minute.
Slide20Left coronary artery (LCA)
Right coronary artery (RCA)
Circumflex branch of LCA
It supplies left atrium and posterior wall of left ventricle.
It supplies both ventricles and anterior two-thirds of the inter-ventricular septum.
It supplies
right atrium and sinoatrial node (pacemaker
).
Anterior view
Right marginal branch of RCA
It supplies lateral aspect of right atrium and ventricle.
It supplies posterior walls of ventricles.
The Coronary Circulation
Left marginal branch of LCA
It supplies posterior wall of left ventricle.
Anterior interventricular branch of LCA
Great cardiac vein
Posterior interventricular branch of RCA
Slide21Posterior view
Right coronary artery (RCA)
Posterior interventricular branch of RCA
Right marginal branch of RCA
Left marginal branch of LCA
Posterior interventricular vein or middle cardiac vein
Left marginal vein
The Coronary Circulation
Coronary sinus
It collects
blood and empties into right
atrium.
Slide22The Circulatory
System
(Part 2)
Lecture # 3
Overview of Cardiovascular System Gross Anatomy of the HeartCardiac Conduction System and Cardiac MuscleElectrical and Contractile Activity of Heart
The Heart
(Chapter
19)
Slide23Conduction System
It is composed of
an internal pacemaker and nervelike conduction pathways through
myocardium that generate and conduct rhythmic electrical signals.
It initiates each heartbeat and determines heart rate.
Sinoatrial node
(pacemaker)
Atrioventricular
node
It acts as insulator to prevent currents from getting to the ventricles from any other route, and delays the electrical excitation.
Atrioventricular
bundle
It is a pathway by which the signals leave the AV node.
Left bundle branch
Right bundle branch
Purkinje fibers
Purkinje
fibers
They distribute the electrical excitation to the cardiocytes of the ventricles.
Slide24Cardiac Conduction System
Slide25Slide26-70 mV
-70 mV
Outside positive
Outside positive
Inside positive
-70 mV
-70 mV
Outside positive
Outside positive
-65 mV
-80 mV
DEPOLARIZATION
HYPERPOLARIZATION
Resting potential
Resting potential
-65 mV
Outside positive
Depolarization
-80 mV
Outside positive
Inside negative
Hyperpolarization
Gated sodium channels are open
Gated Potassium channels are open
Slide27-40
mV
Action Potential
Pacemaker
Potential
-60
mV
Resting Potential
-60
mV
Action Potentials
: They
are
changes
in the
transmembrane potential that, once initiated, affect an entire excitable membrane
Each depolarization of the SA node sets off one heartbeat. At rest, fires every 0.8 seconds or 75 bpm
Slow Na
+
inflow
Fast Ca+ and Na
+
inflow
Fast K+ outflow
SA node does not have a stable resting membrane potential. It starts at -60 mV.
It drifts upward because of a slow inflow of Na
+
.
When it reaches a threshold of -40 mV, voltage-gated Ca
2+
and Na
+ channels open and a faster depolarization occurs peaking at 0 mV.
The K
+
channels then open and K
+
leaves the cell causing repolarization.
Slide28+1
0
Millivolts
P
Q
R
S
T
Depolarization of atria
QRS
complex
Depolarization of ventricles
Repolarization of ventricles
PQ segment
Atrial systole
100 msec
ST segment
Ventricular systole
It represents the time during which the ventricles contract and eject blood
The Electrocardiogram
An ECG is a composite of
all action potentials
of nodal and myocardial cells, detected, amplified and recorded by electrodes on arms, legs and chest.
Slide29+1
0
–1
Millivolts
0.8 second
T wave
QRS interval
R
S
P wave
PR
interval
QT
interval
PQ
segment
ST
segment
Q
QRS
complex
Slide301- Atrial depolarization begins.
2- Atrial depolarization complete (atria contracted).
3- Ventricles begin to depolarize at apex; atria repolarize (atria relaxed).
4- Ventricular depolarization complete (ventricles contracted).
5- Ventricular repolarization begins at apex (ventricles begin relaxation).
6- Ventricular repolarization complete (ventricles relaxed).
Slide31Extra heart beats produced in any region of spontaneous firing other than the SA node.
It is the failure of any part of the of the cardiac conducting system to transmit signals.
The Cardiac Rhythm
It is the normal heartbeat triggered by the SA node.
Sinus rhythm:
At rest, the sinus rhythm is about 70 to 80 times per minute (rates from 60 to 100 bpm).
Any region of spontaneous firing other than the SA node. The most common ectopic focus is the
AV node, which produces a nodal rhythm.
It is the cardiac rhythm produced by the AV node. It is a slower heartbeat of 40 to 50 bpm.
If neither the SA nor AV nodes is functioning, an artificial pacemaker is required.
Arrhythmia:
It is any abnormal cardiac rhythm.
Heart block:
Extra-systoles:
Ectopic focus:
Tachycardia:
It is a persistent, resting adult heart rate above 100 bpm.
Bradycardia:
It is a persistent, resting adult heart rate below 60 bpm.
If the SA node is damaged, other part of the myocardium may take over the governance of the heart rhythm.
Nodal rhythm:
Slide320.8
sec
75 bpm
0.5 sec
120 bpm
Tachycardia
1.4sec
46 bpm
Bradycardia
1.4sec
0.5 sec
0.3 sec
1.4sec
Arrhythmia
Nodal Rhythm
Extrasystole
Heart block
Ventricular fibrillation
Sinus Rhythm (normal)