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BRS Cell Biology and Histology 7th Edition > Comprehensive Examination > Flashcards

Flashcards in Comprehensive Examination Deck (100):
1

Which of the following statements concerning ribonucleic acid (RNA) synthesis is true?
(A) RNA synthesis does not require deoxyribonucleic acid to act as a template.
(B) Syntheses of ribosomal RNA, messenger RNA, and transfer RNA are all catalyzed by the same RNA polymerase.
(C) To yield messenger ribonucleoproteins, introns are excised, whereas exons are spliced together.
(D) Protein moieties are removed from messenger ribonucleoproteins within the nucleolus, yielding functional messenger RNAs to exit via the nuclear pores.
(E) The start codon for RNA synthesis is UAG.

C. To yield messenger ribonucleoproteins (mRNPs), introns are excised, whereas exons are spliced together. Deoxyribonucleic acid does act as the template for the synthesis of ribonucleic acid (RNA). Three RNA polymerases (I, II, and III) are needed to synthesize ribosomal RNA, messenger RNA, and transfer RNA, respectively. Protein moieties are removed from the mRNPs as they leave the nucleus to yield functional mRNAs outside the nucleus. (See Chapter 2 VIII A.)

2

Which of the following factors is primarily responsible for causing osteoporosis in older women?
(A) Decreased bone formation
(B) Lack of physical exercise
(C) Diminished estrogen secretion
(D) Calcium deficiency
(E) Increased bone formation

C. The most common cause of osteoporosis in older women is diminished estrogen secretion. (See Chapter 7 II J Clinical Consideration.)

3

Which of the following bases that makeup deoxyribonucleic acid and ribonucleic acid (RNA) is unique to RNA?
(A) Thymine
(B) Adenine
(C) Cytosine
(D) Guanine
(E) Uracil

E. Although adenine, cytosine, and guanine are found in both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), uracil is found only in RNA. Uracil substitutes for the base thymine in DNA. (See Chapter 2 VIII.)

4

The centroacinar cells of the pancreas secrete
(A) an alkaline enzyme-poor fluid
(B) pancreatic digestive enzymes.
(C) secretin.
(D) cholecystokinin.
(E) glucagon.

A. Pancreatic centroacinar cells form the initial segment ofthe intercalated duct and are part of the exocrine pancreas. They secrete an enzyme-poor alkaline fluid when stimulated by secretin. Pancreatic digestive enzymes are synthesized by the acinar cells of the exocrine pancreas; their release is stimulated by cholecystokinin. Glucagon is produced in the endocrine pancreas (islets of Langerhans). (See Chapter 17 III A 2.)

5

The zona fasciculata of the adrenal cortex synthesizes and secretes
(A) mineralocorticoids.
(B) glucagon.
(C) epinephrine.
(D) aldosterone.
(E) glucocorticoids.

E. The zona fasciculata, the largest region of the adrenal cortex, produces glucocorticoids (cortisol and corticosterone). The zona glomerulosa produces mineralocorticoids, primarily aldosterone. Epinephrine is produced in the adrenal medulla. Glucagon is produced in the pancreas, not in the adrenal gland. (See Chapter 13 VI A 2.)

6

Which of the following statements about
bony joints is true?
(A) Long bones are generally united by synarthroses.
(B) Diarthroses are classified as synovial joints.
(C) Type A cells of the synovial membrane secrete synovial fluid.
(D) Type B cells of the synovial membrane are phagocytic.
(E) Synarthroses are usually surrounded by a two-layered capsule.

B. Diarthroses, the type of joint connecting two long bones, are classified as synovial joints, which are surrounded by a two-layered capsule housing a synovial membrane. Type A cells of the synovial membrane are phagocytic, whereas type B cells secrete the synovial fluid. Synarthrosis joints are those found joining the bones of the skull, which are immovable. (See Chapter 7 III B.)

7

All of the following characteristics can be used to distinguish neutrophils and basophils histologically except one. Which one is the exception?
(A) Size of specific granules
(B) Shape of the nucleus
(C) Number of azurophilic granules
(D) The presence or absence of peroxidase (E) The presence of mitochondria

E. Neutrophils have a nucleus with three or four lobes, many azurophilic granules, and small specific granules that lack peroxidase. In contrast, basophils have an S-shaped nucleus, few azurophilic granules, and large specific granules that contain peroxidase. Both neutrophils and basophils possess mitochondria. (See Table 10.2.)

8

Along-time user of chewing tobacco noticed several whitish, thick, painless patches on the lining of his cheeks. The most probable diagnosis is
(A) aphthous ulcers
(B) adenocarcinoma
(C) keloids
(D) oral leukoplakia
(E) epidermolysis bullosa

D. Oral leukoplakia, which results from epithelial hyperkeratosis, is usually of unknown etiology, but is often associated with the use of chewing tobacco. Although the characteristic painless lesions are benign, they may transform into squamous cell carcinoma. Aphthous ulcers are painful lesions of the oral mucosa that are surrounded by a red border. Adenocarcinoma is a form of cancer arising in glandular tissue. Keloids are swellings in the skin that arise from increased collagen formation in hyperplastic scar tissue. Epidermolysis bullosa is a group of hereditary skin diseases characterized by blister formation after minor trauma. (See Chapter 16 II.)

9

Primordial follicles of the ovary possess
(A) a layer of cuboidal follicular cells.
(B) an oocyte arrested in prophase of
meiosis I.
(C) an oocyte arrested in metaphase of
meiosis II.
(D) well-defined thecae interna and externa.
(E) a thick zona pellucida.

B. A primordial follicle is composed of a flattened layer of follicular cells surrounding a primary oocyte, which is arrested in prophase of meiosis I. Well-defined thecal layers and a thick zona pellucida are found in growing follicles. A graafian (mature) follicle possesses a secondary oocyte, which becomes arrested in metaphase of meiosis II just before ovulation. (See Chapter 19 II B 1.)

10

All of the following statements regarding the membranous labyrinth of the inner ear are true except for one. Which is that exception?
(A) It contains the saccule and utricle.
(B) Maculae contain neuroepithelial cells,
which possess numerous stereocilia
and a single kinocilium.
(C) Cristae ampullares in the semicircular canals detect angular acceleration of the head.
(D) The otolithic membrane contains small calcified particles.
(E) It contains the vestibular membrane.

E. The first four statements are true. Linear acceleration of the head is detected by the neuroepithelial hair cells of the maculae, which are specialized regions of the saccule and utricle. However, the vestibular membrane is a part of the organ of Corti. (See Chapter 21 IV C 2.)

11

Which of the following statements concern­
ing euchromatin is true?
(A) It constitutes about 90% of the chromatin.
(B) It appears as basophilic clumps of nu- cleoprotein when seen under the light
microscope.
(C) It is concentrated near the periphery of the nucleus.
(D) It is transcriptionally active.
(E) It is transcriptionally inactive.

D. Euchromatin, the transcriptionally active form of chromatin, represents only about 10% of the chromatin. In the light microscope, it appears as a light-staining, dispersed region of the nucleus. (See Chapter 2 V 2.)

12

Intercalated disks function in which one of the following?
(A) End-to-end attachments of smooth muscle cells
(B) Intercellular movement oflarge proteins
(C) Ionic coupling of cardiac muscle cells
(D) Storage of Ca2+
(E) Release of neurotransmitters

C. Large protein molecules cannot move across intercalated disks (the steplike junctional complexes present in cardiac, not smooth, muscle). These junctional structures possess three specializations: desmosomes, which provide end-to-end attachment of cardiac muscle cells; fascia adherentes, to which the thin myofilaments attach; and gap junctions, which permit intercellular movement of small molecules and ions (ionic coupling). (See Chapter 8 V B 6.)

13

Release of thyroid hormones from the follicular cells of the thyroid gland depends on thyroid-stimulating hormone (TSH). TSH stimulation involves
(A) binding of TSH to receptors on the apical plasma membrane.
(B) formation of apical microvilli.
(C) exocytosis of colloid droplets.
(D) change in cell shape from flattened to
columnar.
(E) secretion of lysosomes from the basal cell surface.

D. Flattened squamous cells are characteristic of an unstimulated, inactive thyroid gland. TSH binds to G protein-linked receptors on the basal surface of follicular cells. Under TSH stimulation, thyroid follicular cells become columnar and form pseudopods, which engulf colloid. Lysosomal enzymes split thyroxine and triiodothyronine from thyroglobulin; the hormones are then released basally. (See Chapter l3 IV B 2.)

14

Which one of the following statements about the development of the tooth crown is true?
(A) The enamel organ is derived from ectomesenchyme (neural crest).
(B) The dental papilla is derived from the epithelium.
(C) The four-layer enamel organ appears during the cap stage.
(D) Dentin and enamel are formed during the appositional stage.
(E) Cementum is formed at the same time as enamel.

D. The enamel organ is epithelially derived, whereas the dental papilla comes from ectomesenchyme. The bell, not the cap, stage of odontogenesis is characterized by possessing a fourth layer in its enamel organ. Formation of dentin and enamel occurs during the appositional stage of tooth development. Cementum is located on the root and is formed only after the crown is complete and enamel ceases to be elaborated. (See Chapter 16 II C 3.)

15

Which one of the following statements concerning liver sinusoids is true?
(A) Their lining includes Ito cells (fat-storing cells).
(B) They receive bile from the hepatocytes.
(C) They are lined by nonfenestrated
endothelial cells.
(D) The space of Disse is located between
sinusoidal cells and hepatocytes.
(E) Sinusoids convey blood from the central
vein to the portal vein.

D. Liver sinusoids convey blood to the central vein. Their endothelial cells are fenestrated, and material from the sinusoids may enter the space of Disse through the fenestrae, where it may be endocytosed by hepatocytes. The space of Disse houses Ito cells (fat-storing cells). Because bile is the exocrine secretion of hepatocytes, it does not enter the sinusoids.
(See Chapter 17 IV B 2.)

16

A young college student had nausea, vomiting, visual disorders, and muscular paralysis after eating canned tuna fish. The probable diagnosis is botulism, caused by ingestion of the Clostridium botulinum toxin. The physiological effect of this toxin is to
(A) inactivate acetylcholinesterase.
(B) bind to and thus inactivate acetylcholine
receptors at myoneural junctions.
(C) prevent release of calcium ions from the sarcoplasmic reticulum, thus inhibiting muscle contraction.
(D) inhibit release of acetylcholine from presynaptic membranes.
(E) inhibit hydrolysis of adenosine triphosphate during the contraction cycle.

D. The toxin from Clostridium botulinum inhibits the release of acetylcholine, the neurotransmitter at myoneural junctions. As a result, motor nerve impulses cannot be transmitted across the junction, and muscle cells are not stimulated to contract (See Chapter 8 IV 2 Clinical Considerations.)

17

Which of the following statements about nucleosomes is true?
(A) Histones form the nucleosome
core around which the double helix deoxyribonucleic acid is wound.
(B) Nucleosomes without histones form the structural unit of the chromosome.
(C) Nucleosomes are composed of ribonucleic acid (RNA) molecules and two copies each of four different histones.
(D) Histone Hl forms the core of the nucleosome.
(E) Nucleosomes are linked together with RNA.

A. The nucleosome, the structural unit of chromatin packing, does not contain ribonucleic acid. In extended chromatin, two copies each of histones H2A, H2B, H3, and H4 form the nucleosome core around which a deoxyribonucleic acid molecule is wound. Condensed chromatin contains additional histones (H1), which bind to nucleosomes, forming the condensed 30-nm chromatin fiber. (See Chapter 2 VI A.)

18

A high school student complains of fatigue and a sore throat. She has swollen, tender lymph nodes and a fever. Blood test results show an increased white blood cell count with many atypical lymphocytes; the number and appearance of the erythrocytes are normal. This student is likely to have
(A) AIDS.
(B) pernicious anemia.
(C) infectious mononucleosis.
(D) Hodgkin disease.
(E) factor VIII deficiency.

C. Only infectious mononucleosis is characterized by all of the signs and symptoms indicated. AIDS is associated with a decreased lymphocyte count, particularly of T helper cells. Pernicious anemia is associated with a decreased red blood cell count. Hodgkin disease is associated
with fatigue and enlarged lymph nodes, but the nodes are not painful, and the presence of Reed-Sternberg cells is diagnostic of this disease. FactorVIII deficiency, a coagulation disorder, is not associated with any of these signs and symptoms. (See Chapter 10 II B 2 Clinical
Considerations.)

19

Which one of the following statements about the gallbladder is true?
(A) The gallbladder dilutes bile.
(B) Bile enters the gallbladder via the common
bile duct.
(C) Bile leaves the gallbladder via the cystic duct.
(D) The gallbladder is lined by a simple squamous epithelium.
(E) Secretin stimulates the wall of the gallbladder to contract, forcing bile from its lumen.

C. The gallbladder, which concentrates and stores bile, is lined by a simple columnar epithelium. Cholecystokinin stimulates contraction of the gallbladder wall, forcing bile from the lumen into the cystic duct; this joins the common hepatic duct to form the common bile duct, which delivers bile to the duodenum. (See Chapter 17 III A 2.)

20

Which one of the following statements concerning mitochondria is true?
(A) They change from the orthodox to the condensed form in response to the uncoupling of oxidation from phosphorylation.
(B) They are unable to divide.
(C) They possess the enzymes of the Krebs
cycle in their cristae.
(D) They contain elementary particles in their matrix.
(E) They do not contain deoxyribonucleic acid.

A. Uncoupling of oxidation from phosphorylation induces mitochondria to change from the orthodox to the condensed form. Condensed mitochondria are often present in brown fat cells, which produce heat rather than adenosine triphosphate. Mitochondria possess circular deoxyribonucleic acid, and they reproduce (divide) by fission. (See Chapter 3 II 6 e.)

21

Which one of the following components is present in muscular arteries but absent from elastic arteries?
(A) Fenestrated membranes
(B) Vasa vasorum
(C) Factor VIII
(D) A thick, complete internal elastic lamina
(E) Smooth muscle cells

D. Muscular (distributing) arteries have a thick, complete internal elastic lamina in the tunica intima, whereas elastic (conducting) arteries have an incomplete internal elastic lamina. Both types of arteries have vasa vasorum, factor VIII, and smooth muscle cells in their walls. Muscular arteries possess numerous layers of muscle cells in the tunica media, but elastic arteries do not. Only elastic arteries possess fenestrated (elastic) membranes in the tunica media, in which smooth muscle cells are dispersed. (See Chapter 1 1 I B 1 b.)

22

Which one of the following statements concerning the pancreas is true?
(A) Islets of Langerhans secrete enzymes.
(B) It possesses mucous acinar cells.
(C) The endocrine pancreas has more beta-cells
than delta-cells.
(D) Its alpha-cells secrete insulin.
(E) Its delta-cells secrete amylase.

C. In the endocrine pancreas, beta-cells account for about 70% ofthe secretory cells; alpha-cells about 20%; and delta-cells less than 5%. Polypeptide hormones are synthesized by and released from the islets of Langerhans (endocrine pancreas). The exocrine pancreas possesses serous (not mu­cous) acinar cells. Insulin is produced by beta-cells. (See Chapter 17 III B 3.)

23

Which one of the following stimulates the production of hydrochloric acid in the stomach?
(A) Somatostatin
(B) Gastrin
(C) Secretin
(D) Cholecystokinin
(E) Urogastrone

B. Somatostatin and urogastrone both inhibit the production of hydrochloric acid, whereas gastrin enhances it. Secretin and cholecystokinin act on the pancreas to facilitate secretion of buffer and pancreatic enzymes, respectively. (See Chapter 16 III B 2.)

24

A deficiency or an excess of which of the following vitamins results in short stature?
(A) Vitamin A
(B) Vitamin C
(C) Vitamin D
(D) Vitamin K
(E) Vitamin B

A. A deficiency of vitamin A inhibits bone formation and growth, whereas an excess stimulates ossification of the epiphyseal plates, thus leading to premature closure of the plates. Both conditions result in short stature. A deficiency of vitamin D reduces calcium absorption from the small intestine and results in soft bones, whereas an excess of vitamin D stimulates bone resorption. A deficiency of vitamin C results in poor bone growth and fracture repair. Vitamin K plays no role in bone formation. (See Chapter 7 II I.)

25

The intercellular spaces in the stratum spinosum of the epidermis contain lipid­ containing sheets that are impermeable to water. This material is released from
(A) keratohyalin granules.
(B) Langerhans cells.
(C) membrane-coating granules.
(D) sebaceous glands.
(E) melanosomes.

C. Membrane-coating granules are present in keratinocytes in the stratum spinosum (and stratum granulosum). The contents of these granules are released into the intercellular spaces to help waterproof the skin. Keratinocytes in the stratum granulosum also possess keratohyalin granules; these contain proteins that bind keratin filaments together. (See Chapter 14 II B 2.)

26

Which of the following statements concerning basophilic erythroblasts is true?
(A) The nucleus has a fine chromatin network,
(B) The nucleus is in the process of being extruded.
(C) The cytoplasm contains specific granules.
(D) The cytoplasm is pink and reveals a dense reticulum.
(E) The nucleus is bilobed.

A. The nucleus of erythroblasts is not in the process of being extruded and is round with a very fine chromatin network. The cytoplasm is blue and possesses no granules. (See Chapter 10 VI C.)

27

The ileum includes which of the following structures?
(A) Rugae
(B) Peyer patches
(C) Brunner glands
(D) Parietal cells
(E) Chief cells

B. The ileum includes Peyer patches. Rugae, parietal cells, and chief cells are located in the stomach. Brunner glands are present in the submucosa of the duodenum. (See Table 16.1.)

28

A 25-year-old woman complains about a frequently recurring painful lesion on her upper lip that exudes a clear fluid. She probably has
(A) oral leukoplakia.
(B) herpetic stomatitis.
(C) aphthous ulcer.
(D) bullous pemphigoid.
(E) malignant melanoma.

B. Herpetic stomatitis is characterized by painful fever blisters on the lips or near the nostrils. These blisters exude a clear fluid. Aphthous ulcers (canker sores) do not exude fluid. Bullous pemphigoid is an autoimmune disease marked by chronic generalized blisters in the skin. (See Chapter 16 II B Clinical Considerations.)

29

Which of the following statements
concerning the functions of the skin is true?
(A) Infrared radiation, necessary for synthesis of vitamin D, is absorbed by the skin.
(B) The skin provides no protection against desiccation.
(C) The skin contains temperature receptors and plays a role in regulating body temperature.
(D) Melanin is synthesized by melanocytes, which are located in the dermis.
(E) Sunscreen with a sun protection factor rating of 15 or higher protects the skin from harmful effects caused by ultraviolet light.

C. The skin, which consists of the epidermis and dermis, is important in the regulation of body temperature and contains temperature receptors in the dermis. Ultraviolet (not infrared) radiation absorbed by the skin is necessary for the synthesis of vitamin D. Protection against desiccation is provided by the contents of the membrane-coating granules of the epidermis. Melanocytes are located in the deepest layer of the epidermis (stratum basale). Sunscreen with sun protection factor rating of 15 or higher offers no protection against ultraviolet light of longer wavelengths, that is, in the UVA spectrum. (See Chapter 14 I E.)

30

A person with glomerulonephritis will have which of the following signs or symptoms?
(A) Hypotonic urine
(B) Polyuria
(C) Proteinuria
(D) Dehydration
(E) Polydipsia

C. Patients with glomerulonephritis excrete protein in their urine. All of the other symptoms are characteristic of patients with diabetes insipidus, who are incapable of producing adequate amounts of antidiuretic hormone and therefore have polyuria (large volume of hypotonic urine production), polydipsia, and dehydration. (See Chapter 18 III A Clinical Considerations.)

31

Stratified squamous keratinized epithelium
is always present in the
(A) rectum.
(B) esophagus.
(C) pyloric stomach.
(D) jejunum.
(E) anus.

E. The anus is lined by stratified squamous keratinized epithelium. The rectum, jejunum, and pyloric stomach are lined by simple columnar epithelium. The esophagus is lined by stratified squamous (nonkeratinized) epithelium. (See Chapter 16 III D 4.)

32

Which of the following properties is exhibited in all three types of cartilage?
(A) It is involved in bone formation.
(B) It possesses type II collagen.
(C) It possesses type I collagen.
(D) It grows interstitially and appositionally.
(E) It has an identifiable perichondrium.

D. Hyaline cartilage, elastic cartilage, and fibrocartilage all exhibit both interstitial and appositional growth. Hyaline cartilage and elastic cartilage have type II collagen in their matrix and are surrounded by a perichondrium, whereas fibrocartilage has type I collagen and lacks an identifiable perichondrium. Only hyaline cartilage is involved in endochondral bone formation. (See Chapter 7 I A, B, C.)

33

Which of the following is a receptor for fine touch?
(A) Pacinian corpuscle
(B) Crista ampullaris
(C) Ruffini ending
(D) Krause end bulb
(E) Meissner corpuscle

E. Meissner corpuscles, in the papillary layer of the dermis, are fine touch receptors. Pacinian corpuscles perceive pressure, touch, and vibration; they are located in the dermis, hypodermis, and connective tissue of mesenteries and joints. Cristae ampullares are special regions of the semicircular canals that detect circular movements of the head. Ruffini endings, in the dermis and joints, function in pressure and touch perception. Krause end bulbs are cold and pressure receptors in the dermis. (See Chapter 14 III A.)

34

A premature infant has labored breathing, which is eventually alleviated by administration of glucocorticoids. The most probable diagnosis is
(A) immotile cilia syndrome.
(B) emphysema.
(C) hyaline membrane disease.
(D) asthma.
(E) chronic bronchitis.

C. Hyaline membrane disease, which results from inadequate amounts of pulmonary surfactant, is characterized by labored breathing and is typically observed in premature infants. Glucocorticoids stimulate synthesis of surfactant and can correct the condition. (See Chapter 15 VIII D Clinical Considerations.)

35

Which of the following statements concerning the cribriform plate is true?
(A) It is the inner layer of the alveolar bone.
(B) It lacks Sharpey fibers.
(C) It is also known as the spongiosa.
(D) It is composed of cancellous bone.
(E) Normally, it is fused with cementum.

A. The cribriform plate, the inner layer of the alveolar bone, is composed of compact bone. It is attached to the principal fiber groups of the periodontal ligament via Sharpey fibers. The outer layer of the alveolar bone is the cortical plate. The spongiosa is the region of cancellous (spongy) bone enclosed between the cortical and cribriform plates.
(See Chapter 16 II D 3.)

36

Which one of the following substances is synthesized in the pituitary gland?
(A) Oxytocin
(B) Antidiuretic hormone (C) Somatotropin
(D) Neurophysin
(E) Vasopressin

C. Somatotropin (growth hormone) is synthesized by cells called somatotrophs, which are acidophils located in the pars distalis of the anterior lobe of the pituitary gland. Oxytocin and antidiuretic hormone (also called vasopressin) are produced in the hypothalamus and transported to the pars nervosa of the pituitary. Neurophysin, a binding protein, aids in this transport. (See Chapter l3 III A 1 a.)

37

Which one of the following is true in breast cancer cells that involve the BRCAl gene?
(A) Mutated cells are unable to divide because of increased expression of the BRCAl gene.
(B) Mutated cells fail to reach the Gl-S checkpoint.
(C) Mutated cells have an abnormal number of endosomes.
(D) Mutated cells lose their G2-M cell cycle checkpoint.
(E) Mutated cells become haploid owing to the interaction of the BRCAl and p53 genes.

D. Mutations in the BRCA1 gene, a breast tumor suppressor gene, are the major cause
of breast cancer. In most breast cancers involving this gene, deoxyribonucleic acid
synthesis proceeds, indicating that the G1-S checkpoint is not affected; however, the mutated cells cannot control the transition between G2 and M. Moreover, the mutated cells had abnormal centrosome numbers, and their nuclear division did not proceed normally, leading to aneuploidy and genetic instability of the daughter cells. (See Chapter 19 X C Clinical Considerations.)

38

A 42-year-old man arrives in the emergency department with a rash over much of his face, hands, and arms. He states that he was gardening and pulled out a number of weeds. On questioning the patient, the physician realized that the patient inadvertently came in contact with poison ivy.

Which of the following cells is responsible for the release of the pharmacological agents that caused the rash?
(A) Diffuse neuroendocrine system cells
(B) Myofibroblasts
(C) Mast cells
(D) Pericytes
(E) Plasma cells

C. The patient has an immediate (type I) hypersensitivity reaction. The cells responsible for releasing the primary and secondary mediators are the mast cells. (See Chapter 6 III D.)

39

A 42-year-old man arrives in the emergency department with a rash over much of his face, hands, and arms. He states that he was gardening and pulled out a number of weeds. On questioning the patient, the physician realized that the patient inadvertently came in contact with poison ivy.

Which of the following is a secondary mediator produced by the mast cells?
(A) Histamine
(B) Chondroitin sulfate
(C) Neutral protease
(D) Bradykinin
(E) Aryl sulfatase

D. Bradykinins are the only listed pharmacological agents that are produced via the arachidonic acid pathway. All of the others are primary mediators because they are stored in the storage granules of mast cells. (See Chapter 6 III D.)

40

A 42-year-old man arrives in the emergency department with a rash over much of his face, hands, and arms. He states that he was gardening and pulled out a number of weeds. On questioning the patient, the physician realized that the patient inadvertently came in contact with poison ivy.

Which of the following white blood cells can also participate in the reaction ofthis patient to poison ivy?
(A) T cells
(B) B cells
(C) Neutrophils
(D) Basophils
(E) Eosinophils

D. Basophils are very similar in function to mast cells. They also participate in the immediate (type I) hypersensitivity reaction. (See Chapter 6 III H 3.)

41

A 26-year-old woman goes to the dentist because of a toothache. On examination, the dentist notes that the patient has a carious lesion that involves not only the enamel but also the dentin and the cementum of the tooth. Which of these substances cannot repair itself?
(A) Dentin
(B) Enamel
(C) Cementum
(D) Dentin and cementum
(E) Dentin, cementum, and enamel

B. The only hard tissue of the tooth that cannot be repaired by the body is enamel because ameloblasts, the cells that manufacture enamel, are eliminated as the tooth emerges into the oral cavity. (See Chapter 16 II C 2.)

42

Lisa is small and thin in stature. She spends her days indoors and rarely eats dairy products. When she became pregnant at 25 years of age, she had severe lower back and leg pain and tenderness when pressure was applied over bony regions of her body. Radiographs revealed excessive amounts of poorly mineralized osteoid in both femurs. Beneficial treatment of her condition involved high doses of vitamin D, calcium, and phosphorus, a regimen that continued after successful delivery of her baby. Which of the following describes Lisa's disease?
(A) Osteogenesis imperfecta
(B) Osteoporosis
(C) Osteomalacia
(D) Osteopetrosis
(E) Osteopenia

C. Osteomalacia, or adult rickets, is Lisa's disorder. It is characterized by a failure of newly formed osteoid to calcify because there is a lack of calcium, vitamin D, and phosphorus. The bones gradually soften and bend, and pain accompanies the condition, which often becomes severe during pregnancy as the fetus removes calcium from the mother's body. Osteogenesis imperfecta is a genetic condition affecting the synthesis of type I collagen in the bone matrix and results in extreme bone fragility and breakage. Osteoporosis is a dis­ ease characterized by low bone mineral density and structural deterioration, making bone more susceptible to fracture, and osteopenia is reduced bone mass caused by inadequate osteoid synthesis. Osteopetrosis is the excessive formation of bone, which obliterates the marrow cavities and thus impairs the formation of blood cells. (See Chapter 7 II I Clinical Consideration.)

43

Michael had visual problems within a day after being hit in the head with a ball during a soccer game. He saw large floaters and noticed that a dark film was blocking part of the vision in his right eye. An examination by an ophthalmologist revealed that he had a detached retina, and emergency surgery was done to save the vision in that eye. Which of the following retinal layers were separated from one another to cause Michael's condition?
(A) Layer 1 from layer 2
(B) Layer 2 from layer 3
(C) Layer 3 from layer 4
(D) Layer 5 from layer 6
(E) Layer 6 from layer 7

A. The pigmented epithelium (layer 1) was separated from the layer of rods and cones (layer 2), which make up the light-sensitive part of the neural retina. (See Chapter 21 III E Clinical Consideration.)

44

Blood coagulation entails a cascade
of reactions that occur in two interrelated pathways, the extrinsic and intrinsic. All of the following are associated with the intrinsic pathway of blood coagulation except
(A) conversion of fibrinogen to fibrin.
(B) platelet aggregation.
(C) release of tissue thromboplastin.
(D) von Willebrand factor.
(E) calcium.

C. The extrinsic pathway is initiated by the release of tissue thromboplastin after trauma to extravascular tissue. Platelet aggregation is promoted by von Willebrand factor, which is associated with the intrinsic pathway only. Calcium is required in both pathways, and the final reaction-the conversion of fibrinogen to fibrin-is the same in both. (See Chapter 10 III D 1.)

45

A scientist spent a summer in a remote
region of Africa, where he studied exotic plants. On returning to the United States, he developed a cough and fever that would not go away. Laboratory tests revealed that he had contracted a roundworm, Ascaris lumbricoides. Which of the following
cells would be expected to be significantly elevated in a differential count of his blood?
(A) Erythrocytes
(B) Lymphocytes
(C) Monocytes
(D) Eosinophils
(E) Neutrophils

D. Eosinophils are increased in parasitic infections and allergic reactions. Both eosinophils and basophils have receptors for immunoglobulin E, which seems to be important in the destruction of parasites. Both neutrophils and monocytes lack immunoglobulin E receptors. (See Table 10.2.)

46

A 45-year-old musician who played the guitar for 26 years in a rock band noticed he was having difficulty hearing. An otolaryngologist confirmed his loss of hearing and associated it with prolonged exposure to loud sounds. Which of the following structures would show degenerative changes that would account for this man's hearing loss?
(A) The epithelium lining the inner portion of the tympanic membrane
(B) Hair cells in the ampullae of the semicircular ducts
(C) The auditory (eustachian) tube extending to the middle ear cavity
(D) Hair cells of the organ of Corti
(E) Ossicles in the middle ear

D. The inner ear is where sound waves are transduced into nerve impulses that convey auditory information to the brain, and the hair cells of the organ of Corti play a key role in this process. Sound waves are initially received by the outer ear and transmitted via the tympanic membrane (eardrum) to the middle ear, where ossicles transmit the vibrations to the inner ear. The inner ear has an auditory system for hearing (the organ of Corti) and a vestibular system of semicircular ducts that control equilibrium and spatial orientation. (See Chapter 21 IV C e 8.)

47

Which of the following is a protein circulating in the blood that functions in wound healing?
(A) Chondronectin
(B) Plasma fibronectin
(C) Osteonectin
(D) Matrix fibronectin
(E) Laminin

B. Plasma fibronectin functions in wound healing, blood clotting, and phagocytosis of material from the blood. (See Chapter 4 II C 1.)

48

Which of the following is an adhesive glycoprotein that forms fibrils in the extracellular matrix?
(A) Chondronectin
(B) Plasma fibronectin
(C) Osteonectin
(D) Matrix fibronectin
(E) Laminin

D. Matrix fibronectin mediates cell adhesion to the extracellular matrix by binding to fibronectin receptors on the plasma membrane. (See Chapter 4 II C 1.)

49

Which of the following is a multifunctional protein that attaches chondrocytes to type II collagen?
(A) Laminin
(B) Plasma fibronectin
(C) Osteonectin
(D) Matrix fibronectin
(E) Chondronectin

E. Chondronectin has binding sites for type II collagen, proteoglycans, and chondrocyte cell-surface receptors. (See Chapter 4 II C 5.)

50

Which of the following cells in the connective tissue is an antibody-manufacturing cell?
(A) Pericytes
(B) Macrophages
(C) T lymphocytes
(D) Plasma cells
(E) Mast cells

D. Plasma cells, which arise from antigen-activated B lymphocytes, produce antibodies and are thus directly responsible for humoral-mediated immunity. (See Chapter 6 III G.)

51

Principal phagocytes of connective tissue are the
(A) pericytes.
(B) macrophages.
(C) T lymphocytes.
(D) plasma cells.
(E) mast cells.

B. Macrophages, the principal phagocytes of connective tissue, remove large particulate matter and assist in the immune response by acting as antigen-presenting cells. (See Chapter 6 III E.)

52

Cells in the connective tissue that can bind immunoglobulin E antibodies and mediate immediate hypersensitivity reactions are
(A) pericytes.
(B) macrophages.
(C) T lymphocytes.
(D) plasma cells.
(E) mast cells.

E. Mast cells (and basophils) have receptors for immunoglobulin E antibodies on their surface. These cells release histamine, heparin, leukotriene C (slow-reacting substance of anaphylaxis), and eosinophil chemotactic factor, which have effects that constitute immediate hypersensitivity reactions. (See Chapter 6 III D.)

53

Connective tissue cells responsible for initiating cell-mediated immune responses are
(A) pericytes.
(B) macrophages.
(C) T lymphocytes.
(D) plasma cells.
(E) mast cells.

C. T lymphocytes initiate cell-mediated immune responses. (See Chapter 6 III F.)

54

Pluripotential cells located primarily along capillaries in the connective tissue are
(A) pericytes.
(B) macrophages.
(C) T lymphocytes.
(D) plasma cells.
(E) mast cells.

A. Pericytes are smaller than fibroblasts and are located along capillaries. When necessary,
they assume the pluripotential role of embryonic mesenchymal cells. (See Chapter 6 III B.)

55

Which of the following functions in activation of secondary messenger systems?
(A) Phospholipid
(B) Glycocalyx
(C) Carrier protein
(D) Band 3 protein
(E) G protein

E. G proteins are membrane proteins that are linked to certain cell-surface receptors. Upon binding of a signaling molecule to the receptor, the G protein functions as a signal transducer by activating a secondary messenger system that leads to a cellular response. (See Chapter 1 IV B 2 c.)

56

Which of the following is primarily responsible for establishing the potential difference across the plasma membrane?
(A) K+ leak channel
(B) Glycocalyx
(C) Carrier protein
(D) Band 3 protein
(E) G protein

A. K+ leak channels are ion channels that are responsible for establishing a potential difference across the plasma membrane. (See Chapter 1 III C 1.)

57

Which of the following is an amphipathic molecule?
(A) Phospholipid
(B) Glycocalyx
(C) Carrier protein
(D) Band 3 protein
(E) G protein

A. The term "amphipathic" refers to molecules, such as phospholipids, that possess both hydrophobic (nonpolar) and hydrophilic (polar) properties. The plasma membrane contains two phospholipid layers (leaflets), with the hydrophobic tails of the molecules projecting into the interior of the membrane and the hydrophilic heads facing outward. (See Chapter 1 II A 2.)

58

Which of the following is a carbohydrate­ containing covering associated with the outer leaflet of the plasma membrane?
(A) Phospholipid
(B) Glycocalyx
(C) Carrier protein
(D) Band 3 protein
(E) G protein

B. The glycocalyx (cell coat) is associated with the outer leaflet of the plasma membrane. It is composed primarily of proteoglycans, which possess polysaccharide side chains. (See Chapter 1 II C 1.)

59

Which of the following functions in antiport transport?
(A) Phospholipid
(B) Glycocalyx
(C) Carrier protein
(D) Band 3 protein
(E) G protein

C. Membrane carrier proteins are highly folded transmembrane proteins that undergo reversible conformational alterations, resulting in transport of specific molecules across the membrane. The Na+-K+ pump is a carrier protein that mediates antiport transport, the transport of two molecules concurrently in opposite directions. (See Chapter 1 II B 1.)

60

Which of the following is a surface marker on T killer cells (CTL)?
(A) CD4
(B) CDS
(C) Interleukin l
(D) Interleukin 2
(E) Perforin

B. T killer cells (cytotoxic T lymphocytes) have CDS marker molecules on their surfaces.
(See Chapter 12 II B 3.)

61

Which of the following is a surface marker on T helper cells?
(A) CD4
(B) CDS
(C) Interleukin l
(D) Interleukin 2
(E) Perforin

A. T helper cells have CD4 marker molecules on their surfaces (See Chapter 12 II B 3.)

62

Which of the following mediates lysis of tumor cells?
(A) CD4
(B) CDS
(C) Interleukin l
(D) Interleukin 2
(E) Perforin

E. Perforin, which is released by cytotoxic T cells, mediates lysis of tumor cells and
virus-infected cells. (See Chapter 12 II B 3.)

63

Which of the following is released by macrophages and stimulates activated T helper cells?
(A) CD4
(B) CDS
(C) Interleukin 1
(D) Interleukin 2
(E) Interferon-y

C. Interleukin 1, which is produced by macrophages, stimulates activated T helper cells. In turn, activated T helper cells produce interleukin 2 and other cytokines involved in the immune response. (See Chapter 12 II E 2.)

64

Which of the following stimulates activation of natural killer cells?
(A) CD4
(B) Interferon-y
(C) Interleukin 1
(D) Interleukin 2
(E) Perforin

B. Interferon-'{ (macrophage-activating factor) stimulates activation of natural killer cells and macrophages, thereby increasing their cytotoxic and/or phagocytic activity. (See Chapter 12 II D 3.)

65

Identify the cells that replicate their deoxyribonucleic acid during the S phase of the cell cycle and undergo meiosis.
(A) Sertoli cells
(B) Primary spermatocytes
(C) Secondary spermatocytes
(D) Interstitial cells of Leydig
(E) Spermatids

B. Primary spermatocytes undergo the first meiotic division following deoxyribonucleic acid replication in the S phase. The resulting secondary spermatocytes undergo the second meiotic division, without an intervening S phase, forming spermatids. (See Chapter 20 II D 4 b.)

66

Identify the cells that form a temporary
cylinder of microtubules called the manchette.
(A) Sertoli cells
(B) Primary spermatocytes
(C) Secondary spermatocytes
(D) Interstitial cells of Leydig
(E) Spermatids

E. During spermiogenesis, the manchette is formed. This temporary structure aids in elongation of the spermatid. (See Chapter 20 II D 5 c.)

67

Identify the cells that possess receptors for luteinizing hormone (LH) and produce testos­ terone in response to binding ofLH.
(A) Sertoli cells
(B) Primary spermatocytes
(C) Secondary spermatocytes
(D) Interstitial cells of Leydig
(E) Spermatids

D. Interstitial cells of Leydig produce testosterone when they are stimulated by LH. (See Chapter 20 II C 4.)

68

Identify the cells that are responsible for formation of the blood-testis barrier.
(A) Sertoli cells
(B) Primary spermatocytes
(C) Secondary spermatocytes
(D) Interstitial cells of Leydig
(E) Spermatids

A. Sertoli cells are columnar cells that extend from the basal lamina to the lumen of the seminiferous tubules. Adjacent Sertoli cells form basal tight junctions, which are responsible for the blood-testis barrier, thus protecting the developing sperm cells from autoimmune reactions. (See Chapter 20 II D 2.)

69

Identify the cells that synthesize androgen­ binding protein when stimulated by follicle­ stimulating hormone.
(A) Sertoli cells
(B) Primary spermatocytes
(C) Secondary spermatocytes
(D) Interstitial cells of Leydig
(E) Spermatids

A. Sertoli cells produce androgen-binding protein, which binds testosterone and maintains it at a high level in the seminiferous tubules. (See Chapter 20 II D 2.)

70

Which of the following organelles possesses mixed-function oxidases that detoxify phenobarbital and other drugs?
(A) Rough endoplasmic reticulum
(B) Smooth endoplasmic reticulum
(C) Mitochondrion
(D) Annulate lamella
(E) Lysosome

B. Smooth endoplasmic reticulum possesses mixed-function oxidases that detoxify phenobarbital and certain other drugs. (See Chapter 3 II 4.)

71

Which ofthe following organelles contains
ribophorins?
(A) Rough endoplasmic reticulum
(B) Smooth endoplasmic reticulum
(C) Mitochondrion
(D) Polyribosome
(E) Lysosome

A. The membrane of the rough endoplasmic reticulum contains ribophorins, receptors that bind the large ribosome subunit. (See Chapter 3 II A 3.)

72

Which of the following is the site where degradation of foreign material ingested by the cell takes place?
(A) Rough endoplasmic reticulum
(B) Smooth endoplasmic reticulum
(C) Mitochondrion
(D) Annulate lamellae
(E) Lysosome

E. The lysosome is the organelle where the degradation of foreign material takes place
in the cell. The term "heterophagy" refers to the ingestion and degradation of foreign material, in contrast to autophagy, where parts of the cell itself are digested and degraded. (See Chapter 3 III C 2.)

73

Which of the following organelles contains adenosine triphosphate synthase?
(A) Rough endoplasmic reticulum
(B) Smooth endoplasmic reticulum
(C) Mitochondrion
(D) Annulate lamellae
(E) Lysosome

C. The inner membrane of the mitochondrion contains adenosine triphosphate synthase,
a special enzyme consisting of a head portion and a transmembrane H+ carrier; as H+ passes through adenosine triphosphate synthase, the enzyme uses the energy of the proton flow to drive the production of adenosine triphosphate. (See Chapter 3 II A 6 d.)

74

Which of the following stimulates secretion of pepsinogen?
(A) Gastrin
(B) Somatostatin
(C) Motilin
(D) Secretin
(E) Lysozyme

A. Gastrin, a paracrine hormone secreted in the pylorus and duodenum, stimulates pepsinogen secretion by chief cells in the gastric glands. (See Chapter 16 III B 2.)

75

Which of the following is produced by Brunner glands and inhibits hydrochloric acid secretion by parietal cells?
(A) Gastrin
(B) Somatostatin
(C) Urogastrone
(D) Pepsinogen
(E) Lysozyme

C. Urogastrone, produced by Brunner glands in the duodenum, inhibits gastric hydrochloric acid secretion and enhances division of epithelial cells. (See Chapter 16 III C 4.)

76

Which of the following functions as an antibacterial agent?
(A) Gastrin
(B) Somatostatin
(C) Motilin
(D) Pepsinogen
(E) Lysozyme

E. Lysozyme, manufactured by Paneth cells in the crypts of Lieberkiihn, is an enzyme that has antibacterial activity. (See Chapter 16 III C 3 b (3) a.)

77

Which of the following stimulates contraction of smooth muscle in the wall of the digestive tract?
(A) Gastrin
(B) Somatostatin
(C) Motilin
(D) Pepsinogen
(E) Lysozyme

C. Motilin, a paracrine hormone secreted by cells in the small intestine, increases gut motility by stimulating smooth muscle contraction. (See Table 16.2.)

78

Which of the following inhibits secretion by nearby enteroendocrine cells?
(A) Gastrin
(B) Somatostatin
(C) Motilin
(D) Pepsinogen
(E) Lysozyme

B. Somatostatin, produced by enteroendocrine cells in the pylorus and duodenum, inhibits secretion by nearby enteroendocrine cells. (See Table 16.2.)

79

Which of the following is involved in forming cross-links between adjacent tropocollagen molecules?
(A) Lysine
(B) Desmosine
(C) Hydroxyproline
(D) Arginine
(E) Proline

A. Lysine and hydroxylysine residues within and between tropocollagen molecules form cross-links with each other or with other lysines or hydroxylysines. These covalent links add great tensile strength to the newly formed fibril. (See Chapter 4 III A 1 .)

80

Which ofthe following cross-links elastin molecules to form an extensive network?
(A) Lysine
(B) Fibrillin
(C) Hydroxyproline
(D) Arginine
(E) Proline

A. Lysine cross-links elastin molecules, forming a network. Fibrillin is the glycoprotein that organizes elastin into fibers. (See Chapter 4 III B 1.)

81

Inadequate amounts of iodine in the diet lead to which one of the following conditions?
(A) Simple goiter
(B) Exophthalmic goiter
(C) Graves disease
(D) Addison disease
(E) Hyperparathyroidism

A. Simple goiter is an enlargement of the thyroid gland resulting from inadequate dietary iodine (<10 fig/d). It is common where the food supply is low in iodine. (See Chapter 13 IV D Clinical Considerations.)

82

Which of the following conditions is associated with the destruction of the adrenal cortex?
(A) Simple goiter
(B) Exophthalmic goiter
(C) Graves disease
(D) Addison disease
(E) Hyperparathyroidism

D. Addison disease is most commonly caused by an autoimmunity that destroys the adrenal cortex. As a result, inadequate amounts of glucocorticoids and mineralocorticoids are produced. Unless these are replaced by steroid therapy, the disease is fatal. (See Chapter 13 VI A Clinical Considerations.)

83

Which of the following hydrolyzes adenosine triphosphate?
(A) Troponin C
(B) Globular head (Sl fragment) of myosin
(C) Myoglobin
(D) Actin
(E) Tropomodulin

B. The globular head of the myosin molecule has adenosine triphosphatase (ATPase) activity, but interaction with actin is required for the non-covalently bound reaction products adenosine diphosphate (ADP) and Pi to be released. This ATPase activity is retained by the S1 fragment resulting from digestion of myosin with proteases. (See Chapter 8 II F 2.)

84

Which of the following binds oxygen?
(A) Troponin C
(B) Globular head (Sl fragment) of myosin
(C) Myoglobin
(D) Actin
(E) Tropomodulin

C. Myoglobin, a sarcoplasmic protein, like hemoglobin, can bind and store oxygen. The myoglobin content of red (slow) muscle fibers is higher than that of white (fast) muscle fibers. (See Chapter 8 II B 2.)

85

Which of the following binds Ca2+?
(A) Troponin C
(B) Globular head (Sl fragment) of myosin
(C) Myoglobin
(D) Actin
(E) Tropomodulin

A. Troponin C is one of the three subunits of troponin that along with tropomyosin binds to actin (thin) filaments in skeletal muscle. Binding of Ca2+ by troponin C results in unmasking of the myosin-binding sites on thin filaments. (See Chapter 8 II F 2.)

86

Which of the following is a rare form of skin cancer that may be fatal?
(A) Epidermolysis bullosa
(B) Basal cell carcinoma
(C) Malignant melanoma
(D) Psoriasis
(E) Warts

C. Malignant melanoma, a relatively rare form of skin cancer, arises from melanocytes. It is aggressive and invasive. Surgery and chemotherapy are usually necessary for successful treatment of this cancer. (See Chapter 14 II B Clinical Considerations.)

87

Which of the following is a hereditary skin disease characterized by blister formation after minor trauma?
(A) Epidermolysis bullosa
(B) Basal cell carcinoma (C) Malignant melanoma (D) Psoriasis
(E) Warts

87. A. Epidermolysis bullosa is a group of hereditary skin diseases characterized by the separation of the layers in skin with consequent blister formation. (See Chapter 14 II D Clinical Considerations.)

88

Which of the following regions of the respiratory system would concern a patient with an adenoid?
(A) Trachea
(B) Nasopharynx
(C) Terminal bronchiole (D) Alveolar duct (E) Intrapulmonary bronchi

B. The nasopharynx is the site of the pharyngeal tonsil; when enlarged and infected, this tonsil is known as an adenoid. (See Chapter 15 II B.)

89

Which of the following possesses C-shaped rings of hyaline cartilage?
(A) Trachea
(B) Nasopharynx
(C) Terminal bronchiole
(D) Alveolar duct
(E) Intrapulmonary bronchi

A. The trachea and extrapulmonary (primary) bronchi have walls supported by C-shaped hyaline cartilages (C-rings), whose open ends face posteriorly. (See Chapter 15 II D.)

90

Which of the following contains smooth
muscle at the openings into alveoli?
(A) Trachea
(B) Nasopharynx
(C) Terminal bronchiole
(D) Alveolar duct
(E) Intrapulmonary bronchi

D. The alveolar duct has alveoli with openings that are rimmed by sphincters of smooth muscle. Alveoli more distal than these have only elastic and reticular fibers in their walls. (See Chapter 15 III B.)

91

Which of the following is lined by an epithelium containing ciliated cells and Clara cells?
(A) Trachea
(B) Nasopharynx
(C) Terminal bronchiole
(D) Alveolar duct
(E) Intrapulmonary bronchi

C. Terminal bronchioles are lined by a simple cuboidal epithelium containing ciliated cells and Clara cells. Clara cells can divide and regenerate both cell types. (See Chapter 15 II F 2.)

92

Which of the following is associated with rupture of the oviduct and hemorrhaging into the peritoneal cavity?
(A) Endometriosis
(B) Cervical cancer
(C) Ectopic tubal pregnancy
(D) Breast cancer
(E) Teratomas

C. An ectopic tubal pregnancy occurs when the embryo implants in the wall of the oviduct (rather than in the uterus). Because the oviduct cannot support the developing embryo, the duct eventually bursts, causing hemorrhaging into the peritoneal cavity. (See Chapter 19 VI B Clinical Considerations.)

93

Which of the following may be classified as lobular carcinoma?
(A) Endometriosis
(B) Cervical cancer
(C) Ectopic tubal pregnancy
(D) Breast cancer
(E) Teratomas

D. Breast cancer that originates from the epithelium lining the terminal ductules of the mammary gland is classified as lobular carcinoma. (See Chapter 19 X C Clinical Considerations.)

94

Which of the following may be detected by a Papanicolaou smear?
(A) Endometriosis
(B) Cervical cancer
(C) Ectopic tubal pregnancy
(D) Breast cancer
(E) Teratomas

B. Abnormal cells associated with cervical cancer are revealed in a Papanicolaou smear, providing a simple method for the early detection of this cancer. (See Chapter 19 V E Clinical Considerations.)

95

Which of the following commonly results in hemorrhaging into the peritoneal cavity dependent on the stage of the menstrual cycle?
(A) Endometriosis
(B) Cervical cancer
(C) Ectopic tubal pregnancy
(D) Breast cancer
(E) Teratomas

A. Endometriosis is a condition in which uterine endometrial tissue is located in the pelvic peritoneal cavity. The misplaced endometrial tissue undergoes cyclic hormone-induced changes, including menstrual breakdown and bleeding. (See Chapter 19 IV A 1 c Clinical Considerations.)

96

Which of the following facilitates the
absorption of vitamin B12?
(A) Pepsin
(B) Enzyme associated with the glycocalyx
of the intestinal striated border
(C) Lipase
(D) Chylomicron
(E) Gastric intrinsic factor

E. Gastric intrinsic factor, which is produced by parietal cells in the gastric glands, is necessary for absorption of vitamin B12 in the ileum. (See Chapter 16 III B 2.)

97

Which of the following functions in the digestion of carbohydrates?
(A) Pepsin
(B) Enzyme associated with the glycocalyx of
the intestinal striated border
(C) Lipase
(D) Chylomicron
(E) Gastric intrinsic factor

B. Disaccharidases in the glycocalyx of the striated border hydrolyze disaccharides to monosaccharides. (See Chapter 16 IV A 2.)

98

Which of the following functions in the digestion of proteins?
(A) Pepsin
(B) Enzyme associated with the glycocalyx of
the intestinal striated border
(C) Lipase
(D) Chylomicron
(E) Gastric intrinsic factor

A. Digestion of proteins begins with the action of pepsin in the stomach, forming a mixture of polypeptides. Activation of pepsinogen to pepsin only occurs at a low pH. (See Chapter 16 IV B 1.)

99

Which of the following functions in the transport oftriglycerides into lacteals?
(A) Pepsin
(B) Enzyme associated with the glycocalyx of the intestinal striated border
(C) Lipase
(D) Chylomicron
(E) Gastric intrinsic factor

D. After free fatty acids and monoglycerides in micelles enter the surface absorptive cells of the small intestine, they are reesterified to form triglycerides. These are complexed with proteins, forming chylomicrons, which are released from the lateral cell membrane and enter lacteals in the lamina propria. (See Chapter 16 IV C 2.)

100

Which of the following is manufactured and released by parietal cells?
(A) Pepsin
(B) Enzyme associated with the glycocalyx of the intestinal striated border
(C) Lipase
(D) Chylomicron
(E) Gastric intrinsic factor

E. Parietal cells are responsible for establishing the low pH of the stomach by manufacturing hydrochloric acid. Another function of parietal cells is the synthesis and release of gastric intrinsic factor, necessary for the absorption of vitamin B12 in the ileum. (See Chapter 16
III B 2 a.)