Lecture 1 Flashcards
What is immunology?
the study of the physiological mechanisms that animals use to defend their bodies from invasion by pathogens
What is a pathogen?
any organism with the potential to cause disease
How are multicellular organisms attacked by microorganisms (general)?
They are infected and colonized by microorganisms
What are the defense mechanisms for animals?
- skin and contiguous mucosal surfaces (physical and chemical barrier)
- immune system- lymphoid and myeloid cells- (barrier breach protection)
What is immunity?
Provided by previous exposure, exposure can lead to mortality-children (developing countries)
What does vaccination/immunization mean?
prior exposure to infectious agents that cannot cause disease-little risk to health or life
What was the first vaccination?
smallpox
How many microbial species live in the human gut?
Over 1000
What do do microbials do in the gut?
process digested food and make several vitamins
What are the benefits of commensal microorganisms?
prevent colonization by disease causing organisms
What happens to commensal microorganisms when antibiotics are used?
Destruction of commensal organisms and can lead to opportunistic infection
What are opportunistic pathogens?
pathogens tha tdo no cause illness unless immune defenses are weakened
What are the 4 types of infectious organisms?
Bacteria, Viruses, Fungi, Parasites
What are the elements of the immune system?
- )skin and mucosal surfaces form barriers against infection
- ) innate immuntiy
- )Adaptive immunity
What is skin?
Barrier of epithelium protected by keratinized cells
What is the epithelium?
layer of cells that line the outer surface and the inner cavities of the body
What are examples of physical barriers?
wounds, burns, surgical procedures, injections
What was the major reason for soldiers death?
infection
What drove most advancements in surgery and medicine?
War
What areas have mucosal surfaces that protect against infection?
urogenital tract, respiratory tract, gastrointestinal tract
- have well maintained chemical, microbiological barriers
What is mucous and how is it secreted?
thick fluid containing glycoproteins, proteoglycans, and enzymes that is secreted by cells
What is the function of epithelial cells?
produce antimicrobial substances and remove mucous
What is the function of the sebaceous glands?
secrete sebum containing containing fatty acids and lactic acids (antibacterial)
What do tears and saliva secrete?
lysozyme (antibacterial)
What environments are acidic?
stomach, vagina, skin
What is innate immunity?
- Fast mechanisms
- Fixed mode of action
- Effective at stopping infections at an early age
- Key elements:
- pathogen receptors-bind covalently to the surface of pathogens
- proteins that bind covalently to pathogen surfaces-form ligands for receptors on phagocytes
- Phagocytic cells- engulf and kill pathogens
- Cytotoxic cells- kill virus-infected cells
What induces cleavage and activation of complement?
Presence of bacterium
How does a complement fragment bind to a bacterium?
covalently
What binds to the effector cell receptor after a complement fragment binds to a bacterium?
the complement fragment
Where do effector molecules reside that assist in innate immunity?
connective tissue
What activates effector molecules and the innate immune system?
Surface wound introduced by bacteria
What allows inflammatory cells to leave blood and enter tissue?
vasodilation and increased permeability
What are characteristics of adaptive immunity?
- Slow to start
- powerful-eliminates almost all pathogens that escape innate immunity
- improve pathogen detection rather than pathogen destruction
- involves lymphocytes (t cells and Bcells)
- initiated in specialized lymph tissue- Tcell and B cell have receptors that bind to pathogens-selection and activation
- involve long lasting protection
- evolving process throughout lifetime
What is the difference between adaptive and innate immunity?
Innate immunity
- rapid response
- fixed
- limited number of specialities
- constant during reponse
Adaptive immunity
- slow process
- numerous highly selective specialities
- variable
- improve during response
During development, what are the function for progenitor cells?
Give rise to large numbers of lymphocytes each with a different specificity
How do lymphocytes detect pathogen during infection?
During infection, lymphocytes with receptors that recognize the pathogen are activated and then proliferation and differentiation of pathogen-activated lymphocytes give effector cells that terminate the infection
Which type of immunity is more understood?
Adaptive immunity
Generally, how is adaptive immune respinse activated?
innate immune response must be active
What is hematopoiesis?
The process by which blood cells are formed
What are hematopoietic stem cells?
- Pluripotent
- develops into:
- Leukocytes-white blood cells
- erythrocytes- red blood cells
- megakaryotes- platelets
Where is most hematopoietic activity present before birth?
yolk sac
After birth, where is the greatest hematopoietic activity?
bone marrow
Where does hematopoietic activity occur?
bone marrow , fetal liver and spleen, and yolk sac
What do hematopoietic cells form into?
common lymphoid precursor and common myeloid precursor
What do lymphoid precursor cells turn into?
NK/T cell precursor and B cell
What do B cells form?
plasma cells
What do T cells form?
effector cells and NK cells
What do common myeloid precursor form?
granulocyte macrophage progenitor
What is the lineage of macrophage and dendritic cell precursor?
monocytes—> macrophage
and dendritic cells
What can granulocyte macrophage progenitor cells form into?
macrophage/dendritic precursor cells neutrophils eosinophil basophil unknown precursor ---> mast cell
What do megakaryote/erythocyte progenitors form?
megakaryocyte —-> platelets
erythroblasts —-> erythrocyte
What do eosinophils do?
get rid of parasites
What do NK cells do?
kill cells infected with certain viruses
What do lymphocytes do?
produce antibodies (B cells) or cytotoxic and helper function (T cells)
What is the function of a plasma cell?
secrete antibodies
What are mast cells ?
Expulsion of parasites from body through release of granules containing histamine and other active agents
What do dendritic cells do?
Activation of T cells and initiation of adaptive immune responses
How to do stem cells divide?
Assymetrically (stem cell and differentiate)
What is cell type has the least amount of leukocytes?
basophils
What cell type has the most amount of leukocytes?
neutrophils
Where are neutrophils mostly stored?
bone marrow and are released to fight infection
How to neutrophils fight infection?
During infection, they travel to the site of infection and engulf and kill bacteria.
They die in the tissue and are engulfed and degraded by macrophages
How are macrophages activated?
Binding of bacteria to phagocytic receptors on macrophages induces their engulfment and degradation
They are induce the synthesis of cytokines
What are the receptors of adaptive immunity?
Immunoglobulins and T-cell receptors
When do B cells and T cells differentiate into effector cells?
on encountering their specific antigen
What happens when an antibpdy binds ti pathogens?
Cause destruction or inactivation
What is neutralization?
Cells with receptors for toxin leading to ingestion and destruction by phagocyte
What is opsonization?
antibodies mark the pathogen and then prepare for ingestion and destruction by phagocyte while also relasses a complement fragment
How do lymphocytes and lymph return to the blood?
Through lymphatics
Why is the spleen significant?
provides adaptive immunity to blood infections
Tissues of the lamina propria contain a large number of ?
immunoglobulin A (IgS)+ plasma cells, T and B cells., macrophages, dendritic cells, and stromal cells
What is the GALT?
Gut associated lymphoid tissue and it had organized lymphoid structures, ;like peyer’s patches and isolated lymphoid follicles
-tonsils, adenoids, appendix, peyers patches
What is BALT?
Bronchial associated tissue lymphoid tissue
-less organized aggregates of secondary lymphoid tissue that line the respiratory epithelium and other mucosal surfaces (eg GI tract)
What is MALT?
diffuse mucosal lymphoid tissue
What portion of the small intestines contains lymph nodes?
Peyers patch
