Nurs 5315: Adv Patho Exam 3 Set 1 | Latest Version | 2024/2025 | Graded A+

Nurs 5315: Adv Patho Exam 3 Set 1 | Latest Version | 2024/2025 | Graded A+ **Describe the flow of blood through the heart.** **Blood flows from the body into the heart through the vena cavas, enters the right atrium, passes through the tricuspid valve into the right ventricle, exits via the pulmonic valve into the pulmonary artery, travels to the lungs, returns via the pulmonary veins to the left atrium, passes through the mitral valve into the left ventricle, exits via the aortic valve, and then returns to the body.** **What are the key anatomical features of the heart?** **The heart is approximately the size of a closed fist, with two-thirds located to the left of the midline and one-third under the sternum.** **What are the layers of the heart wall?** **The heart wall consists of the endocardium (inner layer), myocardium (middle layer), and pericardium (outer layer).** **Describe phase 0 of the cardiac action potential.** **Phase 0 involves rapid depolarization due to the opening of voltage-gated sodium channels, leading to an influx of sodium.** **Explain phase 1 of the cardiac action potential.** **Phase 1 is characterized by initial repolarization. Voltage-gated sodium channels close, while voltage-gated potassium channels open slowly, allowing potassium to leave the cell.** **What happens during phase 2 of the cardiac action potential?** **Phase 2, known as the plateau phase, involves the opening of voltage-gated calcium channels. Calcium influx balances potassium efflux, triggering further calcium release from the sarcoplasmic reticulum and leading to myocardial contraction.** **Describe phase 3 of the cardiac action potential.** **Phase 3 is marked by rapid repolarization due to increased potassium efflux. Voltage- gated potassium channels open fully, while voltage-gated calcium channels close.** **What is phase 4 of the cardiac action potential?** **Phase 4 represents the resting membrane potential, which is around -85 mV. Potassium channels maintain high permeability during this phase.** **How do potassium imbalances affect myocardial action potentials?** **Hypokalemia increases atrial preload, leading to first to third-degree heart blocks. Hyperkalemia slows depolarization, resulting in sinus bradycardia and junctional rhythms.** Calcium imbalance affect on myocardial action potentials