Unit 18

Pre-text assignments:

1 Learn the key words and phrases:

ducts, pump, mediastinum, bluntly pointed apex, apical heartbeat, atria, ventricles, septum, atrioventricular orifice, cardiac cycle

2 Choose the correct description of the following terms:

1) disease a) the pressure exerted by the blood

against the inner walls of the blood

vessels

2) stroke b) any departure from health, a

particular destructive process in an

organism

3) blood pressure c) a sudden attack, especially of

apoplexy or paralysis

4) drug d) physical or mental exhaustion,

weariness

5) fatigue e) any substance used as a medicine;

narcotic

3 Translate the following expressions:

to be composed of smth; to be protected by smth; to be supplied with smth; to distribute smth; by means of smth; to cause smth; any interruption of smth; to be (not) equal in size;to be of vital importance

Cardiovascular System

The cardiovascular system is the portion of the circulatory system that includes the heart and blood vessels. It moves the blood between the body cells and the organs of the integumentary, digestive, respiratory, and urinary systems that communicate with the external environment. In performing this function, the heart acts as a pump that forces blood through the blood vessels. The blood vessels, in turn, form a closed system of ducts, which transports the blood and allows exchanges of gases, nutrients, and wastes between the blood and the body cells.

A functional cardiovascular system is vital for survival, because without circulation, the tissues lack a supply of oxygen and nutrients, and waste substances accumulate. Under such conditions, the cells soon begin to undergo irreversible changes, which quickly lead to death of the organism.

Heart

The heart is a hollow, cone – shaped, muscular pump located within the mediastinum of the thorax and resting upon the diaphragm. Although heart size varies with body size, the heart of an average adult is generally about 14 centimeters long and 9 centimeters wide.

The heart is located within the mediastinum, and is bordered laterally by the lungs, posteriorly by the backbone, and anteriorly by the sternum. Its base, which is attached to several large blood vessels, lies beneath the second rib. Its distal end extends downward and to the left, terminating as a bluntly pointed apex at the level of the fifth intercostal space. For this reason, it is possible to

sense the apical heartbeat by feeling or listening to the chest wall between the fifth and sixth ribs, about 7.5 centimeters to the left of the midline.

Internally, the heart is divided into four hollow chambers, two on the left and two on the right. The upper chambers, called atria (sing. atrium), have relatively thin walls and receive the blood from veins. The lower chambers, the ventricles, force the blood out of the heart into arteries. (Note: Veins are blood vessels that carry the blood toward the heart; arteries carry the blood away from the heart.)

The atrium and ventricle on the right side are separated from those on the left by a septum. The atrium on each side communicates with its corresponding ventricle through an opening called the atrioventricular orifice, which is guarded by an atrioventricular valve (A-V valve).

The wall of the heart is composed of three distinct layers: an outer epicardium, a middle myocardium, and an inner endocardium.

The epicardium, which corresponds to the visceral pericardium, functions as an outer protective layer. It is a serous membrane that consists of connective tissue covered by epithelium, and it includes blood capillaries, lymph capillaries, and nerve fibers.

The middle layer, or myocardium, is relatively thick and consists largely of the cardiac muscle tissue responsible for forcing the blood out of the heart chambers. The muscle fibers are arranged in planes, separated by connective tissues that are richly supplied with blood capillaries, lymph capillaries, and nerve fibers.

The inner layer, or endocardium, consists of epithelium and connective tissue that contains many elastic and collagenous fibers. The connective tissue also contains blood vessels and some specialized cardiac muscle fibers called Purkinje fibers.

The endocardium lines all of the heart chambers and covers the structures, such as the heart valves, that project into them. This inner lining is also continuous with the inner lining of the blood vessels (endothelium) attached to the heart.

Post-text assignments:

1 Say what heart valve is described in each sentence:

1 This valve connects the atrium and the ventricle of the left heart chamber. 2 This valve connects the atrium and ventricle of the right heart chamber. 3 This valve is located at the point of origin of the aorta in the left ventricle. 4 This valve is located at the point of origin of the pulmonary artery in the right ventricle.

2 Combine the nouns with appropriate verbs:

the heart, the blood, the artery;

contract, pass, dilate, bring, regulate, pump, vary, beat, compose, work, consist of, discharge out, receive, enter, act, serve, send, oxyginate, carry

3 Say what is meant in the following sentences:

1 This part of the heart discharges out the blood received from the pulmonary circulation through the aorta to the systemic circulation. 2 This part of the heart discharges out the blood received from the systemic circulation to the lungs through the pulmonary arteries. 3 These corpuscles have great elasticity and flexibility. These features give them the possibility to pass through very small capillaries. 4 The count of these corpuscles in the blood of a healthy person is 5,000 to 7,000 per cu mm. The number of these corpuscles increases when a person becomes ill.

4 Choose the anatomic terms for the following:

1 The valve between the left atrium and left ventricle of the heart, preventing a flow of blood into the atrium during systole. 2 The flaps on the valves. 3 A muscular wall which is between the two lower chambers of the heart. 4 A septum which separates the two upper chambers (atria) of the heart. 5 The middle, the thickest layer of the heart wall. 6 A delicate membrane (double-folded) which surrounds the heart like a sac. 7 A thin outer layer of the heart wall. 8 The vein that carries (drains) blood from the upper part (portion) of the body. 9 The vein that carries blood from the lower part of the body. 10 A blood vessel that carries blood from some part of the body toward the heart. 11 A blood vessel that carries blood from the heart to the principal parts of the body. 12 The usual contraction of the heart. 13 The usual dilatation of the heart. 14 The main artery of the body which carries blood from the left ventricle of the heart to arteries in all organs and parts.

(a – superior vena cava; b – systole; c – aorta; d – mitral valve; e – vein; f – inferior vena cava; g – pericar-dium; h – interatrial septum; i – cusps; j – epicardium; k – diastole; l – myocardium; m – artery; n – interven-tricular septum)

5 Find the necessary word with a definition that best completes each sentence:

1 The aorta is the main ... of the systemic arteries. 2 Most of the arteries are composed of three ... .3 The blood vessels on the anterior ... of the arm were dilated. 4 The walls of the left ... are three times as thick as the walls of the right one. 5 Blood pressure is measured by a device called a .... 6 Diastole is the ... phase of the heartbeat. 7 Systole is the active ... phase of the heartbeat.

a) coats: the layers of a tissue; b) ventricle: either of the two lower chambers of the heart which receive blood from the atria and pump it into the arteries; c) surface: the outer face or exterior of an object; d) relaxation: loosening, lessening of force, etc.; e) vessel: a tube or duct containing or circulating a body fluid; f) sphygmomanometer: an instrument consisting of a band wrapped around the upper arm to compress the artery, and an attached manometer; g) contraction: the drawing up and thickening of a muscle fiber or a muscle in action

6 What is it?

The innermost layer of the heart, consists of an endothelial lining and its supporting connective tissue. The endothelium is a single layer of flattened epithelial cells, which is continuous with the endothelium of the vessels entering and leaving the heart.

The endothelium is supported by a delicate layer of fibreelastic connective tissue which accomodates gross movements of the myocardium without damage to the endothelium. The endocardium contains blood vessels, nerves and branches of the conducting system of the heart.

7 What it is?

Free surface of it is covered by a single layer of flattened epithelial cells, the mesothelium; a similar mesothelial layer lines the opposing parietal pericardial surface. The mesothelial cells secrete a small amount of serous fluid which lubricates the movement of the epicardium on the parietal pericardium. A thin layer of fibro-elastic connective tissure supports the mesothelium; this layer is connected to the myocardium by a broad layer of adipose connective tissue.