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What is the primary function of the spleen?
What is the primary function of the spleen?
Which type of lymphocytes mature in the thymus?
Which type of lymphocytes mature in the thymus?
What is the structure surrounding each lobe of the thymus?
What is the structure surrounding each lobe of the thymus?
Where do lymphatic capillaries primarily remove fluid from?
Where do lymphatic capillaries primarily remove fluid from?
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What are the two types of pulp found in the spleen?
What are the two types of pulp found in the spleen?
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What structure prevents backflow in lymphatic vessels?
What structure prevents backflow in lymphatic vessels?
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What is referred to as chyle in the lymphatic system?
What is referred to as chyle in the lymphatic system?
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What distinguishes the cortex from the medulla in the thymus?
What distinguishes the cortex from the medulla in the thymus?
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What is the primary function of the spleen?
What is the primary function of the spleen?
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Where do pre-T cells mature into T cells?
Where do pre-T cells mature into T cells?
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Which of the following is NOT a characteristic of innate immunity?
Which of the following is NOT a characteristic of innate immunity?
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Which of the following is a function of lysozyme?
Which of the following is a function of lysozyme?
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What role do interferons play in immunity?
What role do interferons play in immunity?
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What is the primary difference between innate and acquired immunity?
What is the primary difference between innate and acquired immunity?
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Which cells circulate to and populate other lymphatic tissues?
Which cells circulate to and populate other lymphatic tissues?
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Which of the following is a physical barrier in innate immunity?
Which of the following is a physical barrier in innate immunity?
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What type of tonsils are located near the internal opening of the nasal cavity?
What type of tonsils are located near the internal opening of the nasal cavity?
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Which of the following structures surround each lymph node?
Which of the following structures surround each lymph node?
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What is the primary function of the germinal centers found within lymphatic nodules?
What is the primary function of the germinal centers found within lymphatic nodules?
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Which lymph nodes are specifically found in the groin area?
Which lymph nodes are specifically found in the groin area?
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What characterizes lymphatic tissue within lymph nodes?
What characterizes lymphatic tissue within lymph nodes?
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What distinguishes lymphatic nodules from lymph nodes?
What distinguishes lymphatic nodules from lymph nodes?
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What are lymphatic sinuses described as in relation to the lymphatic tissue?
What are lymphatic sinuses described as in relation to the lymphatic tissue?
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Which tonsils are commonly referred to as 'the tonsils'?
Which tonsils are commonly referred to as 'the tonsils'?
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What is the primary function of lymphatic capillaries in relation to fluid balance?
What is the primary function of lymphatic capillaries in relation to fluid balance?
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What happens to the fluid that cannot be absorbed back into the blood capillaries?
What happens to the fluid that cannot be absorbed back into the blood capillaries?
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How does lipid absorption occur in the lymphatic system?
How does lipid absorption occur in the lymphatic system?
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What characteristic of lymphatic capillaries allows easy entry of fluid?
What characteristic of lymphatic capillaries allows easy entry of fluid?
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What is the appearance of lymph after lipid absorption in the lymphatic vessels?
What is the appearance of lymph after lipid absorption in the lymphatic vessels?
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What is one role that lymph nodes play in the lymphatic system?
What is one role that lymph nodes play in the lymphatic system?
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Which statement about the movement of fluid in the lymphatic system is accurate?
Which statement about the movement of fluid in the lymphatic system is accurate?
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What can result from dysfunction in the lymphatic system related to fluid movement?
What can result from dysfunction in the lymphatic system related to fluid movement?
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What is the primary role of B cells in adaptive immunity?
What is the primary role of B cells in adaptive immunity?
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Which type of T cell is responsible for directly destroying infected or cancerous cells?
Which type of T cell is responsible for directly destroying infected or cancerous cells?
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What is the function of Major Histocompatibility Complex (MHC) molecules?
What is the function of Major Histocompatibility Complex (MHC) molecules?
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Where do B cells mature before they migrate to lymphatic tissue?
Where do B cells mature before they migrate to lymphatic tissue?
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What is the role of cytokines in adaptive immunity?
What is the role of cytokines in adaptive immunity?
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Which receptor type is found on the surface of T cells for antigen recognition?
Which receptor type is found on the surface of T cells for antigen recognition?
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Which type of T cell helps activate B cells?
Which type of T cell helps activate B cells?
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What is the purpose of the antigen receptors on lymphocytes?
What is the purpose of the antigen receptors on lymphocytes?
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Study Notes
Lymphatics Capillaries in Tissue
- The lymphatic system is responsible for maintaining fluid balance, absorbing lipids, and defending against pathogens.
- About 3 liters of fluid enter the lymphatic capillaries each day, which will not be reabsorbed into the blood, potentially leading to edema and tissue damage.
- This fluid is called lymph and is filtered by lymph nodes to remove pathogens.
Lymph Formation and Movement
- Fluid moves from blood capillaries into tissues, and from tissues into lymphatic capillaries, forming lymph.
- Overlapping epithelial cells of the lymphatic capillary allow fluid to enter easily but prevent its return to the tissues.
- Valves in the lymphatic vessels ensure unidirectional flow of lymph.
Parts of the Lymph Node
- Each lymph node is surrounded by a dense connective tissue capsule.
- Trabeculae extending from the capsule subdivide the lymph node into compartments containing lymphatic tissue and lymphatic sinuses.
- Lymphatic tissue consists of lymphocytes and other cells aggregated into lymphatic nodules.
- Lymphatic nodules containing rapidly dividing lymphocytes are called germinal centers.
- Lymphatic sinuses are spaces between the lymphatic tissue containing macrophages on a network of fibers.
Tonsils
- There are three groups of tonsils: palatine, pharyngeal, and lingual.
- Palatine tonsils, located on each side of the posterior opening of the oral cavity, are commonly called "the tonsils."
- Pharyngeal tonsils are located near the internal opening of the nasal cavity and are called adenoids when enlarged.
- Enlarged pharyngeal tonsils can interfere with breathing.
- Lingual tonsils are found on the posterior surface of the tongue.
Lymph Nodes
- Lymph nodes are rounded structures varying in size and located near lymphatic vessels.
- Lymph filters through lymph nodes before entering the blood.
- Superficial aggregations of lymph nodes are located in the groin (inguinal), axilla (armpit), and neck (cervical).
The Spleen
- The spleen filters blood instead of lymph.
- It has a capsule of dense connective tissue and a small amount of smooth muscle.
- Trabeculae from the capsule divide the spleen into compartments containing two types of lymphatic tissue: white pulp and red pulp.
- White pulp surrounds arteries and contains lymphocytes.
- Red pulp is associated with veins and is filled with macrophages, red blood cells, and enlarged capillaries connecting to the veins.
The Thymus
- The thymus is the site of T cell maturation.
- It is a bilobed gland located in the superior mediastinum, dividing the thoracic cavity into left and right parts.
- Each lobe of the thymus is surrounded by a connective tissue capsule, with trabeculae dividing it into lobules.
- Near the capsule and trabeculae, lymphocytes are numerous and form dark-staining areas called the cortex.
- The medulla, the lighter-staining central portion of the lobules, has fewer lymphocytes.
Overview of the Lymphatic System
- Lymphatic capillaries and vessels remove fluid from tissues.
- Lymph flows to lymphatic vessels with valves to prevent backflow.
- Lymph is filtered by lymph nodes and then flows back into the lymphatic vessels.
- Lymph from the right side of the body (upper extremity only) flows to the lymphatic duct; lymph from the left side flows to the thoracic duct.
- Both ducts drain into the subclavian vein, then into the superior vena cava (SVC), and finally into the heart.
- Specialized lymphatic vessels called lacteals in the small intestine absorb lipids, resulting in chyle due to its high lipid content.
- Chyle flows into the thoracic duct, then into the subclavian vein, SVC, and heart.
- The spleen filters blood and provides a site for lymphocyte response to infections.
- Pre-T cells originate in red bone marrow and migrate to the thymus for maturation into T cells.
- B cells develop and mature in red bone marrow, then circulate to other lymphatic tissues with T cells.
Immunity
- Immunity is the body's ability to resist damage from foreign substances.
- It provides protection against microbes, toxins, and cancer cells.
Types of Immunity
- Innate immunity is present at birth and defends against any pathogen.
- Adaptive immunity is acquired after birth and specifically recognizes antigens.
Innate Immunity
- Physical barriers like skin and mucous membranes act as the first line of defense.
- Chemical mediators include lysozyme, mucous membranes, histamine and interferons, all contributing to defense against pathogens.
- White blood cells (WBCs) are also part of innate immunity.
Adaptive Immunity
- Adaptive immunity is characterized by specific recognition and response to individual antigens.
Origin and Development of Lymphocytes
- Stem cells in red bone marrow give rise to all blood cells, including pre-T and pre-B cells.
- B cells mature in the red bone marrow and are responsible for antibody-mediated immunity.
- T cells mature in the thymus and are responsible for cell-mediated immunity and antibody-mediated immunity.
Antigen Recognition
- Lymphocytes have antigen receptors on their surface: B-cell receptors (BCRs) on B cells and T-cell receptors (TCRs) on T cells.
- Each receptor binds only with a specific antigen.
- When antigen receptors bind to their specific antigen, the lymphocyte is activated, initiating adaptive immunity.
The MHC Molecule
- Major histocompatibility complex (MHC) molecules contain binding sites for antigens, are specific for certain antigens, and present processed antigens on the cell membrane.
- MHC molecules interact with antigen receptors on B or T cells, stimulating an immune response.
Antibody-Mediated Immunity
- Antibody-mediated immunity is characterized by the production of antibodies in response to specific antigens.
- Antibodies are proteins released into the bloodstream, where they bind to antigens.
- This interaction neutralizes antigens or targets them for destruction by other immune cells.
Cytokines
- Cytokines are proteins released by cells that regulate the activity of neighboring cells.
- Interleukin 1, a cytokine released by macrophages, stimulates helper T cells.
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Description
Explore the functions and structure of the lymphatic system, including lymphatic capillaries, fluid movement, and lymph nodes. Understand how lymph is formed and filtered to defend against pathogens. This quiz covers key components essential for maintaining fluid balance and tissue health.
