direct inhibition of sodium absorption in the renal collecting duct,
increased glomerular filtration rate (GFR), and inhibited aldosterone pro-
duction and secretion. ANP counteracts the renin-angiotensin-aldosterone
system. Increased ANP levels are detected in congestive heart failure,
chronic renal failure, and in severe essential hypertension.
165.The answer is a.(Young, pp 47–57. Junqueira, pp 226–235.)
Neutrophil. The neutrophil (A)contains neutrophilic granules. Neu-
trophils are involved in the acute phase of inflammation and are responsi-
ble for the phagocytosis of invading bacteria. Neutrophils contain
lysozyme and alkaline phosphatase within their granules. They die soon
after phagocytosing bacteria and are added to the pus, which consists of
dead neutrophils, serum, and tissue fluids.
Basophil.The basophil (B)is about the same size as the neutrophil (A)
and contains granules of variable size that may obscure the nucleus. The
nucleus of the basophil is irregularly lobed with condensed chromatin.
Basophils are involved in the attraction of eosinophils to the site of infec-
tion. This occurs in parasitic and nonparasitic infections and involves
chemoattraction by histamine and eosinophil-chemoattractant factor of
anaphylaxis (ECF-A). Basophils are similar in structure and function to the
connective tissue mast cell. Basophils are also phagocytic granulocytes, but
are involved in inflammation through the release of histamine and heparin.
Immunoglobulin E (IgE) produced by plasma cells becomes bound to the
cell surface of mast cells and basophils on first exposure. At the time of sec-
ondary exposure, the antigen binds to the IgE and stimulates the degranu-
lation of mast cell and basophil granules releasing histamine and heparin.
Basophils and mast cells are involved in anaphylactic and immediate
hypersensitivity reactions.
Eosinophil.The eosinophil (C)is bilobed with more regular granules
than the basophil (B).Eosinophils have less phagocytic ability than neu-
trophils and may kill parasites by either phagocytosis or exocytotic release
of granules. Eosinophils contain major basic protein, histaminase, acid
phosphatase, and other lysosomal enzymes. Eosinophils are essential for
the destruction of parasites such as trichinae and schistosomes.
Monocyte.The monocyte (D)contains an eccentric nucleus, which is
often kidney-shaped. The chromatin generally has a ropelike appearance
268 Anatomy, Histology, and Cell Biology