Blood vessels

The vascular system consists of blood vessels. They carry blood from the heart to all parts of the body. Blood vessels can be classified as capillaries, arteries and veins. Arteries normally are classified as elastic arteries, muscular arteries, and arterioles. The veins are classified as venules, small veins, and medium-sized and large veins.

The vessels become smaller as they extend farther from the heart. The aorta (large elastic artery) delivers blood to the large arteries. They, in turn, branch off several times and eventually blood flows into smaller vessels called arterioles. The arterioles supply the tiny capillaries (minute blood vessels) that nourish tissue. Oxygen is given up from capillaries to the tissues, and carbon dioxide from the tissue is taken up into the capillaries. The arteries have to be strong as well as flexible.

From the capillaries, the blood begins its trip back to the heart by way of the venous system. The veins increase in size closer to the heart. As part of circulation, the blood travels through the liver and kidneys, which remove waste products. The veins, under less pressure, are less muscular and less elastic than arteries.

The entire circulatory system is lined with simple squamous epithelium called endothelium. Capillaries consist only of endothelium. The capillary walls consist of endothelial cells, which rest on a basement. Venules are tubes composed of endothelium resting on a delicate basement membrane. Their structure is very similar to that of capillaries. The venules collect blood from the capillaries and transport it to the small veins, which in turn transport it to the medium-sized veins. Except for capillaries and venules, blood vessels have three layers: the inner tunica intima (consisting of endothelium, basement membrane, and internal elastic lamina), the tunica media (containing circular smooth muscle and elastic fibers), and the outer tunica adventitia (which is connective tissue). The relative thickness and composition of each layer varies with the diameter of the blood vessel and its type. The transition from one artery type or from one vein type to another is gradual, as are structural changes.

Vessels transporting blood through essentially all parts of the body from the left ventricle and back to the right atrium are called the systemic vessels. The pulmonary vessels transport blood from the right ventricle through the lungs and back to the left atrium.

Ex. 9. Translate the following words and word-combinations into English:

Сквамозний, покритий лусочками; адвентиціальна оболонка; гнучкий, еластичний; віддалений; капіляр; розгалуджуватися; артерія; внутрішня оболонка; живити; тонка пластинка, тонкий шар; доставляти; базис, основа; зрештою, нарешті, з часом; качати.

Ex. 10. Translate the text “Vessels” into Ukrainian.

Ex. 11. Complete the following sentences.

1. The _ circulation is composed of vessels that carry blood from the right ventricle to the lungs, pulmonary capillaries, and vessels that lead back to the left atrium. 2. The _ circulation is composed of vessels that lead from the heart to the body cells and back to the heart. 3. The aorta is the main _ of the systemic arteries. 4. The walls of vessels consist of three distinct layers, they are _. 5. The peripheral circulatory system can be divided into sets of _ vessels. 6. Blood flows from the _ through arteries and arterioles to the capillaries. 7. Blood returns to the heart from the _ through veins and venules. 8. Blood then flows through the capillary network and into the _.

Ex. 12. Fill in the blanks with the prepositions where necessary.

1. The blood vessels are organs _ the cardio-vascular system, and they form a close circuit _ tubes that carries blood _ the heart _ the body cells and back again. 2. The vessels become smaller as they extend farther _ the heart. 3. Arterioles are branches _ arteries. 5. Veins carry blood _ the cells. 6. The veins increase _ size closer _ the heart. 7. Venous walls are similar _ arterial walls, but are thinner and contain less muscle and elastic tissues. 8. Capillaries form connections _ arterioles and venules. 9. Oxygen is given up _ capillaries _ the tissues, and carbon dioxide _ the tissue is taken up _ the capillaries. 10. The entire circulatory system is lined _ simple squamous epithelium. 11. The various tissue circulations are arranged _ parallel circuits with certain morphological and functional differentiations.

Ex. 13. Answer the following questions:

1. What does the vascular system consist of? 2. What are the three main types of blood vessels? 3. What groups are arteries classified into? 4. What blood do vessels carry from some parts of the body toward the heart? 5. What blood do vessels carry from the heart throughout the body? 6.What types of veins can you distinguish? 7. What are the arterioles? 8. How many layers do capillary walls consist of? 11. What layers are the walls of the blood vessels composed of?

Ex. 14. Read the following terms and try to match them with the Ukrainian equivalents:

Vasoactive drug, vasoconstriction, vasodilation, vasodepression, vasography, vasospasm, vasorelaxant, angioarchitecture, angiodermatitis, angiodysplasia, angiogenesis, angiographic image, angiology, angiometer, angiopathy.

Розвиток кровоносних судин; розширення судин; захворювання судин; вазоактивні (такі, що впливають на судини) ліки; запалення шкірних судин; вазорелаксант; зниження судинного тонусу; звуження судин; ангіометр (інструмент для вимірювання діаметра судин); ангіодисплазія (дегенеративні зміни судин); ангіографічне зображення; рентгеноангіографія; ангіоархітектоніка (розділ анатомії, що вивчає порядок розгалудження артерій та формування вен); ангіологія (розділ анатомії, що вивчає кровоносні та лімфатичні судини); спазм судин.

Ex. 15. Write out key words of the text “Blood Vessels”.

Ex. 16. Make up a plan of the text “Blood Vessels”.

Ex. 17. Give a summary of the text “Blood Vessels”.

Дата добавления: 2015-07-11