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NURS 5315 Module 5 Exam 2023
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NURS 5315 Module 5 Exam 2023 Cardia structure/blood flow - ANSWER The right atrium receives deoxygenated blood from the body. The blood travels from the right atrium, through the tricuspid valve to the right ventricle. From the right ventricle the blood travels through the pulmonic valve, into the pulmonary artery (this is the only artery in the body which carries deoxygenated blood), into the lungs, where it goes to the alveoli and gas exchange occurs. The oxygenated blood then enters the pulmonary vein and is delivered to the left atrium. From the left atrium it travels through the mitral valve into the left ventricle. From the left ventricle the blood travels through the aortic valve into the aorta Fetal circulation - ANSWER The umbilical vein receives oxygenated blood from the placenta. The umbilical vein connects to the hepatic circulation but also connects to the inferior vena cava by the ductus venosus. The ductus venosus allows the oxygen-rich blood to enter the inferior vena cava and some blood does enter the hepatic circulation. From the inferior vena cava, the blood is emptied into the right atrium. The most oxygenated blood in the right atrium is shunted through the foramen ovale (this is an opening between the right and left atria) into the left atrium. The blood then enters the left ventricle and is pumped out to the head and the rest of the body. The deoxygenated blood also enters the right atrium just as the oxygenated blood does. There are two streams that help to keep the blood separate. Sixty percent of the blood in the right atrium (which is oxygenated blood) will be moved forward as described above. The remaining 40% of the blood is mixed blood (oxygenated and deoxygenated) and will move from the right atrium, to the right ventricle, and into the pulmonary artery. From the pulmonary artery it will pass through the patent ductus arteriosus (which is a connection between the pulmonary artery and the aorta) into the aorta. The aorta will connect with the umbilical artery, where the blood will go back to the placenta to exchange gas, get rid of waste products and pick up nutrients. The right side of the heart has the higher pressure prior to birth. After birth, this changes with the neonate's first breath and the left side of the heart becomes the one with the higher pressure. Factors which increase contraction - ANSWER **Catecholamines-increase activity of the calcium pump in the sarcoplasmic reticulum; therefore it increases the release of calcium from the SR**Increases in intracellular calcium**Decreased extracellular sodium-decreases the activity of the Na/Ca exchanger**Digitalis-blocks the Na/K pump which increases intracellular Na, decreases the activity of the NA/Ca exchanger, and increases intracellular Ca Factors which decrease contraction - ANSWER **Beta blockers-block the effects of the catecholamines**heart failure with systolic dysfunction**acidosis**hypoxia/hypercapnia **nondihydropyridine calcium channel blockers Cardiac output (CO) - ANSWER Amount of blood pushed from the left ventricle in 1 minutes. HR X STROKE VOLUME = CO. Normal output is 5L/minute Stroke Volume - ANSWER Amount of blood ejected by the ventricle for each cardiac cycle. Highly dependent on the force of contraction. Contraction is dependent upon amount of preload, stimulation by endogenous positive inotropic agents such as epi and norepi, presence of negative inotropic agents and adequacy of myocardial oxygenation Ejection fraction (EF) - ANSWER Percentage of blood which is ejected from the ventricle with each contraction. Calculated by dividing the stroke volume by the end diastolic volume. Normal EF is 55-65%. EF decreases with systolic heart failure but not in diastolic heart failure Preload - ANSWER Made up of end diastolic volume and end diastolic pressure. Dependent upon the amount of venous return to the heart and the amount of blood left in the left ventricle at the end of systole. Increased preload can cause heart failure from a decline in stroke volume and a back up into pulmonary circulation Afterload - ANSWER Resistance that the ventricle pushes against to contract. This includes aortic pressure and systemic vascular resistance. High afterload increases the work of the ventricle and results in hypertrophy. A low afterload enables the heart to contract faster Diltiazem and verapamil - ANSWER non-dihydropyridine calcium channel blockers. They inhibit the influx of calcium into the myocardium. This decreases intracellular calcium concentration which in turn decreases myocardial tension and contractility. They have negative inotropic effects. As such these medications should be avoided in persons with systolic heart failure. Dobuamine - ANSWER Stimulates the beta 1 receptors in the myocardium and improves contractility and increases heart rate Epinephrine - ANSWER Primarily stimulates beta 1 receptors of the heart which results in an increase in myocardial contractility and heart rate. Also effects beta 2 and alpha 1 receptors which cancel each other out and does not change vascular tone. In high doses alpha 1 overrides beta 2 which causes vasocontriction and increased systemic vascular resistance while still enhancing contractility and cardiac output Norepinephrine - ANSWER Stimulates both beta 1 and alpha 1 receptors. This incrases myocardial contractility and causes vasoconstriction. Result in increase in cardiac output and blood pressure Dopamine - ANSWER Low dose stimulates dopamine 1 receptors and causes vasodilation. Moderate dose stimulates beta 1 receptor and improves myocardial contractility and cardiac output. High dose stimulates alpha 1 and causes vasoconstriction Cardiovascular receptors - ANSWER Beta 1, beta 2, alpha 1 and dopamine receptors. BETA 1 are located in the heart, increase contractility, heart rate and renin secretion. BETA 2 are located in blood vessels and cause vasodilation. Also located in smooth muscle of bronchi and cause bronchial dilation. ALPHA 1 located in blood vessels and cause vasocontriction. DOPAMINE are located in renal, mesenteric,coronary and cerebrovascular blood vessels and cause vasodilation. ConductionSystem - ANSWER Electrical impulses are usually generated from the SA node, located in the right atrium. The SA node generates impulses of around 60-100 action potentials per minute, which translates to 60- 100 heartbeats per minute. The impulse generated from the SA node is transmitted to the AV node. The atrial node is located in the right atrium wall just above the tricuspid valve. It mediates how fast impulses are transmitted to the ventricles. If the SA node fails, then the AV node will generate an impulse. It can generate 40-60 action potentials per minute which translates to 40-60 beats per minute. The AV node will pass the impulse down the conduction system to the bundle of His. If the AV node fails, the bundle of His (right and left branches) will generate an action potential at less than 40 beats per minute. The impulse will then travel to the purkinje fibers which travel up the wall of the ventricles and cause contraction of the ventricles. Venricular action potentials - ANSWER Generated by the bundle of His or purkinje fibers. Cardiac cells start with a resting membrane potential of -85mV. Phase 0:represents a rapid depolarization of cells. Na influx occurs as a result of the voltage gated Na channels opening. Phase 1: initial repolarization of the cells.The benefits of buying summaries with Stuvia:
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