Biological Sciences
Lymphatic System
The lymphatic system is a network of tissues and organs that help rid the body of toxins, waste, and other unwanted materials. It also plays a key role in the body's immune system by producing and transporting white blood cells to fight off infections. Lymphatic vessels, lymph nodes, and lymphatic organs such as the spleen and thymus are all part of this system.
Written by Perlego with AI-assistance
Related key terms
1 of 5
11 Key excerpts on "Lymphatic System"
- Jassin M. Jouria(Author)
- 2018(Publication Date)
- BrownWalker Press(Publisher)
The lymphatic and immune systems work together to protect the body against numerous assaults from viral, fungal, bacterial, parasitic, and environmental dangers. For this reason, we’ll be discussing both in this chapter.The Lymphatic System is an immense and extremely complex network of components that includes capillaries, and blood vessels, valves, ducts, nodes, and entire organs not only responsible for the maintenance of internal environments including fluid balances, but protection against internal invaders.The Lymphatic System is also responsible for the production, filtering capabilities, and transportation of lymph and other blood components in the body. It also plays a role in the transportation of proteins, fats and other substances within the blood system.The lymphatic network is capable of restoring approximately 60% of fluids that are filtered from the capillaries and interstitial spaces. This is a process of normal metabolism.1This chapter provides an introduction and brief overview of lymph system function, including how it circulates and filters, and how lymph is interconnected with the immune system. Further exploration of the immune system will provide students with a solid foundation regarding the function of the immune system and the inborn and adaptive types of immunity.- ■ Overview of the Lymph System
In the previous chapter, students learned about blood and its components. In a progressive study of human anatomy and physiology, the inter-connection between the blood and the lymph system is required. While most associate the Lymphatic System as limited to its ability to fight infection, it’s closely linked with the cardiovascular system, and in turn, to blood, bone marrow, and organs and glands such as the spleen and thymus. The connections or network of this combination of vessels and their functions creates an incredibly interwoven network of vessels that perform a huge number of complex functions.In the last chapter, a description of blood and the vascular channels it travels through were introduced. As previously mentioned, blood commonly contacts fluids found outside of vascular walls, in particular with fluids which exit or leak through the thin walls of blood vessels. This contact introduces many of these fluids with tissue cells called lymph.
eBook - PDF- Ann Scott, Elizabeth Fong(Authors)
- 2018(Publication Date)
- Cengage Learning EMEA(Publisher)
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 298 CHAPTER 15 The Lymphatic and Immune Systems The Lymphatic System can be considered a supplement to the circulatory system. It is composed of lymph, lymph vessels, lymph nodes, tonsils, spleen, thymus gland, Peyer’s patches, lacteals, and lymphoid tissue (See Medical Highlights 15-1). Unlike the circulatory system, it has no muscular pump or heart (Figure 15-1). Figure 15-1 The vessels and organs of the Lymphatic System Tonsils Lymph vessels Thymus Spleen Peyer’s patches Small intestine Lymph nodes Copyright 201 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. CHAPTER 15 The Lymphatic and Immune Systems 299 Functions of the Lymphatic System 1. Interstitial fluid and lymph act as an intermediary between the blood in the capillaries and the tissue. 2. Lymph vessels transport the excess filtered tissue fluid back into the circulatory system. 3. Lymph nodes and organs produce lymphocytes to destroy invading bacteria. 4. Lacteals absorb fat and fat-soluble vitamins. 5. Spleen produces lymphocytes and monocytes 6. Thymus gland produces T lymphocytes 7. Lacteals, specialized lymph capillaries in villi of small intestine, absorb digested fat. Interstitial Fluid and Lymph Interstitial fluid (in-ter-STISH-al) acts as the inter- mediary between the blood in the capillaries and the tissue.
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
In this chapter, we explore the mechanisms that provide defenses against intruders and promote the repair of damaged body tissues. Checkpoint 1. What is a pathogen? 2. Now are innate and adaptive immunity different? 22.2 Overview of the Lymphatic System OBJECTIVES • List the components of the Lymphatic System. • Describe the functions of the Lymphatic System. Components of the Lymphatic System The lymphatic or lymphoid system (lim-FAT-ik) consists of a fluid called lymph, vessels called lymphatic vessels that transport the lymph, a number of structures and organs containing lymphatic tis- sue (lymphocytes within a filtering tissue), and red bone marrow (Fig- ure 22.1). The Lymphatic System assists in circulating body fluids and helps defend the body against disease-causing agents. As you will see shortly, most components of blood plasma filter through blood capil- lary walls to form interstitial fluid. After interstitial fluid passes into lymphatic vessels, it is called lymph (LIMF = clear fluid). The major difference between interstitial fluid and lymph is location: Interstitial fluid is found between cells, and lymph is located within lymphatic vessels and lymphatic tissue. Lymphatic tissue is a specialized form of reticular connective tis- sue (see Table 4.4) that contains large numbers of lymphocytes. Re- call from Chapter 19 that lymphocytes are agranular white blood cells (see Section 19.4). Two types of lymphocytes participate in adaptive immune responses: B cells and T cells (described shortly). Functions of the Lymphatic System The Lymphatic System has three primary functions: 1. Drains excess interstitial fluid. Lymphatic vessels drain excess in- terstitial fluid from tissue spaces and return it to the blood. This function closely links it with the cardiovascular system. In fact, without this function, the maintenance of circulating blood volume would not be possible.
eBook - PDF- Jonathan Bubb(Author)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
667 Chapter 11 The Lymphatic System Chapter Introduction The Lymphatic System could be mistaken for a subdivision of the cardiovascular system, as it plays a very important role in returning fluids to the cardiovascular system. Aside from helping flu- ids and small solutes return to the cardiovascular system, the Lymphatic System transports lipids from the site of absorption in the GI system back to the bloodstream and assists the immune system in the defense of our body against disease. UNIT INTRODUCTION As we progress through this unit, we explore the structure of the Lymphatic System, how this structure impacts the physiological actions of the system, and how it interacts with other organ systems. Lymphatic vessels are struc- turally very similar to veins, as they have thin walls, contain valves, and carry fluid under low pressure. As they carry this fluid back toward the heart, they have a similar function to veins. However, you will discover as we move through this unit that the Lymphatic System has other important functions as well. The vessels and organs comprising the Lymphatic System are seen in Figure 11-1. SECTION 5 Lymphatic and Immune Systems UNIT OBJECTIVE 11.1 Identify the structural components and functions of the Lymphatic System. Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 668 Chapter 11 The Lymphatic System KEY TERMS colloid Substance that is dispersed evenly throughout another substance. edema Localized area of excess fluid. immunity Body’s ability to defend itself.
- Wael Khamas, Josep Rutllant(Authors)
- 2024(Publication Date)
- Wiley-Blackwell(Publisher)
The functions of the Lymphatic System are (i) carrying large molecules from the interstitial tissue back to the gen- eral circulation, acting as a transporter of lipids from the intestinal villi (lacteal), (ii) collecting waste substance from the interstitial spaces, and (iii) playing a role in controlling infection because of its immune function. However, the immune response should be considered the main function in most other body systems in addition to removing the waste substances. The absence of lymph nodes in chicken influenced the distribution of dendritic and macrophages along with cer- tain body systems. Many macrophages and dendritic cells are usually present in the mucosa of the avian large air- ways. The airflow within the chicken respiratory system influences the deposition of antigen along the course of the inspired air. This dictates the distribution of macrophages and dendritic cells accordingly (de Geus and Vervelde 2013). Terms used within this chapter followed the Handbook of Avian Anatomy as close as possible (Baumel et al. 1979). 11.2 Cells of the Lymphatic System 11.2.1 Lymphocytes All lymphocytes are white blood cells (leukocytes) and are also called agranulocytes because they lack granules within their cytoplasm. They comprise 75% of the circulating leukocyte count in normal domestic fowl (Lucus and Jamroz 1961). Lymphocytes, in general, are rounded with a large nucleus occupying most of the cell. One can hardly see a small rim of cytoplasm surrounding the nucleus under the light microscope. Cell nuclei, in general, have either compact dark chromatin (heterochromatin) or less compact lightly stained chromatin (euchromatin). Lymphocyte in circulation and in organs when not acti- vated has compact dark heterochromatin. This kind of chromatin indicates inactivity while the euchromatin is present within the active cells like the proliferating B cells inside the germinal center (Figure 11.1).
eBook - PDF- Craig Freudenrich, Gerard J. Tortora(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
These materials do not dissolve well in the watery plasma, so sending them to the blood via the Lymphatic System helps slow their entry into the blood sup- ply and allows them to be dispersed more evenly through- out the body. Finally, the Lymphatic System contains various cells that participate in immune responses. These cells are lymphocytes, a type of white blood cell, as discussed in Chapter 10. Specifically, the lymph system uses T lympho- cytes (T cells) and B lymphocytes (B cells) in its immune response to fight foreign cells (such as bacteria, fungi, and viruses), other foreign substances, and abnormal cells. The Lymphatic System Consists of Lymph, Lymphatic Vessels, and Several Structures and Organs Like the blood vessels of your cardiovascular system, the Lymphatic System is a type of vascular system for moving fluid. It consists of lymph, lymphatic vessels, a number of structures containing lymphatic tissue, and red bone mar- row. Figure 12.1 is an overview of the system; we will dis- cuss some of the structures shown in Figure 12.1 in more detail in the sections that follow. Lymphatic vessels begin as lymphatic capillaries (see Figure 12.2). These tiny vessels begin in the tissues and carry the fluid that forms there. They are closed at one end and located in the spaces between cells. Lymphat- ic capillaries are slightly larger than blood capillaries and are uniquely structured to permit interstitial fluid to flow into—but not out—of them. The endothelial cells that make up the wall of a lymphatic capillary are not attached end to end; rather, the ends overlap, like roof shingles. Just as blood capillaries unite to form venules and veins, lymphatic capillaries unite to form larger and larger lymphatic vessels. Lymphatic vessels resemble veins in structure but have thinner walls and more valves. Once in- terstitial fluid enters lymphatic vessels, it is called lymph. From the lymphatic vessels, lymph eventually passes into one of two main channels.
- Andrew Kuntzman, Gerard J. Tortora(Authors)
- 2015(Publication Date)
- Wiley(Publisher)
24.2 Lymphatic System STRUCTURE AND FUNCTION O B J E C T I V E S • Describe the components and major functions of the lym- phatic system. • Describe the organization of lymphatic vessels and the cir- culation of lymph. • Compare the structure and functions of the primary and secondary lymphatic organs and tissues. The body system responsible for adaptive immunity (and some aspects of innate immunity) is the Lymphatic System (lim-FAT- ik), which consists of lymph, lymphatic vessels, a number of structures and organs containing lymphatic tissue (Figure 24.1), and red bone marrow, where stem cells develop into various types of blood cells, including lymphocytes (B cells and T cells). Lymphatic tissue is a specialized form of reticular connective tissue (see Table 4.4c, Section 4.4) that contains large numbers of lymphocytes. Most components of blood plasma filter out of blood capillary walls to form interstitial fluid, the fluid that surrounds the cells of body tissues. After interstitial fluid passes into lymphatic ves- sels, it is called lymph (LIMF clear fluid). Both fluids are chemically similar to blood plasma. The main difference is that interstitial fluid and lymph contain less protein than blood plasma because most plasma protein molecules are too large to filter through the capillary wall. Each day, about 20 liters of fluid filter from blood into tissue spaces. This fluid must be returned to the cardiovascular system to maintain normal blood volume. About 17 liters of the fluid filtered daily from the arterial end of blood capillaries return to the blood directly by reabsorption at the venous end of the capillaries. The remaining 3 liters per day pass first into lymphatic vessels and are then returned to the blood. The Lymphatic System has three primary functions: 1. Draining excess interstitial fluid. Lymphatic vessels drain excess interstitial fluid and leaked proteins from tissue spaces and return them to the blood.
No longer available |Learn more- Ann Scott, Elizabeth Fong(Authors)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
Unlike the circulatory system, it has no muscular pump or heart (Figure 15-1). Figure 15-1 The vessels and organs of the Lymphatic System Tonsils Lymph vessels Thymus Spleen Peyer’s patches Small intestine Lymph nodes Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. CHAPTER 15 The Lymphatic and Immune Systems 299 Functions of the Lymphatic System 1. Interstitial fluid and lymph act as an intermediary between the blood in the capillaries and the tissue. 2. Lymph vessels transport the excess filtered tissue fluid back into the circulatory system. 3. Lymph nodes and organs produce lymphocytes to destroy invading bacteria. 4. Lacteals absorb fat and fat-soluble vitamins. 5. Spleen produces lymphocytes and monocytes 6. Thymus gland produces T lymphocytes 7. Lacteals, specialized lymph capillaries in villi of small intestine, absorb digested fat. Interstitial Fluid and Lymph Interstitial fluid (in-ter-STISH-al) acts as the inter- mediary between the blood in the capillaries and the tissue. It is similar in composition to blood plasma; it diffuses from the capillaries into the tissue spaces. Because the fluid fills the surrounding spaces between tissue cells, it is also referred to as intercellular fluid. Interstitial fluid is composed of water, lymphocytes, some granulocytes, digested nutrients, hormones, salts, carbon dioxide, and urea. It does not contain red blood cells or protein molecules, which are too large to diffuse through the capillaries. Interstitial fluid also carries metabolic waste products (carbon dioxide, urea wastes) away from the cells and back into the capillaries for excretion. Most of the fluid is reabsorbed into the capillaries by dif- ferences in osmotic pressure. Some of the fluid enters lymph capillaries and is now called lymph (LIMF).
No longer available |Learn moreVeterinary Anatomy of Domestic Animals
Textbook and Colour Atlas
- Horst Erich König, Hans-Georg Liebich, Horst Erich König, Hans-Georg Liebich(Authors)
- 2020(Publication Date)
- Thieme(Publisher)
14 Immune system and lymphatic organs (organa lymphopoetica) H. E. König, P. Paulsen and H.-G. Liebich The immune system provides specific and non-specific defence mechanisms to protect the body against environmental influ-ences. It is therefore vital in maintaining the animal ’ s health. The immune system can be divided into cellular and vascular compo-nents. The cellular component includes the lymphatic tissue found as single cells, which are di ff usely dispersed within tissues, as aggregations of lymphatic cells (tonsils) or in lymphatic organs (thymus, lymph nodes and spleen). Circulating components in-clude lymphocytes, monocytes, and plasma cells, which are found in lymphatic organs, blood, tissue spaces and the lymph stream. The lymphatic vascular system includes lymph capillaries , lymph vessels and lymph collecting ducts . The thymus plays an essential role in the development of the lymphatic cellular components by controlling growth of the lym-phatic organs in immature animals. Lymphocytes ( ▶ Fig. 14.1) are the predominant cell type of the immune system, and can be divided into B and T lymphocytes . They are formed within the bone marrow and lymphatic organs and are distributed within the lymphatics and in blood. Their cell surface is marked by specific receptors, with which they are able to recognise and bind molecules and trigger a chain of reactions, which leads to a specific immune response . Macrophages are part of the mononuclear phagocytosis sys-tem (MPS) , which is responsible for the non-specific immune re-sponse. This system also comprises the alveolar macrophages of the lung, Langerhans cells of the skin, mesoglia in the central nervous system, and the endothelium of the liver, spleen and bone marrow sinusoids. Formerly the MPS was referred to as the reticuloendothelial system (RES).
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
4. Adaptive immunity involves activation of specific lymphocytes to combat a particular foreign substance. 22.2 Lymphoid System Structure and Function 1. The lymphoid system carries out immune responses and consists of lymph plasma, lymphatic vessels, and structures and organs that contain lymphoid tissue (specialized reticular tissue containing many lymphocytes). 2. The lymphoid system drains interstitial fluid, transports dietary li- pids, and protects against invasion through immune responses. 22.3 Lymphatic Vessels and Lymph Circulation 1. Lymphatic vessels begin as closed-ended lymphatic capillaries in tissue spaces between cells. Interstitial fluid drains into lymphatic 888 CHAPTER 22 The Lymphoid (Lymphatic) System and Immunity capillaries, thus forming lymph plasma. Lymphatic capillaries merge to form larger vessels, called lymphatic vessels, which convey lymph plasma into and out of lymph nodes. 2. The route of lymph plasma flow is from lymphatic capillaries to lymphatic vessels to lymph trunks to the thoracic duct and right lym- phatic duct to the subclavian veins. 3. Lymph plasma flows because of skeletal muscle contractions and respiratory movements. Valves in lymphatic vessels also aid flow of lymph plasma. 22.4 Lymphoid Organs and Tissues 1. The primary lymphoid organs are red bone marrow and the thy- mus. Secondary lymphoid organs are lymph nodes, the spleen, and lymphatic nodules. 2. The thymus lies between the sternum and the large blood vessels above the heart. It is the site of T cell maturation. 3. Lymph nodes are encapsulated, egg-shaped structures located along lymphatic vessels. Lymph plasma enters lymph nodes through af- ferent lymphatic vessels, is filtered, and exits through efferent lymphat- ic vessels. Lymph nodes are the site of proliferation of B cells and T cells. 4. The spleen is the largest single mass of lymphoid tissue in the body.
- Helga Fritsch, Wolfgang Kuehnel(Authors)
- 2011(Publication Date)
- Thieme(Publisher)
384 Blood and Lymphatic Systems Lymphatic Organs Overview The lymphatic organs are important in the specific immune response (see p. 380 ff.) The primary lymphatic organs serve as the sites for production, development, and maturation of immune cells. Secondary lym-phatic organs are where immune cells en-counter foreign substances. Primary Lymphatic Organs Bone marrow. The bone marrow (see p. 376) contains lymphocyte stem cells (derived from hemocytoblasts) as well as precursor cells of the mononuclear phagocyte system (MPS). Thymus. The role of the thymus is para-mount in the development of the immune system (see p. 386). Secondary Lymphatic Organs Lymphoepithelial organs. These include the pharyngeal tonsil , palatine tonsil , lingual tonsil , tubal tonsil at the opening of the audi-tory tube, and the lateral pharyngeal bands in the lateral and posterior walls of the pharynx (see p. 396). Mucosa-associated lymphoid tissue (MALT). This includes gut-associated lym-phoid tissue ( GALT ); intraepithelial lympho-cytes and lymphocytes of the lamina pro-pria; solitary lymph nodules within the lamina propria of the small intestine; aggre-gated lymphoid nodules (Peyer’s patches) within the lamina propria and submucosa of the small intestine and vermiform appen-dix (see p. 398); bronchus-associated lym-phoid tissue ( BALT ); lymphoid tissue of the urogenital system; palpebral conjunctiva and lacrimal drainage system. Skin-associated Lymphoid Tissue (SALT). Lymphoreticular organs . The lymphoretic-ular organs include the lymph nodes (see p. 390) and spleen (see p. 392). Structural Components Cellular elements. The lymphatic organs contain B and T lymphocytes; monocytes ( A ) and macrophages; polymorph nucleated granulocytes; mast cells ( B ) and plasma cells; and natural killer cells. Reticular connective tissue. This is a spe-cial form of connective tissue that contains few fibers.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
