Heart Flashcards
- Describe the location of the heart.
1.Thoracic cavity, within mediastinum, a bit more on left
- Name the membrane that surrounds the heart. What is its function?
2.Pericardial sac protects the heart and prevents over distention of heart.
- Name the 3 layers of the heart wall.
3.Endocardium, myocardium, epicardium
- Where might pericardial fluid be found?
4.Pericardial cavity
- Name the 4 heart chambers, and the septae and valves that separate them.
5.Left & Right atria are separated by interatrial septum. Left and right ventricles are separated by interventricular septum. Valves between atria and ventricles are called atrioventricular valves. The pulmonary semilunar valve lies between the right ventricle and the pulmonary trunk; the aortic semilunar valve lies between the left ventricle and the aorta.
- Define coronary sulcus, chordae tendineae, papillary muscle, and trabeculae carneae.
6.Sulcus is an external depression for the coronary vessels but is also an external feature dividing atrium from ventricle. Chordae tendineae attach inferiorly to AV valves keeping them from pointing backwards. Papillary muscle attach the chordae tendineae inferiorly in the ventricle; trabeculae carnea are irregular myocardium ridges
- Trace the coronary circuit of blood flow.
7.Aorta to coronary arteries to myocardium and then through cardiac veins to a big collecting vein called the coronary sinus which dumps into the Right atrium
- Describe the cells comprising the myocardium. Name the structure between these cells and its primary purpose.
8.Striated cardiac muscle cells linked by intercalated disc that carries excitement for contraction from one heart muscle cell to the next, linking them all together.
- Explain why a refractory period is necessary following cardiac muscle cell excitation.
9.Sustained contraction without relaxation gives no time for filling the heart chambers with blood!
- Name the source of energy for cardiac muscle.
10.ATP from aerobic metabolism
- Describe the excitation of cardiac muscle cells and where this occurs.
11.Spontaneous depolarization can occur in all cardiac muscle cells but happens the quickest at the SA node, thus setting the pace for the entire heart since all cells are linked by the intercalated discs.
- Describe the pathway for conduction of electrical impulses through the heart.
12.SA node spread to both atria, then to AV node with a brief delay for atria to finish their contractions, then down the AV bundle which travels through the interventricular septum, then to the purkinje = conduction fibers in the outer myocardium of ventricles.
- Define systole and diastole. Which heart chamber has the highest systolic pressure and why?
13.Systole is the contraction phase and diastole is the relaxation phase. Highest systolic pressure is the LV since it has to pump blood from head to toes.
- Describe and illustrate the pressure changes in the left atrium, left ventricle, and aorta through one complete cardiac cycle.
14.When LA has higher pressure than LV, the Left AV valve is open. As the LV contracts, its pressure exceed that of the LA and the Bicuspid valve closes causing the first heart sound. As the left ventricle is pushing blood into the aorta with high pressure, the aortic semilunar valve is open, but when the ventricle enters into diastole, quickly, its pressure drops below that of the elastic aorta resulting in semilunar valve closure causing the second heart sound.
- Define cardiac output and cardiac reserve.
15.Cardiac output is the volume pumped out of the ventricle in a minute CO = HR x SV. Cardiac reserve is the difference between the maximum CO and resting CO.
Normal CO is 5-6 liters/minute
