Micro Test 1
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What are the three portals of entry for pathogens? Give examples of diseases associated with each.
Mucous membranes Ex: cold, pneumonia, tuberculosis, typhoid, cholera. Skin Ex: Conjuctivitus, hookworms. The Parenteral Route Ex: HIV, hepatitus, tetanus and gangrene. Orficies Ex:
In order for disease to occur, what events must happen?
Large numbers must gain access through a preferred portal of entry. Once inside pathogens must adhere to host tissue and penetrate host defenses.
What is the difference between a lethal and infectious dose? What does LD50 and ID50 stand for?
A lethal dose is what is needed to kill someone and an infectious dose is what is needed just to infect someone.
What are Ligands?
Molecules on the pathogen surface that bond to the surface receptors on host cells
How do pathogens penetrate host defenses? How do each of these structures specifically help the pathogen
evade the host?
How do capsules help pathogens evade the host?
They resist host defenses by impairing phagocytosis
How do cell wall components help pathogens evade the host?
Various protiens and waxes in cell walls help with attachemnt or to avoid phagocytosis.
How do Enzymes help pathogens evade the host?
Capable of breaking host cells open, may form or dissolve blood clots to evade immune system and enzymes They may form digest matrix between cells
What is the function of leukocidins?
Membrane-disrupting toxins that kill phagocytic leukocytes (white blood cells)
What is the function of hemolysins?
Membrane-disrupting toxins that destroy erythrocytes (red blood cells)
What is the function of collagenase enzymes?
Facilitates the spread of gas gangrene. Breaks down the protein collagen.
What is an invasin? What bacteria utilize this protein?
A surface protein that forces actin of cytoskeleton of host cell to surround and carry pathogen into cell. Utilized by Shigella and Listeria species. Ex: Salmonella
What are the two types of damage caused by bacteria to host tissue?
Endotoxins and exotoxins
What symptoms do toxins in cause in humans?
fever, diarrhea, shock, heart beat irregularities, destroy RBCs, disrupt the CNS
They are produced inside pathogen and are released into the host. Produced mainly by G+ bacteria. Very lethal.
Part of the outer portion of cell wall and are released when bacterial cell lyses. Mainly G- bacteria. Lethal dose much higher than exotoxins.
What do cytotoxins do?
Kill host cell or destroy its function
What do neurotoxins do?
Interfere with nerve impulses
What do enterotoxins do?
Damage the lining of the GI tract
What is Scarlet Fever?
When streptococcal pharyngitis produces an erythrogenic toxin the resulting infection is scarlet fever. The toxin causes a pinkish red skin rash and high fever. The tongue has a spotted, strawberry like appearance and its loses its upper membrane.
Why is tetanus called lockjaw
The tetanus neurotoxin blocks the relaxation pathway in muscles so that both opposing sets of muscles contract resulting in muscle spasms. The muscles of the jaw are affected early in the disease.
What does botulinum toxin cause?
It causes flacid paralysis by inhibiting the release of the neurotransmitter acetylcholine.
What type of toxins do salmonella typhi, proteus, and niesseria meningitidis produce?
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