heart I can.docx.pdf

HEART 1. Distinguish between the pulmonary circuit and the systemic circuit. - The pulmonary circuit sends deoxygenated blood to the lungs to pick up oxygen and unload carbon dioxide. - The systemic circuit sends oxygenated blood and nutrients to all body cells and removes wastes....

HEART 1. Distinguish between the pulmonary circuit and the systemic circuit. - The pulmonary circuit sends deoxygenated blood to the lungs to pick up oxygen and unload carbon dioxide. - The systemic circuit sends oxygenated blood and nutrients to all body cells and removes wastes. 2. Describe the general structure of the heart. - pericardium - sac that covers the heart - myocardium - muscle that is interconnected via intercalated discs - middle layer - contractile and connecting tissue - chambers: - two atria (left and right) - two ventricles (left and right) - AV valve - semilunar valves that separate ventricles - major (“great”) vessels - vena cavas - pulmonary arteries - pulmonary veins - aorta 3. Trace the flow of blood through the heart and adjacent blood vessels. - (deoxygenated) superior/inferior vena cava → right atrium → right AV valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → out to the lungs → (oxygenated) pulmonary veins → left atrium → left AV valve → left ventricle → aortic semilunar valve → aorta and distributed to the rest of the body (systemic circulation) 4. Describe the unique structural and metabolic characteristics of cardiac muscle cells. - Structure: intercalated disks desmosomes gap junctions - metabolic characteristics - aerobic! - tons of mitochondria - mostly fueled by fatty acids 5. Compare and contrast the physiology of conducting (pacemaker) and contractile (myocardial) cells. - conducting - set off the depolarization - SA node has a bunch of these - can create their own action potential - ions involved with depolarization: K+ inside the cell, Na+ outside cell - sodium leak channels, causing the inside of the cell to become more positive - conducting - authorhythmicity - cannot maintain stable resting potential  - spontaneous depolarizaiton - prepotential - Na+ influx (slow) - funny current - sodium leaks in and cell becomes more positive - opens voltage-gate - Ca2+ influx (fast) - acting calcium channels - contractile - sodium floods in and depolarizes the heart muscles. calcium channels open and floods into cell, depolarization lasts longer. - three stages 1. rapid depolarization (na+) (fast) 2. plateau (Ca2+) (slow) 3. repolarization (K+) - refractory periods - Ca2+ levels critical - prolonged depolarization 6. List the components of the cardiac conduction system in order and describe their roles. 1. SA node a. “pacemaker” of the heart located in the right atrium. fastest beating is 80-100 bpm 2. AV node a. delays ventricular contraction. maximum rate is 230 bpm 3. AV bundle, bundle branches, purkinje fibers a. conduction to apex of heart and ventricles 7. Interpret a normal electrocardiogram (ECG) reading. - P wave - atrial depolarization - PR interval - signal conduction through AV node - T wave - ventricular repolarization - QT interval - duration of ventricular depolarization - QRS interval - atrial repolarization and diastole - PQ segment - atrial systole begins - ST segment - ventricular systole and ejection of blood  - 8. List the phases of the cardiac cycle and the events of each phase. - systole - contraction and expulsion - diastole - relation and filling, blood moves from high to low pressure areas - phases: 1. ventricular filling a. ventricular diastole i. AV valves are open if the pressure in the atria is greater than the pressure in the ventricles b. venous return c. atrial contraction d. EDV at end 2. isovolumetric contraction a. beginning of ventricular systole b. increasing ventricular pressure c. can measure EDV up to the end of this phase d. max ventricular pressure 3. ventricular ejection a. ventricular systole b. semilunar valves open c. maximum ventricular pressure 4. isovolumetric relaxation a. early diastole b. all valves open- very low chamber pressure  c. 9. Explain the basis of heart sounds. - results from blood turbulence - blood is hitting the side of the aorta - S1= lub - closing of the AV valves - S2= dub - closing of the semilunar valves 10. Interpret the Wiggers diagram with respect to pressure changes, events of the cardiac cycle, ventricular volume, ECG readings, and heart sounds. - EkG- starting point- deportation - P wave- muscle in the atria is depolarized the orange lines show pressure in the atria - qrs wave- ventricular depolarization- they will squeeze, AV valves closed this causes sound - green line- pressure in the aorta, center lunar valves open - red line- pressure drops in ventricles and lunar vales close d. 11. Calculate cardiac output. - how much blood you pump out - CO=HR x SV = blood ejected per minute - example - CO= 70 bpm x 70 mL= 4900 mL= 4.9 L - CO changes when we change heart rate (factors physiological things affecting HR= hormonal input (epinephrin increases HR), nervous system input (cardioacceletory, cardioinhibitory centers in medullar oblongota)  - CO changes when we change SV= Preload- amount of blood in ventricles before systole which increases SV, afterload frank-starling law, contractility - CO=stroke volume (amount of blood per beat) x heart rate (bpm) 12. Describe the ways that heart rate can be modified. - 13. Calculate stroke volume. - the amount of blood you pump out per beat - end diastolic volume- end systolic volume 14. Describe the three factors that regulate stroke volume. - preload - how full the ventricles are before they contract - ventricular contractility - changes in strength of ventricular contraction - afterload - based on aortic and vasculature pressure - muscle overcome to eject blood * increase in EDV causes stroke volume to increase