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Location and Size of the Heart
The heart is approximately the size of a fist, weighing 250-350 grams, The heart is located in the mediastinum, the central area of the thoracic cavity
The flatter region of the heart, and is located superiorly.
The heart comes to a point which points inferiorly and to the left
a double-walled sac that encloses the heart for protection and for anchoring the heart in its position
Fibrous pericardium -
the outer, thick layer composed of dense connective tissue
Serous pericardium -
the inner, thin double-layer membrane that produces a slippery serous fluid that acts as lubrication to reduce friction
Parietal pericardium -
the layer that lines the inside of the fibrous pericardium
Visceral pericardium -
the layer that clings to the wall of the heart
Pericardial cavity -
the serous fluid-filled space between the visceral and parietal layers
Epicardium -
outermost layer, is the visceral pericardium
Myocardium -
Middle layer, composed of cardiac muscle tissue
Endocardium -
inner layer, a simple squamous lining of the heart chambers
Atria -
the two superior chambers that receive blood.
auricles -
ear-shaped extensions that add some volume to these chambers.
interatrial septum-
a wall that separates the right and left atria
Ventricles -
the two inferior chambers that pump blood, therefore possessing a thicker myocardium than the atria.
interventricular septum -
a wall that separates the right and left ventricles
trabeculae carneae-
in each ventricle and is ridges of muscle
Right Atrium -
Receives blood returning from the body and heart wall via three entrances
Pectinate Muscles-
in each atrium there are ridges of muscles
Superior Vena Cava -
returns -O2 blood from tissues above the diaphragm
Inferior Vena Cava -
returns -O2 blood from tissues below the diaphragm
Coronary Sinus -
returns -O2 blood from the myocardium
tricuspid valve -
blood exits through this valve and enters the right ventricle
Right Ventricle-
Receives blood from the right atrium, Is the pump for the pulmonary circuit, which carries blood to and from the lungs
Pulmonary semilunar valve-
blood exits through this valve into an artery
pulmonary trunk -
an artery, which branches in the R. and L. pulmonary arteries that carry blood to each lung
Moderator band -
a slip of muscle in the right ventricle that ensures the closing of AV valves before heart contraction
4 Pulmonary veins-
blood comes from the lungs and goes to the L. Atrium
Left Atrium -
Receives + O2 blood
Bicuspid Valve-
blood exits through this valve to enter the left ventricle
Left Ventricle-
Receives blood from the left atrium, Is the pump for the systemic circuit, which pumps blood to and from the body tissues. It possesses the thickest myocardium because of the necessary pressure
Aortic Semilunar Valve-
blood exits through this valve into the largest artery.
Aorta -
the largest artery, begins as the ascending aorta, and then curves into the aortic arch, to then become the descending aorta.
Brachiocephalic trunk-
first branch that quickly branches into two arteries:
Right subclavian artery -
supplies the right upper limb
Right common carotid artery -
supplies the right side of the head and neck
Left common carotid artery -
second branch, supplies left side of head and neck
Left subclavian artery -
third branch, supplies the left upper limb
Heart Valves-
Structures in the heart that keep blood flow unidirectional, preventing backflow
Atrioventricular valves -
separate an atrium from a ventricle
Tricuspid valve (Right AV) -
prevents backflow from right ventricle to right atrium
Bicuspid valve (Left AV or Mitral) -
prevents backflow from left ventricle to left atrium
Papillary muscles -
muscles within each ventricle that attach to the AV valves
chordae tendineae-
Strings that attach to papillary muscles, and function to prevent the valve from inverting.
Semilunar valves -
located in each of the major vessels that carry blood out of a ventricle. They are not supported by papillary muscles.
Pulmonary semilunar valve -
located within the pulmonary trunk, prevents backflow of blood into right ventricle
Aortic semilunar valve -
located in the aorta, prevents backflow into the left ventricle
Coronary Circulation -
The series of vessels that carry oxygen rich-blood to the myocardium of the heart wall, then drain oxygen-poor blood back to the right atrium
R and L Coronary Arteries -
branch from the ascending aorta to supply oxygen-rich blood
Anterior interventricular artery -
courses inferiorly through a groove called the anterior interventricular sulcus, which branches off the left coronary artery
Circumflex artery -
courses around the heart's left to the posterior side, branches off the left coronary artery
Marginal artery -
courses inferiorly along the heart's right lateral side, branches off the right coronary artery
Posterior interventricular artery -
courses inferiorly through the posterior interventricular sulcus, branches off the right coronary artery
Cardiac Veins -
the veins that drain oxygen-poor blood from the myocardium
Great cardiac vein -
largest, begins on heart's anterior surface
Middle cardiac vein -
begins in center of heart's posterior surface
Small cardiac vein -
smallest, begins near inferior vena cava
Posterior vein of the left ventricle -
drains blood from posterior side of the left ventricle
Coronary sinus -
the enlarged vein on the posterior heart that collects blood from all of the cardiac veins before emptying into the right atrium
Intrinsic Conduction System-
Composed of a series of autorhythmic cells whose unstable resting potentials leads to a set rhythm of action potentials that trigger heart contractions.
Sinoatrial node -
located in the superior right atrium, sets the sinus rhythm of 75 beats/min
Atrioventricular node -
located in the inferior right atrium, temporarily slows the electrical impulse to allow atrial contraction before ventricular
AV bundle (bundle of His) -
located in the superior interventricular septum
R and L bundle branches -
located in the inferior interventricular septum
Purkinje fibers -
branch from the apex into the ventricular walls
Foramen ovale -
a hole in the interatrial septum that allows blood to flow directly from the right atrium to the left atrium, bypassing pulmonary circulation
Fossa ovalis -
the smooth area in an adult heart where the foramen used to be
Ductus arteriosus -
small vessel connecting the pulmonary trunk to the aorta, allowing blood to bypass the pulmonary circulation
Ligamentum arteriosum -
the fibrous adult remnant of the ductus arteriosus