Case Study Scenario Billy DeWitt was a normal, full-term baby at birth. Beginnin
ID: 63979 • Letter: C
Question
Case Study Scenario Billy DeWitt was a normal, full-term baby at birth. Beginning at about 10 months of age, Billy suffered from a series of infectious processes such as sinusitis, otitis media, and pneumonia. All of these conditions were successfully treated with antibiotics, but within a few weeks of the resolution of one infection, another would occur Now at about four years of age, Billy is examined by a pediatrician who notes that Billy lacks palatine tonsils, although he does not have a history of tonsillectomy. Questioning of Billy's mother reveals that she had two male relatives who died in infancy from infectious disease. The physician orders laboratory tests that reveal that the quantity of immunoglobulin in Billy's serum is about one-fifth of normal, and that there is a marked deficiency in the number of circulating B-lymphocytes in Billy's blood. Tests to determine the functional state of Billy's T- lymphocytes are all normal Questions 1. What are the differences between nonspecific and specific (immunity) body defenses? In what tissue do B- and T-lymphocytes originate and what are the two steps involved in lymphocyte "maturation"? Describe the two “arms" of immunity Define the term antigen and state which class of organic molecules make the best antigens, and why What are the five classes of antibody? 2. 3- 4. 5.Explanation / Answer
The innate immunity is the resistance to infections possessed by individual by his/her own genetic and constitutional makeup. It is either non-specific or specific. The non-specific immunity is the degree of the resistance towards the infections. Specific immunity is resistance towards the specific pathogen. Both the non-specific and specific immunities are influenced by species, race and individual capacity of resistance towards an infection. The physical barriers like protective skin containing sweat and sebaceous glands that produce secretions like sweat and sebum containing antimicrobial enzymes act as frontline defensive mechanism for entry of a pathogen into host. The lysozyme enzyme occurring in secretions like lachrymal secretions and tears wash out the microorganisms. The flushing of urine eliminates the microorganisms from urethra.
Blood contains several defensive factors and antimicrobial substances like beta lysin, leukins and plakins etc. The lactic acid in the muscles also acts as antibacterial agent. The blood contains antiviral compounds called interferons produced by blood cells. The mucus secreted by membranes in the oral cavity and gut removes the colonization of pathogens. The blood contains cells like macrophages, phagocytes, monocytes and polymorpho nuclear leucocytes that inhibit the circulating microorganisms from blood through the process of phagocytosis.
The foreign organism encountered by macrophage is engulfed and formed into a phagosome. The phagosome unites with lysosome forming phagolysosome. The enzymes of lysosomes neutralize the foreign organism.
Inflammation is a non-specific defense mechanism in which the damaged tissue is immediately surrounded by leucocytes that attract several chemo tactic substances and are surrounded by a fibrin barrier that forms a network. The accumulation of fluid and leucocytes at the site of injury result in the inflammation.
Rise in the body temperature is a natural defense mechanism. During infection, the body temperature is increased due to accelerated physiological processes that can stimulate other body defense mechanisms against the pathogens.
Production of interferons by natural killer cells and leukocytes against viral infections is specific immunity mechanism. Production of antibodies by B lymphocytes against a specific pathogen or bacteria is a specific immunity mechanism.