Elements of the Immune System, Roles in Defense Flashcards
What is Immunology?
Immunology- the study of physiological mechanisms that animals use to defend their bodies from invasion by pathogens.
What is a pathogen? What are the 4 types of pathogens?
Pathogen- any organism with potential to cause disease The 4 types of pathogens are: -Bacteria -Viruses -Fungi -parasites
What organisms are infected and colonized by microorganisms? How have animals evolved?
Multicellular animals are infected by microorganisms.
Animals have evolved defense mechanisms such as skin and mucosal surfaces (physical and chemical barrier) and an Immune system-make lymphoid and myeloid cells (barrier breach protection).
Describe what immunity is and how vaccinations are useful. what was the first vaccination created? What has occurred now?
Immunity- provided by previous exposure (ability to resist microorganisms or pathogens)
exposure to pathogen can lead to mortality (seen in children, developing countries)
Vaccinations/immunizations- create prior exposure to infectious agent that cannot cause disease; little risk to health or life
The first vaccination was SMALL POX. Small pox has now been eradicated ever since 1979. Small pox not seen in any patients today.
Compare the size of a pathogen to its cell. Where are microorganisms commonly seen? What is their function? What can be a downside of antibiotics?
Pathogen is smaller than the cell it infects.
Microorganisms commonly seen in human gut, or in healthy human bodies.
> 1000 different microbial species live in healthy human gut (microbiome).
These microorganisms inhabit the skin, mouth, vagina and gut- they each have their own niche with its own microbiota (community of commensal organisms)
These microorganisms process digested foods and make several vitamins, also prevent colonization by disease-causing organisms.
Antibiotics- cause destruction of commensal bacteria (good bacteria) and can lead to opportunistic infection (ex: clostridium difficile)
What are opportunistic pathogen?
pathogens that most of the time do NOT cause illness unless immune defenses are weakened.
What are the three main elements of the immune system?
The three main elements of the immune system:
- Skin and mucosal surfaces- form barriers against infection
- Innate immunity
- Adaptive immunity-
Describe the function of skin and mucosal surfaces and how they do so.
How is the physical barrier in skin breached/broken?
What caused soldiers to die more than anything during war? How did this lead to advancement in medicine?
Skin and mucosal surfaces form barriers against infection.
Skin- barriers of epithelium protected by layers of keratinized cells
epithelium- layers of cells that line outer surface and inner cavities of the body.
The breach of physical barrier- through wounds, burns, surgical procedures, and injections
Soldiers died more from INFECTION more than anything else during war, or history.
The war drove advancements in surgery and medicine.
Ex: development of skin transplants for due to WWII for fighter pilot burns.
Where are these mucosal surfaces that form protective barriers against infection seen in the human body? give examples of these cells involved?
What body parts have acidic environments?
The mucosal surfaces: Respiratory tract (sinuses, trachea and lungs), urogenital tract (kidneys, bladder and vagina) and gastrointestinal tract (esophagus, stomach, intestines).
cells secrete mucous (contain glycoproteins, proteoglycans and enzymes)
-epithelial cells- remove mucous (cilia) and produce antimicrobial substances
-sebaceous glands-secrete sebum containing fatty acids and lactic acids (antibacterial)
-Tears and saliva-lysozyme (antibacterial)
The stomach, vagina and skin have acidic environments.
Compare and contrast the major components of Innate Immunity vs Adaptive immunity.
Innate- fast process (hours), fixed mode of action, able to stop infections at an early stage.
Adaptive- Slow process (days), powerful- eliminates almost all pathogens that escape innate immunity, and improves pathogen DETECTION rather than pathogen destruction.
What are the key elements in Innate vs Adaptive immunity?
Innate- pathogen receptors-bind covalently to surface of pathogens; proteins that bind covalently to pathogen surfaces- form ligands for receptors on phagocytes, phagocytic cells- engulf and kill pathogens, and cytotoxic T cells- kill virus infected cells.
Adaptive- lymphocytes- T and B cells
T and B cells- have receptors that bind to pathogens based selection and activation, provide long-lasting protection, evolving process.
Describe what occurs in innate immunity and what other cells are involved.
In innate immunity- bacteria cell surface induces cleavage and activation of complement. One part of complement covalently binds to surface of bacteria; other part attracts effector cell. The complement receptor on effector cells binds to complement fragment on bacterium. The effector cell engulfs the bacteria, kills it and breaks it down.
How does innate immunity cause inflammation at infection site?
When there is a wound at surface of skin, it allows bacteria to enter which activates effector cells to secrete cytokines
Vasodilation then increases, as well as vascular permeability allowing fluid, proteins and inflammatory cells to leave blood and enter tissue. The infected tissue is now inflamed, causing redness, swelling and pain.
Explain how an adaptive response adds to an innate immune response.
During development, progenitor cells give rise to lymphocytes with different specificity. With an infection, lymphocytes with receptors that recognize a pathogen are activated. This lymphocyte then proliferate and differentiate and give effector cells that terminate infection.
What is Hematopoiesis? What kind of cell is a Hematopoietic stem cell?
How do these cells change?
Hematopoiesis- process by which blood cells (hematopoietic stem cell) are formed
Hematopoietic stem cells are PLURIPOTENT stem cells that can be leukocytes (white blood cells), erythrocytes (RBCS) or thrombocytes (platelets)
The site of hematopoietic cells change during development (yolk sac, spleen, and bone marrow)
