Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2nding tissues as tissue fluid. Most of this fluid re-enters the capillaries at their venous ends. Some of it is, however, returned to the circulation through a separate system of lymphatic vessels (usually called lymphatics). The fluid passing through the lymphatic vessels is called lymph. The small Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2est lymphatic (or lymph) vessels are lymphatic capillaries that join together to form larger lymphatic vessels. The largest lymphatic vessel in the boEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
dy is the thoracic duct. It drains lymph from the greater part of the body. The thoracic duct ends by joining the left subclavian vein at its junction11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2hatic vessels there are numerous small bean-shaped structures called lymph nodes that are usually present in groups. Lymph nodes are masses of lymphoid tissue described below. As a rule lymph from any part of the body passes through one or more lymph nodes before entering the blood stream. (There ar Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2e some exceptions to this rule. For example, some lymph from the thyroid gland drains directly into the thoracic duct). Lymph nodes act as filters remEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
oving bacteria and other particulate matter from lymph. Lymphocytes are added to lymph in these nodes.Each group of lymph nodes has a specific area of11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2mphoid tissue are also found at various other sites. Two organs, the thymus and the spleen are almost entirely made up of lymphoid tissue. Prominent aggregations of lymphoid tissue are present in close relationship to the lining epithelium of the gut. Such aggregations present in the region of the p Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2harynx constitute the tonsils. Isolated nodules of lymphoid tissue, and larger aggregations called Peyer’s patches are present in the mucosa and submuEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
cosa of the small intestines (specially the ileum). The mucosa of the vermiform appendix contains abundant lymphoid tissue. Lymphoid tissue is seen in11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2n to the urinary tract.LymphLymph is a transudate from blood and contains the same proteins as in plasma, but in smaller amounts, and in somewhat different proportions. Suspended in lymph there are cells that are chiefly lymphocytes. Most of these lymphocytes are added to lymph as it passes through Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2lymph nodes, but some are derived from tissues drained by the nodes.Large molecules of fat (chylomicrons) that are absorbed from the intestines enterEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
lymph vessels. After a fatty meal these fat globules may be so numerous that lymph becomes milky (and is then called chyle). Under these conditions th11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2ries (or lymphatic capillaries) begin blindly in tissues where they form a network. The structure of lymph capillaries is basically similar to that of blood capillaries, but is adapted for much greater permeability. There is an inner lining of endothelium. The basal lamina is absent or poorly develo Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2ped. Pericytes or connective tissue are not present around the capillary.As compared to blood capillaries, much larger molecules can pass through theEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
walls of lymph capillaries. These include colloidal material, fat droplets, and particulate matter such as bacteria. It is believed that these substan11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2issues of the body. They are absent in avascular tissues (e.g.. the cornea, hair, nails); in the splenic pulp; and in the bone marrow. It has been held that lymphatics are not present in nervous tissue, but we now know that some vessels are present.Larger Lymph VesselsThe structure of the thoracic d Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2uct and of other larger lymph vessels is similar to that of veins. A tunica intima, media and adventitia can be distinguished. Elastic fibres are promEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
inent and can be seen in all three layers. The media, and also the adventitia contain some smooth muscle. In most vessels, the smooth muscle is arrang11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2ell as large lymphatic vessels. They are more numerous than in veins. The valves often give lymph vessels a beaded appearance.Acute inflammation of lymph vessels is called lymphangiitis. When this happens in vessels of the skin, the vessels are seen as red lines that are painful.Fig. 11.1. Diagram t Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2o show part of a network of lymphatic capillaries.Fig 11.2. Transverse section across the thoracic duct (drawing)190TEXTBOOK OF HUMAN HISTOLOGYLymph NEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
odesEach lymph node consists of a connective tissue framework; and of numerous lymphocytes, and other cells, that fill the interstices of the network.11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2the node on its convex aspect. Usually, a single lymph vessel leaves the node through its hilum.When a section through a lymph node is examined (at low magnification) it is seen that the node has an outer zone that contains densely packed lymphocytes, and therefore stains darkly: this part is the co Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2rtex. The cortex does not extend into the hilum. Surrounded by the cortex, there is a lighter staining zone in which lymphocytes are fewer: this areaEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
is the medulla (Fig. 11.3).Within the cortex there are several rounded areas that are called lymphatic follicles or lymphatic nodules. Each nodule has11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2ranching and anastomosing cords.We will now consider some of these constituents in greater detail.Fig 11.3. Section through a lymph node (Photomicrograph). 1-Cortex. 2, 3-Germinal center and outer zone of lymphatic follicle. 4-Medulla.LYMPHATICS AND LYMPHOID TISSUE191The Connective Tissue FrameworkA Ebook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2 lymph node is surrounded by a capsule. The capsule consists mainly of collagen fibres. Some elastic fibres and some smooth muscle may be present. A nEbook Textbook of human histology (With colour atlas and practical guide - 6th edition): Part 2
umber of septa (or trabeculae) extend into the node from the capsule and divide the node into lobules. The hilum is occupied by a mass of dense fibrou11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surroun11: Lymphatics and Lymphoid TissueIntroductory RemarksWhen circulating blood reaches the capillaries part of its fluid content passes into the surrounGọi ngay
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