Diseases Of The Immune System Flashcards
What Is immunity
Immunity refers to protection against infections.
Give 2 types of immunity
Innate and Adaptive immunity
Describe innate immunity
Innate immunity is mediated by cells and proteins
that are always present and poised to fight against
microbes and are called into action immediately in
response to infection.
4 components of innate immunity
- Epithelial barriers of skin, GIT and respiratory
tract. - Phagocytic leukocytes(Neutrophils,
macrophages) - Natural killer cell
- Several plasma proteins
What is adaptive immunity
Adaptive immunity( acquired or specific immunity)
is silent and responds to the presence of infectious
microbes by becoming active, expanding, and
generating potent mechanism for neutralizing and
eliminating microbes.
What are the components of adaptive immune system
Components of adaptive immune system are
lymphocytes and their products.
Types of adaptive immune responses
- Humoral immunity, mediated by soluble antibody
proteins that are produced by B lymphocytes - Cell mediated immunity, mediated by T
lymphocytes
Describe lymphocytes
Lymphocytes: are the mediators of adaptive
immunity and the only cells that produce specific
and diverse receptors for antigens
Describe t lymphocytes
T lymphocytes: express antigen receptors called T
cell receptors that recognize peptide fragments of
protein antigens that are displayed by MHC
molecules on the surface of the antigen presenting
cells.
Describe (Major histocompitibilty complex) molecules:
MHC(Major histocompitibilty complex) molecules:
the peptide display system of adaptive immunity
Describe B lymphocytes( Bone marrow-derived):
B lymphocytes( Bone marrow-derived): express
membrane bound antibodies that recognize a wide
variety of antigens. B cells are activated to become
plasma cells, which secrete antibodies.
Describe Natural killer cells
Natural killer cells: kills cells that are infected by some
microbes, or are stressed and damage beyond repair.
NK cells express inhibitory receptors that recognize
MHC molecules that are normally expressed on healthy
cells, and are thus prevented from killing normal cells.
Antigens presenting cells
Antigen- presenting cells: capture microbes and
other antigens, transport them to lymphoid organs,
and display them for recognition by lymphocytes.
The most efficient APCs are dendritic cells, which
live in epithelia and most tissue.
Describe the overview of normal immune responses
The physiologic function of immune system is
defense against infectious microbes.
The early reaction to microbes is mediated by the
mechanism of innate immunity, which are ready to
respond to microbes. These mechanism include
epithelial barriers, phagocytes, NK cells, and
plasma proteins, e.g. of the complement system.
The reaction of innate immunity is often manifested
as inflammation
The defense reactions of adaptive immunity develop
slowly, but are more potent and specialized.
Microbes and other foreign antigens are captured by
dendritic cells and transported to lymph nodes, where
the antigens are recognize by naïve lymphocytes. The
lymphocytes are activated to proliferate and
differentiate into effector and memory cells.
Cell-mediated immunity is the reaction of Tlymphocytes,
Design to combat cell- associated microbes( e.g.
phagocytosed microbes and microbes in the
cytoplasm of infected cells)
Humoral immunity is mediated by antibodies and is
effective against extracellular microbes( in the
circulation and mucosal lumens)
CD4+ helper T cells help B cells to make
antibodies, activates macrophages to destroy
Microbes and block their infectivity, and promote
the phagocytosis and destruction of pathogens.
Antibodies also confer passive immunity to
neonates.
Describe the 4 hypersensitive reactions
- I (Immediate Hypersensitivity)
- II (Antibody Mediated Hypersensitivity)
- III (Immune-Complex Mediated Hypersensitivity)
- IV (Cell-Mediated Hypersensitivity)
