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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.
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
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
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)
to separate heart from rest of body cavity
- 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
- 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.
to carry and distribute oxygen rich blood to all arteries
to supply oxygenated blood to the right side of the head and right forelimb, respectively
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
to transmit deoxygenated, carbon dioxide-rich blood from the right ventricle to the lungs
superior venae cava
to bring de-oxygenated blood from upper body regions (head, neck, arm, and chest) of the body to the right atrium
inferior venae cava
to bring de-oxygenated blood from the lower body regions (legs, back, abdomen and pelvis) to the right atrium.
to deliver oxygen rich blood from the lungs to the left atrium
aortic semilunar valve
to prevent the backflow of blood as it is pumped from the left ventricle to the aorta
pulmonary semilunar value
to prevent the backflow of blood as it is pumped from the right ventricle to the pulmonary artery
to permit blood to flow one way only, from the left atrium into the left ventricle
to prevent the back flow of blood as it is pumped from the right atrium to the right ventricle
to anchor AV valves to prevent valve inversion
to separate the left ventricle from the right ventricle
to contract to avert prolapse or inversion of the atrioventricular valves
to convey the right branch of the atrioventricular bundle of the conducting system
to extend from the capsule into the interior of the heart
to increases force of the atrial contraction without increasing heart mass
to run between the superior surface of the origin of the left pulmonary artery and the inferior surface of the arch of the aorta
to shunt blood from the pulmonary arteries to the aorta, bypassing the fluid-filled, developing lungs
to receive the blood from the myocardium and facilitates the movement of the blood into the right atrium
a shallow depression that marks the spot
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
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
- 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
sinoatrial (SA) node
located in the right atrium just inferior to the entrance to the superior vena cava
atrioventricular bundle (AV) node
located in the lower atrial septum at the junction of the atria and ventricles
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.