Flashcards in Immunology Deck (106):
Lymph fluid resembles plasma but contain as a much lower concentration of what?
Primary lymphoid tissues and organs are site where lymphocytes are formed and mature; what are they?
Red bone marrow and thymus.
Secondary lymphoid tissues and organs are where lymphocytes are ____? They include what?
Activated. Include: tonsils, MALT, lymph nodes, and spleen.
Mucosa-associated lymphatic tissue (peyer’s patches, appendix, tonsils)
How to lymphatic capillaries differ from blood capillaries?
1) they are closed at one end rather than forming continuous tubes
2) have larger luminal diameters
3) have thinner walls
4) typically have a flattened or irregular outline
The endothelial cells of a lymphatic capillary are not bound tightly together, but the do ________. Acting as a _______.
One-way valve (preventing them from returning to the intercellular spaces)
Important lymphatic capillaries in the small intestine transport lipids absorbed by the digestive tract.
Base of the thoracic duct that is an expanded, saclike chamber; receives from inferior part of abdomen
Obstruction of lymphatic vessels.
Lymphocytes account for ___% of circulating leukocytes. Three classes include:
1) thymus-dependent cells,
2) bone marrow-derived cells
3) NK cells
Contains dividing lymphocytes
1) pharyngeal tonsil (adenoid) lies in the posterior superior wall of nasopharynx
2) L and R palatine tonsils @ post/int margin of oral cavity
3) L and R lingual tonsils
Aggregated lymphoid nodules, aka:
Peyer’s patches (MALT)
Fibrous partitions of lymph node are called:
Blood vessels and nerves reach the lymph node at a shallow indentation called the _____.
Two set of lymphatic vessels, ____ and ____ are connected to each lymph node.
Afferent (bring to) and efferent (bring out)
The lymph node interior is divided into an ______ and ______, and a region in between the two called the ______.
Outer cortex, inner medulla, and a region between called the parcortex.
_______ cells in subcapsular space are involved in starting immune response.
The periphery of the lymph node cortex contains ___ cells within _____, similar to those of the nodules.
B cells; germinal centers
Paracortex is dominated by ___ cells.
The medulla of lymph node contains ___ cells and ____>
B cells and macrophages.
“Involution” of thymus.
After puberty, the thymus diminishes in size and becomes increasingly fibrous and fatty.
Thymic (Hassall’s) corpuscles
Epithelial reticular cells in the medulla of thymus that cluster together in concentric layers.
The cortex of thymus contains actively dividing ________ cells. A blood thymus barrier separates these developing cells from general circulation.
T lymphocytes. Medulla of thymus has no blood barrier and mature T cells leave after about 3 weeks.
3 functions of the spleen:
1) removing abnormal blood cells via phagocytosis
2) storing iron from recycled blood cells
3) initiating immune responses by B cells and T cells in response to antigens in circulating blood.
Red pulp (spleen):
Contains large quantities of RBCs; macrophages scattered throughout
White pulp (spleen)
Resembles lymphoid nodules; high concentration of lymphocytes and dendritic cells.
The body’s ability to resist and defend against infections organisms or other substances that could damage tissues and organs.
Ability of the body to maintain immunity
Types of immunity:
1) innate (non-specific): skin, NK cells
2) adaptive (specific): T and B cells (respond to specific antigens) and defend against specific pathogens
Lymphocytopoiesis occurs where?
Red bone marrow, thymus, and peripheral lymphoid tissues.
Hemocytoblasts divide in the red bone marrow of adults to generate the lymphoid stem cells that produce all types of lymphocytes.
One group of lymphoid stem cells remain in red bone marrow and other group migrates to thymus.
Lymphoid stem cells in the red bone marrow divide to produce immature ____ cells and ____ cells.
B cells and NK cells.
Produced by stromal cells of red bone marrow; promotes the differentiation of B cells.
Mature B cells move into ____, _____, or ____.
Lymph nodes, the spleen, or other lymphoid tissues.
NK cells move through _____ tissues in search of abnormal cells.
When stimulated, ___ cells can differentiate into ____ cells, which produce and secrete _____.
B cells; plasma cells; antibodies, which attach to pathogens, creating a chain reaction that leads to the destruction of the pathogen.
Immune surveillance and the secretion of lysing chemicals performed by:
Antibody-mediated immunity performed by:
Cell-mediated immunity performed by:
Innate defenses (list 7):
1) physical barriers
3) immune surveillance
Released by activated lymphocytes, macrophages, or virus-infected cells; are the chemical messengers that coordinate the defenses against viral infections.
Inflammation and mast cell(s) limit the spread of injury/infection via (list 7):
1) increases blood flow
2) activates macrophages
3) increases capillary permeability
4) activates complement
5) stimulates regional clotting factors
6) increases regional temp
7) activates adaptive defenses
Phagocytes include two classes:
1) microphages (neutrophils and eosinophils)
Activated macrophage responds to pathogen by:
1) engulfing/destroying with lysosomal enzymes
2) bind/remove from interstitial fluid
3) destroy using toxic chemicals
Fixed macrophages, aka:
Histiocytes. “Microglia” “stellate macrophages”
Alveolar macrophage example:
Dust cell; free macrophage
When phagocytes sneeze between adjacent endothelial cell walls.
Cause attraction/repulsion of phagocytes. Particularly sensitive to Cytokines.
Phagocytosis begins with:
Adhesion, the attachment of the phagocyte to its target. Followed by the formation of a vesicle containing the bound target — which is then digested when vesicle fuses with lysosomes or peroxisomes.
The plasma membrane of an ______cell generally contain ____ that are not found on the membranes of normal cells.
NK cells respond much more (slowly/rapidly) than T cells or B cells?
Activated NK cells react in four predictable steps:
1)recognition and adhesion
2) realignment of Golgi apparatus (and production of secretory vesicles containing perforins
3) secretion of perforins via exocytosis
4) lysis of abnormal cell (using pores)
NK cell membranes contain “protection”
Interferons released by...
Small proteins released by activated lymphocytes and macrophages, and by tissue cells infected with virus.
An interferon binds to...
Binds to surface receptors on the membrane of a normal cell, and by second messengers, triggers the production of antiviral proteins in the cytoplasm.
Antiviral proteins do not prevent viruses from entering the cell, instead, they....
Interfere with viral replication inside the cell.
Three types of interferons:
2)beta (most cells other than lymphocytes and macrophages respond to viral infection with beta)
Interferons are examples of _____, chemicals that tissue cells release to coordinate local activities.
Complement refers to:
The fact that the complement system complements, or even chances, the action of antibodies and phagocytes.
Three routes of complement activation:
1) classical pathway
3) alternative pathway
Produced by cells infected with viruses. It attracts and stimulates NK cells and enhances resistance to viral infection.
Is secreted by fibroblasts and slows inflammation in a damaged area.
Secreted by T cells and NK cells and stimulates macrophage activity
Classical pathway of complement activation is the most rapid and effective of the complement system and has 4 steps:
1) antibodies bind to bacterial cell wall
2) attachment of C1
3) activation and cascade; attached C1 protein acts as an enzyme, catalyzing a series of reactions involving other complement proteins that split C3 into C#a and C3b. C3a diffuses away and activates an inflammatory response.
4) C3b attachment; cb3 binds to the bacterial cell wall and enhances phagocytosis
Lectin pathway (complement activation) is activated by the protein mannose-binding lectin (MLB), which binds to carbs on bacterial surfaces. 3 steps:
1) Lectin binds to cell wall; MBL binds to carbs on bacterial surface
2) C3 activation: bound CBL forms a complex that splits C3 into C3a and C3b. C3a activates inflammatory response
3) C3b attachment; C3b binds to bacterial surface and enhances phagocytosis
Alternative Pathway (complement activation); important in the defense gains bacteria, some parasites, and virus-infected cells. 2 steps:
1)complement proteins interact in plasma: several complement proteins, notably properdin, interact in the plasma causing C3 to split into C3a and C3b. This interaction can be triggered by exposure to foreign materials. C3a activates an inflammatory response.
2) c3b attachment; c3b protein binds to the bacterial cell wall.
Plasma contains over 20 special _____ ______ that form the complement system.
Complement activation causes what? List 3.
1) killing of pathogen
2) enhanced phagocytosis (opsonization)
3)inflammation (histamine release)
Cell lysis (via complement activation)
Once an activated C3b protein has attached to the cell wall, additional complement proteins may for a membrane attach complex (MAC) in the membrane that destroys the integrity of the target cell.
Enhanced phagocytosis or opsonization (via complement activation)
The attached C3b mat also act to enhance phagocytosis because macrophage membranes contain receptors that detect and bind to complement proteins and bound antibodies.
Inflammation or histamine release (via complement activation)
Release of histamine by mast cells and basophils increases the degree of local inflammation, attracts and activates phagocytes, and accelerates blood flow to the region.
When stimulated by physical stress or chemical changes in the local environment, ___ ____ release ____, ____, ____, and ____ into the interstitial fluid.
Mast cells; histamine; heparin; prostaglandins; and other chemicals
As neutrophils circulate through a blood vessel in an injured area, they undergo activation. 3 steps:
1) the stick to the side of the vessel and move into the tissue by emigration
2) their metabolic rate goes up and this respiratory burst generates reactive compounds such as nitric oxide and hydrogen peroxide
3) they secrete cytokines that attract other neutrophils and macrophages to the area
Inflammation and the steps in tissue repair following initial tissue damage:
1 ) Mast cell activation
2) redness, swelling, heat, and pain (dialation and clot formation)
2.1) attraction of phagocytes, especially neutrophils
3) tissue repair
Fever producing agents are called?
Pyrogens; and are produced by bacteria, molds, viruses, and yeasts, etc.
For each rise in 1 degree Celsius, metabolic rate increase by ___%
Approximately 80% of circulating lymphocytes are classified at T Cells. They include (list four)?
1) cytotoxic T cells
2 helper T cells
3) regulatory T cells
3) memory T cells
B cells make up 10-15% of circulating lyphocytes and include ____?
Plasma cells, which produce and secrete antibodies
NK cells make up ____% of the circulating lymphcytes.
The binding of an antibody to its target ____ leads to the destruction of the target invader.
Antibodies (soluable proteins secreted by plasma cells, from B cells)
Cytotoxic T cells provide ____-_____ immunity, which defends against abnormal cells and pathogens inside cells.
B cells provide ___-____ immunity, which defends against antigens and pathogens in body fluids.
Antibody-mediated immunity (aka: humoral immunity)
Most ___ are pathogens, parts or products of pathogens, or other foreign substances. They usually are proteins.
A lymphocyte becomes ____ when it has contact with an appropriate antigen.
Activated; once activated, a lymphocyte begins to divide, producing more lymphocytes with same specificity.
Ability to resist infection and disease
Adaptive (specific immunity)
Not present at birth, acquire immunity to specific antigen only when you have been exposed to that antigen or receive antibodies from another source.
Innate (nonspecific immunity)
Genetically determined — no prior exposure or antibody production involved
Develops in response to antigen exposure; includes naturally and artificially acquired active immunity
Naturally acquired active immunity:
Develops after exposure to antigens in environment
Artificially acquired active immunity
Develops after administration of an antigen to prevent disease
Produced by transfer of antibodies from another source; includes 1) naturally acquired passive immunity and 2) artificially acquired passive immunity
Naturally acquired passive immunity
Conferred by transfer of maternal antibodies across placenta or in breast milk
Artificially acquired passive immunity
Conferred by administration of antibodies to combat infection
T cells only recognize antigens when they are processed and presented by cells called ____-_____ ____, most of which are phagocytes such as macrophages.
Antigens presenting cells
The first and second step in the activation of the immune response:
1) antigen presentation
2) antigen recognition (then differentiation and production of clones of the various defensive cells)
For T cells to recognize an antigen, the antigen must be bound to _____ in the plasma membrane of another cell.
The genes controlling the synthesis of glycoproteins are located along one portion of chromosome ___, in a region called the ____ ____ ____.
Major histocompatibility complex (MHC)
MHC proteins are also called?
Human leukocyte antigens (HLAs)
Class I MHC proteins
In the plasma membranes of all nucleated cells; continuously synthesized and exported to the plasma membrane in vesicles formed by the Golgi apparatus... As they form, Class I proteins pick up small peptides from the surrounding cytoplasm and carry them to the cell surface. If the cell is healthy and peptides normal, T cells ignore them. If abnormal, T cells activated and cell death inevitable.
Describe the 5 steps of class I MHC proteins (in infected body cell)
1) antigen presentation by class I MHC proteins is triggered by viral or bacterial infection of a body cell
2) the infection results in the appearance of abnormal peptides in cytoplasm
3) the abnormal peptides are incorporated into class I MHC proteins as they are synthesized at the Endo plastic reticulum
4)after export to the G.A., the MHC proteins reach the plasma membrane within transport vesicles
5) the abnormal peptides are displayed by class I MHC proteins on the plasma membrane
Describe the 5 steps of antigen-presenting cell:
1) phagocytic APCs engulf the extracellular pathogens
2) lysosomal action produces antigenic fragments
3) the endoplasmic reticulum produces class II MHC proteins
4) antigenic fragments are bound to class II MHC proteins
5) Antigenic fragments are display by class II MHC proteins on the plasma membrane
Class II MHC proteins are present only in the _____ ______ of antigen-presenting cells and lymphocytes.
Antigen presenting cells are specialized cells that activate T cell defenses against foreign cells (including bacteria) and foreign proteins. They include:
1) free and fixed macrophages in connective tissues
2) stellate macrophages of the liver
3) microglia in CNS
Dendritic cells of skin and of lymph nodes and spleen are also APCs that are not phagocytic.
Cluster of differentiation markers; more than 350 types exist.
All T cells have a ___ receptor complex in their plasma membranes, and this complex ultimately activates the ___ cells. Two other CD markers may be bound to the CD3 receptors, including:
CD3; T cells
CD4 and CD8 markers
Found on cytotoxic T cells and regulatory T cells; CD8 T cells respond to antigens presented by class I MHC proteins