Занятие 12

HEART SOUNDS AND MURMURS

Two sounds regularly are heard during each beat of the normal heart. The first sound begins synchronously with ventricular systole and lasts through the isometric contraction phase¹ into the ejection phase.

The second sound occurs near the beginning of the isometric relaxation phase. In some normal subjects a third sound known as the "physiologic third sound" can be heard immediately after the second. Also in some normal subjects a very weak sound can be heard beginning immediately before and fusing with the first sound.

The first sound is caused by (1) vibrations of the walls of contracting ventricles, (2) vibrations set up by the sudden closure of the A-V valves² and (3) distention and vibrations of the aorta and pulmonary artery. Auricular systole contributes little or nothing to the first sound. The second sound is produced by the vibrations set up by the closure of the aortic and pulmonic valves which occurs when intraventricular pressure falls below the pressure in the respective arteries. The physiologic third heart sound when present, occurs at the end of the period of rapid ventricular filling and hence has been attributed to vibrations of the ventricular wall produced by the rapid inrush of blood from the auricles.

When blood is forced at a relatively high velocity through an orifice into a vessel or chamber of somewhat larger cross-sectional area, turbulence is produced. Vibrations induced by this turbulence are heard as murmurs. Most commonly cardiac murmurs are related to the failure of a valve to open completely (stenosis) or to close completely (regurgitation or insufficiency). For example, a murmur is heard during systole if there is insufficiency of the mitral valve or stenosis of the aortic valve, and a murmur is heard during diastole if there is stenosis of the mitral valve or insufficiency of the aortic valve.

Упражнение 1. Озаглавьте абзацы текста своими собственными предложениями.

Упражнение 2. Ответьте на вопросы:

1. What sound are heard in the normal heart? 2. What is the cause of the heart sounds? 3. What are murmurs? 4. What is the cause of murmurs?

Дайте характеристику первого, второго и третьего тона сердца. Подчеркните разницу между тоном и шумом сердца

Тема 2.2: Физиология легких

Этапы занятия и рекомендуемая продолжительность тренировки видов речевой деятельности:

I. Речевая разминка. Пособие “Headway”. Student’s Book. Intermediate. Направлено на формирование компетенции ОК-6 - 30 мин

Тема – “A world guide to good manners. Spain.” (New Headway Intermediate, T.29, p. 130)

Дата добавления: 2014-12-07