The cardiac cycle

The blood entering the right side of the heart returns from the tissues and has been deliv­ered by the veins. The receiving chamber is the right atrium. This atrium also is a low-pres­sure pump, and it moves the blood into the right ventricle through the tricuspid valve.

The right ventricle has thicker, stronger walls than the right atrium. The right ven­tricle pumps the oxygen-poor blood through the pulmonic valve into the lungs, where the blood gives up the carbon dioxide it has car­ried from the tissues. At the same time, the blood is absorbing oxygen. The pump­ing action moves the blood from the lungs to the receiving chamber on the other side of the heart, the left atrium, which pumps the blood into the left ventricle through the mitral valve. The left ventricle sends the oxygen-enriched blood into the aorta, the principal artery that subdivides and delivers the blood to the body's tissues, including the brain, internal organs, and extremities.

The cardiac cycle is repetitive contraction and relaxation of the heart chambers. Contraction of the atrial myocardium is called atrial systole, and relaxation of the atrial myocardium is called atrial diastole. Similarly, ventricular systole is contraction of the ventricular myocardium, and ventricular diastole is relaxation of the ventricular myocardium. Thus the term systole means "to contract", and diastole means "to dilate". The right and left cham­bers contract and relax simultaneously.

The duration of the cardiac cycle varies among humans and also varies during an individual’s lifetime. It may be as short as 0.25 to 0.3 second in a newborn infant or as long as 1 or more seconds in a well-trained athlete. The normal cardiac cycle (0.7 to 0.8 second) depends on the capability of cardiac muscle to contract and on the functional integrity of the conducting system. Abnormalities of cardiac muscle, the valves, or conducting system of the heart may alter the cardiac cycle and thus compromise the pumping effectiveness of the heart.

Ex. 12. Translate the following words and word-combinations into English:

Повертатися, йти назад; передсердний, такий, що має відношення до передсердя; шлуночковий, такий, що має відношення до шлуночку; тиск|тиснення|; отримувати|одержувати|, акумулювати; клапан легеневого стовбура|ствола|; здатність|здібність|, можливість|спроможність|; тривалість, діастола; дротяна|провід| система; патологія; розширювати(ся|ся|); систола; нагнітати кров, погано збагачену киснем; віддавати вуглекислий газ; направляти|спрямовувати,скеровувати| збагачену киснем кров; протягом життя людини; залежати від функціональної цілісності провідної системи.

Ex. 13. Translate the following sentences paying attention to words in bold type:

1. The right ven­tricle pumps the oxygen-poor blood through the pulmonic valve into the lungs, where the blood gives up the carbon dioxide it has car­ried from the tissues. 2. The left ventricle sends the oxygen-enriched blood into the aorta. 3. The duration of the cardiac cycle varies among humans and also varies during an individual’s lifetime. 4. The duration of the cardiac cycle may be as short as 0.25 to 0.3 second in a newborn infant or as long as 1 or more seconds in a well-trained athlete.

Cardiac Systole

Ex. 14. Translate the text "Cardiac Cycle" into Ukrainian.

Ex. 15. Answer the following questions:

1. What is the blood entering the right side of the heart retuning from? 2. What is the right atrium? 3. What walls does the right ventricle have? 4. What does the blood give up in lungs? 5. Where does the pumping action of the heart move the blood from the lungs? 6. Where does the left ventricle send the oxygen-enriched blood? 7. What is the cardiac cycle? 8. What is the atrial systole? 9. What is the atrial diastole? 10. What is the ventricular systole? 11. What is the ventricular diastole? 12. What do the terms “systole” and “diastole” mean? 13. What is the duration of the cardiac cycle? 14. What does the normal cardiac cycle depend on?

Ex. 16.

A. Try to organize the information of the text in table:

Term	Definition
aorta
cardiac cycle
systole
diastole
atrial systole
atrial diastole
ventricular systole
ventricular diastole

B. Make up sentences using the data of table and following model:

MODEL:

Aorta is the principal artery that subdivides and delivers the blood to the body’s tissues.

The principal artery that subdivides and delivers the blood to the body’s tissues is called the aorta.

Ex. 17. What is it:

1. Complete round of cardiac systole and diastole. 2. Relaxation of the heart chambers during which they fill with blood. 3. Contraction of the heart chambers during which blood leaves the chambers. 4. Largest artery in the body; it carries blood from the heart’s left ventricle and distributes it throughout the body.

Ex. 18. Do you agree, disagree or partially agree with the statements below?

1. The right atrium moves the blood into the right ventricle through the tricuspid valve. 2. The duration of the cardiac cycle doesn’t vary among humans. 3. The pumping action moves the blood from the lungs to the left atrium. 4. The left ventricle pumps the blood into the left ventricle through the mitral valve. 5. The cardiac cycle is the contraction and relaxation of the muscles of the abdominal wall. 6. The term systole means to contract, and diastole means to separate.

Ex. 19. Translate into English the following sentences:

Праве передсердя переміщує кров у правий шлуночок через двостулковий клапан. Правий шлуночок через клапан легеневого стовбура|ствола| нагнітає кров до легень. Тут кров насичується|насичує| киснем. Від легенів кров тече|теча| до лівого передсердя, яке нагнітає кров у лівий шлуночок. З лівого шлуночку кров потрапляє|попадає| в аорту, яка переносить кров до мозку, внутрішніх органів, кінцівок|скінченностей|.

Скорочення міокарду передсердя називається систолою передсердя, розширення міокарду передсердя – це діастола передсердя. Систола шлуночків – це скорочення міокарду шлуночку, а діастола – розширення міокарду шлуночків. У людей тривалість серцевого|сердечного| циклу різна. Вона може тривати від 0,3 секунди до 1 секунди або довше. Проте|однак| зазвичай|звично| тривалість серцевого|сердечного| циклу складає 0,7 або 0,8 секунд. Патологія серцевого|сердечного| м'яза або клапана може призвести до порушення серцевого|сердечного| циклу.

Ex. 20. Complete the following dialogues:

A.

- Where is the blood entering the right side of the heart retuning from?

- _ (tissues).

- What has the blood entering the right side of the heart been delivered by?

- _ (veins).

- What is the right atrium?

- _ (the receiving chamber).

- What atrium is the low-pressure pump?

- _ (the right ventricle).

- What atrium moves the blood into the right ventricle?

- _ (the right ventricle).

- What valve does the right atrium move the blood into the right ventricle through?

- _ (the bicuspid valve).

B.

- _?

- The pumping action moves the blood from the lungs to the left atrium.

- _?

- The left atrium pumps the blood into the left ventricle.

- _?

- The left atrium pumps the blood into the left ventricle through the mitral valve.

- _?

- The left ventricle sends the oxygen-enriched blood into the aorta.

- _?

- Aorta is the principal artery of the human body that subdivides and delivers the blood to the body’s tissues, including the brain, organs, and extremities.

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