Lymphatic System Overview

Bone marrow and thymus

Lymph nodes and spleen

Cardiovascular system

<p>The primary and secondary organs work together to transport excess tissue fluid to the bloodstream, transport dietary fat, and help defend the body against disease-causing agents.</p> Signup and view all the answers

<p>Lymphatic capillaries form afferent lymphatic vessels leading to lymph nodes. Efferent lymphatic vessels leave the lymph nodes, merge into lymphatic trunks, and then into two collecting ducts before joining the subclavian veins, where lymph enters the cardiovascular system.</p> Signup and view all the answers

<p>Lymphatic capillaries are microscopic, closed-end tubes that extend into interstitial spaces. They receive lymph through their thin walls, which are permeable to interstitial fluid.</p> Signup and view all the answers

<p>Anchoring filaments are delicate protein strands that attach lymphatic capillaries to surrounding cells. They play a crucial role in edema by allowing the gaps between cells to widen when interstitial fluid pressure increases, permitting more fluid to enter the lymphatic capillaries.</p> Signup and view all the answers

<p>Throughout the body, except in avascular tissues, the central nervous system, splenic pulp, and bone marrow.</p> Signup and view all the answers

<p>Lacteals are specialized lymphatic capillaries located within the villi of the small intestines. They absorb dietary fats and transport them to the bloodstream.</p> Signup and view all the answers

<p>Lymphatic vessels are formed by the merging of lymphatic capillaries. They have walls similar to veins, with valves that prevent backflow of lymph.</p> Signup and view all the answers

<p>Afferent lymphatic vessels carry lymph towards lymph nodes, serving as the entry points for lymph into these filtration stations.</p> Signup and view all the answers

<p>Efferent lymphatic vessels carry filtered lymph away from lymph nodes, continuing its journey towards the bloodstream.</p> Signup and view all the answers

<p>Lymphatic vessels merge into lymphatic trunks, larger vessels that drain lymph from specific body regions.</p> Signup and view all the answers

<p>Lymphatic trunks drain lymph from relatively large body regions, concentrating it before it enters the collecting ducts.</p> Signup and view all the answers

<p>Lumbar</p> Signup and view all the answers

<p>Lymphatic trunks join one of two collecting ducts that connect to the subclavian veins, allowing lymph to enter the bloodstream.</p> Signup and view all the answers

<p>The right lymphatic duct and the thoracic (left) lymphatic duct.</p> Signup and view all the answers

<p>The right lymphatic duct drains the right upper body, encompassing approximately 25% of the total body.</p> Signup and view all the answers

<p>The thoracic (left) lymphatic duct drains the remaining 75% of the body's lymph, covering the left side of the body and lower extremities.</p> Signup and view all the answers

<p>The collecting ducts join the subclavian veins, allowing the filtered lymph to flow into the venous circulation.</p> Signup and view all the answers

<p>Tissue fluid is blood plasma that passes through the walls of cardiovascular capillaries into interstitial spaces, minus large plasma proteins.</p> Signup and view all the answers

<p>Plasma is primarily composed of water, but also contains dissolved substances including small plasma proteins, nutrients, wastes, gases, electrolytes, enzymes, and hormones.</p> Signup and view all the answers

<p>As the protein concentration in interstitial spaces increases, the pressure builds up, forcing fluid into the lymphatic capillaries, forming lymph.</p> Signup and view all the answers

<p>Lymph formation prevents the accumulation of excess tissue fluid, which can lead to edema (swelling).</p> Signup and view all the answers

<p>Lymph is typically under low pressure.</p> Signup and view all the answers

<p>The squeezing of skeletal muscles and one-way valves within lymphatic vessels contribute to lymph flow, despite its low pressure.</p> Signup and view all the answers

<p>The low pressure created in the thoracic cavity by breathing movements helps move lymph upwards.</p> Signup and view all the answers

<p>Edema is the accumulation of excess interstitial fluid, leading to swelling of tissues. It can be caused by obstruction of lymphatic vessels, such as removal of lymph nodes.</p> Signup and view all the answers

<p>Tissue swelling pulls on anchoring filaments, making openings between cells even larger, allowing more fluid to flow into the lymphatic capillary, thus reducing swelling.</p> Signup and view all the answers

<p>Other causes of edema can include inflammation, heart failure, and kidney disease.</p> Signup and view all the answers

<p>Diffuse lymphatic tissue is lymphatic tissue that is not encapsulated; it is found in the submucosa of mucous linings.</p> Signup and view all the answers

<p>MALT stands for Mucosa Associated Lymphoid Tissue; it is found throughout the digestive, respiratory, urinary, and reproductive tracts.</p> Signup and view all the answers

<p>Lymphatic nodules are dense, oval-shaped aggregations of diffuse lymphatic tissue. They form structures like tonsils, the appendix, and Peyer's patches within the body.</p> Signup and view all the answers

<p>A lymphatic nodule is diffuse lymphatic tissue compressed into a solitary, oval-shaped mass, exemplified by tonsils.</p> Signup and view all the answers

<p>Primary lymphatic organs, such as red bone marrow and the thymus, are the sites of production and maturation of immunocompetent cells, B cells, and T cells, which carry out an immune response.</p> Signup and view all the answers

<p>Secondary lymphatic organs, such as lymph nodes and the spleen, are the sites where most immune responses occur.</p> Signup and view all the answers

<p>Lymph nodes are located along lymphatic pathways and contain lymphocytes and macrophages. Lymphatic vessels, including afferent and efferent vessels, connect to the lymph nodes.</p> Signup and view all the answers

<p>Lymph nodes are usually less than 2.5 cm in size and have a bean-like shape, with blood vessels, nerves, and efferent lymphatic vessels attached to a specific indentation called the hilum.</p> Signup and view all the answers

<p>The hilum is an indented region located on the lymph node where blood vessels, nerves, and efferent lymphatic vessels connect.</p> Signup and view all the answers

<p>Afferent lymphatic vessels connect to the concave surface of lymph nodes, bringing lymph for filtration.</p> Signup and view all the answers

<p>The outer region of a lymph node is called the cortex and contains germinal centers, which are densely packed with B cells and macrophages, embedded in spaces called nodules.</p> Signup and view all the answers

<p>Medullary cords are spaces within the medulla of a lymph node where lymph flows, allowing for interaction with immune cells during filtration.</p> Signup and view all the answers

<p>Lymph flows through lymph nodes in a one-way direction. It enters the node via afferent lymphatic vessels, flows through sinuses (spaces between medullary cords), and exits the node via efferent lymphatic vessels at the hilum.</p> Signup and view all the answers

<p>Primary locations for lymph nodes include the cervical (neck), axillary (armpit), supratrochlear (elbow), and inguinal (groin) regions.</p> Signup and view all the answers

<p>Secondary locations for lymph nodes include the pelvic, abdominal, and thoracic cavities.</p> Signup and view all the answers

<p>The main function of lymph nodes is the removal and destruction of potentially harmful foreign particles from lymph.</p> Signup and view all the answers

<p>Foreign materials are destroyed in lymph through phagocytosis, a process where macrophages engulf and digest foreign particles.</p> Signup and view all the answers

<p>The thymus is a soft, bilobed organ located within the mediastinum. Its size decreases after puberty.</p> Signup and view all the answers

<p>The thymus is composed of lymphatic tissue that is subdivided into lobules. Each lobule has an outer cortex and a central medulla.</p> Signup and view all the answers

<p>The outer cortex of a thymus lobule is densely packed with lymphocytes and stains dark, while the central medulla is light staining and contains swirled epithelial cells called Hassall's corpuscles.</p> Signup and view all the answers

<p>The thymus is the site of maturation of T cells, which leave the thymus and provide immunity.</p> Signup and view all the answers

<p>Immature T cells migrate from red bone marrow to the thymus via blood, where they undergo maturation and differentiation.</p> Signup and view all the answers

<p>Thymosin is a hormone secreted by epithelial cells in the thymus that stimulates the further maturation of T cells after they leave the thymus and migrate to other lymphatic tissues.</p> Signup and view all the answers

<p>The spleen is an organ located in the upper left portion of the abdominal cavity, behind the stomach. It resembles a large lymph node.</p> Signup and view all the answers

<p>The two types of tissue found in the spleen are white pulp and red pulp.</p> Signup and view all the answers

<p>White pulp consists of lymphocytes arranged around central arteries, forming areas of immune activity within the spleen.</p> Signup and view all the answers

<p>The spleen is responsible for the removal and destruction of foreign particles and worn blood cells from the blood. B cells within the spleen can differentiate into plasma cells, generating antibodies for immune responses.</p> Signup and view all the answers

<p>Pathogens are viruses and microorganisms, such as bacteria, fungi, protozoans, and parasites, that cause disease.</p> Signup and view all the answers

<p>The body uses two main types of defense mechanisms: innate (nonspecific) resistance and adaptive (specific) resistance.</p> Signup and view all the answers

<p>Innate resistance, also known as nonspecific resistance, is the body's first and second lines of defense against a wide range of pathogens.</p> Signup and view all the answers

<p>Fever</p> Signup and view all the answers

<p>Species resistance is a phenomenon where different species of organisms have varying levels of resistance to specific diseases. Each species may be susceptible to certain diseases but resistant to others.</p> Signup and view all the answers

<p>Mechanical barriers, like the skin and mucous membranes, act as physical barriers to prevent the entrance of pathogens into the body, as long as they remain unbroken.</p> Signup and view all the answers

<p>Inflammation is a tissue response to injury characterized by redness, swelling, heat, and pain. It involves dilation of blood vessels, increased capillary permeability, the attraction of white blood cells, clot formation, and the arrival of fibroblasts to limit the spread of pathogens.</p> Signup and view all the answers

<p>Chemical barriers are substances like enzymes, acids, salts, defensins, collectins, complement, and interferons that provide protection from pathogens.</p> Signup and view all the answers

<p>Enzymes such as pepsin in gastric juices can be lethal to many pathogens. Lysozyme found in tears has antibacterial action.</p> Signup and view all the answers

<p>The low pH environment of the stomach, due to gastric acid, prevents the growth of some bacteria.</p> Signup and view all the answers

<p>The high salt concentration in perspiration kills some bacteria.</p> Signup and view all the answers

<p>Defensins are antimicrobial peptides that destroy bacteria by creating holes in their cell walls or membranes.</p> Signup and view all the answers

<p>Collectins are proteins that attach to microbes, making pathogens more easily phagocytized by immune cells.</p> Signup and view all the answers

<p>Complement is a system of 11 proteins that can lyse infected cells, directly destroy pathogens, and attract phagocytic cells to the site of infection.</p> Signup and view all the answers

<p>Interferons are hormone-like peptides produced by certain infected cells in response to viral infections. They interfere with viral proliferation, preventing the spread of viruses.</p> Signup and view all the answers

<p>Natural killer cells, or NK cells, are a type of lymphocyte that kills infected cells or cancerous cells without requiring prior sensitization to a specific antigen. They are part of the innate immune system's arsenal.</p> Signup and view all the answers

<p>Phagocytosis is a process where cells engulf and destroy foreign particles, such as bacteria or other pathogens. Neutrophils and monocytes are the most active phagocytes in blood.</p> Signup and view all the answers

<p>Chemotaxis is the process where chemical signals from damaged tissues attract phagocytic cells to the site of injury or infection, allowing them to reach the area where they are needed.</p> Signup and view all the answers

<p>Fever is caused by the release of interleukin I, a chemical produced by lymphocytes in response to pathogens, and can also be triggered by exposure to heat, UV light, acids, or bases.</p> Signup and view all the answers

<p>Interleukin I is a chemical produced by lymphocytes that raises body temperature, contributing to fever.</p> Signup and view all the answers

<p>The liver and spleen sequester iron, reducing the level of iron in the blood. Iron is essential for the growth and survival of many bacteria and fungi, so reducing iron levels helps to inhibit their proliferation.</p> Signup and view all the answers

<p>Adaptive resistance, also known as specific resistance, is the body's third line of defense, providing protection against particular disease-causing agents.</p> Signup and view all the answers

<p>The two main branches of adaptive defenses are humoral immunity (mediated by B cells) and cellular immunity (mediated by T cells).</p> Signup and view all the answers

<p>The body distinguishes between self proteins (proteins present within its own tissues) and foreign (non-self) antigens. When non-self antigens enter the body, they bind to B and T cell receptors, triggering an immune response. This response involves the production of antibodies that specifically target the foreign antigen, leading to its elimination.</p> Signup and view all the answers

<p>Lymphocytes originate from red bone marrow and are released into the bloodstream before they differentiate into B cells or T cells.</p> Signup and view all the answers

<p>Undifferentiated lymphocytes travel to the thymus where they mature into T cells.</p> Signup and view all the answers

<p>B cells are undifferentiated lymphocytes that are processed in the bone marrow, becoming fully functional B cells.</p> Signup and view all the answers