Week 5 Flashcards
Mast Cells are found in what tissue type
Mast Cells are found close to small blood vessels in loose connective tissue. They contain large secretory granules of heparin proteoglycan - a weak anticoagulant. They also contain histamine, which promotes an inflammatory reaction when secreted.
_______________ connective tissue is found in the umbilical cord
Mucous connective tissue is found in the umbilical cord
Which receptor type functions using cAMP as a mediator?
G protein
What is the pharmacological phenomena that may be used to explain the development of drug tolerance?
tachyphylaxis
A patient takes a drug that has a Kd of 100 micrograms. The patient had been on a drug that had a Kd of 100 milligrams. Which of the following is TRUE?
B is true
Make each tablet 325 mg, with the recommendation to take one to two tablets. Half of people will respond to 325 mg, and almost all people will respond to 650 mg.
Jill takes a pill for depression. The pharmacokinetic properties show a Kd of 344 pg/ml, and a ED50 of 200 pg/ml. What does this mean?
irreversible antagonists are also known as
non-competitive antagonists
what proteins are involved in cGMP
Guanylate cyclase produces cyclic guanosine monophosphate (cGMP). cGMP subsequently activates protein kinase G which phosphorylates proteins that produce highly specific physiologic actions within the cell.
Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) andnitric oxide (NO) signal via cGMP, but activate guanylate cyclase differently:
ANP and BNP activate a membrane-bound receptor-guanylate cyclase
NO (aka endothelium-derived relaxing factor (EDRF)) activates a soluble guanylate cyclase.
Mycobacteria have ________________in their cell walls, which are stained by acid-fast staining.
mycolic acids
characterize Areolar Tissue.
This is a loose connective tissue widely spread throughout the body. It contains all three types of fibers (collagen, elastin, and reticular) with much ground substance and fibroblasts.
Areolar tissue shows little specialization. It contains all the cell types and fibers previously described and is distributed in a random, web-like fashion. It fills the spaces between muscle fibers, surrounds blood and lymph vessels, and supports organs in the abdominal cavity. Areolar tissue underlies most epithelia and represents the connective tissue component of epithelial membranes
It is characterized by having cells that produce fibers (fibroblasts) and macrophages as well as collagen, reticular, and elastic fibers in the matrix.
What is the purpose of fimbriae on the outer surface of bacteria?
Adhesion to surfaces
Antibiotic resistance
Defense against predators
Ingestion of nutrients
Motility
The correct answer is adhesion to surfaces (A). Fimbriae have no known role in antibiotic resistance (B), defense against predators (C), and ingestion of nutrients (D). Flagella are more associated with bacteria motility (E).
Why do gram-positive bacteria stain violet?
They do not have enzymes that degrade the dye.
They have a thicker layer of cell membrane, which retains the dye.
They have thicker cell walls, which retain the dye.
They have two layers of cell membranes.
The molecular components of their cell walls bind tighter to the dye.
The correct answer is they have thicker cell walls, which retain the dye (C). The Gram stain dye is not known to be degraded by any enzyme (A). Cell membrane thickness does not vary widely or readily between gram-positive and gram-negative bacteria (B). Gram-positive bacteria have one thick outer cell wall, and a layer of cell membrane underneath. Gram-negative bacteria have two layers of membrane, not gram-positive bacteria (D). Gram-positive and gram-negative bacteria have the same composition of cell wall, primarily peptidoglycan (E).
Which of the following bacterial shape is correctly matched with its description?
Bacillus, rod shaped
Coccus, comma shaped
Coccus, oval
Spirillum, spherical
Vibrio, spiral
The correct answer is bacillus, rod shaped (A). Cocci are spherical bacteria, so coccus, comma shaped (B) and coccus, oval (C) are incorrect. A spirillum bacterium is spiral shaped (D). An oval bacterium is termed coccobacillus, and a comma-shaped bacterium is called vibrio; vibrio, spiral (E) is therefore incorrect.
MN: The “ll” in bacilla are rod shaped
does the complement system influence the onset of septic shock
Complement plays a key role in the clinical picture of sepsis (systemic infection). Certain complement factors (ie, C3a and C5a) trigger mast cell degranulation, leading to increased vascular permeability and vasodilation. This causes the low blood pressure seen in sepsis. C3a and C5a are also known as anaphylatoxins (or molecules that trigger anaphylaxis). Anaphylaxis is a severe allergic reaction to an allergen that can rapidly lead to hypotension and death if not treated.
How is the classical pathway activated?
The first complex of the complement cascade (C1)—which is made up of the recognizing protein (C1q) and two proteases (C1s and C1r)—binds to the Fc region of immunoglobulin G (IgG) or IgM antibodies, bound to an antigen (Figure 2). The binding of the C1 complex to the Fc portion of the IgG or IgM activates C1s of the C1 complex to cleave C2 and C4. C4 is split into C4a and C4b. The a fragment of C2 and b fragment of C4 combine to form the enzyme C3 convertase (C4b2a)
How is the alternative pathway of the complement system activated
The Alternative Pathway
Another way for complement to become activated is for microbial products to directly activate the complement cascade. This can occur spontaneously. So how does the body do this? A simplified explanation is that C3 (a complement component) is spontaneously cleaved into C3a and C3b (Figure 3). C3b then recognizes and attaches to the pathogen (eg, a microbe or damaged tissue). After a series of binding and cleavage steps with other serum proteins, this cascade eventually leads to the formation of C3 convertase and stimulation of the immune response, just as in the classical pathway.
The alternative pathway is constantly on the lookout for pathogens. This pathway allows pathogens that have not yet been recognized by the immune system to still be killed!
How is the mannose-binding lectin (MBL) pathway activated.
The final way for complement to become activated is via the mannose-binding lectin (MBL) pathway. MBL proteins bind to certain oligosaccharides on microbial cell surfaces, and this binding activates the complement cascade. This is a form of pattern recognition, meaning that these MBLs are programmed to recognize certain components of pathogens and can then start the cascade.
This pathway is very similar to the classical pathway. Just like the classical pathway, the ultimate end of the lectin pathway is to form C3 convertase to activate an immune response and phagocytosis. However, the MBL pathway has a different starting point from the classical pathway
Instead, the inciting event is the binding of mannose-binding lectin to the oligosaccharides on the pathogens directly rather than to the Fc portion of the IgG and IgM. Instead of C1r and C1s acting as protease, the mannose-binding lectin pathway has the enzyme MASP1 and MASP2. MASP2 cleaves C4 into C4a and C4b and cleaves C2 into C2a and C2b. The C4b and C2a then combine to form C3 convertase just like in the classical pathway.
The classical pathway, the alternative pathway, and the MBL pathway all converge at the terminal complement pathway. Recall that each of these pathways has led to the formation of C3 convertase. In the terminal pathway, this crucial enzyme now converts C3 to C3a and C3b, leading to several important immune events that allow us to rid ourselves of pathogens or damaged cells. These are…
C3a has multiple helpful immune functions, including stimulation of T-cell activation, angiogenesis (formation of blood vessels), chemotaxis (enhanced migration of inflammatory cells), mast cell degranulation, and macrophage activation.
C3b leads to creation of the membrane attack complex (MAC) by activating factors C5-9. The MAC can punch holes in the membrane of the pathogen or abnormal cell through formation of transmembrane channels that disrupt the cellular membrane, leading to cell lysis and death.
C3b also can tag the surfaces of pathogens, marking them for attachment of antibodies and destruction (opsonization).
Anaphylactic shock occurs due to ?
Anaphylaxis is a type 1 hypersensitivity reaction mediated by binding of the anaphylatoxins C3a and C5a to immunoglobulin E (IgE) on mast cells. C3 is a cytokine that is converted to C3a and C3b by one of two C3 convertases. Similarly, C5 is converted to C5a and C5b by one of two C5 convertases. Both C3a and C5a circulate in the bloodstream and trigger mast-cell degranulation by binding to IgE, causing histamine release, smooth-muscle contraction, vasodilation, and enhanced vascular permeability.
what are defensins
circulating proteins involved in innate immune response. They are positively charged peptides that create pores in the membranes of miicrobes
Which type of receptor of the innate immune system responds to viral RNA in the cytosol?
RIG like
mnemonic: R for RIG and RNA
As part of the innate immune response, C3b can do what?
*MAC = membrane attack complex
what happens in Positive selection of T cells
activation of T-helper cells by an APC?
what are the receptors and factors involved?
