Host defenses Flashcards
What are innate defences?
properties of normal host, NON-SPECIFIC defences
What are adaptive defences?
induced by the infection, SPECIF to the pathogen (based on antigens)
what are some examples of first barriers (innate defences)?
skin stomach acidity normal microbiota flushing of urinary tract epithelial cells rapid pH change mucus cilia lining trachea lysozyme in secretions nose hairs
What does the normal microbiome do?
it competes for attachment sites and nutrients, secretes BACTERIOCIN
what are some antimicrobial substances? (4)
- fatty acids
- lysozymes!!!!
- antimicrobial peptides (AMPs)!!!!
- antibodies (if the host is immune)
Whats a mucous membrane?
mucus
skin is a thick layer of ______.
dead cells
How does the innate defense of the airways work?
mucous membrane; mucus traps bacteria; ciliated cells remove mucus and trapped bacteria
What are the three second line of defences if a pathogen manages to overcome the first line of defense (skin, mucosa)? explain each
- complement system: set of proteins that creates pores in the pathogen membrane and induces lysis
- Phagocytes: cells that take up and digest pathogens
- inflammation: general nonspecific response of the innate system to toxins, pathogens and tissue damage
What is the complement system?
set of blood proteins - also present in tissues - known as complement because they complement the action of antibodies. proteins: C1-9.
What are the two action pathways of the complement system?
- activation by classical pathway: antibodies
- activation by alternative pathway: microbial cell wall components (polysaccharides, liposaccharides)
What does the activation of the complement system result in? and what does it cause?
it results in the formation of a membrane attack complex (MAC, made of proteins C5b6789) that causes lysis of SOME gram negatives, NO EFFECT on gram positives.
how do you test pathogen sensitivity to complement system?
by exposing pathogens to serum (blood without red blood cells)
What are the cells of the innate immune system? (5) and their function
- dendritic cell + macrophage: antigen presentation
- neutrophil + dendritic cell + macrophage: phagocytosis
- mast cell: inflammatory response
- > all from myeloid precursor
- natural killer cell: cell-mediated immunity
- > from typhoid precursor
What are the cells of the adaptive immunity? (2)
- T cell: cell mediated immunity
- > from lymphoid precursor
- Plasma cell: antibody-mediated immunity
- > from B cell -> from lymphoid precursor
What are the major cell types found in normal human blood? (4)
- red blood cells (erythrocytes)
- lymphocytes
- neutrophil
- monocyte
What are the three types of white blood cells (leukocytes)?
- monocytes
- granulocytes: their cytoplasm contains granules
- lymphocytes
What are the 2 sub-categories of lymphocytes?
- B cells: antibodies
- T cells: T helper cells, cytotoxic T cells
What are monocytes?
white blood cells that circulate in blood stream, differentiate into macrophages (and dendritic cells) in tissues, attracted to inflamed tissues, PHAGOCYTIC. Macrophages are present in all tissues and take on different forms in different tissues
What are eosinophils, basophils, neutrophils, mast cells? what’s the particularity of neutrophils?
they are granulocytes (white blood cells/ leukocytes).
neutrophils are the most abundant, PHAGOCYTIC, often called polymorphonuclear leucocytes
What are the 4 steps of phagocytosis? carried out primarily by macrophages and neutrophils
- attachment of the organism to the membrane of the phagocyte
- ingestion: the organism become enclosed in a phagosome
- A. granules (endoscopes, lysosomes) containing hydrolytic enzymes fuse with the phagosome, formation of the phagolysosomes. B. oxidative burst: production of reactive oxygen species
- killing and digestion of the microorganism
What is oxidative burst?
rapid increase in uptake in O2 -> produces reactive oxygen species (O2-; H2O2; OH. ; OCl-)
What are the 3 important enzymes in the generation of toxic reactive oxygen species?
- myeloperoxidase
- NADPH oxidase
- V-type ATPases (pumps H+ in)
What are the primary antibodies produced during the primary response?
- Immunoglobin M (IgM)
