L2300: PQs for Final Exam Questions and Correct Answers

L2300: PQs for Final Exam Questions and Correct Answers List two sensor systems of the innate defenses. ✔✔ Pattern recognition receptors Complement system Describe the dual roles played by some types of phagocyte ...

L2300: PQs for Final Exam Questions and Correct Answers List two sensor systems of the innate defenses. ✔✔ Pattern recognition receptors Complement system Describe the dual roles played by some types of phagocytes. ✔✔ They destroy invaders and also communicate with components of the adaptive immune system to enlist their help. What molecules might pattern recognition receptors recognize? ✔✔ PTG, LPS, flagelin How does the mucociliary escalator protect against infection? ✔✔ It moves microbes out of the airways. What is the role of lactoferrin? ✔✔ It binds iron, removing it as an element source that would otherwise support microbial growth. How would damage to the ciliated cells of the respiratory tract predispose a person to infection? ✔✔ The mucociliary escalator would no longer function properly, so microbes wouldn't be removed from the airways. Which type of granulocyte is the most abundant? ✔✔ Neutrophils How are macrophages related to monocytes? ✔✔ Macrophages descend from monocytes; the monocytes circulate in blood, and as they enter the tissues, they develop into macrophages. Why can bone marrow transplants be used to replace defective lymphocytes? ✔✔ Bone marrow has hematopoietic stem cells; in the procedure for a bone marrow transplant, the lymphocytes are destroyed and then another person's bone marrow (containing hematopoietic stem cells) is transferred. The transferred stem cells can develop into new lymphocytes (as well as other blood cells). What is a ligand? ✔✔ The molecule that binds to a given receptor What is the function of a colony-stimulating factor (CSF)? ✔✔ It promotes the development of certain cell types. How could colony-stimulating factors be used as a therapy? ✔✔ It can be used to direct the accumulation of a given cell type. Why would macrophages have TLRs in their endosomal membranes? ✔✔ So they can determine if they have engulfed microbial invaders (as opposed to normal host components). If a cell produces antiviral proteins, what happens to that cell when those proteins encounter long dsRNA? ✔✔ The cell shuts down protein synthesis, eventually leading to apoptosis. Why would the discovery of TLRs alter the view that innate immunity is non-specific? ✔✔ Because they allow cells to detect patterns associated with microbes, indicating that the responses involve some specificity (although not the molecular specificity that characterizes the adaptive responses). What role does C3b play in opsonization and complement system activation? ✔✔ When many molecules of C3b are bound to a particle, macrophages can more easily engulf the particle (opsonization); when even a few molecules of C3b are bound to a particle, other complement components can bind, leading to activation of the complement system. The body's own cells do not trigger the alternative pathway of complement pathway activation. How come? ✔✔ Molecules in host cell membranes bind regulatory proteins that will inactivate any C3b molecules that attach to the membrane. From a pathogen's standpoint, why would it be beneficial to bind regulatory proteins that inactivate C3b? ✔✔ It prevents both opsonization and complement activation. How does a phagolysosome differ from a phagosome? ✔✔ Phagolysosomes have fused with lysosomes, and therefore they contain the enzymes and toxic substances of lysosomes. Tuberculosis is characterized by granulomas called tubercles. What is a granuloma? ✔✔ A concentrated group of macrophages, giant cells, and T cells that surrounds microbes or material that cannot be destroyed What could a microorganism do to avoid engulfment? ✔✔ Destroy C5a (a complement protein that attracts phagocytes), destroy phagocytes, attract complement regulatory proteins to avoid the opsonizing effects co complement.