58. Answer the questions:

1. What can you call the upper and the lower jaws?

2. What is the hard palate?

3. What is known as antrum?

4. What may take place during extraction of premolars and molars?

5. Which jaw is movable?

6. What joint allows the lower jaw to move?

7. What teeth cut the food into smaller pieces?

8. What is chewing brought about by?

59. Translate the sentences.

a) 1. Верхняя челюсть неподвижна. 2. Твердое нёбо отделяет рот от носа. 3. Дно гайморовой пазухи находится как раз над корнями моляров. 4. Верхняя челюсть имеет вид подковы. 5. Место соединения тела и ветви называется углом нижней челюсти. 6. Мышцы, открывающие рот, прикреплены к телу нижней челюсти. 7. Жевание осуществляется вращательными движениями нижней челюсти. 8. Все движения челюстей осуществляются жевательными мышцами.

b) - Как еще называют верхнюю и нижнюю челюсть?

- В латинской терминологии они называются «maxilla» и «mandible».

- Какая из них неподвижна?

- Верхняя, так как крепится к черепу.

- А нижняя?

- Она подвижна благодаря височно-нижнечелюстному суставу.

- Спасибо.

60. Ask 10 questions based on the text “The jaws” and answer them (work in pairs).

61. Give a summary of the text “The jaws”.

62. Guess the meanings of the following words. Practice their pronunciation.

osseous [’ɔsiəs] osteocyte [’ɔstiə‚sait]

osteoblast [’ɔstiə‚blæst] ossification[‚ɔsifi’kei∫(ə)n]

fetus [’fi:təs] embryo [’embriəu]

calcium [’kælsiəm] diaphysis [dai’æfisis]

epiphysis [e’pifisis] periosteum [‚peri’ɔstiəm]

articular [a:’tikjulə] cancellous [’kænsələs]

medullary [’medələri] haversian canal [hə’və:∫n kə’næl]

enzyme [’enzaim] oxygen [’ɔksidʒən]

nutrient [’nju:triənt] membrane [’membrein]

sesamoid [’sesəmɔid] carbon dioxide [’ka:bən dai’ɔksaid]

63. Learn the words from the Vocabulary List 3:

Vocabulary List 3

dense [’dens] a плотный

lack [læk] n недостаток; отсутствие (чего-л.)

deposit [di’pɔzit] n отложение

mature [mə’tjuə] a зрелый

amount [ə’maunt] n количество

replacement [ri’pleismənt] n замена, замещение

split [split] v расщеплять

surface [’sə:fis] n поверхность

layer [’leiə] n слой

spongy [’spÙndʒi] a губчатый, спонгиозный

bone marrow [’mærəu] - костный мозг

flat [flæt] a плоский

broad [brɔ:d] a широкий

64. Read and translate the word combinations:

Sesamoid bones, medullary cavity, cancellous bone, osseous tissue, to consist of osteocytes, intercellular substance, a dense connective tissue, a lack of calcium salts, immature bone cells, a proper supply of calcium, a sufficient [sə’fi∫(ə)nt] amount of vitamin D, irregular shapes, more flexible and less dense, to be filled with calcium salts, calcium deposits, to bring oxygen and nutrients, various stages of development, red bone marrow, to split substances, to produce enzymes, more porous and less dense, large surface, articular cartilage, a layer of hard tissue.

65. Read the text for general understanding. Pay attention to the first sentence of each paragraph. Make the plan of the text. Bones. Formation and Structure

Bones are complete organs, chiefly composed of connective tissue called osseous (bony) tissue plus a rich supply of blood vessels and nerves. Osseous tissue is a dense connective tissue which consists of osteocytes (bone cells) surrounded by a hard, intercellular substance filled with calcium salts.

During fetal development, the bones of the fetus are composed of cartilage tissue, which resembles osseous tissue but is more flexible and less dense because of a lack of calcium salts in its intercellular spaces. As the embryo develops, the process of depositing calcium salts in the soft, cartilaginous bones occurs, and continues throughout the life of the individual after birth. The gradual replacement of cartilage and its intercellular substance by immature bone cells (osteoblasts) and calcium deposits is called ossification (bone formation).

The formation of bone is dependent to a great extent on a proper supply of calcium and phosphorus to the bone tissue. These minerals must be taken into the body along with a sufficient amount of vitamin D. Vitamin D helps the passage of calcium through the lining of the small intestine and into the bloodstream. Once calcium and phosphorus are in the bones, osteoblastic activity produces an enzyme which splits phosphorus substances and causes the formation of a calcium-phosphate compound giving bone its characteristic hard quality.

Bones all over the body are of several different types. Long bones are found in the thigh, lower leg, upper and lower arm. These strong bones are broad at the ends where they join with other bones, and have large surface areas for muscle attachment.

Short bones are found in the wrist and ankle and have small, irregular shapes. Flat bones are found covering soft body parts. These are the shoulder bone, ribs and pelvic bones. Sesamoid bones are small, rounded bones. They are found near joint; the kneecap is the largest example of this type of bone.

The middle region of a long bone is called the diaphysis. Each end of a long bone is called an epiphysis.

The periosteum is a strong, fibrous, vascular membrane that covers the surface of a long bone, except at the ends of the epiphyses. Bones other than long bones are completely covered by the periosteum as well. Beneath the periosteum is the layer of immature cells (osteoblasts).

The ends of long bones are covered by a thin layer of cartilage called articular cartilage. This layer cushions the bones at the place where they meet with other bones (joints).

Compact (cortical) bone is a layer of hard, dense tissue which lies under the periosteum in all bones and chiefly around the diaphysis of long bones. Within the compact bone is a system of small canals called haversian canals. They are filled with blood vessels which bring oxygen and nutrients to the bone and remove waste product such as carbon dioxide. Compact bone is tunneled out in the diaphysis of long bones by a central medullary cavity which contains yellow bone marrow.

Cancellous bone, sometimes called spongy bone, is much more porous and less dense than compact bone. This bone tissue is found in the epiphyses of long bones and in the middle portion of most other bones. Spaces in cancellous bone contain red bone marrow. This marrow, as opposed to yellow marrow which is fatty tissue, is richly supplied with blood and consists of immature and mature blood cells in various stages of development.

In an adult, the ribs, pelvic bone, sternum, vertebrae, as well as the epiphysis of long bones, contain red bone marrow within cancellous tissue.