Cytology Histology - Answers And Explanations

EXAM MASTER Corporation – Retired questions – NOT for resale #1 ( 15600 ) CORRECT: E The mature sperm is an actively motile germ cell consisting of a head and a tail. The junction between the head and tail is called the neck. The head forms most of the bulk of the sperm and contains the haploid nucleus. The anterior two thirds of the nucleus is covered by the acrosome containing more than ten different enzymes, including hyaluronidase and acrosin. #2 ( 15626 ) CORRECT: F Ectoderm gives rise to the central nervous system (brain and spinal cord), the peripheral nervous system, the sensory epithelia of the eye, ear, and nose, the epidermis and its appendages (hair and nails), mammary glands, cerebral hypophysis, subcutaneous glands, and the enamel of the teeth. Neural crest cells, derived from neuroectoderm, give rise to the cells of the spinal, cranial and autonomic ganglia; ensheathing cells of the peripheral nervous system; pigment cells of the dermis; muscle, connective tissues, and bone of branchial arch origin; the suprarenal (adrenal) medulla; and the meninges of the brain and spinal cord. Mesoderm gives rise to connective tissue, cartilage, bone, striated and smooth muscles, the heart, blood and lymph vessels and cells, the kidneys, ovarian and testes, the genital ducts, serous membranes lining the body cavities (pericardial, pleural, and peritoneal), the spleen, and the cortex of the suprarenal gland. Endoderm gives rise to the epithelial lining of the gastrointestinal and respiratory tracts, the parenchyma of the tonsils, thyroid and parathyroid glands, thymus, liver, and pancreas, the epithelial lining of the urinary bladder and most of the urethra, and the epithelial lining of the tympanic cavity, tympanic antrum, and auditory tube. #3 ( 16085 ) CORRECT: D Pulmonary arterioles are constricted by norepinephrine, epinephrine, angiotensin II, thromboxanes, and PGF2α. They are dilated by isoproterenol, acetylcholine, and PGI2. Pulmonary venules are constricted by serotonin, histamine, and E. Coli endotoxin. #4 ( 101102 ) CORRECT: E The part of the neuron described is the axon hillock. Activity at neurotransmitter receptors contributes to graded impulses (EPSPs and IPSPs), which are summed and converted to an all-or-none impulse (action potential) at the axon hillock. All impulses that follow resulting in neurotransmitter release are all-or-none.

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EXAM MASTER Corporation – Retired questions – NOT for resale #5 ( 104919 ) CORRECT: D Parathyroid hormone (PTH) regulates calcium and phosphate levels in the blood. It is secreted by the parathyroid gland being regulated by a negative feedback mechanism based on levels of serum calcium. PTH maintains serum calcium levels by a number of mechanisms: 1. Release of calcium by bone. 2. Increase intestinal absorption of calcium through activation of vitamin D, secreted by the kidney. 3. Stimulation of tubular reabsorption of calcium in the renal tubules. 4. Reduction of reabsorption of phosphate in renal tubules. #6 ( 104925 ) CORRECT: E The thymus is the first organ in fetal development to manufacture lymphocytes. Here, thymic lymphoid cells are coded with specific instructions as to which antigens the T cell will react. The thymus is sufficiently differentiated by the 12th week of fetal life to participate in this immune response mechanism. Removal of the thymus in early life may alter the immune response, and may decrease lymphocytes in the peripheral blood, with marked depletion of T-cells. In the developed fetus and infant, pro-thymocytes from the bone marrow migrate to the thymus where they are changed to T cells. The best answer is all of the items listed are true. #7 ( 104935 ) CORRECT: A Within the cell are several functional components called organelles, which include ribosomes, endoplasmic reticulum, Golgi complex, mitochondria, lysosomes, microtubules, and filaments. Protein synthesis is primarily a function of the ribosomes, endoplasmic reticulum, and Golgi complex. The mitochondria are the site of energy production whereby ATP is produced. The lysosomes are the digestive component of the cell, the microtubules control cell shape and movement, and the filaments provide for contractile activities.

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EXAM MASTER Corporation – Retired questions – NOT for resale #8 ( 104936 ) Correct: C

Stimulus of the cell membrane produces sudden spikes of electrical activity, which change the membrane potential. This occurs with sufficient stimulus to the cell membrane to excite the membrane (threshold potential), thus opening the fast sodium channels allowing a surge of sodium ions into the cell, with abrupt change in membrane potential. The action potential has three phases: 1. Resting phase, characterized by a large negative membrane potential. 2. Depolarization phase, characterized by membrane permeability to sodium ions. 3. Repolarization phase, characterized by return to resting potential. During the repolarization phase, sodium permeability decreases as there is a large outflow of potassium ions from the cell to return the membrane to a negative potential. During this return to normal potential, there is a short period in which the membrane is incapable of being excited. This is known as the absolute refractory period. During the following relative refractory period, the membrane may be excited, but only by a stimulus much greater than normal.

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EXAM MASTER Corporation – Retired questions – NOT for resale #9 ( 104946 ) CORRECT: D The aging process has been a longtime mystery. No one theory accounts for all of the changes, which occur during aging. There are basically two types of categories, which explain the aging process. 1. The theory that asserts that changes that occur during aging are programmed within the genetic mechanism. 2. Stochastic theories which assert that changes occurring within an organism result from accumulation of random events which may induce damage to cells. All of the above items are true. #10 ( 104949 ) CORRECT: E Precocious sexual development may be caused by a number of problems including adrenal, gonadal, CNS, and hypothalamic tumors, or it may be idiopathic. Sexual development is considered precocious when it occurs before the age of 8 years old in females and 9 years old in males. Although individuals with precocious sexual development are usually tall for their age in childhood, as adult they are usually short in stature due to early closing of the epiphysis of long bones. #11 ( 104961 ) CORRECT: E There are two types of synaptic transmission mechanisms: electrical and chemical. Electrical transmission involves passage of ions through sodium and potassium channels to closely linked cell membranes, and chemical transmission involves neurotransmitters which travel across the synaptic junction. The average time required for chemical synaptic conduction is approximately 0.3 milliseconds. The neurotransmitters attach to receptors on the post synaptic membrane and produce either hypopolarization (excitatory) or hyperpolarization (inhibitory) response. Release of calcium ions at presynaptic membrane is associated with neurotransmitter release. Neurotransmitters act according to which type of receptor to which they bind on the post synaptic membrane. Thus, the same neurotransmitter (e.g. acetylcholine) can have either inhibitory or excitatory function.

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EXAM MASTER Corporation – Retired questions – NOT for resale #12 ( 104964 ) CORRECT: C The cornea has the greatest ability to bend light rays entering the eye (refractive power). It has a refractive power of 43 diopters. The lens has a variable refractive power (12 to 26 diopters). Contraction of the ciliary muscle changes the lens' shape. During accommodation, the ciliary muscle contracts to make the lens more rounded, increasing its refractive power and bringing nearby objects into focus. The fovea is the point at which light rays come into focus on the retina when a gaze is directed at a fixed point. #13 ( 104970 ) CORRECT: B Several neuropeptides secreted by the body act as endogenous opioid substances. They include enkephalin, dynorphin, and beta-endorphin. They activate one of the many types of opioid receptors. Substance-P is the transmitter at synapses of primary sensory neurons. Enkephalins act to decrease the release of substance-P, thus inhibiting the pathway for pain sensation. Naloxone is an opioid antagonist which blocks the action of the endogenous and exogenous opioid substances at the receptor sites. #14 ( 106256 ) CORRECT: D The choledochoduodenal junction (also known as the sphincter of Oddi) is an isolated site. However, if in very rare cases it is present on the microscopic slide, it is an excellent diagnostic clue for the identification of the duodenum. From the practical point of view, the only constant, unique histological feature of the duodenum is the presence of Brunner’s glands in the submucosa. Peyer’s patches are characteristics of the ileum. #15 ( 106356 ) CORRECT: A In conditions of emphysema, destruction of the elastin protein network of the lung parenchyma causes loss of radial traction of small airways. The structural proteins, elastin and collagen, impart resiliency to lung tissue. Elastin allows the lung parenchyma to expand, whereas collagen prevents overexpansion. As the walls of alveoli become thin and disorganized, the alveoli enlarge and coalesce. As a result of these histologic changes, the compliance of the lung increases and the lung becomes more distensible. In other words, the loss of elastance within the lung parenchyma results in decreased elastic recoil of the lung. The pathogenesis thus leads to chronic air trapping which increases the size of the airway during inspiration but prolongs the time of various forced expiratory maneuvers. As a result of loss of elastic recoil of the emphysematous lung, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and forced expiratory volume as a percentage of EXAM MASTER Corporation – Retired questions – NOT for resale Page 5 of 9 Any reproduction, distribution, or sale of this material in any format is prohibited by copyright law and the EXAM MASTER Licensing Agreement.

EXAM MASTER Corporation – Retired questions – NOT for resale vital capacity (FEV/FVC %) are all significantly reduced. Expiratory time is greatly increased over the forced expiration. The FVC is reduced because the airways close at a high lung volume. This, in turn, increases the residual volume (RV) of the lung. Because of hyperinflation of the lungs and loss of elastic recoil, the anteroposterior thorax diameter may increase. Chest radiographs reveal low, flat diaphragms. Accessory inspiratory muscles such as the external intercostals, pectoralis major, trapezius, scalenus group, and sternocleidomastoid either elevate the ribs, increase the anteroposterior diameter of the thorax, or increase the lateral diameter of the thorax to increase the chest volume during inspiration and assist the diaphragm. Accessory expiratory muscles such as the internal intercostals depress the ribs during expiration while the abdominal group pressurizes the abdominopelvic cavity to assist the upward excursion of the diaphragm during expiration. #16 ( 106366 ) CORRECT: E If the lung is viewed as a simple “air pump” affected by variables such as the force applied to a piston, the stroke volume of the piston, and the resistance of a tubular system connected to the outlet side of the pump, certain analogies apply. These similarities include the distensibility (compliance) and elastic recoil (elastance) of the lung, and the airway resistance of the conducting passages. Some analogies, however, do not apply. For example, the air passages of the lung are located within the pump, therefore, they are affected by the pressure dynamics of the pump itself. Inspiratory pressures within the lung always expand the airways, therefore, dynamic collapse of the passages is not seen during forced inspiratory maneuvers. Airways collapse, however, with forced expiration when the external pressure applied by the muscles of expiration exceeds the internal pressure of the airways. This feature of dynamic compression of airways during expiration absolutely limits the maximum flow rate of gas leaving the lung at a given volume. Exhaling slowly, forcefully, or a combination of the two expiratory techniques will not alter the maximum flow rate at a given volume. At the point where the internal pressure of the airways can no longer maintain patency, dynamic collapse of the airways occurs, limiting maximum flow rate to a given “envelope” of respiratory performance. The envelope defined by the expiratory flow-volume curve is unique for different respiratory dysfunctions and is, therefore, of diagnostic value: • Pathophysiologic features associated with chronic obstructive pulmonary diseases (COPDs) include changes such as hypertrophy of airway walls and accumulation of mucus and inflammatory exudate in the lumen of airways (e.g. chronic bronchitis), and parenchymal tissue damage leading to increased compliance, reduced elastance, and collapsed airways (e.g. emphysema). The expiratory flow-volume loop of patients with COPD shows a characteristically low flow rate relative to lung volume. In other words, such patients are operating very high in the range of lung volumes due to increased compliance, reduced elastic recoil, and the inability to exhale gas through collapsed or partially occluded airways; • In restrictive lung disorders such as advanced interstitial fibrosis, the lung is prevented from expanding properly, that is, lung compliance is significantly reduced, causing the EXAM MASTER Corporation – Retired questions – NOT for resale Page 6 of 9 Any reproduction, distribution, or sale of this material in any format is prohibited by copyright law and the EXAM MASTER Licensing Agreement.

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patient’s respiratory system to function very low in the range of lung volumes. In addition, the static recoil pressures are elevated due to the restrictive effects of fibrotic changes. As a result, the expiratory flow-volume curve reveals a high flow rate relative to lung volume, although absolute flow rates are lower than normal; Upper airway obstruction caused by a neoplasm that compresses the trachea, or by stenosis of the trachea or glottis produces an expiratory flow-volume loop that is characteristically flattened over much of the range of lung volumes. In other words, such nonvariable, or fixed, obstructions are totally independent of expiratory effort and present an impediment to breathing over the entire range of lung volumes. The upper limit of the expiratory flow rate envelope is severely limited by the obstruction, as evidenced by the plateau portion of the curve. Since the obstruction is fixed, or permanent, it also limits the inspiratory flow-volume curve which also assumes a flattened appearance. (By contrast, the inspiratory flow-volume curves of patients with obstructive or restrictive diseases is normal or near-normal.)

#17 ( 106906 ) CORRECT: D The oculomotor nerve (third cranial nerve) is the chief motor nerve to the muscles of the globe, except the superior oblique and the lateral rectus. It emerges from the brain stem medial to the cerebral peduncle, coursing between the posterior cerebral and superior cerebellar arteries. It divides into a superior and inferior division. The superior division innervates the superior rectus and the levator palpebrae superioris muscles. The inferior division innervates the medial rectus, inferior rectus, and the inferior oblique muscles. #18 ( 106911 ) CORRECT: A The vestibulocochlear nerve emerges from the brain between the pons and medulla and has two components. The vestibular part arises from the vestibular ganglion and the cochlear part arises from the spiral ganglion. It divides after passing through the acoustic meatus into superior and inferior division. The superior division consists of vestibular fibers, which supply the maculae of the utricle, and saccule, and the ampullae of the anterior and lateral semicircular canals. The inferior division contains both cochlear and vestibular fibers. The vestibular fibers of the inferior division also innervate the saccule. #19 ( 106939 ) CORRECT: D Much study is being done on senescence, which may unlock the mystery of aging. Senescent cells are those cells which remain metabolically active, but are no longer capable of dividing. This is an irreversible change which takes place in the cell as a result of a dominant phenotypic expression which is located on the genes. Senescent cells can be identified by the presence of an enzyme, beta-galactosidase, which is present in senescent cells and not in EXAM MASTER Corporation – Retired questions – NOT for resale Page 7 of 9 Any reproduction, distribution, or sale of this material in any format is prohibited by copyright law and the EXAM MASTER Licensing Agreement.

EXAM MASTER Corporation – Retired questions – NOT for resale normal cells. Studies have shown there are cells which are immune to senescence (immortal cells) which exist as a recessive phenotype. The very mechanism of senescence is the antithesis of the mechanism which produces the cancer cell. In a sense, senescent cells are "anti-cancer" cells. The most correct answer is 1, 3, and 4 as listed above. #20 ( 106952 ) CORRECT: E The thymus is the first organ in fetal development to manufacture lymphocytes. Here thymic lymphoid cells are coded with specific instructions as to which antigens the T cell will react. The thymus is sufficiently differentiated by the 12th week of fetal life to participate in this immune response mechanism. Removal of the thymus in early life may alter the immune response, and may decrease lymphocytes in the peripheral blood, with marked depletion of T-cells. In the developed fetus and infant, pro-thymocytes from the bone marrow migrate to the thymus where they are changed to T cells. Thymosin, a hormone secreted by the thymus, facilitates learning and maturation of lymphocytes. The best answer is all of the items listed are true. #21 ( 106962 ) CORRECT: E The hormones associated with the hypothalamic-pituitary-adrenal axis are very much affected by stress. The production of the tropic hormones is affected by stressful situations with changes occurring in end production of cortisol, thyroid hormones, growth hormones, sex hormones, and others. The best answer is all of the above. #22 ( 107028 ) CORRECT: B During the uterine, or menstrual cycle, the stratum functionalis (indicated by letter B) or functional layer of the endometrium changes in thickness, vascularity, and glandularity. Under the influence of estrogens from the developing follicle, the endometrium thickens and the surface epithelium invaginates to form simple tubular glands, the uterine glands. Branches of the spiral artery provide a rich supply of blood to the developing endometrial layer. These changes are typical of the proliferative stage. Following ovulation, during the secretory phase, the endometrium is influenced by progesterone from the corpus luteum of the ovary, and the extensive uterine glands become enlarged, torturous and glycogen-rich. The endometrial stroma becomes highly cellular and the endometrium is prepared to accept and sustain the fertilized ova. Without fertilization and implantation, the corpus luteum degenerates, and the stratum functionalis layer of the uterine endometrium (B) responds by becoming ischemic, and eventually sloughing off as the menses occurs. The basal portion of the endometrium, or stratum basalis (indicated by letter A) remains to serve as the source for regeneration of the stratum functionalis in the next uterine cycle.

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EXAM MASTER Corporation – Retired questions – NOT for resale #23 ( 107404 ) CORRECT: C The photomicroscopic image best depicts the appearance of the placenta early in pregnancy. At this stage of development, the placental histology is composed primarily of chorionic villi consisting of a connective tissue core surrounded by two layers, the outermost syncytiotrophoblast layer, and the inner layer of cytotrophoblasts. The letter ‘d’ identifies the nuclei of the syncytiotrophoblast layer, which lines the entire compartment through which maternal blood flows. The arrowheads that do not have letters near them identify the nuclei of the inner cytotrophoblast layer. This layer of cells becomes discontinuous in the tertiary villi. The letter ‘e’ indicates a developing capillary through which fetal blood will flow. The space outside of the syncytiotrophoblast layer is the intervillous space, which contains the maternal blood.

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