Flashcards in Unit 3- Non-Specific Resistance (Innate Immunity) Deck (80):
defense mechanisms present at birth
defense mechanisms acquired by exposure to pathogens
first line of defense
surface protection, anatomical/physiolgoical, genetic barriers, non-specific chemical barriers
second line of defense
cellular and more specific chemical barriers
third line of defense
specific immune response developed against individual pathogens
physical barrier of respiratory tract?
epithelial tissue lining along the tract
chemical barrier of respiratory tract?
mucous secreted into tract
anatomical barrier of respiratory tract?
hair-like cilia sweeping mucous out of tract
what line of defense are T and B lymphocytes, and antibodies?
what line of defense are phagocytosis, inflammation, fever and interferon?
what are 3 behaviours that act as 1st line barrier?
hygine, contagion avoidance, healthy choices (avoid high-risk behaviours)
what are 2 physical first line barriers?
2) mucous/wax (lines portals of entry)
what are 3 chemical barriers of 1st line defense?
1) acid (stomach, lactic)
2) salt (tears, sweat)
3) proteins (lysozymes and defensins in tears, digestive enzymes)
mechanism of lysozymes?
targets peptidoglycans of bacterial cell wall (non-specific defense)
Example of how some have a 1st line genetic barrier to HIV?
HIV-1 R5 requires CCR5 receptor to infect cells, but some Caucasian populations have a 32 bp deletion in the CCR5 gene, conferring to some resistance to infection
how does H.pylori overcome physical barriers of body?
uses flagellum to burrow into mucosal layer
how does H.pylori overcome chemical barriers of the body?
it produces basic NH4+ through urease to neutralize stomach acid
How does H. pylori overcome genetic barriers of the body?
It is well-adapted to survive in the human stomach
what are WBCs/leukocytes
cells of the immune system; they recognize non-self cells and molecules
which leukocytes are not active at birth?
B-cells and T-cells. all other leukocytes are part of the innate immune system and are active at birth
what is the common stem cell WBCs and RBCs share?
hematopoietic stem cell
what 4 locations can WBCs be found in?
2) lymphatic vessels
3) reticuloendothelial system (mesh-like network of connective tissue holding tissues together)
4) extracellular fluid
what are the components blood separates into after centrifugation?
plasma (blood minus cells), buffy coat (WBCs), red blood cells (unclotted)
what is serum?
plasma minus clotting proteins
Neutrophil (class, action)
most abundant WBC, first responder, granulocyte, phagocytic (polymorphonuclear cell)
what are PRR?
pattern recognition receptors (special proteins) that can feel abnormal proteins on non-self cells
pathogen associated molecular patterns (abnormal proteins on invading cells)
toll-like receptors, whcih are special PRRs (pattern recognition receptors) that are on phagocytes (neutrophils, macrophages)
an eating and destructive body
7 steps of phagocytosis?
1) PRRs recognize PAMPs
2) phagocytic cell engulfs pathogen
3) bubble forms inside the cell- phagosome
4) destructive chemicals/enzymes stored in lysosomes and granuals
5) phagolysosome forms (fused together)
6) digestion and nutrient absorption into the cell
7) waste is excreted from cell
phagocytosis results in...
intracellular killing of microbes
what is the oxygen-dependent mechanism of intracellular killing of microbes?
toxins are called reactive oxygen species (either OH radicals or hypochlorite)
what is the oxygen-independent mechanism of intracellular killing of microbes?
electrically charged proteins damage membrane, lysozymes damage cell wall, lactoferrins compete for Fe binding, proteases digest and degrade proteins
what is a platelet?
a thrombocyte, is anucleate, and a fragment of a larger cell, megakaryocyte. it aggregates to seal up fissures in the blood vessels and skin to form blood clots or scabs
chemical signal released by neutrophils to attract monocytes and macrophages by chemotaxis. coordinates 2 effects of inflammation: vasoactive or chemotactic effects
process where neutrophils send chemokines to attract monocytes and macrophages
have granules, but NOT granulocytes, are the largest WBCs, are phagocytic, and produce cytokines, leading to inflammation. (premature form of macrophages)
granulocyte, non-phagocytic, releases peroxides, lysozymes and toxins into invader and targets fungi, worms that are too large to consume. involved in allergy/inflammation
4 parts of 2nd line defense of inflammation?
1) rubur (redness)
2) calor (warmth)
3) tumor (swelling)
4) dolor (pain)
cells migrate to site of damage, mediators released, phagocytes
substances with chemotactic effects
endotoxins, platelet activating factor, leukotriene, mast cell chemotactic factors, bacterial peptides, PAMPs, endotoxin
substances with vasoactive effects
histamine, serotonin, bradykinin, prostaglandins
substances with both vasoactive and chemotactic effects
complement components, cytokines such as interferon and interleukin, arachidonic acid metabolism products, platelet activators
formed by basophils and mast cells, released from granules and act quickly
from basophils and mast cells; made when needed and act slowly
invovled in intestinal movements and happy feelings after feeding. secreted by platelets to induce blood clotting
increases sensation of pain, and vasodilation
steps of 2nd line inflammation
endothelial cells of blood vessels express ICAMs (intercellular adhesion molecules) and stick to WBCs in teh damaged area
intercellular adhesion molecules
endothelial cells shrink and there's an opening
WBCs are pulled through the opening, and attracted to the site of infection
name 3 chemical mediators of immunity
1) TNF- tumor necrosis factor
2) IFN- interferon
3) IL- interleukins (IL-1, IL-6, IL-8, IL-12)
tumor necrosis factor made by macrophages, T and B cells to increase chemotaxis, phagocytosis, temperature. also involved in weight loss
interferon: made by leukocytes, fibroblasts, and is an anti-viral/anti-tumor
interleukins, made by leukocytes and others
1) IL-1: vasodilation, B/T cell activation, pyrogen
2) IL-6: B/T cell activation, pyrogen
3) IL-8, chemotactic, non-pyrogenic
4) IL-12, activates NK cells and T helper cells, non-pyrogenic
which interleukins are pyrogenic?
which interleukins activate B/T-cells
which interleukins are non-pyrogenic
a systemic induction of cytokines, leads to shock
what is the complement system?
a complex of proteins that pokes a hole in the surface of the cell; it is vasoactive and chemotactic, increasing inflammatory response
where are complement proteins produced?
in teh liver
what is an APP
acute phase protein- a protein that increases many-fold during early stage inflammation
3 complement pathways?
1) classical pathway
2) MB-Lectin Pathway
3) Alternate Pathway
complement-fixing antibodies (C3--> C3b)
sugars on teh surface of pathogens is binded by mannose-binding lectin (nonspecific for bacteria and viruses)
C3 binds pathogens directly, molecules on surfaces of bacteria, fungi, viruses and parasites (nonspecific)
what do all the pathways end up at?
C5b does what to the membrane?
starting point for polymerization of a pore through membrane: MAC
membrane attack complex (pore through the membrane)
what does C3b do?
coverts C5--> C5b
C3a and C5a?
involved in inflammation, chemokine
C3b and C5b?
what does C5b also lead to?
induces binding of C6, C7, C8
what is an opsonin?
any protein that opsonizes the cell
which complement proteins induces opsonization?
what does C9 do?
complete the pore complex (MAC)