JUNQUIERA Flashcards
(100 cards)
1
Q
- Which of the following is characteristic of the chromatophilic material called Nissl substance in neural tissue?
a. Found throughout neurons
b. Site of mRNA translation for proteins of the axolemma
c. Most abundant in unipolar neurons
d. Becomes more abundant as an individual gets older
e. An example of intermediate filament proteins
A
b. Site of mRNA translation for proteins of the axolemma
Rationale: Nissl substance, which is composed of rough endoplasmic reticulum and free ribosomes, is involved in protein synthesis. The proteins synthesized here are used for the neuron’s membrane (including the axolemma) and other structures, which is essential for neuron function.
2
Q
- Which of the following events occurs immediately after an action potential reaches a synapse at an axon terminal?
a. Vesicle fusion with the presynaptic terminal membrane
b. Calcium ion influx at the presynaptic terminal
c. Neurotransmitter binding to receptors on the postsynaptic membrane
d. Neurotransmitter release into the synaptic cleft
e. Binding of the neurotransmitter at the presynaptic terminal
A
b. Calcium ion influx at the presynaptic terminal
Rationale: When an action potential reaches the axon terminal, it triggers the opening of voltage-gated calcium channels, allowing calcium ions to enter the presynaptic terminal. This influx of calcium is crucial for the subsequent vesicle fusion and neurotransmitter release.
3
Q
- A report from a hospital pathology laboratory indicates that a microscope slide with a small specimen of neural tissue contains “numerous GFAP-positive” cells. What is the most likely source of this specimen?
a. A region of white matter
b. A sensory ganglion
c. An autonomic ganglion
d. A region of gray matter
e. Pia mater
A
d. A region of gray matter
Rationale: GFAP (Glial Fibrillary Acidic Protein) is a marker for astrocytes, which are abundant in the gray matter of the central nervous system. Astrocytes provide structural and metabolic support for neurons.
4
Q
- In the choroid plexus, water from capillaries is transported directly into the cerebrospinal fluid by what structure(s)?
a. Ependyma
b. Astrocytes
c. Cells of the arachnoid mater
d. Lining of the central canal
e. Microglial cells
A
a. Ependyma
Rationale: The ependymal cells in the choroid plexus are responsible for producing cerebrospinal fluid (CSF) by filtering blood plasma and actively transporting water and solutes into the ventricular system.
5
Q
- What term applies to collections of neuronal cell bodies (somata) in the central nervous system?
a. Ganglia
b. Neuroglia
c. Nodes
d. White matter
e. Nuclei
A
e. Nuclei
Rationale: In the central nervous system, collections of neuronal cell bodies are referred to as nuclei. This term is used to distinguish them from ganglia, which are collections of neuronal cell bodies in the peripheral nervous system.
6
Q
- Which structure contains trabeculae around which cerebrospinal fluid (CSF) flows?
a. Arachnoid mater
b. Ependyma
c. Dura mater
d. Pia mater
e. Gray matter
A
a. Arachnoid mater
Rationale: The arachnoid mater contains a web-like network of trabeculae in the subarachnoid space, through which cerebrospinal fluid flows. This space also contains blood vessels.
7
Q
- Which of the following is a characteristic of the connective tissue layer that surrounds individual fascicles in large peripheral nerves?
a. A delicate region of connective tissue in contact with Schwann cells
b. Called the dura mater
c. Important as part of the blood-nerve barrier in the nerve
d. Rich in myelin
e. The thickest sheath of connective tissue in the nerve
A
c. Important as part of the blood-nerve barrier in the nerve
Rationale: The perineurium is the connective tissue layer that surrounds each fascicle within a nerve. It acts as a barrier to protect the nerve fibers and maintains the blood-nerve barrier, which is crucial for nerve function.
8
Q
- A 35-year-old woman presents with weakness and spasticity in the lower left extremity, visual impairment, and throbbing in the left eye, and difficulties with balance, fatigue, and malaise. There is an increase in CS protein, elevated gamma globulin, and moderate pleocytosis. MRI confirms areas of demyelination in the anterior corpus callosum. Imaging identifies plaques that are hyperintense on T2-weighted and fluid attenuated inversion recovery (FLAIR) images, and hypointense on T1-weighted scans. Which of the following cells are specifically targeted in her condition?
a. Microglia
b. Oligodendrocytes
c. Astrocytes
d. Schwann cells
e. Multipolar neurons
A
b. Oligodendrocytes
Rationale: The described symptoms and MRI findings are indicative of multiple sclerosis (MS), a disease characterized by the destruction of myelin sheaths in the central nervous system. Oligodendrocytes are the cells responsible for myelinating axons in the CNS and are targeted in MS.
9
Q
- A 22-year-old man receives a severe, traumatic compression injury to his radial nerve during a motorcycle crash. He shows an advancing Tinel sign. Which one of the following characterizes regeneration of axons after this nerve injury?
a. It occurs in the absence of motor nerve action potentials.
b. It occurs at a rate of about 100 mm/d.
c. It occurs in the segment distal to the site of axon damage.
d. It occurs by a process that involves Schwann cell proliferation.
e. It occurs in conjunction with degeneration and phagocytosis of the endoneurium.
A
d. It occurs by a process that involves Schwann cell proliferation.
Rationale: Schwann cells play a crucial role in the regeneration of peripheral nerves. After injury, Schwann cells proliferate and form a regeneration tube that guides the regrowth of the axon.
10
Q
- A 2-year-old boy presents with hearing impairment, poliosis (a white shock of hair), complete heterochromia and sectoral heterochromia, hypertelorism, a low hairline with eyebrows that touch in the middle, white pigmentation of the skin, and suspected neurological deficits. He is diagnosed with Waardenburg syndrome with a mutation in the PAX-3 gene that affects neural crest differentiation. Which of the following structures would most likely also be affected in this patient?
a. Purkinje cells
b. Pyramidal neurons
c. Ventral horns of the spinal cord
d. Astrocytes
e. Neurons and satellite cells of the spinal ganglion
A
e. Neurons and satellite cells of the spinal ganglion
Rationale: Waardenburg syndrome affects the development of neural crest cells, which give rise to various structures, including neurons and satellite cells in the spinal ganglion. These cells are essential for sensory function and are likely to be affected in this condition.
11
Q
- Which function is carried out by all lymphoid tissues and organs?
a. Filtration of lymph
b. Filtration of blood
c. Extramedullary hemopoiesis
d. Production of lymphocytes
e. Destruction of old erythrocytes
A
d. Production of lymphocytes
Rationale: All lymphoid tissues and organs are involved in the production of lymphocytes, which are essential for the immune response. Lymphocytes are produced and mature in primary lymphoid organs (bone marrow and thymus) and are further activated in secondary lymphoid organs (lymph nodes, spleen, etc.).
12
Q
- Which structure is partly encapsulated and covered by nonkeratinized stratified squamous epithelium?
a. Appendix
b. Lymph node
c. Palatine tonsil
d. Peyer’s patch
e. Thymic (Hassal’s) corpuscle
A
c. Palatine tonsil
Rationale: The palatine tonsils are partly encapsulated lymphoid organs located at the back of the throat and are covered by nonkeratinized stratified squamous epithelium, which is typical of the oral mucosa.
13
Q
- Which cell type gives rise to both memory and effector cells and is primarily associated with humoral immunity?
a. B lymphocyte
b. NK cell
c. Macrophage
d. T lymphocyte
e. Reticular cell
A
a. B lymphocyte
Rationale: B lymphocytes are responsible for humoral immunity. Upon activation, they differentiate into memory B cells and plasma cells (effector cells) that produce antibodies.
14
Q
- Recycling of iron and heme, the major complex containing iron, occurs most actively in which lymphoid organ(s)/tissue(s)?
a. Lymph nodes
b. Peyer’s patches
c. Tonsils
d. Spleen
e. Lymphatic vessels
A
d. Spleen
Rationale: The spleen is responsible for filtering blood and recycling iron from old erythrocytes. The macrophages in the spleen break down heme into iron, which is then reused or stored.
15
Q
- Which description is true of all secondary (peripheral) lymphoid organs?
a. Capable of antigen-independent lymphopoiesis
b. Contain crypts
c. Contain epithelial-reticular cells
d. Lack connective tissue capsules
e. Contain lymphoid nodules
A
e. Contain lymphoid nodules
Rationale: Secondary lymphoid organs, such as lymph nodes, spleen, and mucosa-associated lymphoid tissues (MALT), all contain lymphoid nodules, which are sites of lymphocyte activation and proliferation.
16
Q
- Which structure would be most heavily labeled by an immunohistochemical method targeting the CD8 surface antigen?
a. Germinal centers
b. Paracortex
c. Peyer’s patch
d. Sheathed arterioles
e. Splenic cords
A
b. Paracortex
Rationale: The paracortex of lymph nodes is rich in T lymphocytes, particularly CD8+ T cells, which can be identified using immunohistochemical methods targeting the CD8 surface antigen.
17
Q
- A baby is born with a cleft palate and a condition called DiGeorge syndrome, which involves the failure of third and fourth pharyngeal pouch derivatives to develop properly. The palate defect is corrected surgically, but regarding the pharyngeal pouch defect, the parents are advised that the growing child may expect which of the following health problems?
a. Insufficient B-cell production by lymph nodes in the head and neck
b. Inability to secrete IgA
c. Excessive numbers of circulating but defective erythrocytes
d. Increased oral infections due to the lack of palatine and pharyngeal tonsils
e. Conditions related to autoimmunity
A
e. Conditions related to autoimmunity
Rationale: DiGeorge syndrome often involves defects in the thymus, leading to immunodeficiency, particularly affecting T cells. This can result in an increased risk of autoimmune diseases due to improper immune regulation.
18
Q
- Many immune-related cellular activities are often impaired in aged patients. Which lymphoid organ(s) normally develop less functionality and increasing amounts of adipose tissue with age?
a. Axillary lymph nodes
b. Lingual tonsils
c. Thymus
d. Splenic white pulp
e. Splenic red pulp
A
c. Thymus
Rationale: The thymus gradually involutes with age, becoming less functional and being replaced by adipose tissue. This reduction in thymic activity impacts the production and maturation of T cells.
19
Q
- A 12-year-old girl of African descent presents with anemia, and a large percentage of her peripheral erythrocytes appear sickle-shaped. Genetic testing reveals homozygosity for sickle cell disease. In which of the following sites will the abnormal RBCs be removed from the circulation?
a. Thymic cortex
b. Periarteriolar lymphoid sheaths of splenic white pulp
c. Medullary sinuses of lymph nodes
d. Thymic medulla
e. Splenic cords (of Billroth)
A
e. Splenic cords (of Billroth)
Rationale: The splenic cords (of Billroth) are part of the red pulp in the spleen where abnormal or old erythrocytes are filtered out and phagocytosed by macrophages. Sickle-shaped erythrocytes are removed here due to their abnormal shape and rigidity.
20
Q
- A 6-year-old boy is brought to the clinic where his mother reports that he was bitten by a neighbor’s dog two days earlier. The child’s right hand is lacerated between the thumb and index finger and this area is inflamed but healing. The doctor’s examination reveals small but painless swellings beneath the skin inside the right elbow and armpit, and he explains to the mother that these are active lymph nodes enlarged in response to the infection in the hand. What has produced the swelling?
a. Increased flow of lymph through the nodes’ afferent lymphatics
b. Formation of germinal centers for B-cell proliferation in each node’s cortex
c. Arrival of antigen-presenting cells in each node’s medulla
d. Enlargement and increased activity of the nodes’ high endothelial venules
e. Increased thickness of each node’s paracortex
A
b. Formation of germinal centers for B-cell proliferation in each node’s cortex
Rationale: The swelling of lymph nodes in response to infection is due to the formation of germinal centers within the cortex, where B cells proliferate and differentiate in response to antigens. This increases the size of the lymph nodes as they work to mount an immune response.
21
Q
- In which of the following structures of the oral cavity would taste buds be localized in the highest concentration?
a. Fungiform papillae
b. Gingiva
c. Filiform papillae
d. Ventral surface of the tongue
e. Vallate papillae
A
e. Vallate papillae
Rationale: Vallate (or circumvallate) papillae are large papillae located at the back of the tongue and contain the highest concentration of taste buds, making them the primary site for taste sensation.
22
Q
- Certain antibiotic therapies slow the replacement of the cells lining the small intestine. This may cause the loss of what tissue type?
a. Ciliated pseudostratified columnar epithelium
b. Simple cuboidal epithelium
c. Simple columnar epithelium
d. Pseudostratified columnar epithelium with stereocilia
e. Stratified squamous, nonkeratinized epithelium
A
c. Simple columnar epithelium
Rationale: The lining of the small intestine is composed of simple columnar epithelium, which includes absorptive cells and goblet cells. Antibiotics that slow cell turnover can lead to a loss of this epithelium, impacting nutrient absorption.
23
Q
- The teniae coli of the large intestine represent an organ-specific specialization of which layer of the intestinal tract wall?
a. Epithelium
b. Lamina propria
c. Muscularis mucosa
d. Muscularis externa
e. Serosa
A
d. Muscularis externa
Rationale: The teniae coli are three distinct bands of smooth muscle in the muscularis externa layer of the large intestine, which help in the peristaltic movement of feces.
24
Q
- Which of the following would most likely result from a reduction in the number of Paneth cells?
a. Thinning of the glycocalyx
b. Reduced breakdown of fats
c. Elevated levels of undigested proteins
d. Decreased mucus in the intestine
e. Increased number of intestinal bacteria
A
e. Increased number of intestinal bacteria
Rationale: Paneth cells, found in the small intestine, secrete antimicrobial peptides and enzymes that help control the gut microbiota. A reduction in Paneth cells would decrease this antimicrobial activity, leading to an increase in intestinal bacteria.
25
5. A medical student on a rotation in the pathology laboratory is given an unlabeled microscope slide with tissue provided by a gastroenterologist from a cancer patient she is attending. The mucosa and submucosa are poorly preserved, with only the thick muscularis well-stained, showing striated fibers. The slide most likely shows a biopsy of which region of the GI tract?
a. Pyloric sphincter
b. Esophagus
c. Colon
d. Corpus of the stomach
e. Ileum
b. Esophagus
Rationale: The esophagus is unique in the GI tract for having striated (skeletal) muscle in its upper part, making it the most likely site for this biopsy with well-preserved muscularis showing striated fibers.
26
6. Diarrhea may result if which of the following organs fails to carry out its role in absorbing water from the feces?
a. Anal canal
b. Cecum
c. Colon
d. Jejunum
e. Duodenum
c. Colon
Rationale: The colon (large intestine) is primarily responsible for absorbing water from the feces. If the colon fails in this function, it can lead to diarrhea.
27
7. Which of the following is true of the absorptive cells of the small intestine?
a. Also called enteroendocrine cells
b. Have many microvilli covering their basal surfaces
c. Absorb lipids by active transport
d. Synthesize triglycerides from absorbed lipids
e. Undergo mitosis at the tips of villi and are sloughed off into crypts
d. Synthesize triglycerides from absorbed lipids
Rationale: Absorptive cells, or enterocytes, of the small intestine are responsible for absorbing nutrients, including lipids. They synthesize triglycerides from absorbed fatty acids and monoglycerides.
28
8. A 52-year-old man is diagnosed with a carcinoid after an appendectomy. The enteroendocrine cells producing this disorder differ from goblet cells in which of the following?
a. The direction of release of secretion
b. The use of exocytosis for the release of secretory product
c. Their presence in the small and large intestines
d. The origin from a crypt stem cell
e. Their location in a simple columnar epithelium
a. The direction of release of secretion
Rationale: Enteroendocrine cells release their secretions (hormones) basally into the underlying connective tissue and bloodstream, whereas goblet cells secrete mucus apically into the lumen of the gut.
29
9. A 14-month-old girl is brought to the pediatric dentistry clinic because her erupted deciduous teeth are opalescent with fractured and chipped surfaces. X-rays reveal bulb-shaped crowns, thin roots, and enlarged central cavities. Tissue immediately surrounding one tooth's central cavity is biopsied and prepared for histology, which reveals irregular, widely spaced tubules. Which of the following applies to this irregular tissue layer?
a. It has a composition similar to that of bone and is produced by cells similar in appearance to osteocytes.
b. It is formed on a noncollagenous matrix that is resorbed after mineralization by the same cells that secreted it.
c. It contains abundant nerves, microvasculature, and loose connective tissue.
d. It consists of mineralized collagen secreted by cells derived from the neural crest.
e. It is the site of inflammation in diabetic patients and is sensitive to vitamin C deficiency.
d. It consists of mineralized collagen secreted by cells derived from the neural crest.
Rationale: This description matches dentin, a tissue with mineralized collagen produced by odontoblasts, which are derived from neural crest cells. The irregular, widely spaced tubules are characteristic of defective dentin formation.
30
10. A 39-year-old woman presents with dyspnea, fatigue, pallor, tachycardia, anosmia, and diarrhea. Laboratory results are: hematocrit 32% (normal 36.1%-44.3%), MCV 102 fL (normal 78-98 fL), 0.3% reticulocytes (normal 0.5%-2.0%), 95 pg/mL vitamin B, (normal 200-900 pg/mL), and an abnormal stage I of the Schilling test. Autoantibodies are detected against a cell type located in one region of the GI tract. In which regions would those cells be found?
a. Esophagus
b. Body of the stomach
c. Pyloric region of the stomach
d. Cardiac region of the stomach
e. Duodenum
b. Body of the stomach
Rationale: The patient's symptoms and laboratory findings suggest pernicious anemia, which is caused by autoantibodies against parietal cells in the body of the stomach. These cells produce intrinsic factor, necessary for vitamin B12 absorption.
31
1. In a liver biopsy from a long-time drug user, which of the following hepatocyte organelles would be expected to be more extensive than normal?
a. Rough endoplasmic reticulum
b. Golgi apparatus
c. Lysosomes
d. Peroxisomes
e. Smooth endoplasmic reticulum
e. Smooth endoplasmic reticulum
Rationale: The smooth endoplasmic reticulum (SER) is involved in detoxification processes. In response to chronic drug use, hepatocytes increase the amount of SER to enhance their ability to metabolize and detoxify the drugs.
32
2. Which description is true of pancreatic zymogens?
a. Are packaged for secretion in the SER
b. Are synthesized on free ribosomes
c. Are inactive until they reach the duodenal lumen
d. Are stored in the basal cytoplasm of acinar cells
e. Are produced by cuboidal cells lining the pancreatic duct
c. Are inactive until they reach the duodenal lumen
Rationale: Pancreatic zymogens are inactive enzyme precursors that are activated in the duodenum to prevent autodigestion of the pancreas. Activation occurs through the action of enterokinase, which converts trypsinogen to trypsin, initiating the activation of other zymogens.
33
3. Which process increases in response to parasympathetic stimulation of the salivary glands?
a. Volume of secretion
b. Cell division in secretory acini
c. Mucus content of saliva
d. Inorganic salts content of saliva
e. Cell division in interlobular ducts
a. Volume of secretion
Rationale: Parasympathetic stimulation increases the secretion of saliva, resulting in a higher volume of a watery, enzyme-rich fluid to aid in digestion and oral lubrication.
34
4. Which feature is unique to the exocrine pancreas?
a. Insulin-secreting ß cells
b. Centroacinar cells
c. Predominately serous secretory cells
d. Striated interlobular ducts
e. Striated intralobular ducts
b. Centroacinar cells
Rationale: Centroacinar cells are unique to the exocrine pancreas and are located at the beginning of the intercalated ducts within the acinar units. They play a role in the secretion of bicarbonate-rich fluid.
35
5. Which description is true of the bile canaliculi?
a. Are bordered directly by endothelial cells
b. Are part of the portal triad
c. Are surrounded by the hepatic sinusoids
d. Lumens are entirely sealed by junctional complexes
e. Normally contain some blood plasma
d. Lumens are entirely sealed by junctional complexes
Rationale: Bile canaliculi are small ducts between hepatocytes that collect bile. Their lumens are sealed by tight junctions to prevent bile leakage and maintain the directional flow of bile toward the bile ducts.
36
6. Which description is true of the gallbladder?
a. Dilutes bile
b. Absorbs bile
c. Secretes mucus
d. Has a thick submucosa
e. Is covered entirely by serosa
c. Secretes mucus
Rationale: The gallbladder secretes mucus to protect its lining and facilitate the storage and concentration of bile. Its epithelium contains goblet cells that produce and release mucus.
37
7. Which description is true for the hepatic space of Disse?
a. Is surrounded by the hepatic sinusoid
b. Contents flow toward the central vein
c. Is directly contacted by hepatocytes
d. Lumen sealed by junctional complexes
e. Contents empty into canals of Hering lined by cholangiocytes
c. Is directly contacted by hepatocytes
Rationale: The space of Disse is located between hepatocytes and sinusoidal endothelial cells, allowing for the exchange of materials between blood and liver cells. Hepatocytes have direct contact with this space, facilitating nutrient and waste exchange.
38
8. A 50-year-old woman presents to the family medicine clinic. She admits to drinking a six-pack of beer each day with a little more intake on weekends. Laboratory tests show elevated alanine aminotransferase/serum glutamic oxaloacetic transaminase (AST/SGOT). Her sclerae appear jaundiced, and her serum bilirubin is 2.5 mg/dL (normal 0.3 - 1.9 mg/dL). A biopsy shows hepatic fibrosis with significant loss of normal lobular structure. Jaundice is most likely to result when the proper location or orientation of what hepatic structures is disrupted?
a. Central veins
b. Spaces of Disse
c. Kupffer cells
d. Hepatocytes
e. Merging sinusoids
d. Hepatocytes
Rationale: Jaundice results from impaired bilirubin processing and excretion. Disruption in the structure and function of hepatocytes, which are responsible for metabolizing and conjugating bilirubin, leads to jaundice.
39
9. A 48-year-old woman is referred to an allergy and rheumatology specialist with itching eyes, dryness of the mouth, difficulty swallowing, loss of the sense of taste, hoarseness, fatigue, and swollen parotid glands. She reports increasing joint pain over the past 2 years. She complains of frequent mouth sores. Laboratory tests show a positive antinuclear antibody (ANA) and rheumatoid factor (RF) levels of 70 U/mL (normal < 60 U/mL) by the nephelometric method. A parotid gland biopsy shows inflammatory infiltrates in the interlobular connective tissue with damage to the acinar cells and striated ducts. In this case, resorption of which of the following will be most altered by destruction of those ducts?
a. Na+
b. HO
с. НСО;
d. Cl
e. Ca2+
a. Na+
Rationale: Striated ducts in the salivary glands are responsible for the reabsorption of sodium (Na+) from the saliva. Destruction of these ducts impairs sodium reabsorption, affecting the ionic composition of saliva.
40
10. A young child presents with hepatomegaly and renomegaly, failure to thrive, stunted growth, and hypoglycemia. A deficiency in glucose-6-phosphatase is identified and the diagnosis of von Gierke disease is made. What cellular structures would be expected to accumulate in hepatocytes during the progression of this disorder?
a. Chylomicrons
b. Glycogen granules
c. Mitochondria
d. Zymogen granules
e. Ribosomes
b. Glycogen granules
Rationale: Von Gierke disease (Glycogen Storage Disease Type I) is characterized by a deficiency in glucose-6-phosphatase, which leads to the accumulation of glycogen in the liver because it cannot be broken down to release glucose into the bloodstream.
41
1. Which of the following components increases as a proportion of the respiratory tract wall from trachea to alveoli?
a. Cilia
b. Elastic fibers
c. Smooth muscle
d. Cartilage
e. Goblet cells
b. Elastic fibers
Rationale: As the respiratory tract transitions from the trachea to the alveoli, the proportion of elastic fibers increases. These fibers are essential for the elasticity and recoil of the lung tissue during respiration.
42
2. Air moving rapidly across the vocal cords and causing them to vibrate and produce sound is contacting what type of epithelium?
a. Pseudostratified ciliated
b. Stratified squamous keratinized
c. Stratified squamous nonkeratinized
d. Simple squamous
e. Simple cuboidal
c. Stratified squamous nonkeratinized
Rationale: The vocal cords are covered by stratified squamous nonkeratinized epithelium, which protects them from the mechanical stress caused by air flow and vibration.
43
3. Which structural feature distinguishes between terminal and respiratory bronchioles?
a. Alveoli
b. Cilia
c. Exocrine bronchiolar cells
d. Mucous glands in lamina propria
e. Smooth muscle
a. Alveoli
Rationale: The presence of alveoli distinguishes respiratory bronchioles from terminal bronchioles. Respiratory bronchioles have alveoli in their walls, indicating the start of the gas exchange portion of the respiratory tract.
44
4. Which of the following features distinguishes a bronchus within a lung from the primary bronchi?
a. Glands in the submucosa
b. Pseudostratified ciliated columnar epithelium
c. Smooth muscle in the wall
d. Irregular plates of cartilage
e. Goblet cells in the epithelium
d. Irregular plates of cartilage
Rationale: Intrapulmonary bronchi have irregular plates of cartilage in their walls, whereas the primary bronchi have C-shaped cartilaginous rings.
45
5. Which feature involved in the protection of the respiratory tract is absent from the digestive tract?
a. Goblet cells
b. Cilia
c. Lymphoid nodules
d. Secretory IgA
e. Tight junctions
b. Cilia
Rationale: Cilia are present in the respiratory tract to help move mucus and trapped particles out of the airways. This feature is absent in the digestive tract.
46
6. Which of the following is true of pulmonary surfactant?
a. Secreted by type I pneumocytes
b. Forms a layer rich in phospholipid overlying a thin aqueous phase
c. Prevents alveolar collapse by increasing surface tension
d. Does not affect bacterial survival
e. Is secreted by goblet cells
b. Forms a layer rich in phospholipid overlying a thin aqueous phase
Rationale: Pulmonary surfactant, secreted by type II pneumocytes, forms a phospholipid-rich layer that reduces surface tension in the alveoli, preventing their collapse and facilitating gas exchange.
47
7. The pulmonary (functional) and bronchial (nutritive) arterial systems enter the lungs separately at the hilus but anastomose into a single system at which level?
a. Bronchi
b. Larynx
c. Terminal bronchioles
d. Segmental bronchioles
e. Respiratory bronchioles
e. Respiratory bronchioles
Rationale: The pulmonary and bronchial arterial systems anastomose at the level of the respiratory bronchioles, where gas exchange begins.
48
8. After 35 weeks of gestation, a 5-lb 5-oz girl is born to a 30-year-old gravid 2, para 2 (G2P2) woman. The infant has rapid and labored breathing, which is viewed as transient tachypnea of the newborn. The infant's 1- and 5-min APGAR scores are 8 and 9, respectively. She has respiratory distress, with a normal pulse and no heart murmurs. She is transported to the neonatal intensive care unit with worsening tachypnea. In this infant, which of the following is likely to be involved?
a. Failure of the type I pneumocytes to form complete blood-air barriers
b. Absence of elastic fibers from the bronchiolar walls and interalveolar septa
c. Failure of type II pneumocytes to complete differentiation and become fully functional
d. Failure of type II pneumocyte progenitors to proliferate adequately during gestation
e. Inadequate development of the parietal and visceral pleura
c. Failure of type II pneumocytes to complete differentiation and become fully functional
Rationale: Transient tachypnea of the newborn is often related to delayed clearance of fetal lung fluid and insufficient surfactant production. Type II pneumocytes are responsible for surfactant production, and their immaturity can lead to respiratory distress.
49
9. A teenage girl presents at the ER with paroxysms of dyspnea, cough, and wheezing. Her parents indicate that she had these "attacks" during the past winter and that they have worsened and become more frequent during the spring. Which of the following cell types and their location is correctly matched to a function it may perform in this patient's disorder?
a. Cilia in alveolar ducts, enhanced mucociliary transport
b. Plasma cells in bronchus-associated lymphoid tissue (BALT), bronchoconstriction
c. Eosinophils in BALT, bronchodilation
d. Goblet cells in bronchioles, hyposecretion
e. Mast cells in BALT, bronchoconstriction, and edema
e. Mast cells in BALT, bronchoconstriction, and edema
Rationale: Mast cells in bronchus-associated lymphoid tissue (BALT) release mediators such as histamine during allergic reactions, leading to bronchoconstriction and edema, which are characteristic features of asthma.
50
10. A 28-year-old man is diagnosed with a testicular germ cell tumor. The tumor is surgically removed and he begins chemotherapy with cisplatin, etoposide, and bleomycin. Bleomycin chemotherapy is known to affect the lung blood-air barrier. Which of the following best describes the structural site of those effects?
a. Fused basal laminae of epithelial and endothelial cells
b. Alveolar pores of Kohn
c. Alveolar macrophages in interalveolar septa
d. Type II pneumocytes linked by junctional complexes
e. Smooth muscle cells of the pulmonary and bronchial arteries
a. Fused basal laminae of epithelial and endothelial cells
Rationale: The blood-air barrier in the lungs is primarily composed of the fused basal laminae of the alveolar epithelial cells (type I pneumocytes) and the endothelial cells of the capillaries. Bleomycin can damage this barrier, leading to pulmonary toxicity.
51
1. Blood in the renal arcuate arteries flows next into which vessels?
a. Afferent arterioles
b. Efferent arterioles
c. Glomerular capillaries
d. Interlobar arteries
e. Interlobular arteries
e. Interlobular arteries
Rationale: The renal arcuate arteries branch into interlobular arteries, which then give rise to the afferent arterioles that supply the glomeruli.
52
2. Which cell type comprises the visceral layer of Bowman capsule?
a. Endothelial cells
b. Juxtaglomerular cells
c. Mesangial cells
d. Podocytes
e. Extraglomerular mesangial (or Lacis) cells
d. Podocytes
Rationale: Podocytes are specialized cells that form the visceral layer of the Bowman capsule and play a crucial role in the filtration barrier of the glomerulus.
53
3. Which type of epithelium lines the thick ascending limb of the loop of Henle?
a. Pseudostratified columnar
b. Simple columnar
c. Simple cuboidal
d. Simple squamous
e. Transitional (urothelium)
c. Simple cuboidal
Rationale: The thick ascending limb of the loop of Henle is lined with simple cuboidal epithelium, which is involved in the active transport of ions, making it impermeable to water.
54
4. Which cell is a modified smooth muscle cell that secretes renin?
a. Macula densa cells
b. Mesangial cells
c. Podocytes
d. Juxtaglomerular cells
e. Endothelial cells
d. Juxtaglomerular cells
Rationale: Juxtaglomerular cells are specialized smooth muscle cells located in the walls of the afferent arterioles near the glomerulus. They secrete renin in response to decreased blood pressure or sympathetic stimulation.
55
5. Epithelial cell membrane domains containing many stiffened plaques of protein are an important feature in which part of the urinary system?
a. Juxtaglomerular apparatus
b. Bladder mucosa
c. Collecting ducts
d. Renal pyramids
e. Membranous urethra
b. Bladder mucosa
Rationale: The bladder mucosa is lined with transitional epithelium, which contains plaques of uroplakin proteins that provide a barrier to prevent urine from penetrating the epithelial cells.
56
6. An immunohistochemical technique using antibodies against aquaporins to stain a section of kidney would be expected to stain cells in which structures most intensely?
a. Collecting ducts
b. Lining of the major and minor calyces
c. Proximal convoluted tubules
d. Distal convoluted tubules
e. Glomeruli
a. Collecting ducts
Rationale: Aquaporins are water channels that are highly expressed in the collecting ducts, facilitating water reabsorption under the influence of antidiuretic hormone (ADH).
57
7. What type of epithelium lines the prostatic urethra?
a. Simple columnar
b. Pseudostratified columnar
c. Stratified squamous
d. Simple squamous
e. Transitional (urothelium)
e. Transitional (urothelium)
Rationale: The prostatic urethra is lined with transitional epithelium, which allows for the distensibility needed for the passage of urine.
58
8. A 14-year-old patient presents in the nephrology clinic with fatigue, malaise, anorexia, abdominal pain, and fever. She reports a loss of 6 lb in the past 2 months. Serum gamma globulin and the immunoglobulins IgG, IgA, and IgM are all elevated. Her serum creatine is 1.4 mg/dL (normal 0.6-1.2 mg/dL) and urinalysis of glucose and protein are 2+ on a dipstick test, confirmed by laboratory at 8.0 g/dL and 0.95 g/dL, respectively. A renal biopsy is prepared for light microscopy, and an infiltrate containing lymphocytes, plasma cells, and eosinophils is found among tubules having cells with prominent brush borders. Which one of the following statements correctly pertains to these epithelial cells?
a. Impermeable to water despite the presence of ADH
b. The primary site for the reduction of the tubular fluid volume
c. The site of the countercurrent multiplier
d. The site of action of aldosterone
e. Indirectly involved in the release of renin
b. The primary site for the reduction of the tubular fluid volume
Rationale: The cells with prominent brush borders are in the proximal convoluted tubule (PCT). The PCT is the primary site for reabsorbing the majority of the filtered load, including water, ions, and nutrients, leading to a significant reduction in tubular fluid volume.
59
9. A 45-year-old man presents with nephrolithiasis or kidney stones. The process of calcium oxalate stone formation as seen in this patient begins with Randall plaques found in the basement membranes of which one of the following structures found only in the renal medulla?
a. Proximal convoluted tubules
b. Distal convoluted tubules
c. Thin loops of Henle
d. Afferent arterioles
e. Collecting ducts
e. Collecting ducts
Rationale: Randall plaques are calcium deposits that form in the basement membranes of the collecting ducts in the renal medulla. These plaques can serve as nucleation sites for kidney stones.
60
10. A 15-year-old male presents with hematuria, hearing loss, lens dislocation, and the onset of cataracts. Genetic analysis reveals a mutation in the COL4A5 gene. Transmission EM examination of a renal biopsy confirms that the disorder has affected a component of the renal corpuscles in which damage disrupts normal glomerular filtration. Which one of the following structures would most likely be abnormal in the TEM of this patient's biopsy?
a. Pedicels
b. Filtration slits
c. Slit diaphragms
d. Glomerular basement membranes
e. Fenestrated endothelium of glomerular capillaries
d. Glomerular basement membranes
Rationale: A mutation in the COL4A5 gene, which encodes for type IV collagen, affects the glomerular basement membrane. This mutation is characteristic of Alport syndrome, which leads to abnormalities in the basement membrane, disrupting glomerular filtration.
61
1. Which of the following accurately describes glucocorticoids?
a. Include the steroid hormone aldosterone
b. Are produced in response to stimulation by ACTH
c. Are produced primarily by the zone glomerulosa
d. Typically enhance the immune response
e. Include the steroid hormone DHEA
b. Are produced in response to stimulation by ACTH
Rationale: Glucocorticoids, such as cortisol, are produced in the adrenal cortex in response to adrenocorticotropic hormone (ACTH) from the anterior pituitary gland. They play a role in metabolism, immune response, and stress.
62
2. Pregnant women who have begun labor but in whom this process is no longer progressing are often given an IV injection of Pitocin to stimulate uterine contractions and facilitate parturition. Pitocin is a trade name of a hormone produced in what endocrine tissue?
a. Pars distalis
b. Ovarian follicles
c. Pars nervosa
d. Placenta
e. Pars tuberalis
c. Pars nervosa
Rationale: Pitocin is a synthetic form of oxytocin, which is produced in the hypothalamus and released by the pars nervosa (posterior pituitary). Oxytocin stimulates uterine contractions during labor.
63
3. What hormone is produced in response to decreased blood calcium levels?
a. Pancreatic polypeptide
b. β-endorphin
c. Somatostatin
d. Calcitonin
e. PTH
e. PTH
Rationale: Parathyroid hormone (PTH) is secreted by the parathyroid glands in response to low blood calcium levels. It acts to increase blood calcium by stimulating bone resorption, increasing calcium reabsorption in the kidneys, and promoting activation of vitamin D.
64
4. Addison disease (or adrenal cortex insufficiency) is a disorder, usually autoimmune in origin, which can cause degeneration and cell loss in the adrenal glands. Fludrocortisone is a mineralocorticoid used to treat Addison patients. Response to this drug indicates that which region of the adrenal glands was involved in the disease?
a. Medulla
b. Zona glomerulosa
c. Zona reticularis
d. Macula densa
e. Zona fasciculata
b. Zona glomerulosa
Rationale: The zona glomerulosa of the adrenal cortex produces mineralocorticoids, such as aldosterone. In Addison's disease, degeneration of this region leads to insufficient production of these hormones, and fludrocortisone acts to replace the deficient mineralocorticoid.
65
5. A glucagonoma is a malignant tumor consisting of what cells?
a. α or A cells
b. β or B cells
c. Chromophils
d. δ or D cells
e. Mucous cells
a. α or A cells
Rationale: A glucagonoma is a tumor of the alpha cells of the pancreas, which secrete glucagon. Glucagon raises blood glucose levels by promoting glycogenolysis and gluconeogenesis.
66
6. Secretion, chemical modification and storage, reuptake, and digestion of a protein occur in epithelial cells of what endocrine tissue?
a. Neurohypophysis
b. Adrenal medulla
c. Adenohypophysis
d. Thyroid gland
e. Neuroendocrine cells in the duodenum
d. Thyroid gland
Rationale: The thyroid gland's epithelial cells (thyrocytes) are involved in the production and processing of thyroid hormones. These cells synthesize thyroglobulin, modify it, store it in colloid, reuptake it, and digest it to release thyroid hormones T3 and T4.
67
7. Secretion in what neuroendocrine cell is controlled directly by neural activity and involves a hormone that generally slows metabolic activity at night?
a. Pituicyte
b. Melanocyte
c. Herring body of the neurohypophysis
d. Chromaffin cell
e. Pinealocyte
e. Pinealocyte
Rationale: Pinealocytes in the pineal gland secrete melatonin, a hormone that regulates sleep-wake cycles and slows metabolic activity at night. Its secretion is directly controlled by neural signals.
68
8. Some mammalian endocrine tissues or cells can be experimentally transplanted to other well-vascularized sites (such as the oral mucosa) in genetically similar hosts and the tissues' function continues normally and with proper regulation. The pars distalis is not a good candidate for such transplantation studies for which one of the following reasons?
a. More severe rejection of neurally related tissue occurs compared with other endocrine organs.
b. Its hormonal source is unavailable after its axonal connections to the hypothalamus are disrupted.
c. Its cells stop functioning when separated from the hypothalamo-hypophyseal portal system.
d. Neogenesis of blood vessels into this tissue will not occur at the transplant site.
e. The vascular wall of the superior hypophyseal arteries is unique.
c. Its cells stop functioning when separated from the hypothalamo-hypophyseal portal system
Rationale: The pars distalis (anterior pituitary) relies on regulatory hormones from the hypothalamus, which reach it through the hypothalamo-hypophyseal portal system. Disruption of this connection would impair its function.
69
9. A 45-year-old corporate executive presents with the primary complaint of "always being tired." She comments that she has been tired for 4 months even though she is sleeping more. She complains of being unable to finish chores at home and "dragging at work." She indicates that she is often constipated and is intolerant of cold. She is continuously turning the thermostats in the house and office to higher temperatures, to the dismay of family and coworkers. She also complains that her skin is very dry; use of lotions and creams have not helped the dryness. A biopsy of her thyroid gland shows dense lymphocytic infiltration with germinal centers throughout the parenchyma and a battery of further tests is carried out, which also suggest thyroiditis. Which of the following results of blood tests would be most likely in this patient?
a. Elevated TSH levels
b. Elevated T3 and T4 levels
c. Autoantibodies to the thyroid hormone receptor
d. Elevated calcitonin levels
e. Elevated glucocorticoid levels
a. Elevated TSH levels
Rationale: The symptoms and biopsy findings are indicative of hypothyroidism, likely due to Hashimoto's thyroiditis. In this condition, the thyroid gland is underactive, leading to elevated levels of thyroid-stimulating hormone (TSH) as the body attempts to stimulate more thyroid hormone production.
70
10.A 9-year-old girl, the youngest of four daughters, is taken to the pediatrician by her mother, who indicates that for at least 4 months the child has seemed "hyperactive," unable to sleep soundly because "she says her room is too hot," and no longer able to concentrate in school. Upon questioning, the mother also remembers that her daughter's periods also began within the past few months. Blood tests indicate high levels of estrogen-related hormones and cortisol. Which of the following tentative diagnoses is consistent with all of these symptoms?
a. Graves' disease, caused by antibodies stimulating the TSH receptor
b. A defect in the PVN
c. Excessively active cells of the adrenal cortex zona glomerulosa
d. A benign tumor involving cells in the adenohypophysis
e. A disabling mutation in the gene for thyroglobulin
d. A benign tumor involving cells in the adenohypophysis
Rationale: A benign tumor in the adenohypophysis (anterior pituitary) can cause overproduction of hormones such as ACTH, leading to increased cortisol levels, and gonadotropins, leading to elevated estrogen levels and early puberty symptoms. This could explain the hyperactivity, heat intolerance, and other symptoms described.
71
1. Which of the following accurately describes spermiogenesis?
a. Occurs before puberty
b. Involves stem cells, meiosis, and spermatogenesis
c. Involves cytodifferentiation of early spermatids
d. Occurs in diploid cells
e. Results in the formation of primary spermatocytes
c. Involves cytodifferentiation of early spermatids
Rationale: Spermiogenesis is the final stage of spermatogenesis, where early spermatids undergo cytodifferentiation to become mature spermatozoa. This process involves the formation of the acrosome, condensation of the nucleus, and development of the flagellum.
72
2. A man with a pituitary gonadotrophic tumor causing hyposecretion of FSH is most likely to exhibit which condition?
a. No symptoms, since he has no ovarian follicles
b. Loss of libido (sex drive)
c. Low serum testosterone levels
d. Low sperm count
e. Prostatic hypertrophy
d. Low sperm count
Rationale: Follicle-stimulating hormone (FSH) is essential for the stimulation of spermatogenesis. A deficiency in FSH due to a pituitary tumor would result in a low sperm count, known as oligospermia.
73
3. Interstitial cells of Leydig have an important function in male gamete production. Because of this function, which of the following organelles is abundant within these cells?
a. Lysosomes
b. Smooth endoplasmic reticulum
c. Peroxisomes
d. Polyribosomes
e. Golgi complexes
b. Smooth endoplasmic reticulum
Rationale: Interstitial cells of Leydig produce testosterone, a steroid hormone. The smooth endoplasmic reticulum (SER) is abundant in these cells as it is involved in the synthesis of steroid hormones.
74
4. While studying a germ cell line developed from a patient's testicular biopsy, the researcher notes that colchicine-treated cells blocked in metaphase have 46 chromosomes. From which of the following regions of the male genital tract would you expect these cells to have originated?
a. Within the rete testis
b. At the basal lamina of the seminiferous tubule
c. In the middle region of the germinal epithelium
d. Within the adluminal compartment of the seminiferous tubule
e. Within the straight tubules
b. At the basal lamina of the seminiferous tubule
Rationale: Spermatogonia, which are diploid germ cells with 46 chromosomes, reside at the basal lamina of the seminiferous tubule. These cells undergo mitosis and meiosis to produce haploid sperm cells.
75
5. Which of the following organs is normally characterized by the accumulation of corpora amylacea with increasing age?
a. Prostate
b. Seminal vesicles
c. Bulbourethral (Cowper) glands
d. Epididymis
e. Ductus (vas) deferens
a. Prostate
Rationale: Corpora amylacea are small hyaline masses that accumulate in the prostate gland with increasing age. They are composed of glycoproteins and can be found in the lumen of the prostate gland.
76
6. Within the male reproductive tract, stereocilia project from cells lining which of the following regions?
a. Rete testis
b. Seminiferous tubules
c. Ampulla of the ductus deferens
d. Epididymis
e. Penile urethra
d. Epididymis
Rationale: Stereocilia, which are long, non-motile microvilli, are found on the epithelial cells lining the epididymis. They aid in the absorption of fluid and the maturation of sperm.
77
7. As sperm pass through the male genital ducts, proteins and low-molecular-weight products are added from several sources producing semen. Which of the following provides a nutritive, fructose-rich secretion?
a. Interstitial cells of Leydig
b. Bulbourethral (Cowper) glands
c. Prostate gland
d. Epididymis
e. Seminal vesicles
e. Seminal vesicles
Rationale: The seminal vesicles secrete a fructose-rich fluid that provides energy for the sperm and contributes to the volume of semen.
78
8. A 20-year-old man contracts cholera during a long tour of military duty in a remote, completely undeveloped region. After a 5-day period of severe diarrhea and treatment, he gradually recovers and slowly returns to work. He is married 3 years later but after a few years of trying to conceive a child, semen analysis reveals that his sperm are few in number and malformed, and blood tests show a high titer of antibodies against sperm antigens. The causative agent of cholera, Vibrio cholera, secretes a toxin that interferes with tight (occluding) junctions. What cells in the gonad are the likely target of this toxin in the male reproductive system?
a. Spermatogonia
b. Sertoli cells
c. Myoid cells
d. Interstitial cells of Leydig
e. Differentiating spermatozoa
b. Sertoli cells
Rationale: Sertoli cells form the blood-testis barrier through tight junctions. This barrier protects developing germ cells from immune attack. Disruption of these tight junctions by cholera toxin could expose germ cells to the immune system, leading to the production of antibodies against sperm antigens and infertility.
79
9. A 29-year-old man presents with testicular pain and a burning sensation during urination. Tests reveal the presence of Neisseria gonorrhea and penicillin is prescribed. Gonorrhea often produces acute or chronic inflammation of the testes and frequently involves the channels that connect the testis to the epididymis. What is the name of these channels?
a. The mediastinum testis
b. The rete testis
c. Efferent ductules
d. The straight tubules (tubuli recti)
e. The seminiferous tubules
c. Efferent ductules
Rationale: The efferent ductules connect the rete testis to the epididymis. They transport sperm from the testis to the epididymis, where they mature and are stored.
80
10. A 39-year-old man undergoing an extensive series of tests for infertility is found to have a genetic mutation preventing formation of a functional synaptonemal complex during meiosis, causing almost complete failure of sperm formation. Which cells would be directly affected by this mutation?
a. Primary spermatocytes
b. Spermatogonia
c. Secondary spermatocytes
d. Spermatids
e. Cells undergoing spermiogenesis
a. Primary spermatocytes
Rationale: The synaptonemal complex is essential for the pairing of homologous chromosomes during meiosis I, which occurs in primary spermatocytes. A mutation affecting the formation of the synaptonemal complex would disrupt meiosis in primary spermatocytes, leading to infertility.
81
Which stage of ovarian follicle development is characterized by an initial period of follicular fluid accumulation?
a. Graafian follicle
b. Mature follicle
c. Primordial follicle
d. Oocyte
e. Secondary follicle
e. Secondary follicle
Rationale: The secondary follicle stage is marked by the formation of antral spaces filled with follicular fluid, which coalesce to form the antrum. This distinguishes it from the primary and primordial follicle stages.
82
Which of the following is characteristic of granulosa lutein cells?
a. Are a minor cell type in the corpus luteum
b. Derive from the theca interna
c. Contain abundant rough endoplasmic reticulum
d. Are small and dark-staining
e. Secrete progesterone
e. Secrete progesterone
Rationale: Granulosa lutein cells, which derive from the granulosa cells of the follicle after ovulation, are responsible for secreting progesterone, a hormone critical for maintaining the uterine lining in preparation for pregnancy.
83
Which of the following hormones is primarily responsible for inducing ovulation?
a. Relaxin
b. LH
c. Progesterone
d. FSH
e. Estrogen
b. LH
Rationale: Luteinizing hormone (LH) surges mid-cycle and triggers ovulation, the release of an oocyte from the ovarian follicle.
84
Which feature is characteristic of the corpora albicans but not of atretic follicles?
a. May contain degenerating granulosa cells floating in remnants of follicular fluid
b. Resemble large collagenous scars
c. Eventually removed by macrophages and replaced by stroma
d. Are remnants of follicles that degenerate before maturation
e. May contain degenerating oocytes
b. Resemble large collagenous scars
Rationale: The corpora albicans is a scar-like structure formed from the corpus luteum after it ceases to function. It is characterized by dense connective tissue, unlike atretic follicles which degenerate before reaching full maturation.
85
Endometrial glands are typically most fully developed and filled with product during which days) or phase of a woman's menstrual cycle?
a. Menstrual phase
b. Days 1-4
c. The day ovulation occurs
d. Proliferative phase
e. Days 15-28
e. Days 15-28
Rationale: During the secretory phase (days 15-28) of the menstrual cycle, endometrial glands are highly developed and secrete nutritive substances to support potential embryo implantation.
86
Which feature is characteristic of the endometrium's basal layer but not of its functional layer?
a. Includes the uterine surface epithelium
b. Includes connective tissue
c. Contains cells that replace the surface epithelium after menstruation
d. Relies solely on spiral arteries for its blood supply
e. Undergoes cyclic thickening and shedding
c. Contains cells that replace the surface epithelium after menstruation
Rationale: The basal layer of the endometrium contains stem cells that regenerate the functional layer after it is shed during menstruation.
87
Most lipid in milk is released from cells by which mechanism?
a. Apocrine secretion
b. Paracrine secretion
c. Holocrine secretion
d. Merocrine secretion
e. Autocrine secretion
a. Apocrine secretion
Rationale: In apocrine secretion, lipid droplets are released from mammary gland cells along with a small portion of the cell membrane, which is a key mechanism in the secretion of milk lipids.
88
A 33-year-old woman with an average menstrual cycle of 28 days comes in for a routine Pap smear. It has been 35 days since the start of her last menstrual period, and a vaginal smear reveals clumps of basophilic cells. As her physician, you suspect which of the following?
a. She will begin menstruating in a few days.
b. She will ovulate within a few days.
c. Her serum progesterone levels will be found to be very low.
d. There will be detectable levels of hCG in her serum and urine.
e. She is undergoing early menopause.
d. There will be detectable levels of hCG in her serum and urine.
Rationale: The absence of menstruation for more than a week beyond the expected date, along with the presence of basophilic cells, suggests pregnancy. Human chorionic gonadotropin (hCG) levels would be elevated in serum and urine.
89
A 17-year-old girl with a history of pelvic inflammatory disease presents at the emergency department with severe pain in her lower right side that came on fairly quickly. Upon questioning, she replies that her last menstrual period was 6 weeks ago and that she has never missed a period before. The doctor suspects she has an ectopic pregnancy and this is quickly confirmed by ultrasound testing. The surgeon removes her right uterine tube that is inflamed, scarified, and contains the implanted embryonic tissue in the region where fertilization normally occurs. Where is this?
a. The uterine part of the oviduct
b. The ampulla region with highly folded mucosa
c. The only oviduct region attached to the mesosalpinx
d. The infundibulum region with fimbriae
e. The isthmus region
b. The ampulla region with highly folded mucosa
Rationale: The ampulla is the widest section of the uterine tube and has a highly folded mucosa. It is the most common site for fertilization and often the location for ectopic pregnancies.
90
A 42-year-old woman visits her physician complaining of recurrent vaginal yeast infections. The doctor explains the likelihood that the woman's vaginal lining is temporarily out of proper acid-base balance, leading to the increased susceptibility to yeast infections. The normally low pH in the vagina is maintained by which of the following?
a. A proton pump in the epithelial cells similar to that in osteoclasts and parietal cells
b. Secretions derived from intracellular carbonic acid
c. Secretion of lactic acid by cells of the stratified squamous epithelium
d. Bacterial metabolism of glycogen to produce an organic acid
e. Synthesis and accumulation of acid hydrolases in the epithelium
d. Bacterial metabolism of glycogen to produce an organic acid
Rationale: The normal low pH of the vagina is maintained by the production of lactic acid through the metabolism of glycogen by lactobacilli. This acidic environment inhibits the growth of pathogenic microorganisms, including yeast.
91
Which of the following is the thickest component of the cornea?
a. Corneal epithelium
b. Stroma
c. Descemet membrane
d. Bowman membrane
e. Corneal endothelium
b. Stroma
Rationale: The stroma makes up about 90% of the cornea's thickness and consists of regularly arranged collagen fibers that provide structural support and transparency.
92
Which description is accurate for lens fibers?
a. Are terminally differentiated fibroblasts
b. Consist of specialized type I collagen
c. Derived from epithelial cells that produce proteins called crystallins
d. Consist of type III collagen
e. Have the same embryonic origin as the neural retina
c. Derived from epithelial cells that produce proteins called crystallins
Rationale: Lens fibers are elongated, specialized cells derived from epithelial cells that produce crystallins, which are proteins essential for the lens's transparency and refractive properties.
93
Which structure is the most anterior extension of the eye's vascular layer?
a. Ciliary body
b. Cornea
c. Lens
d. Iris
e. Zonule
d. Iris
Rationale: The iris is the most anterior extension of the vascular layer (uvea) of the eye, containing blood vessels and pigmented cells that control the diameter of the pupil.
94
Which cells transmit visual signals from the retina to the brain?
a. Bipolar cells
b. Amacrine cells
c. Ganglion cells
d. Horizontal cells
e. Müller cells
c. Ganglion cells
Rationale: Ganglion cells are the final output neurons of the retina. Their axons form the optic nerve, which transmits visual information to the brain.
95
The epithelial cells within the organ of Corti are supported by which of the following structures?
a. Spiral limbus
b. Tectorial membrane
c. Vestibular membrane
d. Basilar membrane
e. Spiral ligament
d. Basilar membrane
Rationale: The basilar membrane supports the organ of Corti, which contains hair cells that transduce sound vibrations into neural signals.
96
The middle ear contains which of the following structures?
a. The labyrinth
b. The modiolus
c. The perilymph
d. The vestibular apparatus
e. The ossicles
e. The ossicles
Rationale: The middle ear contains the ossicles (malleus, incus, and stapes), which transmit sound vibrations from the tympanic membrane to the inner ear.
97
Which structure in the cochlea is analogous in composition and function to the cupola of each semicircular canal?
a. Tectorial membrane
b. Pillar cells
c. Inner tunnel
d. Saccule
e. Spiral ganglion
a. Tectorial membrane
Rationale: The tectorial membrane in the cochlea is a gelatinous structure that interacts with hair cells in a manner similar to the cupola in the semicircular canals, playing a role in the mechanotransduction of sound.
98
A 47-year-old woman is referred to an ophthalmologist after reporting increased difficulty with tasks at night or in dark places for the past 3 or 4 years. She has trouble walking in dimly lit rooms and the movie theater. She has given up driving at night and describes a prolonged adaptation period going from light to dark. She also describes her daylight vision as "tunneled," as she frequently walks into furniture. A family history indicates that her father had a similar condition. In this disease, a single point mutation in the rhodopsin gene leads to disruption of signal transduction. Visual transduction in the affected cells involves which of the following?
a. Inactivation of phosphodiesterase
b. Increase in cGMP levels
c. Conversion of all-trans-retinal to 11-cis-retinal
d. Closing of Na+ channels
e. Depolarization of the cell membranes
d. Closing of Na+ channels
Rationale: In the phototransduction process, light activates rhodopsin, leading to a cascade that closes Na+ channels in photoreceptor cells, causing hyperpolarization and the transmission of the visual signal.
99
During an eye examination, a 55-year-old man is found to show intraocular pressure exceeding 40 mm Hg and blockage of fluid flow within the eye is suspected. Such a diagnosis would involve a blockage at which of the following sites?
a. Choroid body
b. Vessels at the optic disk
c. Pupillary junction of the posterior and anterior chambers
d. Choroid layer
e. Trabecular meshwork
e. Trabecular meshwork
Rationale: Elevated intraocular pressure is often due to the impaired drainage of aqueous humor through the trabecular meshwork, leading to conditions such as glaucoma.
100
During a boxing match, a 23-year-old fighter sustains a direct blow to the right ear. He presents with dizziness, vertigo, imbalance, nausea, vomiting, tinnitus, and fullness in the ears. His vertigo increases with activity and is relieved by rest. He has some hearing loss. The symptoms worsen with coughing, sneezing, or blowing his nose, as well as with exertion. He is diagnosed with perilymphatic fistula, which allows leakage of perilymph. In which of the following structures is perilymph normally found?
a. Scala media
b. Scala tympani
c. Semicircular canals
d. Saccule
e. Utricle
b. Scala tympani
Rationale: Perilymph is found in the scala tympani and scala vestibuli of the cochlea, which are fluid-filled chambers that help transmit sound waves to the auditory receptors.
