Ch. 11 Flashcards
innate immunity
- inborn and ancient protection
- exist in one form or another in all eukaryotic organisms
- generalized responses = don’t vary based on the pathogen being fought
- 1st and 2nd line defenses. barrier defenses, like skin or stomach acid, as well as specialized molecules, cells, and tissues
- nonspecific immunity.
adaptive immunity
- newer and exists only in vertebrate animals
- includes specialized immune cells and their products—most importantly, antibodies
- set of defenses matures over time, tailoring its responses to the pathogens it encounters
- specific immunity and acquired immunity
- 3rd line defense
- remembers pathogens
- comes in when innate immune response fails
How does normal microbiota impact immune responses and limit pathogens?
- play a central role in inducing, training, and calibrating immune responses
- when normal microbiota changes, our immune system may be confused and start attacking ourselves
- could be linked to rise in allergies and autoimmunity
what do first line defenses aim to prevent?
pathogen entry. have mechanical, physical, and chemical barriers
mechanical barriers
rinse, flush, or trap pathogens to limit their spread into the body.
Ex: tears (wash away pathogens), urine (flush them out of the body), saliva, mucous membrane
chemical barriers
molecules that directly attack microbes or generate the environment that limits their survival
- lysosome: found in secretions (tears, breast milk) and breaks down bacterial cell walls
- stomach acid, pH
- antimicrobial peptides (AMPs): defensins -> kill microbial invaders. insert themselves directly in the cell wall
physical barriers
structural blockage
Ex: skin and epidermis (has cells that creates barrier to prevent pathogens from entering)
lymphatic system
- collection of tissues and organs
- collect, circulate, and filter fluid in body tissues before it is returned to the blood
plasma
liquid portion of blood -> some will exit via capillaries
interstitial fluid
plasma that seeps into spaces btw cells
edema
pooling of liquid in tissues
lymph
reenters lymphatic system. screened in lymph nodes and checks if lymphs have pathogens
lymph and lymphatic vessels
Interstitial fluid flows into lymphatic capillaries, where it is then called lymph. Lymph flows toward lymph nodes, is filtered and screened for invading agents, and finally rejoins the venous blood supply. Upon rejoining the blood it is no longer called lymph, but is now plasma.
granulocytes - neutrophils
- most numerous
- first recruits to site of infxn
- release potent antimicrobial peptides (AMPs)
-> fight off pathogens - phagocytize foreign cells and viruses and NETs
- elevated neutrophil count
- neutropenia = lower that normal neutrophils (signals viral infxn)
granulocytes - eosinophils
- <5% of the total WBC population
- exhibit moderate phagocytic activity
- possess granules
- eosinophilia: elevated eosinophils
granulocytes - basophils
- <1% of WBC population
- contain cytoplasmic granules
- role: histamine: stimulate inflammation, parasitic infxns, allergic responses
granulocytes - mast cells
- reside in tissues
- release histamine
- role in allergies and fighting parasites
- conduct phagocytosis
- common in tissues near body openings (skin and mucous membranes of the airway and gastrointestinal tract)
- send out alarms to site of infxn
phagocytes
(macrophages, dendritic cells, and neutrophils) target bacterial cells, viral particles, or general debris
leukocytosis
increase in leukocytes. increase in the white blood cells
monocytes
- Largest agranular white blood cells
- Contain horseshoe-shaped nuclei
- ~10% of circulating leukocytes
- Levels can increase due to: chronic infection
- Migrate out of the circulatory system into tissues and mature into macrophages
macrophages
- Destroy a wide range of pathogens
- Fixed macrophages - relatively immotile macrophage found in connective tissue, lymph nodes, spleen, and bone marrow
- Wandering macrophages – leaves area and migrates to infected tissue
dendritic cells
- Found in most body tissues
- Patrol tissues and phagocytize a broad range of antigens
lymphocytes
- Natural killer cells
- Abundant in the liver
- Innate protection against viruses, bacteria,
parasites, and even tumor cells
- T and B cells
- coordinate the adaptive immune response
how do leukocytes work with molecular factors as part of second-line defenses?
they buy time by slowing or outright killing the pathogen while the other parts of the immune system kick into gear
signs of inflammation
redness, pain, localized heat (not fever), swelling, loss of function
three goals of inflammation
recruit WBCs to injured tissue, limit spread of pathogens, deliver O2, nutrients, and chem factors
chronic inflammation
- May develop when an inflammatory response goes on too long
- Not useful or protective
- Exacerbates tissue injury and causes further damage to tissues
- Promotes atherosclerosis (disease in the arteries), certain cancers, and progressive neurodegenerative disorders
what is a fever?
a systemic innate immune response
- controversy regarding treatment of low-grade fever
- low grade= 99.5-101F
- has protective effects
- fever reaches 105F
studies suggest what about fevers?
increase efficiency of interferons, increase efficiency of phagocytes, limit growth of pathogens, promotes tissue repair
complement cascades
- innate -> not specific to any pathogen
- consists of >30 different proteins = work together in cascade fashion
- circulate in the blood in activate form
- when activated, a cascade of events result in a boost to the immune system
complement cascade outcomes
- opsonization: invader has been tagged w/ a protein so it stands out to WBCs
- cytolysis: MAC -> membrane attack complex
- inflammation
iron-binding proteins
- hemoglobin: RBCs, transport oxygen
- ferritin: found in most body cells
- lactoferrin: milk, tears, mucous, saliva
- transferrin: found in blood plasma and extracellular fluids
what is iron?
vital nutrient for most cells
cytokines
- signaling proteins
- allow cells to communicate w/ one another
- coordinate immune response
chemokines
- signaling - attract WBC -> serve to attract WBC to a site of infxn
- induce chemotaxis
- > 40 known chemokines
Aid in:
wound healing, blood vessel, lymphoid tissue development, activate both parts of immune response
interleukins (ILs)
- activate adaptive and innate immune responses
- stimulate hematopoiesis: stimulates production of new blood cells and platelets
- IL-1 family: neg inflammation, stimulate adaptive and innate response, generates fever
- IL-2 family: T cells develop, self tolerance, trigger apoptosis (programmed cell death)
interferons (IFNs)
- send out signals when tumor/pathogen/virus is detected
- can also trigger apoptosis
Ex) virus-infected cells make IFN-alpha and IFN-beta as alarms that stimulate nearby uninfected cells to mount antiviral defenses
tumor necrosis factors (TNFs)
- signaling proteins
- TNF-alpha
- made primarily by macrophages -> monocytes that migrated to tissues
- role: stimulate inflammation, kill tumor cells, stimulate fever
- TNF-α inhibitors treat certain immune disorders (e.g., rheumatoid arthritis, IBS)
3 roles of second-line molecular defenses
cytokines, iron-binding proteins, complement proteins
3 general phases of inflammation
- vascular changes: chemical alarm signals released by damaged cells and leukocytes increase blood flow and vessel permeability
- leukocyte recruitment: cytokines recruit leukocytes. neutrophils arrive first, followed by monocytes, which mature into macrophages. neutrophils and macrophages phagocytize invaders and recruit other leukocytes
- resolution: inflammation signals decrease; tissue repair initiated
