No, they understand it very well. But philosophical consistency is just too damn inconvenient.
SODOMY : Texas Phys.Resource Council, Christian Med. & Dental Association, Catholic Med.Association
The CDC has identified men who have sex with men as among the groups that "are most vulnerable to STDs and their consequences . . . ." Id . at 39 (Introduction to "Special Focus Profiles"). One reason that men who have sex with men are at high risk of STDs is the nature of anal sex. Anal sex is not the same as sexual intercourse because of the differences between the vagina and the anus. 10 "The vagina is surrounded by thick muscular tissue which distends and changes shape to accommodate the erect penis during intercourse." Jeremy Agnew, Some Anatomical and Physiological Aspects of Anal Sexual Practices , 12 Journal of Homosexuality No. 1, 75, 91 (Fall 1985). The nature of these muscles make them "capable of protecting against abrasion during intercourse . . . ." Id . In contrast, the anus has a far more limited capacity to expand because it is firmly attached to the tail bone, and it is vulnerable to tears at its point of attachment. Because the anus is surrounded by veins and arteries, any tears may lead to substantial bleeding. See Keith L. Moore, C LINICALLY O RI ENTED A NATOMY 385 (2 nd ed. 1985). Accordingly, receptive anal sex may cause physical trauma to the anus and the rectum:
the lining of the rectum consists of a single layer of [membranous cellular tissue] with numerous goblet [mucous secreting] cells. The function of this thin layer is to promote the absorption of water and electrolytes. In spite of the limited protective capacity of secreted mucus from the goblet cells, the mucosa is incapable of much mechanical protection against abrasion. . . . . . . One of the commonest problems associated with anal sexual activity is tearing of the anal canal. The external anal sphincter is biologically intended to have material pass through it out of the body. The sudden or forceful insertion of objects in the "reverse" direction stimulates the anal reflex and produces a natural tendency of the sphincter to contract to prevent inser- tion. Unlike the vagina, the anus and rectum lack a nat- ural lubricating function, and insertion of unlubricated objects or inadequate dilation prior to the insertion of large objects can result in the tearing of perianal and anal canal tissue.