Comprehensive Examination Flashcards

Question

``` 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. ```

Answer 1

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.)

Answer 2

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.)

Answer 3

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.)

Answer 4

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.)

Answer 5

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.)

Answer 6

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.)

Answer 7

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.)

Answer 8

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.)

Answer 9

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.)

Answer 10

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.)

Answer 11

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.)

Answer 12

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.)

Answer 13

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.)

Answer 14

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.)

Answer 15

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.)

Answer 16

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.)

Answer 17

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.)

Answer 18

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.)

Answer 19

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.)

Answer 20

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.)

Answer 21

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.)

Answer 22

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.)

Answer 23

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

Answer 24

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.)

Answer 25

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

Answer 26

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.)

Answer 27

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.)

Answer 28

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.)

Answer 29

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

Answer 30

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.)

Answer 31

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.)

Answer 32

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.)

Answer 33

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.)

Answer 34

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.)

Answer 35

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.)

Answer 36

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

Answer 37

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

Answer 38

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

Answer 39

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.)

Answer 40

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.)

Answer 41

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.)

Answer 42

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

Answer 43

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

Answer 44

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.)

Answer 45

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.)

Answer 46

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

Answer 47

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

Answer 48

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.)

Answer 49

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.)

Answer 50

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.)

Answer 51

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.)

Answer 52

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.)

Answer 53

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

Answer 54

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

Answer 55

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 .)

Answer 56

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

Answer 57

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.)

Answer 58

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.)

Answer 59

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.)

Answer 60

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.)

Answer 61

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.)

Answer 62

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.)

Answer 63

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.)

Answer 64

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.)

Answer 65

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.)

Answer 66

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.)

Answer 67

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.)

Answer 68

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.)

Answer 69

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.)

Answer 70

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.)

Answer 71

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.)

Answer 72

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.)

Answer 73

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

Answer 74

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.)

Answer 75

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.)

Answer 76

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.)

Comprehensive Examination Flashcards

(100 cards)