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Cardiovascular System (Clinical terms (blood pressure (end diastolic…
Cardiovascular System
Anatomy of the heart
valves
Left atrioventricular valve/Bicuspid/Mitral valve- is on the left side of the heart in between the left atrium and left ventricle
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Right atrioventricular valve/Tricuspid valve- is on the right side of the heart in between the right atrium and right venricle
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chambers
Right ventricle- lower right chamber of the heart, pumps deoxygenated blood to lungs
Left atrium- superior left chamber, receives oxygenated blood from the lungs
Right atrium- superior right chamber of the heart, receives deoxygenated blood from the body
Left ventricle- inferior left chamber, pumps oxygenated blood to the body, since it has to pump to most of the body the muscle wall is 3x thicker than the right ventriccle
major vessels
Arteries
Pulmonary trunk- splits into pulmonary arteries, they transport deoxygenated blood from the right ventricle to the lungs
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internal muscle
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trabeculae carneae- large,smooth, irregular muscular ridges on the internal wall of the right ventricle and in left ventricle
papillary muscles- extend from the internal wall of the right ventricle, also in left ventricale
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Sinoatrial node/ SA node- posterior wall of right atrium, pacemaker
Atrioventricular node/ AV node- floor of the right atrium between AV valve and opening to coronary sinus
tendon structures
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fossa ovalis- in the right atrium, former fetal foramen ovale
Purkinje fibers- extend from right and left bundles to the apex of heart to walls of both ventricles
Heart wall
Myocardium- middle layer composed of cardiac muscle, 3x thicker on left ventricle wall
Endocardium- internal surface, contains endothelium and areolar connective tissue
Epicardium- outermost heart layer, contains simple squamous epithelium, adipose and areolar connective tissue
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Clinical terms
blood pressure
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end systolic volume- volume of blood in a ventricle at the end of contraction, lowest volume of blood in ventricle at any point of cardiac cycle
Frank Starling Law- "as the volume of blood entering the heart increases, there is greater stretch of the heart wall /preload."
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stroke volume- the volume of blood ejected during 1 beat, milliliters per beat
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cardiac output- amount of blood that is pumped by 1 ventricle in 1 min, HRxSV=CO
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Electrical conduction
Atrioventricular node- the action potential is delayed 0.1 sec at the AV node before it gets to the Av bundle located in the interventricular septum. Delayed because AV node cells have smaller fiber diameters and less gap junctions. allows atriums to finish contacting and the ventricles fill completely before they contract
Ventricular myocardium- action potential continues from the purkinje fibers up the walls of each ventricle by gap junctions between cardiac muscle cells. they begin to contract within 120-200 milliseconds after SA node starts
Sinoatrial node and atrial myocardium- an action potential is generated at the SA node, spreads through gap junctions between cardiac muscles cells throughout the atriums to the AV node
Bundle branches and purkinje fibers- AV bundle continue the action potential along the right & left bundle branches leading to purkinje fibers
Autonomic nervous system- pathways extend from the cardiac center within the medulla oblongata to the heart. modifies cardiac activity
Parasympathetic innervation-comes from cardioinhibitory center through the right vegus nerve (innervates SA node) and left vegus nerve (innervates the AV node). can decrease heart rate but no effect on force of contraction.
Sympathetic innervation- comes from cardioacceleratory center, nerve signals along sympathetic nerves resulting in increased heart rate and increase in force of contraction
Cardiac cycle
Ventricular ejection-ventricles continue to contract, semilunar valves forced open because pressure of blood in ventricles >blood pressure in trunks. blood ejected into trunks
Isovolumetric relaxation- beginning of ventricular relaxation, ventricles expand to their resting state, blood pressure in ventricles < blood pressure in trunks, casing blood to flow backward but it closes the semilunar valves preventing backflow
Isovolumetric contraction- beginning of ventricular contraction initiated by the purkinje fibers. moves blood from ventricles to aorta or pulmonary trunk, all valves close to prevent backflow
Atrial relaxation and ventricular filling- late ventricular diastole, blood pressure in relaxed atrium> blood pressure in ventricle causing AV valve to open and fill ventricle 70%. semilunar valves remain closed
Atrial contraction and ventricular filling- ventricles relaxed, SA node-> atria contact causing its blood to go into the ventricles. Av vales stay open but the semilunar valves are closed. ventricles are filled
ECG- graphic recording of electrical changes in the heart that initiate atrial and ventricular contractions
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P wave- electrical changes of atrial depolarization, 0.08 -0.1 secs
Segments
P-Q segment- atrial plateau at the sarcolemma when cardiac muscle cells within the artia are contracting
S-T segment- ventricular plateau when the cardiac muscle cells within the ventricles are contracting
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