Module 1 Flashcards
Introduction to the Immune System
Describe the human microbiome
- 10^14 microorganisms (10x more than human cells)
- Contains microorganisms principally harmless or beneficial to our health and proper functioning of our bodies and a smaller proportion of types that can cause a disease state
What are pathogenic microorganisms?
Microorganisms that can cause a disease state
What are Commensal microorganisms
Microorganisms that are beneficial to our health
What are the 2 major components of the immune system?
Innate Immune System
Adaptive Immune system
What is the immune response?
Reaction of immune cells to the presence and actions of microbes of danger signals in the body
What are 2 normal functions of the immune system?
Discriminate (recognize self from non-self)
Eliminate (Destroy non-self eg: pathogen and altered self cells eg: cancer)
What are 2 dysfunctions that make the immune system overly active?
Autoimmunity
Hypersensitivity
What is dysfunction that make the immune system underactive?
Immunodeficiency (eg AIDS)
What is an antigen?
Foreign protein that induces an immune response, typically including the production of antibodies.
Contraction of the words ANTIbody GENerator
What is an antibody
Protein that is produced in response to, and countering, a specific antigen
What is the relation between antigen and antibody
Antibodies bind to foreign substances (antigens) in the body and provide a signal for their elimination
What is the most important property in order for these defence mechanisms to work properly and protect us?
magic word is BALANCE
Each component must be functional to avoid immunodeficiencies
BUT also regulated so that it does not become overly active and attack self
What are the 3 body systems that create an efficient filtering system for the body?
circulatory, lymphatic, and immune systems
What are lymphoid organs?
Organs shared in both the immune and lymphatic system
What is the lymphatic system?
Network of vessels that drains fluid (Lymph) that filtrated from the blood in the capillaries and entered the surround tissues, also called interstitial space
Prison break analogy: Lymphatic system?
Corridors of a prison, where guards circulate to make sure that everything is in order
What is the relationship between the lymphatic system and circulatory system?
Circulatory system is where the lymph comes from and goes after being filtered
Lymphatic vessels pick up the lymph and carry it toward the heart where it re-enters the circulatory system
What is the relationship between the immune system and the lymphatic + circulatory systems? (3)
1- Cells of the immune system travel between the circulatory system and the lymphatic system
2- Some immune cells reside in the tissues and can directly interact with an antigen
3- Other mature immune cells travel within the blood to the site of infection
What are the major lymphoid organs and tissues? (5)
1- Bone marrow 2- Lymph nodes 3- MALT 4- Spleen 5- Thymus
Describe the structure, location and function of the bone marrow
Structure:
- flexible, 2 types (yellow and red), filled with hematopoietic cells
Location:
- central cavity inside the bones
Function
- Red : important for immune system, site of hematopoiesis, site of B cell development
- Yellow: Some leukocyte development, produces fat and cartilatge
What are hematopoietic cells?
Cells lodged within the bone marrow and which are responsible for producing the cells which circulate in the blood (RBC, WBC and platelets)
Prison break analogy: Bone marrow
The police academy for prison guards
Describe the structure, location and function of the Lymph Nodes
Structure:
- Small (1-25mm) numerous (600 approx) bean shaped
- Divided into 3 roughly concentric regions (cortex, paracortex, medulla)
- Filled with lymphocytes, macrophages, and dendritic cells
Location:
- Grouped along the lymphatic vessels
Functions:
- Filters the lymph
- Often it is the first organized lymphoid structure that foreign molecules encounter when first entering the body
Prison Break analogy: Lymph Nodes
Locked doors within a prison that prisoners have to get permission from guards in order to pass through
What are lymphocytes?
White blood cells which arise from the lymphoid progenitor lineage during hematopoiesis. Generally refers to B- and T-cells
Describe the structure, location and function of the MALT
Structure
- Combined surface area of various areas in the body including BALT, GALT, Lamina propria of intestinal villi, Peyer’s patches, Tonsils, appendix
- Filled with various types of immune cells depending on the location
Location:
- Mucous membranes lining the digestive, respiratory, and urogenital systems
Function:
- Initiates immune responses to specific antigens encountered along all mucosal surfaces
What is the MALT?
Mucosal Associated Lymphoid Tissues
What is the BALT
Bronchus-associated lymphoid tissue; lymphoid structure part of the MALT located in lungs and bronchus
What is the GALT?
Gut-Associated lymphoid tissue; lymphoid structure part of the MALT located in the gut
What is the Lamina propria of intestinal villi?
Thin layer of connective tissue rich in immune cells located into the lumen of the small intestine
What is Peyer’s patches?
Small masses of lymphatic tissue found throughout the ileum region of the small intestine
What are the tonsils?
Collection of lymphoid tissue facing the aerodigestive tract, mainly located into the pharynx
What is the appendix
A small, pouch-like sac of tissues located in the first part of the colon (cecum) in the lower-right abdomen. Harbours bacteria and aids in immune function. Recent research suggests that it plays a larger role in estabilishing the core gut microbiome than previously thought
Prison Break analogy: MALT
Watchtowers, where guards control the weaker spots of passage between the prison walls and the outside
Describe the structure, location and function of the Spleen
Structure:
- Large ovoid divided in 2 compartments; white pulp and red pulp
Location:
- Situated in the left abdominal cavity
Function:
- Red pulp filters the blood
- White pulp is the site of development of immune responses against antigens found in the bloodstream
Prison Break analogy: Spleen
Locked door that a prisoner has to get access from the guards in order to pass through to get to the courtyard inside the prison walls
Compare and contrast Red pulp and White pulp in the spleen
White pulp: filled with macrophages, lymphocytes, T-cells, B-cells, and RBCs
Red pulp: composed of cords of billroth and splenic sinuses that are filled with blood
What are cords of Billroth?
Fibrils and connective tissue cells with a large population of monocytes and macrophages located in the the Red Pulp of the spleen
Which spleen compartment is more important to the immune system (red or white)
White, because it is made of lymphatic tissue filled with immune cells
Describe the structure, location and function of the Thymus
Structure:
- Flat and bi-lobed (each lobes are divided into lovules which are organized each in 2 compartments, cortex and medulla)
- Filled with thymocytes, epithelial cells, dendritic cells, and macrophages
Location:
- Situated above the heart
Funtion:
- Site of T-cell development and maturation
What are thymocytes?
T-cells found in the thymus
Prison Break analogy: Thymus
Police academy for officers who becomes member of the S.W.A.T. team or detectives
What are the 2 classifications of Lymphoid organs and tissues
Primary and Secondary, according to their function in the immune system
What are the Primary Lymphoid Organs? (2)
- Thymus
- Bone Marrow
What is the function of the Primary Lymphoid Organs?
Site of lymphocyte maturation into and immunocompetent cell
- B-cell -> Bone marrow
- T-cell -> Thymus
What is an immunocompetent cell?
Denoting a mature lymphocyte that is capable of recognizing a specific antigen and mediating an immune response
What are the Secondary Lymphoid Organs? (3)
- Spleen
- Lymph Nodes
- MALT
What is the function of Secondary Lymphoid Organs?
Site of lymphocyte activation into an effector cell
- through interaction with trapped antigens
What is an effector cell?
Denoting a mature lymphocyte that has been activated and mediates an immune response against a specific antigen
What is discrimination?
Ability of immune cells to distinguish between self and non-self components
How is discrimination achieved?
Almost every nucleated cell in the body expresses a molecule at their surface called Major Histocompatibility Complex class I (MHC I), which presents a “sample” of proteins found inside the cell. Another class, MHC II are present on special cells of the immune system. Immune cells are able to scan their area and recognize if there are abnormalities or antigens. If abnormalities and antigens found (non-self), an immune response can be initiated
What is elimination
Ability of immune cells to initiate an immune response
What are the 4 steps of the immune system response
1- Pathogen (antigen) enters the body
2- Immune system recognizes the antigen
3- Activation of effector cell (innate and adaptive response)
4- Elimination of pathogen
What is the MAJOR function of the immune system?
Preserve and protect the integrity of the body from environmental agents such as microbes, chemicals, or in some instances, abnormal self antigens