A client with chronic hypertension develops left ventricular hypertrophy.
Which cellular adaptation is occurring?
Hypertrophy.
Hyperplasia.
Metaplasia.
Dysplasia.
The Correct Answer is A
Choice A rationale
Hypertrophy is an increase in the size of individual cells, which leads to an increase in the overall size of the organ. In chronic hypertension, the left ventricle must pump against increased systemic vascular resistance. To compensate for this increased workload, the cardiac myocytes synthesize more proteins and organelles, becoming larger to generate more force. This is a common adaptive response in non-dividing cells like those found in the heart and skeletal muscles when facing stress.
Choice B rationale
Hyperplasia is an increase in the number of cells in an organ or tissue resulting from increased cellular division. This occurs in tissues capable of mitosis, such as the liver or the glandular epithelium of the breast during pregnancy. Since cardiac muscle cells are largely post-mitotic and have a very limited capacity for regeneration or division, the heart cannot adapt to hypertension by making more cells; it must rely on increasing the size of existing cells.
Choice C rationale
Metaplasia is a reversible change in which one adult cell type is replaced by another adult cell type of the same germ line. This is usually a protective response to chronic irritation. An example is the change from ciliated columnar epithelium to squamous epithelium in the airways of chronic smokers. This adaptation is not seen in the heart in response to pressure overload, as the tissue remains muscular but simply becomes thicker and less compliant.
Choice D rationale
Dysplasia refers to abnormal changes in the size, shape, and organization of mature cells. It is often a precursor to cancerous changes and is characterized by a loss of cellular uniformity and architectural orientation. While it can occur in various epithelial tissues due to chronic irritation or inflammation, it is not the mechanism by which the heart adapts to the mechanical stress of high blood pressure, which is a physiological/pathological growth process. .
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Correct Answer is C
Explanation
Choice A rationale
Increased bicarbonate excretion would be an appropriate compensation for metabolic alkalosis, not metabolic acidosis. In metabolic acidosis, the body is experiencing a deficit of base or an excess of hydrogen ions. The renal system attempts to compensate by retaining bicarbonate and excreting hydrogen ions to raise the pH. Excreting more bicarbonate would worsen the acidic state by further depleting the body of its primary buffer system, leading to a dangerous drop in pH.
Choice B rationale
A decreased respiratory rate would lead to the retention of carbon dioxide, which combines with water to form carbonic acid. This process increases the concentration of hydrogen ions in the blood, leading to respiratory acidosis. If a client is already in metabolic acidosis, slowing the breathing would be a maladaptive response that causes a combined acid-base disorder. Respiratory compensation for an acidic state must involve increasing the removal of volatile acids to normalize blood pH.
Choice C rationale
In metabolic acidosis, the body compensates by increasing the respiratory rate and depth, often referred to as Kussmaul respirations. This physiological response facilitates the rapid removal of carbon dioxide from the lungs. Since carbon dioxide acts as a volatile acid in the bloodstream, lowering its partial pressure helps to increase the overall pH back toward the normal range of 7.35 to 7.45. This respiratory compensation occurs quickly to offset the primary metabolic imbalance.
Choice D rationale
Oxygen saturation is a measure of the percentage of hemoglobin binding sites occupied by oxygen and is not a direct compensatory mechanism for acid-base imbalances. While severe acidosis can shift the oxyhemoglobin dissociation curve and affect how easily oxygen is released to tissues, a decrease in saturation does not serve to neutralize excess hydrogen ions. Compensation involves specific adjustments in the partial pressure of carbon dioxide or the concentration of bicarbonate to stabilize pH levels.
Correct Answer is C
Explanation
Choice C rationale
Graves' disease is an autoimmune condition characterized by thyroid-stimulating immunoglobulins that continuously activate the TSH receptors. When this state is exacerbated by stress, infection, or trauma, it can lead to a thyroid storm. This involves a massive, sudden release of triiodothyronine (T3) and thyroxine (T4) into the circulation. These hormones significantly increase the basal metabolic rate, resulting in severe hyperthermia, tachycardia, and central nervous system agitation. This hypermetabolic state is life-threatening and requires immediate clinical intervention.
Choice B rationale
A sudden decrease in thyroid hormone production would lead to symptoms of hypothyroidism or, in extreme cases, myxedema coma. Myxedema coma is characterized by hypothermia, bradycardia, and depressed mental status, which is the exact opposite of the fever, tachycardia, and confusion seen in this patient. In Graves' disease, the pathology is driven by overactivity of the gland. Therefore, a decrease in hormone levels would not explain the acute hypermetabolic presentation described in the scenario of a thyroid storm.
Choice A rationale
Autoimmune destruction of thyroid tissue is the primary pathophysiology of Hashimoto thyroiditis, which eventually results in hypothyroidism. While Graves' disease is autoimmune, it is stimulatory rather than destructive. In Graves', antibodies mimic TSH and cause the gland to enlarge and overproduce hormones. If the tissue were being destroyed, the patient would not have the excessive levels of T3 and T4 necessary to drive the acute, high-energy symptoms of fever and tachycardia that characterize an untreated or exacerbated hyperthyroid state.
Choice D rationale
In Graves' disease, TSH secretion from the pituitary is already suppressed to near-zero levels because the high levels of circulating T3 and T4 provide constant negative feedback. While decreased TSH is a diagnostic finding (normal: 0.5 to 5.0 mU/L), it is a result of the disease rather than the cause of the acute crisis. The symptoms of tachycardia and fever are driven by the peripheral actions of the thyroid hormones themselves on the heart and thermoregulatory centers, not the pituitary's TSH levels.
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