1. The Cardiovascular System: The Heart
CHAPTER 20
The Cardiovascular System: The Heart
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Location of the Heart
The heart is located in the mediastinum
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Location of the Heart
The heart is located in the mediastinum
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Heart Anatomy
Location: mediastinum
Tip or apex faces left side
Top of the heart is the base
Fluid filled sac to protect is pericardium
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Pericardium
The pericardium consists of an outer fibrous pericardium and an inner serous pericardium
The serous pericardium has 2 layers:
Visceral
Parietal
The visceral and parietal layers are separated by the serous cavity, a fluid-filled space – pericardial cavity
The pericardial fluid reduces friction between the pericardial membranes when the heart moves within them
Pericardial rub
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6. Layers of the Heart Wall
Made up of three (3) distinct layers:
Outer/Superficial epicardium/visceral pericardium
Middle/Intermediate myocardium
Inner/Deep endocardium
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Heart Wall
Epicardium Also called visceral pericardium. Functions as an outer protective layer. Myocardium Relatively thick. Consists largely of cardiac muscle tissue responsible for forcing blood out of the heart chambers. Endocardium Lines all of the heart chambers and covers heart valves. Is continuous with the inner lining of blood vessels--endothelium
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8. Characteristics of cardiac muscle tissue
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Cardiac Muscle Tissue
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Chambers of the Heart
The heart has 4 cavities or chambers.
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Heart Chambers
Internally, the heart is divided into four (4) hollow chambers Upper chambers--atria Have relatively thin walls and receive blood from veins. Lower chambers—ventricles, which force blood out of the heart into the arteries. The atrium and ventricle on the right side are separated from those on the left by the interatrial septum and interventricular septum respectively.
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The atrium on each side communicates with its corresponding ventricle through an opening called the atrioventricular orifice which is guarded by an A-V valve. Grooves on the surface of the heart mark the divisions between its chambers and also contain the major coronary arteries
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The deepest groove is the coronary sulcus which encircles the heart between the atrial and ventricular portions. It contains the coronary sinus What is the function of the coronary sinus? The anterior and posterior interventricular sulci indicate the location of the septum that separates the right and left ventricles. Small ear-like projections--auricles--extend outward from the atria.
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Heart Anatomy
The anterior interventricular sulcus contains the left coronary artery and the great cardiac vein. The posterior interventricular sulcus contains the right coronary artery and middle cardiac vein
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Right Atrium
The right atrium receives blood from the superior vena cava and inferior vena cava and the coronary sinus. What type of blood is this? ______________________
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Right Atrium
Receives blood from the superior vena cava and inferior vena cavae.
The returned blood is low in O2 from the body.
Also receives blood from the coronary sinus.
The opening between the right atrium and right ventricle are guarded by a large tricuspid valve.
Valve permits blood to move from the right atrium into the right ventricle and prevents it from passing in the opposite direction
Fossa ovalis
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17. Atrioventricular valves open Semilunar valves closed
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18. Atrioventricular valves
Chordae Tendineae - are attached to the cusps of the valve. Originate from small mounds of muscle tissue--papillary muscle--which project inward from the wall of the ventricle. When the tricuspid valve closes the chordae tendineae and papillary muscles prevent the cusps from swinging into the atrium.
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Right Ventricle
The right ventricle receives blood from the right atrium and sends blood to the lungs What type of blood is this? ______________________
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Right Ventricle
The right ventricle has a much thicker wall than the right atrium. The arrangement of muscle is called trabeculae carnae. The right ventricle has much thinner walls than the left ventricle. Pumps blood a relatively short distance to the lungs against relatively low resistance to blood flow. When the right ventricles constricts, blood in the chamber is subjected to increasing pressure and the tricuspid valve closes passively.
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21. Blood Flow through the Heart
Blood from the right ventricle passes into the pulmonary trunk which divides to form the right and left pulmonary arteries.
At the base of this trunk is the pulmonary semilunar valve which consists of three cusps.
This valve opens when the right ventricle contracts.
When the right ventricular muscles relax, blood begins to back up causing the semilunar valve to close
Blood via the pulmonary arteries goes to the right and left lung where it is oxygenated
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Left Atrium
The left atrium receives blood from the pulmonary veins What type of blood is this? ______________________
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23. Blood Flow through the Heart
The left atrium receives blood from four pulmonary veins (two from the right lung and two from the left lung).
Blood then passes from the left atrium into the atrioventricular orifice which consists of two leaflets and is named the bicuspid or mitral valve.
Prevents blood from flowing back to the left atrium from the left ventricle
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Left Ventricle
The left ventricle receives blood from the left atrium and sends blood out of the heart through the aorta which transmits it to the rest of the body.
The wall of the left ventricle is much thicker than that of the right ventricle. Why do you suppose that is?
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25. Blood Flow through the Heart
When the left ventricle contracts, the bicuspid valve closes and the only exit for the blood is through the aorta.
Branches of the aorta distribute blood to all parts of the body.
At the base of the aorta is an aortic semilunar valve that consists of three cusps.
It opens and allows blood to leave the left ventricle.
When the ventricular muscles relax, this valve closes and prevents blood from backing up into the ventricle.
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26. Heart valves: prevent blood backflow between chambers
Atrioventricular (AV) valves
Between atria and ventricles
Left is biscuspid or mitral valve
Right is tricuspid valve
Semilunar valves
Between ventricles and major arteries leaving heart
Right is pulmonary semilunar valve
Blood to lung via pulmonary artery
Left is aortic semilunar valve
Blood to body via aorta
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Fibrous Skeleton
The fibrous skeleton of the heart:
Forms the foundation for which the heart valves attach
Serves as a point of insertion for cardiac muscle bundles
Prevents overstretching of the heart valves
Acts as an electrical insulator
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28. Heart Valves and Circulation of Blood
The valves of the heart open and close in response to pressure changes as the heart contracts and relaxes
Right and left atrioventricular valves
Prevent back flow from the ventricles into the atria
Right and left semilunar valves
Prevent back flow from the arteries into the ventricles
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29. Heart Valves and Circulation of Blood
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30. Heart Valves and Circulation of Blood
When one set of valves is open, the other set is closed
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31. Systemic and Pulmonary Circulations
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Coronary Circulation
Blood flow through coronary arteries delivers oxygenated blood and nutrients to the myocardium
Branches arise from the ascending aorta
Coronary veins remove carbon dioxide and wastes from the myocardium
Branches converge at the coronary sinus
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Coronary Circulation
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