Week 2 Lec: Lymphoid System Flashcards
All those 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
The _______ is 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
The ability of an individual to resist infections by means of normally present body functions.
Natural Immunity
It is considered as first line of defense. Physical barriers such as our skin, and secretions.
External defense system
It is considered as second line of defense. The most important process is process of phagocytosis. It is incorporated with the different types of WBC such as the polymorphonuclear cells, monocytes, and macrophages.
Internal defense system
The type of resistance that is characterized by specificity for each individual pathogen, or microbial agent. Referred to as the 3rd line of defense.
Acquired Immunity
Lymphocytes represent _____ of the circulating WBCs.
20-40%
What is the second most common type of leukocyte?
Lymphocyte
The typical small lymphocyte is between _____ in diameter.
7 and 10 μm
Nucleus characteristics of lymphocyte?
a large rounded nucleus that may be somewhat indented
Color of lymphocyte when stained?
lighter blue appearance
Cytoplasm characteristics of lymphocytes?
- sparse
- few organelles
- no specific granules
- narrow ring surrounding the nucleus
Why are lymphocytes unique?
because they arise from a hematopoietic stem cell and are further differentiated in the primary lymphoid organs
2 main classifications of lymphocytes depending on where lymphocyte differentiation takes place?
Primary and Secondary Lymphoid Organs
Main function of Primary Lymphoid Organs?
maturation of B and T cells
Main function of Secondary Lymphoid Organs?
proliferation and differentiation of B and T cells
Lymphocyte circulation is complex and is regulated by different cell surface adhesion molecules and by chemical messengers called?
cytokines
They influence other activities of the cell.
cytokines
3 major populations of lymphocytes?
- T cells
- B cells
- Natural Killer cells
T cells account for how many percent in the total population of lymphocytes?
61-80%
B cells account for how many percent in the total population of lymphocytes?
20%
Natural killer cells account for how many percent in the total population of lymphocytes?
10-15%
Once T and B cells mature, they go to?
Secondary Lymphoid Organs
What is the precursor cell mainly associated with B, T, and NK cells?
common lymphoid precursor
Primary Lymphoid Organs consist of?
- Bone marrow
- Thymus
Secondary Lymphoid Organs consist of?
- Spleen
- Lymph nodes
- Mucosal-Associated Lymphoid Tissue (Appendix, Tonsils, Peyer’s Patches)
- Cutaneous-Associated Lymphoid Tissue
It consists of flat, long bones that is a source of hematopoietic stem cells.
Bone marrow
All lymphocytes arise from?
pluripotential hematopoietic stem cells
Aside from lymphocytes, it accounts for the different cell types such as RBC, WBC, macrophages and megakaryocytes/thrombocytes/platelets.
pluripotential hematopoietic stem cells
Weight of bone marrow in humans?
1,300-1,500 g (adult)
It fills the core of all long bones and is the main source of hematopoietic stem cells, which develop into different cell types.
Bone marrow
_____________ are released from the marrow and travel to additional primary lymphoid organs where further maturation takes place.
Lymphocyte stem cells
The mother cell of all cells.
hematopoietic stem cell
Hematopoietic stem cells give rise to what 2 different cell lines?
CLP (Common Lymphoid Precursor) and CMP (Common Myeloid Precursor)
Common Lymphoid Precursor gives rise to which cells?
- T cell
- B cell
- Dendritic cell
- Natural Killer cell
Common Myeloid Precursor gives rise to which cells?
- monocytes
- eosinophils
- basophils
- neutrophils
- erythrocytes
- platelets
It is 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
Weight of thymus at birth?
30 g
Weight of thymus at puberty?
35 g
A decrease in the size of thymus when it reaches its matured/maximum form is an example of what process?
atrophy
Each lobe of the thymus is divided into _____ filled with _____ that play a central role in this differentiation process.
lobules, epithelial cells
________ are acquired as the lymphocytes travel from the cortex to the medulla over a period of 2 to 3 weeks.
Surface antigens
Part of the thymus where T cells stay before they mature.
Cortex
Once matured T lymphocytes are formed, they are then released from the?
Medulla
Each lymphocyte spends most of its life span in ___________, entering the circulation only periodically to go from one secondary organ to another.
solid tissue
A specific lymphocyte may make the journey from blood to secondary lymphoid organs and back _____ times per day.
one to two
Largest secondary lymphoid organ.
Spleen
Dimensions and weight of the spleen?
12cm in length and weighs 150g in adult
A large discriminating filter that can remove foreign antigens and all RBCs from the blood.
Spleen
Spleen is located?
in the upper-left quadrant of the abdomen, just below the diaphragm
Spleen is surrounded by a?
thin connective tissue capsule
Splenic tissue can be divided into two main types?
- Red Pulp
- White Pulp
It makes up more than one half of the total volume, and its function is to destroy old red blood cells.
Red Pulp
In the red pulp of the spleen, blood flows from the arterioles into the red pulp and then exits by way of the?
splenic vein
It comprises approximately 20 percent of the total weight of the spleen.
White Pulp
The White Pulp comprises approximately ___ percent of the total weight of the spleen.
20
The White Pulp contains the lymphoid tissue, which is arranged around arterioles in a?
periarteriolar lymphoid sheath
Attached to the periarteriolar lymphoid sheath are?
primary follicles
It contains B cells that are not yet stimulated by an antigen.
primary follicles
Surrounding the PALS is a ___________ containing dendritic cells that trap antigen.
marginal zone
The marginal zone contains what cells that trap antigen?
dendritic cells
The most potent phagocytic cell and is considered as the best APC (Antigen Presenting Cell).
dendritic cell
Each day, an adult blood passes through the spleen approximately ___ times.
4
Why does the blood pass through the spleen ~4 times a day?
it allows lymphocytes and macrophages to constantly survey for infectious agents or other foreign matters
When B cells contained in the primary follicle are stimulated by an antigen, it results to a structure called?
germinal center
Tagalog term for lymph nodes?
kulani
Located along lymphatic ducts and serve as central collecting points for lymph fluid from adjacent tissues.
Lymph Nodes
Lymph Nodes are located along?
lymphatic ducts
Functions of lymph nodes?
- collecting points for lymph fluid from adjacent tissues
- contribute for the ideal environment of foreign antigens
Lymph nodes are especially numerous near?
joints and where the arms and legs join the body
Size of lymph node?
1 mm to 25 mm in diameter
Major purpose of lymph nodes?
filtration
The lymph fluid flows slowly through spaces called ______, which are lined with macrophages, creating an ideal location for phagocytosis to take place.
sinuses
The lymph fluid enters the lymph nodes via?
afferent lymphatic vessel
The lymph fluid exits the lymph nodes via?
efferent lymphatic vessel
Swelling of lymph nodes?
Lymphadenopathy
Region of lymph nodes: the outermost region. An aggregation of lymph nodes. Contains macrophages and aggregations of B cells in primary follicles, follicular dendritic cells, secondary follicles (germinal center), plasma cells, and memory cells.
Cortex
Consists of stimulated B cells and site where germinal center is seen.
Secondary follicles
They are fully differentiated lymphocytes found in the cortex of lymph nodes for antibody production and secretion.
Plasma cells
Region of lymph nodes: where T cells are found. Region between the cortex and medulla.
Paracortex
Region of lymph nodes: contains some T cells, B cells and numerous plasma cells.
Medulla