Cells of the epidermis: keratinocytes are the most numerous and are responsible for the production of the family of keratin proteins that provide the barrier function of the epidermis.
Melanocytes are derivatives of neural crest ectoderm. They are found in the dermis and are also scattered among the keratinocytes in the basal layers of the epidermis. These dendritic cells produce the pigment melanin in the form melanosomes that are transferred to kerati-nocytes.
Langerhans cells are dendritic cells but are members of the immune system and function as antigen-presenting cells. They have also been found in other parts of the body, including the oral cavity and lymph nodes.
Merkel cells are found in the basal epidermis and appear function in concert with nerve fibers that are closely associated with them. At the electron microscopic level, their cytoplasm contains numerous membrane-bound granules that resemble those of catecholamine-pro-ducing cells.
New words
epidermis – эпидермис
dermis – дерма
largest – самый большой
approximately – приблизительно
weight – вес
to protect – защищать
injury – рана
cytoplasmic – цитоплазматический
several – несколько
level – уровень
flat – плоский
palm – ладонь
thick – толстый
pigment – пигмент
melanin – меланин
nerve – нерв
closely – тесно
Запомните следующие словосочетания, в которых артикль не употребляется.
1) at – school;
2) at – home;
3) at – work.
Вставьте артикль, где необходимо.
1. I have two… sisters. My… sisters are… students.
2. We are at… home.
3. My… brother is not at… home, he is at. school.
4. My. mother is at… work. She is… doctor.
5. I am not… doctor.
6. I have no… sisters.
7. He is not… pilot.
8. I have thirty-two… teeth.
9. He has. child.
10. She has two… children. Her children are at… school.
11. Is your father at… home? – No, he is at… work.
12. Where is your… brother? – He is at… home.
Answer the questions.
1. What is epidermis?
2. What is the largest body organ?
3. How many per cents does the integument comprise of total body weight?
4. What is the main function of the integument?
5. Where it also participates in?
6. What is the outermost layer of the integument?
7. What is stratum granulosum consists of?
8. Where is the a thin, transitional zone of flat eosinophilic?
9. What keratin proteins provide?
10. What cells produce the pigment melanin?
Make the sentences of your own using the new words (10 sentences).
Find the definite and indefinite articles in the text.
Find one word, which is a little bit different in meaning from others (найдите одно слово, которое немного отличается от других по смыслу):
1) a) rain; b) epidermis; c) dermis;
2) a) weight; b) person; c) poster;
3) a) palm; b) foot; c) shoes;
4) a) brush; b) pigment; c) skin;
5) a) lash; b) wound; c) injury.
ЛЕКЦИЯ № 4. Dermis
Dermis is a connective tissue layer of mesodermal origin subjacent the epidermis and its basement membrane. The dermis-epidermal junction, especially in thick skin, is characterized by numerous papillary interdigitations of the dermal connective tissue and epidermal epithelium. This increases the surface area of attachment and brings blood vessels in closer proximity to the epidermal cells. The epidemis, like epithelia in general, is devoid of blood vessel. Histologically, der-mis consists of two identifiable regions.
Papillary layer, associated principally with the dermal papillae, is the most superficial layer. It consists of a loosely packed, irregular meshwork of collagen fibrils that contain fine blood vessels and nerve endings.
Reticular layer is the deeper dermal layer and consists of coarse collagen bundles intertwined with elastic fibers in a gel matrix. This layer is a typical dense irregular connective tissue.
HYPODERMIS: this layer of loose vascular connective tissue is infiltrated with adipocytes and corresponds to the superficial fascia of gross anatomy. However, since it contains the deepest portions of the cutaneous glands and hairs, it is also an important part of the skin. The hypodermis fastens the skin to underlying muscles and other structures.
New words
dermis – дерма
connective – соединительный
membrane – мембрана
junction – соединение
to be characterized by – характеризоваться чем-то
numerous – значительный
to increase – увеличивать
surface – поверхность
area – площадь
bring – приносить
to consists of – состоять из
to contain – содержать
collagen – коллагеновый
Если перед существительным употребляется прилагательное, оно стоит между артиклем и существительным.
E. g. This is a book. This is a