Chapter 22 - Lymphoid System Flashcards
What are the cells involved in Innate immunity?
Macrophages, Neutrophils, and Eosinophils
What are the cells involved in Adaptive immunity?
B & T Lymphocytes
What are the differences between Innate & Adaptive Immunity?
Innate is front line, nonspecific, localized, and has no memory. Adaptive is second line, specific, specialized, and has memory.
What is the function of Lymphoid Vessels?
Carries lymph from peripheral tissues to the venous system. Starts with the smallest vessels: Lymphatic Capillaries.
How do Lymphatic Capillaries differ from blood capillaries?
- Start as pockets instead of tube
- Have larger diameters
- Have thinner walls
- Flat or irregular in section
What is the function/structure of the Lymphatic Tissues?
Tissues are connective tissues that are dominated by lymphocytes
Antibodies crossing the placenta to provide immunity for the fetus is an
Passive Immunity
What are the components of the Lymphoid System Organs?
Lymph nodes, Thymus, Spleen
What is Active Immunity?
Antibodies develop after exposure to antigen. Induced through vaccines containing pathogens. Naturally acquired through environmental exposure to pathogens.
What is Passive Immunity?
Antibodies are transferred from another source. Naturally acquired from mother to fetus. Induced by an injection of antibodies.
What are the organs of the immune system?
- Tonsils & Adenoids
- Thymus
- Lymph Nodes
- Appendix
- Bone Marrow
- Lymphatic Vessels
- Spleen
- Peyer’s Patches
What is the function of the Lymphoid System?
produce, maintain, and distribute lymphocytes
Where are lymphocytes produced?
Lymphoid Tissues, Organs, and Red Bone Marrow
How do lymphocytes circulate?
from blood to interstitial fluid through capillaries.
What is lymph?
Interstitial fluid that has entered a lymphatic vessel or organ
What are lacteals?
special lymphatic capillaries in a small intestin transport lipids from digestive tract.
Where does lymph flow?
From capillaries to small vessels to large lymphatic vessels.
What are lymphatic capillaries composed of?
Endothelial cells loosely bound together without overlapping, include a one-way valve that allows fluids, solutes, viruses, and bacteria to enter, but not return to intercellular space.
What are the two major sets of lymphatic vessels?
Superficial Lymphatics and Deep Lymphatics
What are Superficial lymphatics?
Skin, mucous membranes, serous membranes lining body cavities
What are deep lymphatics?
Larger vessels that accompany deep arteries and veins supplying skeletal muscles and organs
Where do Deep and Superficial Lymphatics join and where do they empty?
They join to form large lymphatic trucks that empty into two major collecting vessels: Right Lymphatic Duct and Thoracic Duct.
What is a lymphoid nodule?
areolar tissue with densely packed lymphocytes and a germinal center that contains dividing lymphocytes
Where are lymphoid nodules located?
Lymph nodes, spleen, respiratory tract (tonsils), digestive, and urinary tracts.
What are the tissues of the lymphoid system?
MALT, Appendix
What is MALT?
Mucosa-Associated Lymphoid Tissue in the digestive system that has aggregated lymphoid nodules clustered deep to intestinal epithelial lining
What are Peyer’s Patches?
Located in the MALT, they are aggregated lymphoid nodules clustered deep to intestinal epithelial lining.
What are the components of Lymphoid Organs?
Lymph nodes, Thymus, Spleen
What is the structure of a Lymph Node?
covered by capsule of dense connective tissue
What is Trabeculae?
bundles of collagen fibers extend from capsule into interior of lymph node
What is Hilum?
Shallow indentation where blood vessels and nerves reach the lymph node
What are the function of Efferent Vessels in the lymph nodes?
Leave the node at hilum and carry lymph to venous circulation
What are the function of Afferent Vessels in the lymph nodes?
Carry lymph from peripheral tissues to the node
What is the flow sequence of lymph flow from afferent lymphatics?
- From subcapsular space
- Through outer cortex
- through deep cortex
- Through the core (medulla)
- Into Hilum and efferent lymphatics
What is the function of Lymph Nodes?
purify lymph before it returns to venous circulation
How do Lymph Nodes cleanse lymph?
fixed macrophages, dendritic cells engulf pathogens and present them to the B & T Lymphocytes
Where this the thymus located?
in the mediastinum
What are the components of the Thymus?
Left and Right lobes composed of Septa (septums) that divide lobes into smaller lobules
What are the components of a Thymic Lobule?
dense outer cortex and central medulla containing T-Lymphocytes
What is the purpose of the reticular epithelial cells that surround lymphoctyes in the Thymic lobules cortex?
Maintain Blood-Thymus Barrier and Secrete Thymic Hormones that stimulate Stem Cell Division and T Cell differentation.
What are Thymus Hormones?
thymosin - promotes the development of lymphocytes
What are Thymic Hassall Corpuscles?
concentric layers of reticular epithelial cells in the Thymic lobule medulla.
What are the defining characteristics and functions of the Spleen?
- largest lymphoid organ in the body
- removes abnormal cells, pathogens, and other blood components by phagoctytosis
- stores iron recycled from RBCs
- initiates immune responses from B & T Cells that react to antigens in circulating blood
What is the structure of the Spleen?
- attached to the stomach by gastroplenic ligament
- contacts diaphragm and left kidney
- splenic veins, arteries, lymphatic vessels communicate with the spleen at the hilum
What are the components of the Spleen?
Red Pulp (RBCs) and White Pulp (WBCs)
What are the two categories of defenses?
Nonspecific and Specific (innate and acquired)
What are the 7 Major Categories of Nonspecific Defenses?
- Physical Barriers (skin, hair, epithelia)
- Phagocytes (Macrophages, Eosinphils, Neutrophils)
- NK Cells
- Interferons
- Complement System
- Inflammation
- Fever
What’s the function of Microphages? (Eosinphils and Neutriphils)
leave the bloodstream, enter peripheral tissues to fight infections. Neutrophils are abundant, fast, and effective.
What are two kinds of Macrophages?
- Fixed (Kuppfer cells, liver and Glial Cells, brain)
2. Free (wandering) cells that circulate through the body (ex. alveolar macrophages)
What are macrophages?
large, phagocytic cells derived from MONOCYTES
How do macrophages respond to pathogens?
- Engulf and destroy with lysosomal enzymes
- Bind to pathogen so other cells can destroy it
- Destroy pathogen by releasing toxic chemicals into interstitial fluid
What are natural killer cells?
surveillance cells that release proteins called perforins that lyse abnormal plasma membranes
What are interferons?
chemical messengers that are activated by lymphocytes and macrophages and trigger production of antiviral proteins in normal cells.
Do interferons kill viruses?
No, they just block replication in a normal cell.
What is a cytokine?
chemical messenger that are released by tissue cells and coordinate immune response and active/inhibit other cells.
What is the Complement System?
A nonspecific defense and protein cascade including plasma that has 11 special complement (C) proteins.
What actives that Complement System?
- Classical Pathway - complements antibodies
2. Alternative pathway - binds pathogen directly
What are the 3 types of Interferons?
- Alpha - stimulate NK Cells
- Beta - secrete fibrocytes
- Gamma - secreted by T & NK Cells + stimulate macrophage
What are the effects of Complement System Activation?
- stimulation of inflammation
- attraction of phagocytes
- enhancement of phagocytosis by opsonization
- destruction of target plasma membranes
What is the purpose of Inflammation as a defense?
localized response that temporarily repairs and creates a barrier against pathogens; slows spread of pathogens into surrounding areas; mobilizes local and systemic defenses, and facilitates repair and regeneration.
What are the signs of Inflammation ?
- Swelling
- Redness
- Heat
- Pain
What is the purpose of Fever as an Innate Defense?
increases body’s metabolism, accelerates defenses, and inhibits some viruses and bacteria.
How does the body create a fever?
Pyrogens that cause the hypothalamus to raise body temperature
What is the most common pyrogen in the body to create a fever?
Interleukin-1 (IL-1)
Perforins are proteins associated with the activity of…
NATURAL KILLER CELLS
What cells are involved in Acquired (Specific) Immune Response?
B & T Cells
What are T Cells?
cell-mediated immunity cells that fight viruses and INTRAcellular pathogens
What are B Cells?
anti-body (humoral) Immunity that fights bacteria (usually EXTRAcellular)
What are the 4 Characteristics of Specific Immune Response?
Specific, Diverse, Memory, Tolerance