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the position of the heart in the body
- located within the mediastinum of the throax, flanked laterally by the lungs, posteriorly by the vertebral column, and anteriorly by the sternum.
- Its apex extends slightly to the left and rests on the diaphragm, approximately at the level of the fifth intercostal space.
- Its base lies beneath the second rib and points toward the right shoulder.
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the membranes that surround the heart
- fibrous pericardium: dense CT, protect the heart and anchor it to surrounding structures which are fused with pleural laterally and diaphgram's fascia parietal layer
- serous pericardium: (parietal layer) lines the internal surface of fibrous layer & (visceral layer) areolar CT + epithelial, innermost layer, also called epicardium
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abnormal conditions associated with these membranes and possible causes and possible causes of these conditions
pericarditis: inflammation of the pericardium, causes painful adhesions between the serous pericardial layers
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Major vessels that connect the heart to the pulmonary and systemic circulatory systems
and type of blood flows through these vessels
- to pulmonary system: pulmonary arteries (deoxygenated blood) pulmonary veins (oxygenated blood)
- to sysemic system: superior and inferior venae cavae (deoxygenated blood), aorta (oxygenated blood)
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pericardial membranes
to separate heart from rest of body cavity
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auricles
- LEFT: to collect oxygenated blood as it leaves the lungs and moves the blood into the left ventricle
- RIGHT: to collect deoxygenated blood from the bloodstream and moves it into the heart's right ventricle
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ventricles
- to pump blood to the entire body.
- RIGHT: Receives blood from the right atrium and pumps it to the main pulmonary artery.
- LEFT: Receives blood from the left atrium and pumps it to the aorta.
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aorta
to carry and distribute oxygen rich blood to all arteries
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brachiocephalic arterty
to supply oxygenated blood to the right side of the head and right forelimb, respectively
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L (from the aortic arch to the left side of the body) & R (from the brachiocephalic artery to the right side of the body) subclavian arteries
to supply oxygenated blood to the arms
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pulmonary trunk
to transmit deoxygenated, carbon dioxide-rich blood from the right ventricle to the lungs
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superior venae cava
to bring de-oxygenated blood from upper body regions (head, neck, arm, and chest) of the body to the right atrium
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inferior venae cava
to bring de-oxygenated blood from the lower body regions (legs, back, abdomen and pelvis) to the right atrium.
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pulmonary veins
to deliver oxygen rich blood from the lungs to the left atrium
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aortic semilunar valve
to prevent the backflow of blood as it is pumped from the left ventricle to the aorta
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pulmonary semilunar value
to prevent the backflow of blood as it is pumped from the right ventricle to the pulmonary artery
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bicuspid valve
to permit blood to flow one way only, from the left atrium into the left ventricle
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tricuspid valve
to prevent the back flow of blood as it is pumped from the right atrium to the right ventricle
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chordae tendineae
to anchor AV valves to prevent valve inversion
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intraventricular septum
to separate the left ventricle from the right ventricle
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papillary muscle
to contract to avert prolapse or inversion of the atrioventricular valves
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moderator band
to convey the right branch of the atrioventricular bundle of the conducting system
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trabeculae muscle
to extend from the capsule into the interior of the heart
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pectinate muscle
to increases force of the atrial contraction without increasing heart mass
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ligamentum arteriosum
to run between the superior surface of the origin of the left pulmonary artery and the inferior surface of the arch of the aorta
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ductus arteriosus
to shunt blood from the pulmonary arteries to the aorta, bypassing the fluid-filled, developing lungs
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coronary sinus
to receive the blood from the myocardium and facilitates the movement of the blood into the right atrium
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fossa ovalis
a shallow depression that marks the spot
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autorhythmic cardiac cells (Atrioventricular node)
- location: in the inferior portion of the interatrial septum immediately above the tricuspid valve
- function: to regulate the signals to the ventricles to prevent rapid conduction(atrial fibrillation), as well as making sure that the atria are empty and closed before stimulating the ventricles
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autorhythmic cardiac cells (Sinoatrial node)
- location: in the right atrial wall, just inferior to the entrance of the superior vena cava
- function: to set the rate of contraction for the heart and spontaneously contracts and generates nerve impulses that travel throughout the heart wall causing both atria to contract
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Purkinje fibers
- location: beneath the endocardium, which is the innermost layer of the heart
- function: to relay cardiac impulses to the ventricular cells causing the ventricles to contract
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sinoatrial (SA) node
located in the right atrium just inferior to the entrance to the superior vena cava
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atrioventricular bundle (AV) node
located in the lower atrial septum at the junction of the atria and ventricles
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conductive fiber systems of the heart
- 1. SA node pacemaker generates impulses and brings nodal cells to threshold (-40 mv)
- 2. It spreads via gap junctions through atrial muscle to AV node
- 3. The impulses delay for 0.1 sec at AV node
- 4. The AV bundle connects the atria to the ventricles.
- 5. The bundle branches conduct the impulses through the interventricular septum.
- 6. Rapid spread through bundles & Purkinje fibers through ventricles
- 7. The Purkinje fibers depolarize the contractile cells of both ventricle.
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