Junqueira Questions Exam 1

1) Which of the following connective tissue components is located in the ECM but not in the ground substance? A) Collagen bundles B) Fibronectin C) GAGs D) Hyaluronan E) Proteoglycans

A) Collagen bundles

9. A 36-year-old man is referred by his family physician to the pulmo- nary clinic. He complains of shortness of breath following physical activity and decreased capacity for exercise. He says that strenuous exercise including yard work is impossible without sitting down and resting every few minutes. After taking several deep breaths during the physical examination, he begins to wheeze. He is not a smoker and works in an office not exposed to dust, fumes, or other irritants. He appears slightly jaundiced. Serum alpha-1-antitrypsin (AAT) concentration analysis is below normal and is followed up with AAT phenotype and DNA testing which indicates one copy of S and one of Z mutations with 40% abnormal AAT production. Uri- nalysis shows elevated levels of desmosine and isodesmosine. These excreted compounds normally contribute to efficient lung function by which of the following mechanisms? A) Post-translational modification of fibrillin B) Cross-linking elastin C) Activating elastase D) Activating AAT E) Binding type IV collagen to elastin

B) Cross-linking elastin

2) What cells numerous in loose connective tissue are filled with secretory granules and stain with metachromasia? A) Macrophages B) Mast cells C) Fibrocytes D) Active fibroblasts E)Leukocytes

B) Mast cells

3) What is the first step of collagen production that occurs after the protein undergoes exocytosis? A) Cross-linking of collagen fibrils with a short linking collagen B) Removal of the terminal nonhelical domains by peptidases C) Hydroxylation of lysine and proline D) Assembly of subunits to form a larger structure E) Disulfide bond formation

B) Removal of the terminal nonhelical domains by peptidases

10. A 33-year-old homeless woman has been living in an abandoned building eating dried meat and bread from the dumpster behind a delicatessen. She smokes cigarettes "bummed" from others. She presents at a free clinic with bleeding under the skin, particularly around hair follicles, and bruises on her arms and legs. She is irrita- ble, clinically depressed, and fatigued with general muscle weakness. Her gums are bleeding, swollen, purple, and spongy, with several loose teeth. She has an infected toe, which may be broken. She is afe- brile, a glucose finger-stick is normal, and the urine dipstick shows no sugar, protein, or ketones. You suspect a vitamin deficiency. What might be the underlying mechanism for this patient's symptoms? A) Decreased degradation of collagen B) Stimulation of prolyl hydroxylase C) Formation of unstable collagen helices D) Excessive callus formation in healing fractures E) Organ fibrosis

C) Formation of unstable collagen helices

8) Research scientists at a small biotech firm are investigating new methods of controlling the growth and metastasis of malignant cells in patients diagnosed with breast cancer. They have developed a novel peptide-based drug, potentially deliverable therapeutically, that disrupts the tumor cells' ability to adhere to the ECM, which in turn triggers apoptosis. Which of the following is a most likely target of such drugs? A) Cadherins B) Adhesins C) Integrins D) Glycolipids of the cell membrane E) Fibrillin

C) Integrins

4) What is an important part of the role played by macrophages during maintenance and renewal of strong extracellular fibers in connective tissue? A) Storage for a major energy source needed for ECM maintenance B) Production of specific collagen subunits C) A sentinel function against invaders entering the ECM D) Secretion of matrix metalloproteinases E) Presentation of antigens important for assembly of collagen bundles

D) Secretion of matrix metalloproteinases

6) Which of the following contains binding sites for integrins and is an important part of the ECM in both loose connective tissue and dense irregular connective tissue? a. Aggrecan b. Fibronectin c. Perlecan d. Fibrillin e. Most types of collagen

b. Fibronectin

5) Sulfated GAGs are important constituents of what extracellular structures? a. Hyaluronan b. Elastic fibers c. Type I collagen d. Proteoglycans e. Multiadhesive glycoproteins

d. Proteoglycans

7) Dense regular connective tissue typically involves which of the following features? a. Contains mostly synthetically active fibroblasts b. Contains much ground substance c. Contains a similar cell population as areolar connective tissue d. Predominant tissue type in the stroma of most organs e. Predominantly located in tendons and ligaments

e. Predominantly located in tendons and ligaments