Ebook Millers textbook (Vol 1 - 8/E): Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Millers textbook (Vol 1 - 8/E): Part 2
Ebook Millers textbook (Vol 1 - 8/E): Part 2
Chapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2chanical events during the course of a single heartbeat.•Cardiac output is determined by the heart rate, myocardial contractility, and preload and aftertoad.•The majority of cardiomyocytes consist of myofibrils, which are rodlike bundles that form the contractile elements within the cardiomyocyte.•T Ebook Millers textbook (Vol 1 - 8/E): Part 2he basic working unit of contraction is the sarcomere.•Gap Junctions are responsible for the electrical coupling of small molecules between cells.•ActEbook Millers textbook (Vol 1 - 8/E): Part 2
ion potentials have four phases in the heart.•The key player in cardiac excitation-contraction coupling Is the ubiquitous second messenger calcium.•CaChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2pling and regulation of automaticity and contractility.•P-Adrenoreceptors stimulate chronoưopy, Inotropy, lusitropy, and dromotropy.•Hormones with cardiac action can be synthesized and secreted by cardiomyocytes or produced by other tissues and delivered to the heart.•Cardiac reflexes are fast-actin Ebook Millers textbook (Vol 1 - 8/E): Part 2g reflex loops between the heart and central nervous system that contribute to the regulation of cardiac function and the maintenance of physiologic hEbook Millers textbook (Vol 1 - 8/E): Part 2
omeostasis.In 1628, English physician, William Harvey, first advanced the modern concept of circulation with the heart as the generator for the circulChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2omyocyte and regulation of cardiac function by neural and humoral factors. Cardiac physiology is a component of the interrelated and integrated cardiovascular and circulatory physiology'. This chapter discusses only the physiology' of the heart. It begins with the physiology of the intact heart. Tir Ebook Millers textbook (Vol 1 - 8/E): Part 2e second part of the chapter focuses on cellular cardiac physiology'. Finally, the various factors that regulate cardiac function are briefly discusseEbook Millers textbook (Vol 1 - 8/E): Part 2
d.The basic anatomy of the heart consists of two atria and two ventricles that provide two separate circulations in series. The pulmonary circulation,Chapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2hange. Tile left side of the heart provides output for the systemic circulation. It functions to deliveroxygen (O2) and nutrients and to remove carbon dioxide (CO2) and metabolites from various tissue beds.PHYSIOLOGY OF THE INTACT HEARTUnderstanding of mechanical performance of the intact heart begi Ebook Millers textbook (Vol 1 - 8/E): Part 2ns with the knowledge of the phases of the cardiac cycle and the determinants of ventricular function.CARDIAC CYCLEThe cardiac cycle is the sequence oEbook Millers textbook (Vol 1 - 8/E): Part 2
f electrical and mechanical events during the course of a single heartbeat. Figure 20-1 illustrates (1) the electrical events of a single cardiac cyclChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2ressure pulses correlated in time with aortic tlow and ventricular volume.'473474 PART II: Anesthetic PhysiologyTime (sec)Figure 20 1. Electrical and mechanical events dunng a single cardiac cycle. The pressure curves of aortic blood flow, ventricular volume, venous pulse, and electrocardiogram are Ebook Millers textbook (Vol 1 - 8/E): Part 2shown, (from Be/ne UM. Levy MN: The cardiac pump In Cardiovascular physiology, ed 8. St louii, 2001. Mosby. pp 55-82.)The cardiac cycle begins with thEbook Millers textbook (Vol 1 - 8/E): Part 2
e initiation of the heartbeat. Intrinsic to the specialized cardiac pacemaker tissues is automaticity and rhythmicity. The sinoatrial (SA) node is usuChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2cal events of the pacemaker and the specialized conduction system are represented by the ECG at the body surface (also see Chapters 45 and 47). The ECG is the result of differences in electrical potential generated by the heart at sites of the surface recording. The action potential initiated at the Ebook Millers textbook (Vol 1 - 8/E): Part 2 SA node is propagated to both atria by specialized conduction tissue that leads to atrial systole (contraction) and the p wave of the ECG. At the junEbook Millers textbook (Vol 1 - 8/E): Part 2
ction of the interatrial and interventricular septa, specialized atrial conduction tissue converges at the atrioventricular (AV') node, which is distaChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2 occurs at this locus. The PR interval represents the delay between atrial and ventricular contraction at the level of the AV node. From the distal His bundle, an electrical impulse is propagated through large left and right bundle branches and finally to the Purkinje system fibers, which are the sm Ebook Millers textbook (Vol 1 - 8/E): Part 2allest branches of the specialized conduction system. Finally, electrical signals are transmitted from the Purkinje system to individual ventricular cEbook Millers textbook (Vol 1 - 8/E): Part 2
ardiomyocytes. The spread of depolarization to the ventricular myocardium is exhibited as the QRS complex on the ECG. Depolarization is followed by veChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2of blood to the right and left atria from the systemic and pulmonary circulation, respectively. As blood accumulates in the atria, atrial pressure increases until it exceeds the pressure within the ventricle, and the AV valve opens. Blood passively flows first into the ventricular chambers, and such Ebook Millers textbook (Vol 1 - 8/E): Part 2 flow accounts for approximately 75% of the total ventricular filling.' The remainder of the blood flow is mediated by active atrial contraction or syEbook Millers textbook (Vol 1 - 8/E): Part 2
stole, known as the atrial kick. The onset of atrial systole is coincident with depolarization of the sinus node and the p wave. While the ventricles Chapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2ds to the end of the R wave on the ECG. The first part of ventricular systole is known as isovolumic or isometric contraction. The electrical impulse traverses the AV region and passes through the right and left bundle branches into the Purkinje fibers, which leads to contraction of the ventricular Ebook Millers textbook (Vol 1 - 8/E): Part 2myocardium and a progressive increase in intraventricular pressure. When intraventricular pressure exceeds pulmonary artery and aortic pressure, the pEbook Millers textbook (Vol 1 - 8/E): Part 2
ulmonic and aortic valves open and ventricular ejection occurs, which is the second part of ventricular systole.Ventricular ejection is divided into tChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2pressure is maximally deseloped. In the reduced ejection phase, flow and great artery pressure taper with progression of systole. Pressure in both ventricular chambers decreases as blood is ejected from the tieart, and ventricular diastole begins with closure of the pulmonic and aortic valves. The i Ebook Millers textbook (Vol 1 - 8/E): Part 2nitial period of ventricular diastole consists of the isovolumic (isometric) relaxation phase. This phase is concomitant with repolarization of tile vEbook Millers textbook (Vol 1 - 8/E): Part 2
entricular inycxardium and corresponds to the end of the I wave on the E.CCỈ. I lie final portion of ventricular diastole involves a rapid decrease inChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mec Ebook Millers textbook (Vol 1 - 8/E): Part 2occurs, and the cycle repeats itself.VENTRICULAR STRUCTURE AND FUNCTIONVentricular structureChapter 20Cardiac PhysiologyLENA s. SUN • JOHANNA SCHWARZENBERGER • RADHIKA DINAVAHIKey Points•The cardiac cycle is the sequence of electrical and mecGọi ngay
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