QUESTION: 33

In emphysema, which of the following components of the bronchioles is affected?

ciliated cuboidal epithelial cells
Clara cells
elastic fibers
goblet cells
squamous type I alveolar epithelial cells

Answer(s): C

Explanation:

Elastic fibers are destroyed in emphysema by elastase. This protease is released by neutrophils recruited by macrophages under abnormal stimulus such as cigarette smoke. The loss of elasticity in the bronchioles and alveolar walls gives rise to emphysema, characterized by chronic airway obstruction. Ciliated cuboidal epithelial (choice A) and Clara (choice B) cells line the terminal bronchioles. Goblet cells (choice D) may be found at the beginning of the bronchioles and squamous type I alveolar epithelial cells line the respiratory bronchioles.

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QUESTION: 34

During development, the notochord grows in a cranial direction until it reaches the prechordal plate. This plate is the primordium of the oropharyngeal (or buccopharyngeal) membrane, which, in the embryo, will separate the stomodeum from the foregut. At 26 days of gestation, the oropharyngeal membrane will break down, allowing communication of the foregut with the oral cavity. Of the following structures in the adult, which one lies at the same location as the embryonic oropharyngeal membrane?

buccinators
palatoglossus
palatopharyngeus
stylopharyngeus
superior constrictor

Answer(s): B

Explanation:

The palatoglossus muscle, which can be observed in the oral cavity to form the palatoglossal arch anterior to the palatine tonsil, lies in the same location as the embryonic oropharyngeal membrane. It lies at the junction line between the stomodeum and the foregut. The buccinator (choice A) is a muscle of the cheek and thus is located in the original stomodeum. The palatopharyngeus (choice C) is located posterior to the palatoglossus and palatine tonsil, forming the palatopharyngeal arch. The palatopharyngeus, stylopharyngeus (choice D), and superior constrictor (choice E) muscles are all pharyngeal muscles and thus are located in the original foregut.

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QUESTION: 35

Referring to following figure, arrow 2 indicates which of the following structures?

intercalated disk
motor end-plate
sarcoplasmic reticulum
tendinous junction
transverse tubule or T tubule

Answer(s): A

Explanation:

The intercalated disks are specialized junctional complexes found only in cardiac muscle and they appear as dark lines between the muscle fibers. The motor end-plate (choice B) is a specialized group of synapses between the axon terminals of a motor neuron and the sarcolemma of a skeletal muscle fiber. It is not seen in cardiac muscle. The sarcoplasmic reticulum (choice C) is a specialized modification of the smooth endoplasmic reticulum for sequestering calcium ions. The transverse tubule or T tubule (choice E) is an invagination of the sarcolemma, which penetrates the muscle fiber and overlies the surface of the myofibrils. The sarcoplasmic reticulum and T tubule can only be seen in electron micrographs. There is no tendinous junction (choice D) in cardiac muscle.

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QUESTION: 36

The most common type of testicular cancer is germ cell carcinoma. However, testicular tumors arising from other cell types in the testis also occur. Arrow 1 in following figure, indicates which of the following structures?

Leydig cell
Sertoli cell
spermatid
spermatocyte
spermatogonia

Answer(s): A

Explanation:

Arrow 1 indicates an interstitial cell of Leydig. These cells are recognizable by their location in the intertubular space, close to the capillaries and lymph vessels. Sertoli cells (choice B) are columnar cells with a large nucleolus. They span the distance from the seminiferous tubular wall to the lumen. However, their nuclei are located closer to the tubular wall. Spermatids (choice C; arrow 4) have a condensed nucleus, which becomes elongated with further maturation. This cell type is located closest to the lumen of the seminiferous tubule. Spermatocytes (choice D; arrow 2) are seen above the layer spermatogonia (choice E; arrow 3) which are located against the basal lamina.

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