81.In restoring a mandibular first molar, lingual cusps are important for which movement?

A. Centric occlusion B. Protrusive
C. Retrusive D. Working E. Nonworking

ANS. D. To answer this question, place your own teeth in centric occlusion(maximum intercuspation). Notice that the occlusion is held in place by the lingual cusps of maxillary teeth and the buccal cusps of mandibular teeth. Mandibular lingual cusps are not in contact. In protrusion, the anterior teeth act to separate the maxilla and mandible as the mandible moves forward. The anterior teeth act as guides in retrusion as well (try it). So far the mandibular lingual cusps are not involved. If you make a left working movement (slide your mandible left), notice that the mandibular lingual cusps on the left, drag against the lingual side of the maxillary lingual cusps. In the nonworking side (in this case, the right side), the mandibular lingual cusps move AWAY from contact.


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80. Which of the following hormones is secreted by anterior pituitary cells that stain with acidic dyes?

A. ACTH B. FSH
C. LH D. Prolactin

E. TSH

ANS. D. The cells of the anterior pituitary can be classified as chromophils (stain
with dyes) or chromophobes (do not stain with dyes). The chromophils can be further divided inacidophils (stain with acidic dyes) and basophils (stain with basic dyes). The acidophils include thesomatotrophs, which secrete growth hormone, and the mammotrophs, which secrete prolactin.The basophils include the corticotrophs, which secrete ACTH (choice A), the gonadotrophs, which secrete FSH and LH (choices B and C), and the thyrotrophs, which secrete TSH (choice E).

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79.The epithelium of the mucous membrane of the mouth is:

A. simple squam. B. strtified squam.

C. simple colum. D. strtified colum.

ANS. B. Squamous cells are flattened, pancake-like cells, and when in layers are known as stratified. The stratified squamous cells lining the mucosa of the oral cavity are similar to those lining the outer skin, although less keratinized. They do, however, flake off continuously into the mouth. Simple squamous tissue would be too thin and not allow for the constant flaking and replacement ^Mcq. Columnar epithelium is found in both the respiratory system and other organs of the digestive system. ^Mcq

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