eventually form platelet demarcation membranes. These membranes fuse to give rise to the membranes of the platelets.
A single megakaryocyte can shed (i. e., produce) up to 3,500 platelets.
New words
reticular – сетчатый
sinusoids – синусоиды
granulocytes – гранулоциты
agranulocytes – агранулоциты
active – активный
yellow – желтый
glycoprotein – гликопротеин
erythropoietin – эритропоэтин
large – большой
amount – количество
hemoglobin – гемоглобин
degenerating – вырождение
capable – способный
division – разделение
spherical – сферический
indented – зазубренный
condensed – сжатый
chromatin – хроматин
Запомните следующие застывшие словосочетания.
to play _ chess to play the piano to play _ football to play the guitar out of _ doors
Запомните, что перед обращением артикль опускается.
Е. g. What are you doing, _ girls?
Заполните пропуски, где необходимо.
1. Do you play… piano?
2. There is… big black piano in our living-room.
3. It is at… wall to… left of… door opposite… sideboard.
4. My mother likes to play. piano.
5. She often plays… piano in… evening.
6..boys like to play… football.
7. What do you do in… evening? – I often play… chess with my grandfather.
8. Where are… children? – Oh, they are out of… doors… weather is fine today.
9. They are playing… badminton in… yard.
10. What… games does your sister like to play?
11. She likes to play… tennis.
12. Do you like to play… guitar?
13. What… colour is your guitar?
14. When we want to write… letter, we take… piece of… paper and… pen.
15. We first write our… ad dress and… date in… right-hand corner.
16. Then on… left-hand side we write… greeting.
17. We must not forget to leave… margin on… left-hand side of… page.
18. On… envelope we write… name and address of… person who will receive it.
19. We stick… stamp on… top of right-hand corner.
20. We posted… letter.
Answer the questions.
1. What is hematopoietic tissue composed of?
2. Where is myeloid found?
3. How is red marrow characterized?
4. What does yellow bone marrow contain?
5. Where does hematopoiesis takes place in the human adult?
6. What is erythropoiesis?
7. What is myeloblast?
8. What is band neutrophil?
9. How long are megakaryocytes?
10. How many platelets can a single megakaryocyte shed?
11. Make the sentences of your own using the new words (10 sentences).
12. Find the definite and indefinite articles in the text.
ЛЕКЦИЯ № 18. Arteries
Arteries are classified according to their size, the appearance of their tunica media, or their major function.
Large elastic conducting arteries include the aorta and its large branches. Unstained, they appear yellow due to their high con tent of elastin.
The tunica intima is composed of endothelium and a thin sub jacent connective tissue layer. An internal elastic membrane marks the boundary between the intima and media.
The tunica media is extremely thick in large arteries and con sists of circularly organized, fenestrated sheets of elastic tissue with interspersed smooth muscle cells. These cells are responsi ble for producing elastin and other extracellular matrix com ponents. The outermost elastin sheet is considered as the external elastic membrane, which marks the boundary between the media and the tunica adventitia.
The tunica adventitia is a longitudinally oriented collection of colla-genous bundles and delicate elastic fibers with associated fibroblasts. Large blood vessels have their own blood supply (vasa vasorum), which consists of small vessels that branch profusely in the walls of larger arteries and veins. Muscular distributing arteries are medium-sized vessels that are characterized by their predominance of circularly arranged smooth muscle cells in the media interspersed with a few elastin compo nents. Up to 40 layers of smooth muscle may occur. Both internal and external elastic limiting membranes are clearly demonstrated. The intima is thinner than that of the large arteries.
Arterioles are the smallest components of the arterial tree. Generally, any artery less than 0,5 mm in diameter is considered to be a small artery or arteriole. A subendothelial layer and the inter nal elastic membrane may be present in the largest of these vessels but are absent in the smaller ones. The media is composed of sev eral smooth muscle cell layers, and the adventitia is poorly devel oped. An external elastic membrane is absent.
New words
arteries – артерии
to be classified – классифицированный
according – соответственно
their – их
size – размер
appearance – вид
tunica – оболочка
major – главный
elastic – упругий
conducting – проведение
arteries – артерии
to include – включать
aorta – аорта
branches – ветви
up to – до
layers – слои
