Immune System Flashcards
What is the immune system?
- Protects body from harmful pathogens
- Differentiate between individual’s own cells and those of pathogens
- Made up of INNATE AND ADAPTIVE immune systems
Who invented the smallpox vaccine and how did they do it?
EDWARD JENNER
- Noticed that people who contracted cowpox were immune
- Innoculated a child using experimental vaccine (he gave the child a house as a reward)
Who is Louis Pasteur and what did he do?
- Discovered germ theory
- Developed vaccines for cattle anthrax, rabies etc.
What is the evidence for effectiveness of immunisation?
- Eradication of smallpox
- 100% decrease in poliovirus
- 99% decrease in MMR
Describe the origin of immune cells.
- Blood stem cells
- Progenitor cells (lymphoid and myeloid)
- Immune cells (lymphoid progenitor cells produce lymphocytes/ myeloid produce RBCs, phagocytes, mast cells etc.)
Describe the primary lymphoid organs.
- Bone marrow - where most immune cells are produced and multiply
- Thymus - site of maturation of T cells
Describe the secondary lymphoid organs
- Lymph nodes, spleen and tonsils
- Networks of nodes connected by lymphatic vessels
- Lymph nodes contain immune cells - B/T lymphocytes, phagocytes
- Pathogens filtered and destroyed before lymph returns to bloodstream
What happens in immune over-reactions?
- Allergic Responses
- Autoimmune Problems
What can immune under-reactions occur?
- Cancer
- Infections
What are the nonspecific defence mechanisms i.e the first and second lines of defense?
FIRST LINE OF DEFENSE - Skin, mucous membranes
SECOND LINE OF DEFENSE - INNATE IMMUNITY: Phagocytes, inflammatory response by cytokines, macrophages
What are the specific defence mechanisms i.e the third line of defense?
ADAPTIVE IMMUNITY
- LYMPHOCYTES
- ANTIBODIES - made by plasma cells (HUMORAL IMMUNITY)
- CELLULAR IMMUNITY - T cells that mediate responses using receptors
Outline the first line of defence.
- Keratinocytes in skin secrete defensins. Many immune cells e.g mast cells reside in skin
- Cornea - neutrophils kill pathogens here by phagocytosis
- Mucosa of respiratory, GI and GU tracts - mucus contains antimicrobials such as lysozyme, SIgA
Give examples of active and passive naturally acquired immunity.
- ACTIVE - Antigens naturally enter body. Innate/adaptive immune systems respond and provide long-term protection
- PASSIVE - Passage of antibodies from mother to fetus across placenta/through breast milk. Provides short-term protection
Describe active and passive artifically acquired immunity.
- ACTIVE: Vaccination - provides long-term protection
- PASSIVE: Antibodies from immune individuals injected into body. Provides short-term protection
Why is it important for rapid responses such as the innate immune system to occur?
- Bacteria divide very quickly and can spread infection quickly
How does the innate immune response stimulate adaptive immune respones?
Cytokine production
What is the difference between innate and adaptive immune responses? PART 1
- Innate responds in minutes to hours/ adaptive responds in days (lag time between exposure and response)
- Adaptive immunity is more pathogen specific, more rapid and effective with repeat infections (due to immunological memory). Innate responses are fixed and non-specific.
Define innate immunity.
- Doesn’t require prior exposure to antigens so responses are non-specific
- Response - no immunological memory
- Involves NK cells and granulocytes
What are the two main branches of adaptive immunity? Describe them.
- HUMORAL - Involves B lymphocytes. Mediated by antigen-specific antibodies
- CELLULAR - Involves T lymphocytes. Eliminate intracellular microbes that survive within phagocytes/infected cells
Why is the secondary response faster than primary response?
- PRIMARY RESPONSE initiated upon first exposure to antigen
- SECONDARY RESPONSE - antigen restimulates immunological memory
Does the lymphatic system contain red blood cells?
No
