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| Study of the normal heart and diseases associated with it |
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| Between lungs in mediastinum with about 2/3 of its mass to the left of the midline - heart lies between two rigid structures - vertebral column and sternum |
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| Heart is enclosed and held in place by this |
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| inner area - parietal layer and visceral layer, pericardial cavity, and pericardial fluid |
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| between the parietal and visceral layers of the serous pericardium |
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| fills the potential space and reduces friction between the two membranes |
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| inflammation of the pericardium-bleeding into the pericardial cavity compresses the heart (cardiac tamponade) and is potentially lethal |
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| Three layers of the heart wall |
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Definition
epicardium-epithelium and connective tissue
myocardium-cardiac contractile muscle
endocardium-endothelium and connective tissue |
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| 2 upper atria and 2 lower ventricles |
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| small pouches on the anterior surface of each atrium that slightly increases the volume of each atrium |
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| grooves that contain blood vessels and fat |
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receives blood from the superior and inferior vena cava and the coronary sinus
-blood passes from the right atrium into the right ventricle through tricuspid valve |
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right ventricle forms most of the anterior surface of the heart
-blood passes from the right ventricle to the pulmonary trunk via the pulmonary semilunar valve |
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left atrium receives oxygenated blood from pulmonary veins
-blood passes from the left atrium to the left ventricle through the bicuspid valve |
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left ventricles form the apex of the heart
-blood passes from the left ventricle through the aortic semilunar valve into the aorta |
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| Myocardial thickness and function |
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Definition
| the thickness of the myocardium of the four chambers varies according to the function of each chamber |
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| thin because they deliver blood to the ventricles |
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thicker because they pump blood greater distances at high pressure
-right and left ventricle walls |
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| thinner than left because they pump blood into the lungs and they are nearby and offer very little resistance to blood flow |
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| thicker because they pump blood through the body when the resistance to blood flow is greater |
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| Fibrous skeleton of the heart |
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Definition
-forms the foundation for which heart valves attach
-serves as points of insertion for cardiac muscle bundles
-prevents over stretching of the valves as blood passes through them
-acts as an electrical insulator that prevents direct spread of action potentials from the atria to the ventricles |
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| Heart valves and circulation of blood |
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Definition
| heart valves open and close in response to pressure changes as the heart contracts and relaxes |
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Definition
allows movement of blood from atria-ventricles-
-prevent blood flow from the ventricles back intro the atria
-back flow is prevented by the contraction of papillary muscles tightening the chord tendinae which stops valve cusps from everting |
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three crescent cups without chordae tendinae each
-allow ejection of blood from the ventricles-arteries
-prevent back flow of blood into the ventricles
-open when pressure in the ventricles exceeds the pressure in the arteries
-close from top down |
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right side of the heart is the pump
-receives deoxygenated blood from the body and sends it to the lungs for oxygenation |
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left side of the heart is the pump
-receives oxygenated blood from the lungs and sends it to the body |
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Definition
flow of blood through the many vessels that pierce the myocardium of the heart
-delivers oxygenated blood and nutrients to and removes carbon dioxide and wastes from the myocardium |
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| Principal arteries in coronary circulation |
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Definition
| branching from the ascending aorta and carrying oxygenated blood are the right and left coronary arteries |
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| deoxygenated blood returns to the right atrium primarily via the principal vein- principal vein |
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| results from partial obstruction of coronary blood flow and can give the symptom of angina pectoris |
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| contractile muscle fibers and auto rhythmic muscle fibers |
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| Cardiac muscle fibers vs. skeletal muscle fibers |
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Definition
shorter in length
larger in diameter
exhibit branching
-have less sarcoplasmic reticulum and therefore require Ca2+ from ECF for contraction |
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| Cardiac fibers form two separate functional networks in heart |
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Definition
| atrial and ventricular networks |
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fibers within each network are connected by these and they consist of desmosomes and gap junctions
-allow fibers in the network to work together so that each network serves as a functional unit |
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self excitable
-repeatedly generate spontaneous action potentials that then trigger heart contractions
-act as pacemaker to set the rhythm for the entire heart
-form conduction system |
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| Components of conduction system |
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Definition
SA-sinoatrial node
AV node
AV bundle of His |
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Definition
cluster of auto rhythmic cells in wall of right atria near the opening of the SVC-begins heart activity that spreads to both atria
-excitation spreads to AV node |
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Definition
| in atrial septum-transmits signal to bundle of His |
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connection between atria and ventricle
-divides into bundle branches (right and left) and purkinje fibers (large diameter fibers that conduct signals quickly |
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| pacemaker/intrinsic rate=75-100 |
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autonomic nervous system
hormones
ectopic pacemaker
caffeine and nicotine
ectopic beats-result in extra beats or very fast heart rate |
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| Action potential and contraction of contractile fibers |
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Definition
impulse in a ventricular contractile fiber - rapid depolarization, plateau, repolarization
-refractory period is longer than contraction itself |
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-relies on aerobic cellular respiration for ATP
-muscle also produces some ATP from creatine phosphate |
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Definition
adds a phosphate group onto ADP-ATP
-usually found in cells
-presence of this in the blood indicates injury of cardiac muscle caused by myocardial infraction |
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Definition
| impulse conduction through the heart generates electrical currents that can be detected at the surface of the body-EKG |
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conduction pathway is abnormal
heart is enlarged
certain regions are damaged |
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-P wave -spread of impulse from SA node over atria
-QRS Complex-spread of impulse through ventricles
-T wave-ventricular repolarization
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