Antihistamines are most likely to interfere directly with which of the following nonspecific immune responses?
a. constriction of bronchioles
b. leaking of fluid into infected tissues
c. production of mucus
d. production of antibody
e. activation of natural killer cells
B; Histamines act on capillaries, making them leaky. This causes a runny nose and teary eyes, which tend to wash out viral particles. It also permits leaking of fluid into infected tissues, and the fluid will bring with it phagocytes and, eventually, antibodies. Constriction of bronchioles and increase of mucus secretion (choices a and c) are the results of prostaglandin stimulus. Antibody production (choice d) is part of the specific immune response. Histamine is not thought to directly activate killer cells (choice e).
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Leptin is a circulating hormone that is produced by fat cells and plays a role in body metabolism and obesity. It normally binds to receptors in the brain and inhibits appetite. Studies have demonstrated that when obese mice that are leptin deficient are injected with leptin they quickly lose their excess weight. Interestingly, however, many overweight people have high levels of leptin in their bloodstream. Why do you think that the high levels of leptin in obese individuals are insufficient to curb their appetite?
A. In obese people with high levels of leptin, the leptin is a non-functional second messenger. B. The form of leptin released by obese people may lack protein kinase activity. C. Obese people who have high levels of leptin may have a leptin receptor with decreased sensitivity. D. Paracrine signaling may be disrupted in obese people with high levels of leptin.
Describe and diagram the various zones and provinces in the ocean. What adaptations to these variable
conditions are seen in the biota that inhabit these regions? What will be an ideal response?
The atmosphere became rich with oxygen due to the activity of:
A) plants B) bacteria C) eukaryotes D) cyanobacteria E) multicellular animals
Some areas of the genitourinary tract are normally sterile, whereas other areas have a variety of microbiota. Describe the defense mechanisms of the genitourinary tract that contribute to this dichotomy
What will be an ideal response?