Immunology π Flashcards
What is immunology?
is the study of the immune system, including its responses to microbial pathogens and damaged tissues and its role in disease.
What is the most important physiological function of the immune system?
prevent or eradicate infections.
What is the immune system and what does it consist of?
The immune system is the bodyβs defense against infectious agents and other foreign substances (antigens) in its environment, It consists of a complex network of cells, tissues, and organs β¦β¦β¦.. Immune response (immunity)
What are the primary lymphoid organs?
BM
Thymus
What is bone marrow?
- The BM is the site of B cell maturation.
* Also, the site of generation of all blood cells from a common stem cell (hematopoiesis).
What is the thymus?
Site of T cell maturation.
What are secondary lymphoid organs?
- Include the lymph nodes and the spleen.
- Mucosa-associated lymphoid tissues including tonsils in the nasopharynx and Peyerβs patches in the sub-mucosal surfaces of the small intestine; also act as secondary lymphoid aggregates.
What is the function of secondary lymphoid organs?
Trap and concentrate antigens.
What are the cells of the immune system?
- A common lymphoid progenitor producing:
a. T lymphocytes
b. B lymphocytes
c. Natural killer (NK) cells. - A common myeloid progenitor producing:
a. Leukocytes:
b. Erythrocytes.
c. Platelets
What are immune cells that come from BM?
Lymphocytes:-
β’ B lymphocytes
β’ T lymphocytes
β’ NK cells
Phagocytes:-
β’ Macrophages
β’ Neutrophils
Antigen-presenting cells:-
β’ Macrophages
β’ Dendritic cells
β’ B lymphocytes
What is immune system discrimination?
self/non-self
Self-antigen ββ> no immune response
Foreign antigen pathogenββ-> immune response
How many layers does the immune system consist of?
3
What are the types of immunity?
The immune system has two lines of defense:
- Innate (non-specific) immunity.
- Adaptive (specific) immunity.
What do the innate and acquired immune systems use to sense potential threats?
The innate and adaptive immune systems utilize cell-surface receptors to sense potential threats (microbes).
What are the characters of innate immunity?
- the First line of defense against pathogens and give a rapid response.
- Nonspecific
- no memory.
- Always present in healthy individuals.
- recognize and react against microbes onlyβ¦β¦. PAMPs
What are the components of innate immunity?
- Barriers to infections
- Innate immunity cells
- Soluble defense
What are barriers to infection?
o Physical barriers: include the epidermis and mucous membranes.
o Chemical and environmental barriers:
βͺ pH: the acidic pH of the skin, stomach, and vagina inhibits the growth of pathogens.
βͺ Microcidal molecules: Ξ±- and Ξ²- defensins), lysozyme, RNases, and DNases that.
o Biological barriers (commensal microbes): are
microbes (like flora) that exist in a symbiotic relationship with the body. They colonize skin, GIT, upper respiratory, urogenital tracts, and eyes and inhibit the establishment of pathogenic microbes.
What are innate immunity cells?
a. Phagocytic cells: are cells having the ability to phagocytose (recognize, ingest, and
kill) microbes and any foreign antigen (phagocytosis)
β’ Macrophages
β’ Neutrophils
b. Natural killer (NK) cells: function in killing tumor cells and virus-infected cells
What are examples of soluble defense?
- The complement system.
- Cytokines of innate immunity.
- Other plasma proteins of innate immunity:
βͺ Mannose-binding lectin (MBL). βͺ C-reactive protein (CRP)
What happens to the circulating levels of plasma proteins after infection?
- The circulating levels of these plasma proteins increase rapidly after infection.
- This protective response is called βacute phase responseβ.
What are the characters of adaptive immunity?
- Second line of defense.
- Develops as a response to infection.
- Specificity and memory are characteristic features of adaptive immunity
- Lymphocytes are the cells of adaptive immunity
Specificity of the adaptive immunity
the immune response is specific for a certain antigen Specificity ensures that different antigens elicit specific responses.
memory of the adaptive immunity
is the ability to βrememberβ and respond more strongly to repeated exposure to the same microbe.
What is the function of B lymphocytes?
produce antibodies that neutralize and eliminate the extracellular microbes and toxins (Humoral immunity).
What is the function of T lymphocytes?
eradicate intracellular microbes (Cell-mediated immunity).
What is another function for B and T lymphocytes?
recognize antigen by antigen-specific receptors present on their surfaces.
What are the types of adaptive immunity?
Humoral (antibody-mediated)
β’ B lymphocytes
Cell-mediated
β’ T lymphocytes
What are the sequences of adaptive immune response?
- Antigen recognition by lymphocytes receptors.
- Activation of lymphocytes leads to proliferation & differentiation into effector cells (cells that carry the function) and memory cells.
- Elimination of the microbes.
- Decline and termination of the immune responses (homeostasis) once the pathogen is eliminated to avoid damaging host tissues.
- Long-lived memory (memory cells).