What compensation mechanism takes place in the body when a person has dehydration?
Increased heart rate.
Increased skin elasticity.
Decreased antidiuretic hormone secretion.
Decreased hematocrit.
The Correct Answer is A
Choice A rationale
When dehydration occurs, the total blood volume decreases, leading to a drop in blood pressure. The body compensates through the baroreceptor reflex, which detects the decrease in stretch within the carotid sinuses and aortic arch. This triggers the sympathetic nervous system to increase the heart rate, known as tachycardia. By increasing the heart rate, the body attempts to maintain adequate cardiac output and ensure that vital organs continue to receive sufficient oxygenated blood despite the lower circulating volume.
Choice B rationale
Dehydration leads to a decrease in skin elasticity, often referred to as poor skin turgor. When the body is dehydrated, fluid is pulled from the interstitial spaces and intracellular compartments to maintain vascular volume. This loss of fluid from the dermal layers causes the skin to lose its resiliency. Scientifically, skin that stays "tented" when pinched is a classic sign of dehydration, representing a failure of the compensation mechanism to keep peripheral tissues hydrated during a fluid deficit.
Choice C rationale
In response to dehydration and increased serum osmolality, the posterior pituitary gland actually increases the secretion of antidiuretic hormone, also known as vasopressin. This hormone acts on the collecting ducts of the kidneys to increase water reabsorption, thereby concentrating the urine and conserving as much fluid as possible. A decrease in antidiuretic hormone secretion would lead to more fluid loss through urine, which would exacerbate the dehydration rather than serving as a compensatory mechanism.
Choice D rationale
Dehydration typically causes an increase in hematocrit, not a decrease. Hematocrit is the ratio of the volume of red blood cells to the total volume of blood. When the plasma volume decreases due to water loss, the concentration of red blood cells becomes relatively higher, a condition called hemoconcentration. A decreased hematocrit would suggest anemia or fluid overload. Therefore, an elevated hematocrit level is a common laboratory finding that reflects the state of fluid volume deficit in the body.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is {"A":{"answers":"C"},"B":{"answers":"A"},"C":{"answers":"A"},"D":{"answers":"C"},"E":{"answers":"B"}}
Explanation
Choice A rationale
Kidney stones, or nephrolithiasis, cause acute kidney injury by creating a physical obstruction in the urinary tract, either in the ureters or the urethra. This blockage prevents the outflow of urine, leading to increased retrograde pressure within the renal pelvis and parenchyma, which impairs glomerular filtration. Because the problem occurs after the urine has already been formed and is located within the collecting system, it is classified as a post-renal cause of injury.
Choice B rationale
Fluid volume deficit, such as that caused by severe dehydration or hemorrhage, leads to decreased systemic blood volume. This reduction in volume results in decreased renal perfusion pressure, which prevents the kidneys from receiving enough blood to maintain an adequate glomerular filtration rate. Since the injury is caused by factors that reduce blood flow to the kidneys before it reaches the renal vasculature itself, it is categorized as a pre-renal acute kidney injury.
Choice C rationale
Low blood pressure, or hypotension, directly diminishes the mean arterial pressure required to drive blood through the renal arteries and into the glomeruli. Without sufficient pressure, the kidneys cannot effectively filter waste products from the blood, leading to a rise in blood urea nitrogen and creatinine. Similar to fluid volume deficit, the underlying issue is a lack of adequate perfusion to the kidney, which defines this as a pre-renal cause of acute kidney injury.
Choice D rationale
Benign prostatic hypertrophy involves the enlargement of the prostate gland, which can compress the urethra and obstruct the normal flow of urine out of the bladder. This urinary retention creates back-pressure that can eventually damage the kidneys and impair their function if the obstruction is bilateral or sufficiently severe. Like kidney stones, this is an obstructive issue occurring distal to the kidney itself, making it a classic example of a post-renal acute kidney injury.
Choice E rationale
Glomerulonephritis is an inflammatory condition that directly damages the glomeruli, the filtering units within the kidney. This inflammation can be caused by autoimmune reactions or infections and leads to the destruction of the basement membrane and capillary endothelium. Because the pathological process is occurring within the actual tissue and functional units of the kidney, it is classified as an intra-renal, or intrinsic, cause of acute kidney injury, as the damage is internal.
Correct Answer is D
Explanation
Choice A rationale
A pulmonary embolism is a blockage in one of the pulmonary arteries in the lungs, usually caused by blood clots that travel from the legs. While severe cases can cause right heart strain leading to a slight rise in troponin, it is not the diagnostic marker for the disease. Diagnosis relies on clinical symptoms, D-dimer levels, and imaging studies. Troponin is specific to myocardial cell death, which is not the primary pathological event in a pulmonary embolism.
Choice B rationale
The diagnosis of liver disease involves evaluating liver enzymes such as ALT and AST, along with markers of synthetic function like the International Normalized Ratio (INR) and albumin. Troponin is a contractile protein specific to cardiac and skeletal muscle, with the cardiac isoforms being unique to the heart. It is not found in the liver, and therefore, its presence in the blood does not provide any information regarding the health or disease state of the liver.
Choice C rationale
Congestive heart failure is a clinical syndrome where the heart cannot pump enough blood to meet the body's needs, often diagnosed by a BNP level above 100 pg/mL. While troponin may be elevated in heart failure due to myocardial wall tension, it is not the diagnostic criteria for the condition. The troponin test's main purpose is to rule in or rule out an acute coronary syndrome, specifically myocardial infarction, by detecting cellular necrosis.
Choice D rationale
Myocardial infarction involves the death of heart muscle cells due to prolonged ischemia. Cardiac troponins I and T are highly specific markers of this damage. When the cell membrane of a myocyte is compromised, troponin leaks into the interstitial space and then into the systemic circulation. A rising or falling pattern of troponin levels above the 99th percentile is the definitive biochemical requirement for diagnosing an acute heart attack in a clinical setting.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.