HISTO LYMPHATIC Flashcards
provides defense or immunity against infectious agents ranging from viruses to multicellular parasites
immune system
Lymphocytes are formed initially in ________________________ organs
primary lymphoid
What are the primary lymphoid organs
the thymus and bone
marrow
most lymphocyte activation and proliferation occur in _______________________ organs
secondary lymphoid
What are the secondary lymphoid organs
the lymph nodes,
the spleen, and diffuse lymphoid tissue found in the mucosa of the digestive system, including the tonsils, Peyer patches,
and appendix
The immune cells located diffusely in the
digestive, respiratory, or urogenital mucosae comprise what is collectively known as __________________________
mucosa-associated lymphoid tissue (MALT)
involves immediate, nonspecific actions, including physical barriers
such as the skin and mucous membranes of the gastrointestinal, respiratory, and urogenital tracts that prevent infections
or penetration of the host body
Innate Immunity
short cationic polypeptides produced by
neutrophils and various epithelial cells that kill bacteria by disrupting the cell walls
Defensins
an enzyme made by neutrophils and cells of
epithelial barriers, which hydrolyzes bacterial cell wall components, killing those cells
Lysozyme
a system of proteins in blood plasma, mucus, and macrophages that react with bacterial surface components to aid removal of bacteria.
Complement
paracrine factors from leukocytes and virus-infected cells that signal NK cells to kill such cells and adjacent cells to resist viral infection.
Interferons
acquired gradually by exposure
to microorganisms, is more specific, slower to respond,
and an evolutionarily more recent development than innate
immunity
ADAPTIVE IMMUNITY
The adaptive immune response involves __ and
__ lymphocytes
T and B
adaptive immune responses are aimed at specific microbial invaders and involve production of ________________________ so that a similar response can be mounted very rapidly if that invader ever appears again
memory lymphocytes
Within lymphoid organs and during inflammation at sites of infection or tissue injury, cells in the immune system communicate with each other primarily via __________ to coordinate defensive measures
cytokines
Cytokines for Growth and differentiation factors for
leukocyte progenitor cells in bone
marrow
GM-CSF, M-CSF
Cytokines for Stimulation of inflammation and fever
TNF-α, TGF-β, IL-1
Cytokines for Stimulation of growth in T lymphocytes and NK cells
IL-12
Cytokines for Growth factors for T helper cells and B lymphocytes
IL-2, IL-4
Cytokines for Eosinophil proliferation, differentiation,
and activation
IL-5
Cytokines for Activation of macrophages
Interferon-g, IL-4
Cytokines for Inhibition of macrophages and specific
adaptive immune responses
IL-10
Cytokines for Antiviral activity
Interferon-α, interferon-β
Cytokines for Chemokine for neutrophils and
T lymphocytes
IL-8
They coordinate cell
activities in the innate and adaptive immune responses
CYTOKINES
is known as the Directed cell movements toward and cell accumulation at sites of inflammation, for example, during diapedesis
chemotaxis
Cytokines for producing the effect of chemotaxis are called ___________________
Chemokines
Stimulation or suppression of lymphocyte activities
in adaptive immunity. A group of cytokines with such effects were named ____________________ because they were thought to be produced by and to target only leukocytes.
interleukins
A molecule that is recognized by cells of the adaptive immune
system is called an ________________ and typically elicits a response
from these cells.
antigen
Immune cells recognize and react to small molecular domains
of the antigen known as ________________________
antigenic determinants or epitopes
Two types of antigen immune response
Cellular
Humoral
Antigen immune response in which
lymphocytes are primarily in charge of eliminating the antigen)
cellular immune response
Antigen immune response in which antibodies are primarily responsible
for the response
humoral immune response
_______________________ is a glycoprotein of the immunoglobulin
family that interacts specifically with an antigenic determinant.
antibody
_________________ are secreted by plasma cells that arise by terminal
differentiation of clonally proliferating B lymphocytes whose
receptors recognize and bind specific epitopes
Antibodies
antibody molecules that have a common design, consisting of two identical light chains and two
identical heavy chains bound by disulfide bonds
Immunoglobulins
The isolated carboxyl-terminal portion of the heavy-chain
molecules is called the _______________________
constant Fc region
The first 110 amino acids near the amino-terminal ends of the light and heavy chains vary widely among different antibody molecules, and this region is called
the _____________________
variable region
The variable portions of one heavy and
one light chain make up an antibody’s _____________________
antigen-binding site.
is present in almost all exocrine secretions as a
dimeric form in which the heavy chains of two monomers
are united by a polypeptide called the J chain
IgA
is produced by plasma cells in mucosae of the digestive, respiratory, and reproductive tracts
IgA
constitutes 5%-10% of blood immunoglobulin and usually exits in a pentameric form united by a J chain.
IgM
usually a monomer, is much less abundant in the
circulation and exists bound at its Fc region to receptors
on the surface of mast cells and basophils.
IgE
the least abundant immunoglobulin in plasma, is
also the least understood class of antibody.
IgD
Monomers of IgD are bound to the surface of __________________ where
they (along with IgM monomers) act as antigen receptors in triggering B-cell activation
B lymphocytes
IgG Antibody
percentage in the
plasma
75%-85%
IgM Antibody
percentage in the
plasma
5%-10%
IgA Antibody
percentage in the
plasma
10%-15%
IgD Antibody
percentage in the
plasma
0.001%
IgE Antibody
percentage in the
plasma
0.002%
IgG, IgD, IgE Structure
Monomer
IgM Structure
Pentamer
IgA Structure
Dimer with J chain
and secretory
component
IgG Presence in sites
other than blood,
connective tissue,
and lymphoid
organs
Fetal circulation in
pregnant women
IgM Presence in sites
other than blood,
connective tissue,
and lymphoid
organs
B lymphocyte
surface (as a
monomer)
IgA Presence in sites
other than blood,
connective tissue,
and lymphoid
organs
Secretions (saliva,
milk, tears, etc)
IgD Presence in sites
other than blood,
connective tissue,
and lymphoid
organs
Surface of B
lymphocytes
IgE Presence in sites
other than blood,
connective tissue,
and lymphoid
organs
Bound to the surface of
mast cells and basophils
Immunoglobulin that has the function of Activation
phagocytosis,
neutralizes antigens
IgG
Immunoglobulin that has the function of First antibody produced in initial immune response;
activates complement
IgM
Immunoglobulin that has the function of Protection of mucosae
IgA
Immunoglobulin that has the function of Antigen receptor triggering initial
B cell activation
IgD
Immunoglobulin that has the function of Destroys parasitic worms and
participates in
allergies
IgE
Antigen-antibody complexes containing IgG or IgM bind polypeptides of the
complement system
Complement activation
a group of around 20 plasma proteins produced mainly in the liver, and activate
them through a cascade of enzymatic reactions.
complement system
This refers to the ability of receptors on
macrophages, neutrophils, and eosinophils to recognize
and bind the Fc portions of antibodies attached to surface antigens of microorganisms.
Opsonization
Antibodies bound to antigens on
virus-infected cells of the body are recognized by the primitive lymphocytes
NK cells
two proteins release by NK cells
perforin
granzyme
Antigens recognized by lymphocytes are often bound to specialized integral membrane protein complexes on cell surfaces. These abundant antigen-presenting proteins are parts of the ______________________________
major histocompatibility complex (MHC),
bind a wide variety of
proteasome-derived peptide fragments representing the range
of all proteins synthesized in that cell.
MHC class I proteins
are synthesized and transported
to the cell surface similarly but only in cells of the mononuclear phagocyte system and certain other cells under some conditions
MHC class II proteins
when the donor and the host are the same individual, such as
a burn patient for whom skin is moved from an undamaged
to the damaged body region
autografts
are those involving
identical twins. Neither of these graft types is immunologically rejected
isografts
which involve two
related or unrelated individuals, consist of cells with MHC class
I molecules and contain dendritic cells with MHC class II molecules, all presenting peptides that the host’s T cells recognize as “foreign,” leading to immune rejection of the graft.
Homografts (or allografts)
number of T lymphocytes and B lymphocytes in Thymus
100
0
number of T lymphocytes and B lymphocytes in Bone Marrow
10
90
number of T lymphocytes and B lymphocytes in Spleen
45
55
number of T lymphocytes and B lymphocytes in Lymphnodes
60
40
number of T lymphocytes and B lymphocytes in Blood
70
30
Lymphocytes both regulate and carry out __________ immunity
adaptive
is usually reticular connective tissue
filled with large numbers of lymphocytes
Lymphoid tissue
are long-lived lymphocytes and constitute nearly 75%
of the circulating lymphocytes
T lymphocytes
T Lymphocytes recognize antigenic epitopes via surface protein complexes termed __________________
T-cell receptors (TCRs)
the coreceptor with the TCR for binding MHC class II molecules and the peptides they display
Helper T cells (CD4)
Lymphocytes with Their TCRs together with the CD8 coreceptors
recognize specific antigens displayed by MHC class I
molecules on “foreign” cells, which include tumors cells,
tissue grafts, and cells infected with virus or replicating
bacteria
Cytotoxic T lymphocytes (CD8)
serve to inhibit specific immune responses. These cells, also identified by the presence
of the Foxp3 transcription factor, play crucial roles in
allowing immune tolerance, maintaining unresponsiveness to self-antigens and suppressing excessive immune
responses
Regulatory T cells (CD4+CD25)
Regulatory T cells produce __________________,
which acts to supplement the central tolerance that
develops in the thymus.
peripheral tolerance
represent a smaller subpopulation
whose TCRs contain γ (gamma) and δ (delta) chains
instead of α and β chains
γδ T lymphocytes
Because the
antibodies specified by B cells circulate in lymph and blood throughout the body, B cells are said to provide _________________
immunity
humoral
A main function of the thymus is
_______________________, which along with regulatory
T cells prevents autoimmunity.
induction of central tolerance
Squamous TECs form a layer creates an isolated cortical compartment and, together with the vascular endothelial cells and pericytes, forms a _________________________ preventing unregulated
exposure of thymocytes to antigens
blood-thymus barrier
Large aggregates of TECs, sometimes concentrically
arranged are called ____________________
Hassall corpuscles
is the site of T-lymphocyte differentiation and the
selective removal of T cells reactive against self-antigens, a key
part of inducing central self-tolerance.
The thymus
This interaction determines whether the newly made TCR proteins of these cells
are functional
Positive Selection
the focus is on removing T cells whose TCRs strongly bind
self-antigens, a process called __________________ because survival depends on a cell not binding to MHC molecules with such
peptides
negative selection
occurs in the cortex and allows survival
only of T cells with functional TCRs recognizing MHC class I and
class II molecules
Positive selection
occurs in the medulla
and allows survival only of T cells that do not tightly bind self antigens presented on dendritic cells there.
Negative selection
Largest lymphoid organs, containing up to 70% of all the
body’s immune cells
Mucosa Associated Lymphoid Tissue
located posteriorly on the soft palate,
are covered by stratified squamous epithelium
Palatine tonsils
Palatine tonsils surface area of each is enlarged with 10-20 deep invaginations or ___________________ in which the epithelial lining
is densely infiltrated with lymphocytes and other leukocytes
tonsillar crypts
are situated along the base of the
tongue, are also covered by stratified squamous epithelium with crypts, and have many of the same features as
palatine tonsils but lack distinct capsules.
Lingual tonsils
situated in the posterior
wall of the nasopharynx, is covered by pseudostratified
ciliated columnar epithelium, and has a thin underlying capsule. The mucosa with diffuse lymphoid tissue and lymphoid nodules is invaginated with shallow infoldings but lacks crypts
pharyngeal tonsil
are bean-shaped, encapsulated structures, generally only 10 mm by 2.5 cm in size, distributed throughout
the body along the lymphatic vessels
Lymph Nodes
Embedded in loose connective tissue, a lymph node has a
convex surface where __________________ enter and a concave depression, the ________ , where an ______________________
and where an artery, vein, and nerve penetrate the organ
afferent lymphatics, hilum, efferent lymphatic leaves
All of these cells are arranged in a stroma of reticulin fibers and
reticular cells to form three major regions within each lymph
node: an outer _______ containing the nodules; a deeper extension of cortex called the _____________, which lacks nodules; and a ___________ with prominent draining sinusoids adjacent
to the hilum
cortex, paracortex, medulla
The medulla of a lymph node has two major components
Medullary cords and Medullary sinuses
The cortex includes the following components
subcapsular sinus
cortical sinuses
are branched cordlike masses of lymphoid tissue extending from the paracortex. They contain T and B lymphocytes and many plasma cells.
Medullary cords
are dilated spaces lined by discontinuous endothelium that separate the medullary
cords.
Medullary sinuses
splenic pulp has two components:
the ____________ (20% of the spleen) and the __________________
white pulp, red pulp
The small masses of white pulp consist of __________________ and the ________________________________
lymphoid nodules, periarteriolar lymphoid sheaths (PALS)
ed pulp consists of blood-filled _____________ and
________________________.
sinusoids, splenic cords
the site where effete
RBCs in blood are removed
red pulp
Unusual elongated endothelial cells called ___________________
line these sinusoids, oriented parallel to the blood flow and
sparsely wrapped in reticular fibers and highly discontinuous
basal lamina
stave cells
circulation where capillaries branching from the penicillar arterioles connect directly to the sinusoids
and the blood is always enclosed by endothelium.
closed circulation
circulation where capillaries from about half of the penicillar arterioles are uniquely open-ended,
dumping blood into the stroma of the splenic cords
Open circulation
is present from birth and involves leukocytes
(mainly granulocytes) and proteins such as defensins, complement, lysozyme, and interferons;
Innate immunity
develops more slowly and is based on antigen presentation to lymphocytes
adaptive immunity
Immune cells communicate with one another and regulate one
another’s activities via polypeptide hormones called __________________
cytokines.
are the regions of macromolecules, usually proteins, that
are recognized by lymphocytes to elicit a specific immune response
against them
Antigens
are immunoglobulins produced by plasma cells after a progenitor B cell is activated by a specific antigen and rearranges its immunoglobulin genes so that the antibody matches the antigen
Antibodies
MALT is found in the mucosa of most tracts but is concentrated in
the ______________ tonsils, _____________________, and
the appendix
palatine, lingual and pharyngeal tonsils,
is a large lymphoid organ without a cortex/medulla
structure; instead, it has two intermingled but functionally different
regions: white pulp and red pulp
SPLEEN
Blood flow in red pulp is either a _________________, moving from
capillaries into the venous sinusoids, or an ______________________, with
capillaries opening directly into the splenic cords.
closed circulation, open circulation
