The heart & the vascular system

The heart is an inner hollow muscular organ placed within the chest & included in the pericardium. The base of the heart is against the third rib. Its apex is against the interspace between the fifth & the sixth costal cartilages. The weight of the heart is about 300 grams in the male & about 220 gr in the female.

The heart consists of two separate chambers divided by the septum. Each of the chambers has two connected parts: the atrium & the ventricle. The atrioventricular valves separate the atria from the ventricles.

The right atrium is larger than the left one, but the walls of the left atrium are thicker than those of the right one. The right ventricle is triangular (треугольный) in form & has thick walls. The right ventricle is in the anterior part of the heart. The left ventricle is longer & more conical than the right one. The walls of the left ventricle are three times as thick as the walls of the right one. The valves are located at the entrance & exit of each ventricle.

The muscular structure of the heart consists of fibrous bands divided into two groups – the first ones are the fibrous bands of the atria & the second ones are the fibrous bands of the ventricles.

The vascular system consists of three groups of vessels – arteries, veins & capillaries.

The vessels carrying blood to & from the tissues of the body compose the general system. They are called the systemic vessels.

The pulmonary system is formed by the vessels carrying blood to & from the lungs.

The portal system is formed by the veins passing to the liver.

Most of the arteries are composed of three coats. The arteries dilate & contract simultaneously with the action of the heart.

Blood Flow Through the Heart

The right atrium receives blood low in oxygen from all body tissues through the superior vena cava and the inferior vena cava. The blood then enters the right ventricle and is pumped to the lungs through the pulmonary artery. Blood returns from the lungs high in oxygen and enters the left atrium through the pulmonary veins. From here it enters the left ventricle and is forcefully pumped into the aorta to be distributed to all tissues.

Blood is kept moving in a forward direction by one-way valves. The valve in the septum between the right atrium and ventricle is the tricuspid valve; the valve in the septum between the left atrium and ventricle is the bicuspid valve, usually called the mitral valve.

The Heartbeat

Each contraction of the heart, termed systole, is followed by a relaxation phase, diastole, during which the chambers fill. Each time the heart beats, both atria contract and immediately there- after both ventricles contract. The wave of increased pressure produced in the vessels each time the ventricles contract is the pulse.

The vascular system consists of:

1. Arteries that carry blood away from the heart. Arterioles are small arteries that lead into the capillaries.

2. Capillaries, the smallest vessels, through which exchanges take place between the blood and the tissues.

All arteries, except the pulmonary artery, carry blood high in oxygen.

They are thick-walled, elastic vessels that carry blood under high pressure. All veins, except the pulmonary vein, carry blood low in oxygen. Veins have thinner, less elastic walls and tend to give way under pressure. Like the heart, veins have one-way valves that keep blood flowing forward.

3. Veins carry blood back to the heart.

1. Find in the text English equivalents for these words & word combinations:

внутрішній порожній м’язовий орган; в середині грудної клітини; напроти третього ребра; вага серця; дві окремих камери; відокремлювати від шлуночків; стінки лівого передсердя; трикутний за формою; втричі товщі; м’язова структура; волокнистий пучок; три групи судин; судини, які переносять кров; від легенів; більшість артерій, розширювати та скорочувати, отримувати кров з усіх тканин тіла, перекачуватись у легені, входи через легеневі вени, доставлятися до усих тканин, перегородка між лівим передсердям та шлуночком, кожне скорочення серця, кожен раз, хвиля підвищеного тиску, вести до капілярів, обмін має місце, переносити кров збагачену киснем, еластичні судини, мати тонші та менш еластичні стінки, запобігає витіканню крові назад.

2. Answer the following questions:
1. Where is the heart located?

2. What kind of organ is the heart?

3. Where is the base of the heart located?

4. How many chambers does the heart consist of?

5. Is the left atrium larger than the right one?

6. Where are the valves located?

7. What does the muscular structure of the heart consist of?

8. Does the vascular system consist of three or four groups?

9. Where do the vessels of the general system carry the blood?

10. What is portal system formed by?

11. Most of the arteries are composed of three coats, aren’t they?

3. Complete the following sentences:

1. Blood low in … comes from …to …

2. From the right ventricle … is pumped …

3. Blood … in oxygen comes from the ….

4. Tricuspid valve is the valve …

5. Mitral valve is the valve …

6. Systole is the …

7. Diastole is the …

8. Arteries carry …

9. Exchanges between the blood & … take place in …

10. Arteries are …vessels they carry blood under …

11. The walls of veins are …

12. Veins carry …

4. Choose the suitable word from the brackets & complete the sentences:

1. The (right, left) atrium receives blood (low, high) in oxygen.

2. Then the blood enters the right (atrium, ventricle).

3. From the right atrium blood is pumped to the (aorta, lungs).

4. The septum in the right heat is called (tricuspid valve, mitral valve).

5. Mitral valve is the valve with (3 cusps, two cusps).

6. Arteries carry blood (away from, to\ heart, lungs).

7. Exchanges between blood & tissues take place in (arteries, capillaries).

8. All (arteries, veins) carry blood high in (oxygen, carbon dioxide).

9. (Veins, arteries) are thick walled, elastic (vessels, valves).

5. Translate the sentences into English & write them down:

1. Праве передсердя отримує кров з усіх тканин тіла.

2.З легенів кров вертається збагачена киснем.

3. Перегородка правого серця – це тристулковий клапан.

4. Артерії переносять кров від серця.

5. Капіляри це маленькі кров’яні судини.

6. Артерії дуже еластичні судини, чи не так?

7. Вени переносять кров з малою кількістю кисню.

6. Say if it is true or false:

1. Blood low in oxygen is received by the right atrium.

2. Blood is pumped to the lungs through the pulmonary veins.

3. From the lungs blood enters the right atrium.

4. From the left atrium blood enters the left ventricle & pumped into the aorta.

5. Blood in high oxygen is distributed to all tissues.

6. Tricuspid valve can be found in the left heart.

7. Mitral valve separates left atrium & left ventricle.

8. Systole is a relaxation phase.

9. Both atria & ventricles contract at different time.

10. Blood from the heart is carried by arteries.

11. Pulmonary artery carries blood low in oxygen.

12. Veins are vessels with thin & less elastic walls.

Дата добавления: 2015-11-14