Cardiovascular

7 Cardiovascular Sunday, July 05, 2009 10:21 AM

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Anatomy Muscle Layers of the Heart 3 layers ○ Pericardium • Covers whole heart • Helps heart so it can't overy distend. • Chambers can't overly dialate • Double layer that folds back on itself, creating potential space (pericardial space) where a small amount of fluid (30-50ml) helps heart beat without friction.  Inflammatory response can push more fluid into this space --> problems ○ Myocardium • Muscle part of heart ○ Endocardium • Smooth layer of endothelial cells and CT that is continuous with greater vessels that leave the heart.

Screen clipping taken: 7/5/2009, 10:22 AM

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Cardiac Chambers Returning blood go to atria

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Right and left Ventricle ○ Pumping parts of the heart. ○ Right pumps into pulmonary artery, ○ Left pumps into aorta and systemic circulation. Heart about the size of a male fist, broad top (base), apex (at bottom) Septum ○ Wall that divides heart in center

Screen clipping taken: 7/5/2009, 10:22 AM

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Cardiac Valves Blood flows through in a unidirectional manner (unless there's a prob) 2 Atrial ventricular valves ○ Tricuspid Valve ○ Mitral Valve ○ Go from atrium to ventricales, supported by papillary (originates in ventricles) muscles help close valves during systolic. ○ Chordae tendinae - attach to valve and prevent from everting (flopping forward) when closing. 2 Semilunar valves (look like half moons) (blood out of ventricles) ○ Pulmonary Valve ○ Aortic Valve

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Cardiac Blood Supply Large epicardial arteries supply heart muscle with blood/nutrients. ○ Supplies heart with blood ○ Opening is at root of aorta ○ Several small coronary arteries. (See below) • Left coronary (main) artery [widow maker] comes off of aorta, supplies left ventricle and part of left atria with nutrient/blood supplies • Fibricated into left descending artery • Left circumplex artery • Right coronary artery, supplies right side of heart with blood supply, smaller arteries that shoot off.

Screen clipping taken: 7/5/2009, 10:24 AM

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Conduction System Starts in SA(synoatrial) node ○ Initiates contractions by sending off electrical signal/impulse --> down right atrium, left atrium, hits Bundle of His, AV node, divides down either side of ventricular septum to perkinji fibers (can instigate ventricular contraction (15-40 bpm), ventricles depolarize and contract. ○ If SA node out, AV node can work for awhile (40-60 bpm) ○ Sends off impulses at 60-100 beats per min.

Screen clipping taken: 7/5/2009, 10:24 AM

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Cardiac Cycle ○ Right atrium (de oxy blood) --> right ventricle --> pulmonary artery ->lungs --> pulmonary vein --> left atrium --> left ventricle --> aorta ○ Systole • Heart and ventricles contract • 2 parts  Isovolumetric contraction - onset of systolic. no volume is moving, begins with closure of AV valves (first heart sound, lub) .02 seconds before semilunar valves open, pressure rises quickly and dramatically, ventricle contracts until pressure in left/right ventricle exceeds pressure in artery/aorta.  Ejection Period - Blood pushed into artery/aorta. When pressure larger in artery/aorta is greater, semilunar valves close (thump) • 60% blood comes out in first part of ejection period, relax and less blood comes out (about 20%). • At end of systole only about 50 ml left within ventricle. End systolic volume. ○ Diastole • Ventricles relax and fill with blood (passive) • Drop in pressure, blood returns to atria, atrial kick (S4 sound on kids on small people) pushes blood from atria to ventricles. • Ventricles can fill up to around 120 ml of blood each, called the end diastolic volume.

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Difference is stroke volume, between end diastole and end systole (about 70 ml) Ejection Fraction. 55-75% Stroke volume divided by end diastolic volume. higher in runner, higher in hypertrophic condition

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ECG ○ P-wave (hump) • Depolarization of SA node, conduction of depolarization through atrial tissue • Disatolic ○ QRS complex • Depolarization of Ventricles • Systolic ○ T-Wave • Occurs in last part of systole, ventricles start to repolarize

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Cardiac output ○ How much blood pumped through body per minute. ○ Size of person, needs, physically active effects CO. ○ Stroke volume X Heart rate = blood pumped per minute. ○ 3.5-8 liters/min normal.

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Screen clipping taken: 7/5/2009, 10:27 AM

Pulmonary circulation ○ Goes to lungs to be oxygenated ○ Right ventricle to Include pulmonary artery (only artery that carries deoxygenated blood) ○ Pulmonary capillaries (exchange CO2 and O2) Lower pressure and slower system for gas exchange. ○ Pulmonary veins (oxygenated blood) into left atrium. Systemic Circulation ○ From Left ventricle --> goes to the system via aorta. Include veinous return. Comes back through veins (superior and inferior vena cava moves back to heart) ○ Higher pressure system, transports to entire body, sometimes against gravity, functions under higher pressure. ○ Mean arterial blood pressure 90-100 mmHg.