Introduction to the immune and lymphatic systems
The following are two basic stages to the inflammatory response:
(1) Damaged cells release inflammatory mediators that cause local changes in the damaged tissue, then (2) Phagocytes arrive and clean up the damaged tissue
What two populations do B cells differentiate into?
(1) plasma cells, which secrete antibodies; and (2) memory B cells, which are long-lived cells that do not secrete antibodies but will respond to antigens upon a second exposure.
What are the four cardinal signs of inflammation?
(1) redness, (2) heat, (3) swelling (edema), (4) pain, which are caused by the following actions of inflammatory mediators : vasodilation, increased capillary permeability, occurrence of pain, recruitment of other cells: chemotaxis.
The second arm is antibody-mediated immunity
(also known as humoral immunity), is carried out by B cells and proteins they produce, called antibodies.
Innate Immunity: Internal Defenses The rapid response of the innate immunity consists of two main components:
- a group of antimicrobial molecules, including the antimicrobial proteins known collectively as complement and a variety of cytokines - and several types of cells, including neutrophils, macrophages, and NK cells.
Activated complement proteins lead to the following main effects:
- cell lysis - formation of a membrane attack complex (MAC) - enhanced inflammation, neutralization of viruses - enhancing phagocytosis, opsonization - clearance of immune complexes.
Class II MHC molecules are found _____________. Helper T (TH) cells generally interact with _________. Class II MHC molecules present _________________.
- only on the surfaces of antigen-presenting cells - class II MHC molecules - exogenous antigens or those the cell takes in by phagocytosis
The main cells of the immune system are the different types of leukocytes:
- the agranulocytes (B and T lymphocytes and monocytes) - the granulocytes - many cells of innate immunity can function as phagocytes, cells that "eat" foreign or damaged cells.
The primary antibody involved in the secondary response is _____, whereas it's ____in the primary response. The antibodies secreted in the secondary immune response are more effective—they bind more tightly and have a higher affinity for their antigens.
IgG IgM
There are five basic classes of antibody, which are grouped according to the structure of their C regions. Each antibody is named with the two-letter abbreviation "Ig," which stands for "immunoglobulin," followed by a letter that designates its class. This gives us the types
IgG, IgA, IgM, IgE, and IgD.
The first arm is cell-mediated immunity brought about by:
two types of T cells.
Lymphoid organs activate cells of the immune system.
Lymphoid organs house cells such as dendritic cells, which play a crucial role in activating B and T cells. In addition, the thymus is required for the selection of a functional population of T cells.
.Lymph return to the heart is assisted by ______, contracting _______ muscles, and _____ muscle in the walls of lymph-collecting vessels.
valves skeletal smooth
Other Cells of Innate Immunity. The nonphagocytic cells include:
NK cells, dendritic cells, and basophils.
The lymphatic system has the following basic functions that are carried out by its vessels and organs:
Regulation of interstitial fluid volume Absorption of dietary fats Immune functions
Summarize the role of TH Cells
TH cells exert their effects through the secretion of cytokines that activate and enhance various components of the immune response. Some of the main functions of TH cells include the stimulation of macrophages, the activation of TC cells, and the stimulation of B cells.
Part 2: Phagocyte Response:
The arrival and activation of phagocytes is divided into stages that are based on which phagocytes enter the area and the processes occurring there.
Where are specific clusters of lymph nodes located?
The axillary lymph nodes in the axillae, cervical lymph nodes in the neck, inguinal lymph nodes in the groin, and the mesenteric lymph nodes in the abdominal cavity around the abdominal organs.
Lymphoid organs and tissues trap pathogens for the immune system.
The fine networks of reticular fibers in lymphoid tissues form "nets" that trap pathogens so that leukocytes may interact with them more easily.
Summarize the second line of defense.
The second line of defense, which includes the responses of the cells and proteins that make up innate immunity.
Summarize the third line of defense.
The third line of defense, which includes the responses of the cells and proteins of adaptive immunity.
Secondary Immunodeficiency Disorders :
These disorders have multiple forms, many of which are induced artificially to combat cancers originating in the bone marrow or to prevent transplant rejection
The ________ is a small, encapsulated organ in the superior mediastinum that consists of two lobes that doesn't trap pathogens . It secretes hormones that enable it to carry out its primary function, which is: generating a population of functional T cells capable of protecting the body from pathogens.
Thymus
Lymphatic Vessels are
a system of blind-ended tubes.
Outline the basic steps of how exogenous antigens are displayed by class II MHC molecules:
a. The cell ingests a pathogen by phagocytosis. b. The phagocytic vesicle fuses with a lysosome; the pathogen is degraded and its antigens are fragmented. c. The lysosome fuses with a vesicle from the RER that contains class II MHC molecules, and an antigen fragment binds to the MHC molecule. d. The MHC-antigen complex is inserted into the cell's plasma membrane.
The most common cause of secondary immunodeficiency by far is the virally induced disease ____________.
acquired immunodeficiency syndrome, or AIDS.
There are two types of antibody-mediated immunity:
active and passive.
Functions of Secreted Antibodies. Actions of antibodies are based on their ability to bind antigens, which leads to multiple effects on pathogens. The basic effects of secreted antibodies are shown in and include the following :
agglutination and precipitation, opsonization, neutralization, complement activation, and stimulation of inflammation.
The other main components of the immune system are groups of different types of proteins:
antibodies, the complement system, and cytokines
The antibodies secreted by a B cell clone bind to the same ______ as the B cell receptor.
antigen
Antimicrobial Proteins. In addition to these cell types, the innate immune response is mediated by a variety of plasma _______________, including complement proteins and several types of cytokines :
antimicrobial proteins
The innate immune system consists of ____________ and certain cells that respond quickly and is the dominant response to pathogens for the first ______ after exposure. The cells and proteins exist in the bloodstream, even in the absence of a stimulus.
antimicrobial proteins 12 hours
TC cells also bind to proteins on the plasma membrane of target cells that induce the process of _______, or programmed cell death. When the target cell begins to degrade, the TC cell detaches and searches for a new target cell.
apoptosis
Organ and Tissue Transplantation and Rejection. The four basic kinds of tissue and organ transplants, also known as grafts, are:
autografts, isografts, allografts, and xenografts
Why does the lymphatic vessels make up a low-pressure circuit?
because there is no main pump to drive lymph through the vessels, and most of them are transporting lymph against gravity.
There are two "arms" of the adaptive immune system:
cell-mediated immunity antibody-mediated immunity
The intestinal trunk and lumbar trunks all drain into a large, swollen vessel called the ______.
cisterna chyli
B cells have B cell receptors that bind to specific antigens, and a group of B cells that bind to a specific antigen is known as a clone.
clone
T cells undergo gene rearrangements that lead to a huge variety of genetically distinct T cells. Each population of T cells that can respond to a specific antigen is known as a _____. The thymus ensures that an individual is _______, or able to mount a normal response to foreign antigens. Self-reactive T cells are destroyed, ensuring ___________, which prevents T cells from attacking self cells.
clone immunocompetent self tolerance
Lymphatic tissue and organs which includes
clusters of lymphoid follicles such as the tonsils, as well as the lymph nodes, spleen, and thymus.
Primary Immunodeficiency Disorders may impair either innate or adaptive immunity. The most common dysfunctions of innate immunity involve deficient _________or abnormalities in ___________.
complement proteins phagocytes
Naïve B cells that do encounter their antigens become activated by binding its antigen . The sensitized B cell processes the antigen and presents it on its class II MHC molecules. The B cell then binds to a TH cell to become ________.
fully activated
Adaptive immunity has the capacity for _________________, in which exposure to an antigen is "remembered" by specific lymphocytes and antibodies.
immunological memory
Along the pathway of lymphatic vessels, we find clusters of the lymphoid organs called _____________.
lymph nodes
Lymph is collected in vessels called _____________ vessels which merge to form larger vessels, the ___________.
lymph-collecting vessels lymph trunks
Lymphatic reticular tissue is typically called lymphoid tissue, which is found in _________
lymphoid organs and also as independent clusters
There are _______ lymph trunks that drain lymph from specific body regions.
nine
Cells of Innate Immunity: Pathogens that are able to bypass the body's surface barriers next meet the second line of defense: the cells and proteins of innate immunity. The cells of innate immunity are divided into two types:
phagocytic cells and nonphagocytic cells
MHC Molecules and Antigen Presentation. T cells can only interact with: ________________________________ The name comes from the fact that MHC molecules are major determinants of compatibility among tissue and organ donors and recipients.
pieces of antigen bound to glycoproteins, called major histocompatibility complex (MHC) molecules .
The primary immune response involves an initial 4- to 5-day lag phase as the B cells proliferate, differentiate into _____ cells and _____ cells, and begin to secrete antibodies. Antibody levels peak about ______ days after the antigen is encountered. It is during the lag phase that you generally feel "sick."
plasma memory 7-14
The predominant tissue type of the lymphatic system is a type of loose connective tissue called _______________ that contains specialized cells and thin reticular fibers, which interweave to form "nets" that trap disease-causing pathogens.
reticular tissue
Cells and proteins of the innate and adaptive immune systems produce the response of the _____________________.
second and third lines of defense
Only certain antigens, called immunogens, are capable of generating a response from the immune system. Antigens present on your own cells, called ______________, are not immunogens in your body.
self antigens
A vaccine may consist of:
several different components, including live, attenuated vaccines, "killed" vaccines, and subunit vaccines.
The group of molecules collectively known as the complement system consists of _____________ plasma proteins produced primarily by the liver.
20 or more
Why is adaptive immunity slower than innate immunity?
Adaptive immunity is slower because one must be exposed to a specific antigen for the response to be initiated. Hence the name acquired immunity, as it takes 3-5 days to mount a response, but after this point, it is the dominant response.
Lymph drains into the blood of the low-pressure venous circuit at the__________________.
subclavian veins
Phase 3: Immunological Memory. Memory B cells are responsible for antibody-mediated immunological memory, which allows B cells to respond more efficiently when
the antigen is encountered a second time.
Lymphoid organs house leukocytes; including macrophages, B lymphocytes, and T lymphocytes, commonly referred to as ______.
B cells and T cells, respectively
Phase 1: B Cell Activation, Clonal Selection, and Differentiation. The following features are associated with the first phase of the antibody immune response:
B cells develop and mature within the bone marrow from the lymphoid cell line, where billions of B cells are produced each day
Lymphoid organs and tissues provide a residence for cells of the immune system.
B cells, T cells, and macrophages frequently take up residence in lymphoid organs such as the lymph nodes, MALT, and the spleen.
Autoimmune Disorders occur when _______________ Populations of self-reactive T cells or B cells that secrete antibodies bind to self antigens, called autoantibodies.
the immune system is unable to distinguish between "self and non-self".
What do these cells primarily respond to? (helper T (TH) cells or CD4 cells and cytotoxic T (TC) cells or CD8 cells)
Cells infected with intracellular pathogens (viruses and intracellular bacteria), cancer cells, and foreign cells such as those from a transplanted organ.
What happens when the pressure in the interstitial fluid decreases?
Endothelial cells flap shut, playing a crucial role in precise control of the amount of fluid between cells.
The cisterna chyli and the other lymph trunks drain into one of two lymph ducts:
thoracic duct and the right lymphatic duct
T Cell Response to Antigen Exposure T cells are formed in the bone marrow, but they leave the bone marrow and migrate to the ______ to mature:
thymus
Mucosa-Associated Lymphatic Tissue (MALT) are loosely organized clusters of lymphoid tissue that protects the mucous membranes, which are exposed to a large number of pathogens. Specialized MALT is found in three locations:
tonsils Peyer's patches appendix
Part 1: Release of Inflammatory Mediators and the Cardinal Signs of Inflammation.
- Tissue damage initiates the inflammatory response as damaged cells and local mast cells release inflammatory mediators. - Inflammatory mediators can include histamine, serotonin, cytokines, bradykinin, prostaglandins and leukotrienes. - Activated complement proteins trigger the release of inflammatory mediators from cells such as basophils and mast cells, and act as inflammatory mediators themselves. - The injured area becomes red and swollen, feels warm to the touch, and hurts.
Class I MHC molecules are found _______________________. Cytotoxic T (TC) cells generally interact only with _________________. Class I MHC molecules present _______________________.
- on the surface of the plasma membrane on nearly all nucleated cells. - class I MHC molecules. - endogenous antigens or those synthesized inside the cell.
C. Immunodeficiency Disorders are caused by a decrease in the function of one or more components of the immune system. There are two basic types of immunodeficiency disorders:
- primary immunodeficiencies, which are genetic or developmental in nature, - secondary immunodeficiencies, which are acquired through infection, trauma, cancer, or certain medications.
Discuss active immunity.
Active immunity is so named because the body's cells actively respond to an antigen, may be received naturally through exposure to an antigen via infection or via a vaccination. Active immunity results in the production of memory cells and large numbers of antibodies and is, therefore, relatively long-lasting, ranging from years to a lifetime.
Define antibodies
Antibodies, also known as immunoglobulins or gamma globulins, are directly responsible for the actions or effects of that lead to the destruction of antigens to which they bind.
What is the function of the lymph nodes?
Lymph nodes trap the majority of pathogens in lymph, which prevents these pathogens from being delivered to the blood, where they could easily spread to other tissues and organs.
The lymphatic system consists of the following two main components:
Lymphatic vessels Lymphatic tissue and organs
Cytokines are proteins produced by several types of immune cells that enhance the immune response in some way.
Several cytokines that are involved in innate immunity are tumor necrosis factor, interferons, and interleukins.
The ________ is the largest lymphoid organ in the body, which is located on the lateral side of the left upper quadrant of the abdominopelvic cavity. It protects the body from pathogens that have entered the blood.
Spleen
_________________ are the first line of defense against any potential threat to the body is the coverings that line body surfaces: the skin and the mucous membranes, and certain products they secrete.
Surface Barriers
The components of adaptive, or specific, immunity respond individually to unique glycoprotein markers called ________. Antigens are present on all cells and most biological molecules, including our own cells, and they identify a cell or molecule as belonging to a specific group.
antigens
Cell-mediated immunity involves the different classes of T cells, including:
helper T (TH) cells or CD4 cells and cytotoxic T (TC) cells or CD8 cells. (Note that "CD" stands for cluster of differentiation).
A. Disorders of the immune system take three forms:
hypersensitivity, immunodeficiency, or autoimmune.
Adaptive immunity and innate immunity are not independently functioning arms of the immune system. Each type of immunity relies on the other, and the response to a pathogen involves a highly integrated series of events within both parts of the ___________________.
immune system
lymphatic system
is a group of organs and tissues that not only works with the immune system but also participates in a number of functions such as fluid homeostasis.
Lymphatic vessels begin in the tissues with __________, which surround blood capillary beds. Lymphatic capillaries are _________, making the lymphatic vasculature a one-way system that only moves lymph away from the tissues.
lymphatic capillaries blind-ended
Phagocytes include _________________________________ and the process by which cells ingest particles and other cells is called phagocytosis.
macrophages, neutrophils, and eosinophils
The cells of lymphatic capillary walls are ___________________________, and instead are able to flap open and closed. Fluid that leaks from the__________________ increases the pressure in the interstitial fluid, which forces the lymphatic endothelial cells apart and allows large volumes of fluid to enter the lymphatic capillaries.
not tightly joined blood capillaries
An activated TC cell binds its target cell, after which it releases a protein called __________. Perforin forms pores in, or perforates, the target cell's plasma membrane. And the TC cell then releases enzymes that enter the target cell's cytosol and catalyze reactions that degrade target cell proteins, leading to fragmentation of the target cell's DNA and its death.
perforin
The set of diverse processes that protect the body from both cellular injury and disease-causing cells and molecules known as pathogens.
Immunity - definition
How the Lymphatic and Immune Systems Work Together. The lymphatic and immune systems are closely connected both structurally and functionally. Some of the ways in which they are connected include the following:
1. Lymphoid organs and tissues provide a residence for cells of the immune system. 2. Lymphoid organs and tissues trap pathogens for the immune system. 3. Lymphoid organs activate cells of the immune system. 4. The lymphatic system plays a greater role in adaptive immunity than in innate immunity.
Hypersensitivity Disorders include include those disorders in which the immune system's response causes tissue damage. The following four types of hypersensitivity disorder (numbered I-IV) are classified according to the exact immune components causing the hypersensitivity:
1. Type I: Immediate Hypersensitivity, 2. Type II: Antibody-Mediated Hypersensitivity 3. Type III: Immune Complex-Mediated Hypersensitivity 4. Type IV: Delayed-Type Hypersensitivity or delayed-type, hypersensitivity (DTH)
There are two types of MHC molecules:
1.Class I MHC molecules 2.Class II MHC molecules
Antibody Structure and Classes . The basic subunit of an antibody is a Y-shaped molecule formed from four peptide chains, two heavy (H) and two light (L) chains. Each of these chains has two types of regions:
: (1) a constant (C) region that is relatively similar among antibodies and is responsible for many of the antibodies' effects and (2) a variable (V) region, which is a unique sequence of amino acids responsible for antigen recognition and binding. An antibody has V regions at the tips of the two arms of the molecule, so the basic subunit of an antibody has two antigen-binding sites, one on each arm.
The _______________________ is an innate response that occurs when a cell is damaged by anything, including trauma, bacterial or viral invasion, toxins, heat, or chemicals.
Inflammatory Response
_______________________responds to all pathogens or classes of pathogen in the same way.
Innate, or nonspecific, immunity
Types of Immunity. Immunity is classified according to the way it responds to different pathogens or forms of cellular injury:
Innate, or nonspecific, immunity adaptive, or specific, immunity acquired immunity
_________________ located in the blood and spleen, function primarily in innate immunity. Dendritic cells, located in many lymphoid organs, are immune cells that are part of the innate immune response, but their main role is to activate the T cells of adaptive immunity.
Natural killer (NK) cells
Discuss passive immunity
Passive immunity occurs when preformed antibodies are passed from one organism to another. Passive immunity may be naturally acquired or artificially acquired. Passive immunity lasts only the amount of time that the antibodies stay in the bloodstream, which is about 3 months on average.
Summarize the first line of defense.
The first line of defense includes cutaneous and mucous membranes that act as surface barriers to block the entry of pathogens into the body.
Summarize the role of TC Cells
The primary function of cytotoxic T cells is to kill other cells, specifically those with foreign antigens bound to class I MHC molecules . TC cells can detect abnormalities in any cell type with a nucleus, which is critical for the detection of cancer cells, foreign cells, and cells infected with intracellular pathogens such as viruses and bacteria.
T Cell Activation, Clonal Selection, and Differentiation. Summarize the process by which T cells are activated:
a. Cells display the antigen fragments on their MHC molecules, and the MHC-antigen complex binds to the receptor of a specific TH or TC cell clone. b. When the T cell receptor recognizes and binds this complex, multiple changes are triggered inside the T cell and the process of activation begins; a process known as clonal selection. c. The TH or TC cell binds a co-stimulator and becomes activated. The activated TH or TC cell clone proliferates and differentiates into effector cells and memory T cells. d. Memory T cells are responsible for cell-mediated immunological memory, in which these cells respond more quickly and efficiently to subsequent exposures to an antigen.
Phagocyte Response stages:
a. Local macrophages are activated and contain invading pathogens. Neutrophils migrate by chemotaxis to the damaged tissue and phagocytize bacteria and cellular debris. b. Inflammatory mediators and activated complement proteins attract neutrophils and enable them to leave the blood and enter the tissue. Inflammatory mediators make the capillary endothelium in the damaged area "sticky," and the neutrophils adhere to the capillary wall, a process called margination. The inflammatory mediators increase capillary permeability, which provides space between endothelial cells for neutrophils to squeeze through into the damaged tissue; a process known as diapedesis. Once the neutrophils are in the tissue, they then begin to destroy bacteria and other cellular debris. c. Monocytes migrate to the tissue by chemotaxis and become macrophages, which phagocytize pathogens and cellular debris. d. The bone marrow increases production of leukocytes, leading to leukocytosis. E. Fever is defined simply as a body temperature above the normal range, which is generally between 36 and 38° C (or 97-99° F); an individual with a fever is referred to as febrile. Fever is an innate response to cellular injury that is initiated when chemicals called pyrogensare released from damaged cells or certain bacteria. Pyrogens cause the hypothalamic thermostat to reset to a higher range.
Outline the basic steps by which a class I MHC molecule processes and displays an endogenous antigen:
a. The cell synthesizes either a self antigen or a foreign antigen. b. The antigen is broken down by enzymes in the cytosol. c. An antigen fragment containing the antigenic determinant is transported into the rough endoplasmic reticulum (RER) and is coupled with a class I MHC molecule in the RER membrane. d. The MHC-antigen complex leaves the RER by a vesicle and is inserted into the cell's plasma membrane.
Describe the three phases of the antibody-mediated immune response:
a. The first phase involves a B cell clone recognizing its specific antigen, which triggers it to undergo changes and start secreting antibodies. b. The second phase begins when the antibody level in the blood rises dramatically. c. The third phase of antibody-mediated immunity is the persistence of a population of B cells called memory B cells that react much more rapidly and efficiently if the antigen is encountered again.
A. Introduction to Adaptive Immunity: Cell-mediated immunity is the first arm of the _____________________.
adaptive immune system
Lymph flows into the node through multiple small lymphatic vessels called ______________________then percolates through the reticular network, where pathogens in the lymph become trapped in the reticular "net." Lymph that has been "cleaned" of pathogens drains out through _____________________.
afferent lymphatic vessels efferent lymphatic vessels
Lymph Nodes are small, vaguely bean-shaped clusters of lymphatic tissue located ______________________.
along lymphatic vessels throughout the body
Introduction to the second arm of adaptive immunity, antibody-mediated immunity: antibody-mediated immunity involves B cells and proteins secreted by B cells, called _______.
antibodies
class I MHC molecule and class II MHC molecules both processes end up with the same result:
portions of antigens displayed on the plasma membrane attach to MHC molecules. These MHC-antigen complexes then interact with and activate T cells.
Vaccinations: A vaccination, also known as an immunization, involves exposing an individual to an antigen to elicit a ____ immune response and generate _____ cells. Then if the individual is exposed to the antigen a second time, a ________ immune response will occur and symptoms will be minimal.
primary memory secondary
The Primary and Secondary Immune Responses: The first exposure to an antigen, a B cell specific for that antigen recognizes it and the activated B cell proliferates and differentiates into plasma and memory B cells, and plasma cells begin to secrete antibodies; a response called _____.
primary immune response
Future exposure to the same antigen results in the activation of memory B cell formed during the primary immune response. When these memory B cells encounter the antigen for which they are specific, the __________begins.
secondary immune response
Cancers of immune cells and lymphoid organs that depress the immune response in some way also cause ____________.
secondary immunodeficiency.
An activated TC cell binds its target cell, after which it releases a protein called perforin. perforin forms pores in, or perforates, ___________________. And the TC cell then releases enzymes that _________________________.
the target cell's plasma membrane enter the target cell's cytosol and catalyze reactions that degrade target cell proteins, leading to fragmentation of the target cell's DNA and its death.
Lymph nodes limit the spread of pathogens through the body by acting as filters by ________________________________.
trapping pathogens and preventing them from traveling elsewhere.
Immune system
works to defend the body against internal and external threats. This system consists only of cells and proteins located in the blood and the tissues of other systems, including the lymphatic system. This system includes leukocytes and immune proteins located in the plasma.
