LYMPHOID SYSTEM Flashcards
structured to recognize,
respond to, and destroy a wide variety of invading organism that would otherwise be capable of promoting infections, harmful to the body
IMMUNE SYSTEM
ability of an individual to
resist infections by means of normally present body functions.
natural immunity
type of resistance that is
characterized by specificity for each individual pathogen, or microbial agent.
acquired immunity
represents 20-40% of the circulating
WBCs. Considered as the 2nd dominant circulating WBC in the bloodstream next to neutrophil.
lymphocytes
is sparse, containing few organelles and
no specific granules, and consists of a narrow ring surrounding the nucleus
Cytoplasm
Lymphocyte circulation is complex and is regulated by different cell surface adhesion molecules and by chemical messengers called
cytokines
it’s function is for maturation of the B cell and T cell
Primary Lymphoid organs
If the lymphocyte matured in the thymus the cell is known as
T-cell
Example of primary Lymphoid organs
Bone marrow, thymus
Example of secondary Lymphoid Organs
Spleen, lymph nodes, appendix, tonsils, peyer’s patches
further maturation, differentiation,
proliferation of T cells and B cells.
secondary lymphoid organ
fills the core of all long bones and is the
main source of hematopoietic stem cells, which develop into different cell types
bone marrow
what are the 3 major population of lymphocytes?
T cell, B cell, Natural Killer Cells
portal of entry for macrophages
mucosal-associated lymphoid tissue
an organ which is small, flat, bilobed organ found in the thorax, or chest cavity, right below the thyroid gland and overlying the heart.
thymus
Largest secondary lymphoid organ.
spleen
makes up more than one-half of the total volume, and its function is to destroy old red blood cells
red pulp
comprises approximately 20 percent of the total weight of the spleen and contains the lymphoid tissue, which is arranged around arterioles in a
periarteriolar lymphoid sheath (PALS)
white pulp
occurs in the secondary tissue, but this is strictly
dependent on antigenic stimulation, while
formation of lymphocytes in the bone marrow is
antigen-independent
lymphopoiesis
When antigen entered the spleen, it will activate B cells and form a structure known as the
germinal center
Germinal center is also known as
Secondary follicle
The lymph fluid flows slowly through spaces called
sinuses
main function of lymph nodes
filtration
Contains macrophages and aggregations of B cells in primary follicles, follicular dendritic cells, secondary follicles (germinal center), plasma cells, and memory cells
cortex
T lymphocytes are in close proximity to antigen presenting cells called
interdigitating cells.
physiological mechanisms that endow the
animal with the capacity to recognize materials as foreign to itself and to neutralize, eliminate or metabolize them with or without injury to its own tissues.
immunity
Serves as an antigen trapping site. Increase the probability of an immune response
Secondary Lymphoid Organs
main source of hematopoietic stem cells, which develop into different cell types.
bone marrow
released from the marrow
and travel to additional primary lymphoid organs
where further maturation takes place.
Lymphocyte stem cells
T cells percentage
61-80%
B cells percentage
20%
Natural Killer Cells percentage
10-15%
predominant in the bone marrow compared
to other cells.
WBC
In thymus, what cell play a central role in this differentiation process.
epithelial cells
acquired as the lymphocytes travel from the cortex to the medulla
Surface antigens
2 major parts of thymus
- cortex
- medulla
What lymphocytes are released from the medulla
Mature T lymphocytes
Each of these lines has specific precursors that
originate from
Bone Marrow
characterized as a large discriminating filter,
as it removes old and damaged cells and foreign
antigens from the blood
Spleen
Splenic tissue can be divided into two main
types
- red pulp
- white pulp
It contains B cells that are not yet stimulated
by antigens.
primary follicles
What surrounds the periarteriolar lymphoid sheath or PALS
marginal zone
marginal zone contains _____ that trap antigen
dendritic cell
increases its diameter accumulate
more lymph fluid that contains antigen
Afferent lymphatic
decrease its diameter for better trapping of antigens
efferent
lymphatic
Accumulation of lymphocytes
and other cells causes the lymph nodes to become
enlarged, a condition known as
lymphadenopathy