Chapter 13
Define ergosterol
sterol is found in the cell membrane to protect the membrane structure, fluidity, and permeability.
- Target for many antifungal agents
Why is the skin a hostile place for pathogenic organisms
physical barrier, skin dryness, acidic pH, competition with normal flora, and high salt concentration.
What are defensins and what is their purpose?
They are small cationic peptides that make pores in the bacterial membrane and are effective against bacteria with slight negative charges, gram-positive, gram-negative, fungi, and viruses.
What is the relationship between antigens, epitopes, immunogens, and haptens?
Antigen: anything that can elicit an immune response when introduced into a person
Immunogen: an antigen that can elicit an immune response/ antibody production by itself
Epitope (antigenic determinants): a specific binding site on an antigen, can have more than one
Hapten: small molecule that cannot elicit an immune response unless attached to a larger protein
What is the protein factor H?
Prevents activation of complement in the absence of infection.
What are the six basic mechanisms of antibiotic resistance?
1) destroy antibiotic
2) pump antibiotic out
3) decrease membrane permeability
4) alter the target
5) modify the antibiotic
6) protect the ribosome
What compartments in the body are considered sterile?
internal organs: brain, heart, liver, and kidneys
Parts of the urogenital tract
Blood
Cerebrospinal fluid
Bone and bone marrow
Differentiate between neutrophils, basophils, and eosinophils.
Neutrophils are the majority of the WBCs and engulf microbes by phagocytosis. Basophils and eosinophils release products toxic to the microbe and release vasoactive chemical mediators important for inflammation.
Differentiate between isotype, allotype and idiotype of an antibody
Isotype: the types of antibodies found in all different individuals in related species: GAMED
Allotype: the types of antibodies found within one species
Idiotype: the types of antibodies found within one individual
What is the main difference between toll-like receptors and nod-like receptors?
TLR detects MAMPs outside the cell, and NLR detects MAMPs made inside the cell.
Explain how drug resistance develops
An antibiotic-susceptible bacterial pathogen causes a disease. A spontaneous mutant that is resistant to an antibiotic arises as the cells replicate. When the patient is treated with the antibiotic, the susceptible bacteria die, but the antibiotic-resistant cells survive and multiply. The patient relapses and risks transmitting the antibiotic-resistant strain to a new person.
What is dysbiosis, and give me a specific example of this term
Occurs when the balance of members of the gut microbiome is altered
example: Crohn's disease!
What are the organisms that can avoid phagocytosis, and how do each avoid it? (there are 4!)
Coxiella: lives within the phagosome,
Shigella and listeria escape from the phagosome,
Salmonella prevents phagosome-lysosome fusion,
And Shigella triggers apoptosis.
Explain each of the immunoglobulin proteins that act as antibodies.
IgG:
IgM:
IgA:
IgD:
IgE:
What is the membrane attack complex pore and what is the outcome of it?
The MAC pores are formed by C5b, C6, C7, C8, and C9 to cause a massive influx of water into the cell, causing cytolysis.
How do sulfonamides block folic acid formation?
replace PABA with SFA and therefore there is no synthesis
What are methanogens and what is their impact on weight gain?
1) H2 buildup from bacterial fermentation normally feeds back-inhibits fermentation
2) H2 oxidation by methanogens, if present, counteracts H2 buildup, allowing fermentation to continue.
3) Fermentation end-products such as acetate and butyrate (short-chain fatty acids) are readily used by human cells, resulting in weight gain.
Explain the steps of acute inflammation
1) Host cells are damaged by invaders, releasing initiation factors for inflammation
2) Macrophages in local area ingest microbes and release cytokines
3) cytokines cause capillary vasodilation (capillaries become more permeable)
4) Cytokines start the synthesis of selectins (endothelial adhesion molecules. Also produces integrins (neutrophil binding proteins)
5) extravasation: neutrophils squeeze through and exit the bloodstream
Explain the process of humoral immunity vs. cell-mediated immunity.
What are the specific oxygen-independent and oxygen-dependent mechanisms that can digest pathogens in the phagolysosome?
Oxygen-independent: lysozyme, lactoferrin (prevents organisms from getting iron), defensins
Oxygen-dependent: oxygen radicals (superoxide, H202, hydroxyl radicals, myeloperoxidase)
Which antibiotics work by destroying the integrity of the cell membrane, and how do each of them specifically do this?
Gramicidin: pokes holes in the bacterias cell membrane
Polymixin: disrupts the inner and outer membrane because of the positive charge interacting with the negatively charged membrane. (only for gram negative because they have inner and outer membranes)
Name the 8 primary functions of the gut microbiome
1) Ferment unused energy substrates
2) Train the immune system
3) prevent growth of pathogenic bacteria
4) regulate the development of the gut
5) Synthesize essential vitamins for the host
6) produce hormones to direct the host to store fats
7) Aid in digestion
8) gut-brain-axis: communication with the brain to influence appetite regulation, hormonal release, and liver metabolism.
What are the three types of cascade pathways for the complement system, and what are the outcomes of these pathways?
Classical pathway: increase and facilitate phagocytosis C1--> C9 forming MAC to burst cell
Lectin pathway: increases and facilitates phagocytosis--> skips to spontaneous clevage of C3 into C3a and b (fastest!)
Alternative pathway: attract neutrophils to the site of infection --> synthesis of mannose-binding lectin in response to cytokines released by macrophages --> cleavage of C2 and C4
What are the three different kinds of vaccines and explain each one of them
1) Killed pathogens
2) live but crippled (attenuated) strains: weakened so wont cause disease, but are not good for immunocompromised people.
3) Inactivated microbial toxins: inactivated proteins or lipids
How do M cells, MALT, peyer's patches, and GALT all relate to eachother?
MALT encompasses the GALT which has Peyer's patches, and M cells are on the Peyer's patches