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CH 22 - Lymphatic system and immunity

Terms in this set (97)

2 main branches of the immune system
Innate (nonspecific) defenses
Adaptive (specific) defenses
2 functions of the immune system
1. Maintain homeostasis
2. Defend against invaders/pathogens (such as bacteria, fungi, viruses)
Lymphatic system functions (3)
1. drain excess interstitial fluid
2. transport dietary lipids
3. transport cells & molecules of the immune system
The immune system is a. . .
coordinated defense system
Which branch of the immune system distinguishes invaders/infection from something of the body?
the adaptive branch
2 aspects of lymphatics:
lymph (fluid) and lymphatic vessels
Lymph fluid has similar consistency, osmolarity, etc. too. . .
interstitial fluid
(excess interstitial fluid is drained into lymphatic capillaries & formed into lymph)
Lymph appearance
clear, pale-yellow (except after excess lipid intake which makes it cloudy)
Lymphatic vessels (unique characteristic, location, example)
-only allows lymph to flow in
-located in subcutaneous tissue
-Ex: lacteals
2 main channels of lymph drainage
1. Thoracic duct
2. Right lymphatic duct
Thoracic duct
drains most of the body's lymph (the entire L side of the body & everything inferior to ribs on the R side), and enters venous blood at the L subclavian vein
Right lymphatic duct
drains the upper right side of the body, and enters venous blood at the R subclavian vein
Pathway of lymph
blood--> interstitial fluid--> lymphatic vessels--> lymphatic ducts--> [deoxygenated] blood
3 ways that lymph is moved:
valves (one way movement)
skeletal pump
respiratory pump
primary organs and tissues:
such as bone marrow and the thymus, produce and/or mature cells of the immune system
bone marrow produces and matures:
B cells
dendritic cells of the thymus mature:
T cells
secondary organs:
such as lymph nodes, are in charge of communication/interaction between cells of the adaptive immune system
spleen
the largest mass of lymphatic tissue (secondary) which filters pathogens from the blood
examples of secondary lymphatic tissues
"follicles"
adenoid, lingual, palatine tonsils
MALT/GALT in the small bowel
3 functions of the red pulp of the spleen:
1. removes RBCs (with macrophages)
2. stores platelets
3. produces blood cells in the fetus
white pulp of the spleen:
lymphatic tissue which activates the adaptive/specific immune response
Innate Immune system =
"first line of defense"
nonspecific, ready and waiting, and utilizes physical and chemical barriers
Physical external barriers (of the innate immune system)
skin and mucus membranes
normal flora (the good "healthy competition")
6 external barriers involving skin and mucus membranes

(innate immune system)
1. the closely packed upper layer of skin
2. mucus, hairs, and cilia of mucus membranes
3. tears, which dilute microbes and remove them from the surface of the eye
4. saliva, which washes bacteria out of the mouth
5. urine flow & vaginal secretions
6. defecation & vomiting
4 CHEMICAL external barriers (of the innate immune system):
1. lysozyme (of tears, saliva, perspiration, & nasal secretions)

2. sebum (of the skin's oil glands)
- (fatty acids inhibit pathogenic bacteria and fungi)

3. gastric juice of the stomach (a mixture of acid, enzymes, & mucus)

4. slightly acidic vaginal secretions
Antimicrobial substances=
an internal defense that fights microbial growth
4 types of innate antimicrobial substances:
1. interferons
2. complement system
3. iron-binding proteins
4. peptides (antimicrobial proteins)
interferons
-an innate internal defense
-"pirates" that, once produced by virally-infected cells, diffuse to unaffected cells and prevent the virus from replicating
complement system
-an innate internal defense
-multiple proteins in a cascade which end up enhancing certain immune reactions, activation inflammation, and attaching to pathogens to draw phagocytes to them ("opsonization")
Iron-binding proteins
-an innate internal defense
-reduce available iron, inhibiting the growth of any bacteria which requires Fe for growth
Peptides
-an innate internal defense
-have a broad spectrum of functions and attract/recruit other cells of the immune system
Ex: defensins insert into the plasma membrane of a pathogen
4 types of cells providing innate internal defense:
1. natural killer cells
2. phagocytes
3. macrophages
4. dendritic cells
Natural killer cells
-an innate internal defense
-make up about 5-10% of lymphocytes; responsible for surveillance and attack body cells with abnormal surface proteins, kill virally-infected cells and are important in removing tumor cells
2 substances that NK cells release:
1. perforin, which inserts into the plasma membrane of a target cells and leads to it bursting (cytolysis)
2. granzymes, whcich digest proteins and cause the target cell to self-destruct (induce "programmed cell death")
Phagocytes
such as neutrophils or macrophages, migrate to the infection site ("chemotaxis")

they can move through vessel walls and attach well b/c of complement proteins and antibodies, and they ingest and digest pathogens
2 varieties of macrophages:
fixed or wandering
Fixed macrophage ex: Kuppfer cells (in the liver), alveolar (lungs), microglia (CNS)
Dendritic cells
a link between the innate and adaptive immune system which moves microbes (antigens) to secondary lymphoid tissues
Innate internal defense:
Inflammation:
redness--> pain--> heat--> swelling
Inflammation =
-an innate internal defense; a nonspecific response to tissue damage

may be caused by pathogens, abrasions, chemical irritation, or extreme temperatures
5 steps/aspects of the Inflammatory process:
1. Mast cells of the damaged tissue releases histamine
2. Histamine causes blood vessels to dilate, increases the permeability of vessel walls, causes the release of prostoglandins and leukotrienes, and is complemented by chemotaxis and phagocytosis
3. temperature rises, inhibiting pathogen growth
4. coagulation
5. fever
Once histamine makes the vessel wall more permeable:
phagocytes and fluid can enter more readily, and phagocytes arrive within an hour (neutrophils first)
Effects of fever:
Interferons effect is intensified, certain microbes' growth is inhibited, body reactions (metabolism) needed for repair speeds up
4 properties of Adaptive immunity:
1. specific
2. distinguishes self from non-self
3. diverse
4. memory
Antigens
a substance (usually a protein) that is recognized as "foreign" and binds to an antibody, and may invoke an immune response
Adaptive immunity specificity
reactions are specific for particular foreign particles
epitopes =
aka "antigenic determinants" are the particular site on an antigen (protein) that triggers a certain antibody or T cell
Cells are replete with. . .
proteins
during fetal development, your immune system. . .
is educated and becomes "tolerant" of your own cells' proteins
Pathogen diversity
There are bacteria, fungi, and viruses, each with numerous proteins
Adaptive immunity diversity is generated by. . .
DNA rearrangements & mutations (sometimes)--thus, immune diversity differs from person to person
Memory cells. . .
develop a memory of previously encountered antigens and can store the memory for a lifetime; and they can start dividing quickly, which enables the body to have a more rapid & vigorous response if a pathogen returns
2 types of adaptive immunity:
1. humoral
2. cell-mediated
Humoral immunity:
"antibody-mediated immunity" which involves B cells transforming into plasma cells, which synthesize and secrete specific proteins (antibodies) and fight "exogenous" pathogens
Cell-mediated immunity:
involves T cells which directly attack invading antigens
B cells:
lymphocytes produced & matured in red bone marrow
-there are billions of different B cells & each makes only 1 type of antibody (which reacts with just one epitope on an antigen)
T cells:
lymphocytes produced in bone marrow & matured in the thymus
exogenous pathogens:
pathogens that are outside of the body's cells (bacteria, viruses, fungi in blood, tissues, lymph)
Clones:
a group of identical cells which can recognizes the same specific antigen as the original lymphocyte
Antibody receptor =
an immunoglobin (Ig) molecule on the surface
soluble antibodies are secreted by. . .
plasma cells
antibodies are made-up of:
a pair of identical heavy chains, and a pair of identical light chains
Lymphocytes are the only cells that can. . .
divide outside of bone marrow
antibodies bind. . .
epitopes
a B cell is "activated" once it binds an antigen and then it becomes 1 of 2 things:
plasma cell or a "memory cell*
B cell activation is helped along by:
T cells
plasma cells
develop from B cells as "clones" and divide and secrete antibodies (Ig: immunoglobulins)
antibodies are present in:
lymph and plasma ("humors")
what type of pathogen does humoral immunity fight?
exogenous
Functions of antibodies/immunoglobulins:
1. to neutralize bacterias or viruses
2. to enhance phagocytosis
3. to agglutinate bacteria/antigens
4. to activate the complement cascade
How do antibodies neutralize bacteria & viruses?
Igs often bind to the site that allows a virus to infect a cell (it binds to the virus' protein receptor)
5 classes of immunoglobulins:
IgD
IgM
IgG
IgA
IgE
IgM:
the first antibody of the primary response and cannot cross the placenta because it is so large
IgG:
the most prevalent antibody of the blood, can cross the placenta via passive immunity (b/c its small), and appears later in the immune response
IgA:
present in secretions: predominant in saliva, tears, sweat
made by epithelial cells in the lining of the gut and lungs and fights antigens before they enter the blood stream
5-15g is secreted per day!!!
IgE
mediates "immediate hypersensitivity" (for allergic reactions, asthma, hay fever, anaphylaxis, hives, etc.)
barely present in blood
IgD
located on B cells in very low concentrations, unknown function
Antibody responses:
1. Primary response (the first encounter with the pathogen)
2. Secondary response (the memory response after encountering it once before)
Which response of Ig is more rapid and intense?
The secondary response
The predominant Ig of the secondary response:
IgG
Adaptive immunity fights. . .
"endogenous" pathogens
(which are intracellular), thus, it is very effective against viruses (which are always intracellular
Adaptive immunity is mediated by. . .
T cells
2 types of T Cells:
"helper" and "cytotoxic"
Adaptive (cell-mediated) immunity:
T cells kill & eliminate infected cells of the body

(however, T cells have receptors which only allow them to bind to a specific part of a pathogen's protein)
First step of cell-mediated immunity:
T cells recognize an antigen on the MHC
MHC class I is on the surface of nucleated cells and binds to:
CD8 (cytotoxic) cells
MHC class II is on the surface of special antibody-presenting cells and binds to:
CD4 (helper cells)
antigen-present cells=
macrophages, dendritic cells, B cells
once a T cell is activated:
it secretes cytokines to activate other cells
When there is an endogenous pathogen:
1. the intracellular pathogen is digested into smaller pieces by lysosomes
2. the smaller pieces (peptides) bind to a specific molecule of MHC
3. the MHC/peptide complex is transported to the surface of the cell it infected
4. cytotoxic T cells specific for that peptide/MHC complex, recognizes that it's foreign, bind to it, and begin the killing process
a T cytotoxic cell is activated via co-stimulation and then. . .
1. divides to begin forming clones
or
2. becomes a memory cell
How do you get adaptive immunity?
1. naturally acquired active immunity
2. naturally acquired passive immunity
3. artificially acquired active immunity
4. artificially acquired passive immunity
"artifically" acquired immunity =
taking an engineered Ig or Ag, or someone else's Ig
"active" immunity =
your immune system had to fight an Ag and develop immunity
"passive" immunity =
your immune system was "given" Ig
vaccines must. . .
1. induce immunological memory
(induce humoral AND cell-mediated responses)
2. be stable & in an easily administered form (in order to be effective)
4 types of vaccines:
1. live low grade infection (which triggers a strong immune response)
2. an entire, killed virus
3. a subunit--the neutralized epitope of an antigen
4. a toxoid (an inactivated toxic compound)
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