Innate Immunity Flashcards
Immunity
ability to ward off disease
suceptibility
lack of resistance to a disease
innate immunity
defence against any pathogen
- rapid
- present at birth
- first and second lines of defense
first line of defense
skin and mucous membranes
second line of defense
natural killer cells, phagocytosis, inflammation, fever, and antimicrobial substances
adaptive immunity
specific
slower
memory
Skin
dermis = inner portion of connective tissue
epidermis = outer portion of tightly packed epithelial cells with keratin (protective protein)
-shedding + drying inhibits microbial growth
Mucous membrane
- epithelial layer that lines GI, respiratory, and genitourinary tract
- mucous = viscous glycoproteins that trap microbes and prevent drying out
ciliary escalator
-transports microbes trapped in mucous away from lungs
physical first line defenses
- tears
- saliva
- ear wax
- urine
- vomit
- poop
- vaginal secretions
sebum
forms a protective film that lowers pH of skin bc of unsaturated fatty acids
lysozyme
in sweat, tears, saliva, and urine
-destroys bacterial cell wall
gastric juices
-super acidic, so it kills bacteria
vaginal secretions
pretty acidic, so it inhibits microbes
normal microbiota
- compete with pathogens via competitive exclusion
- well adapted
- create substances (like hydrogen peroxide in vagina) that are harmful to pathogens
- commensalism
probiotics
live microbial cultured administered for beneficial effect
3 things in blood
erythrocytes (RBC)
leukocytes (WBC)
Platelets
-created in red bone marrow stem cells via hematopoiesis
Granulocytes
leukocytes with visible granules in cytoplasm with light microscope
- neutrophils = phagocytic + work in early stages of infection
- basophils = release histamine + work in allergic responses
- eosinophils = phagocytic + toxic against parasites + helminths
Agranulocytes
leukocytes w/o visible granules
- monocytes = mature into macrophages in tissues where they’re phagocytic
- dendritic cells = found in skin, mucous membrane, and thymus + phagocytic
- lymphocytes = T cells, B cells, and NK cells
lymph system
lymph carries microbes to lymph nodes where lymphocytes and macrophages destroy them
fixed vs free macrophages
pretty obvious
Phases of Phagocytosis
- Chemotaxis = chemical signals attract phagocytes to microorganisms
- adherence = attachment of phagocyte to surphace of microbe
- ingestion = sometimes uses opsonization where microbe is coated with serum proteins to make it easier to eat
- digestion = eated inside phagolysosome
Inflammation
- PRISH
- destroys or inhibits injurious agents
- repairs and replaces tissue
- activates acute phase proteins that cause vasodilation
1. vasodilation of blood vessels
2. phagocyte migration + phagocytosis
3. tissue repair + inflammation
acute phase proteins
histamine kinins prostaglandins leukotrienes cytokines
fever
cytokines cause hypothalamus to release prostaglandins that reset body temp
- temp stay high until cytokines are eliminatied
- as temp falls (crisis) vasodilation and sweating happens
advantages and disadvantages of fever
advantages: increases transferrins which bind iron
- increases IL-1 activity which promotes T cell production
- produces interferon which stops replication of some virueses
- tissue repair could be faster
Disadvantages: tachycardia
- acidosis
- dehydration
- 44-46 C is fatal
complements system
- serum proteins produced by liver that enhance immune system
- act in cascade –> complement activation
1. classic pathway = activated by antibody
2. alternative pathway = activated by proteins or polysacchrides on virus or host surface
3. activated by lectins = proteins that bind to carbs
classic pathway
- antibodies bind to antigens, activating C1
- C1 splits and activates C2 and C4
- C2a and C4b combine and activate C3
- C3a function in inflammation
- C3b functions in cytolysis and opsonization
Alternative pathway
C3 in the blood combines with factors BDP on microbe surfaces
-C3 splits into Ca and C3b
Lectin Pathway
- macrophages ingest pathogens, releasing cytokines that stimulate lectin production in liver
- Mannose-binding lectin binds to mannose on pathogens, activating C2 and C4
- C2a and C4b activate C3
outcomes of complement activation
- cytolysis = complement proteins create a membrane attack comlex
- opsonization = promotes attachment of phagocyte
- inflammation = activated complement proteins bind to mast cells, releasing histamine
- regulatory proteins break don complement proteins after
- sometimes capsules prevent comllement activation
interferons
- cytokines produced by cells –> antiviral activity
- proteins, not antibodies
- interfere with viral replication
- alpha and beta are produced by cells in response to viral infections –> cause neighboring cells to produce antiviral proteins
- gamma causes neutrophils and macrophages to kill
- not specific
- species specific bacteria
iron binding proteins
- transferrin = blood and tissue
- lactoferrin = milk, saliva, and mucus
- ferritin = liver, spleen, and red bone marrow
- hemoglobin = RBC
- bacteria produce siderophores
