In the kidney, where are the mechanisms found that are responsible for increasing urine concentration?
Calyx.
Proximal convoluted tubule.
Renal pelvis.
The loop of Henle.
The Correct Answer is D
The loop of Henle, a critical structure within the nephron of the kidney, plays a key role in the concentration of urine through the process of countercurrent multiplication. Here's why option D is the correct choice:
A) Calyx:
The calyx is a structure in the kidney that collects urine from the renal papillae and channels it into the renal pelvis. It does not directly participate in the concentration of urine.
B) Proximal convoluted tubule:
The proximal convoluted tubule primarily reabsorbs water, electrolytes, and nutrients from the glomerular filtrate, but it does not contribute significantly to the concentration of urine.
C) Renal pelvis:
The renal pelvis is a funnel-shaped structure that collects urine from the calyces and funnels it into the ureter. It is not directly involved in the concentration of urine.
D) The loop of Henle:
Correct. The loop of Henle is the nephron segment responsible for generating a hypertonic medullary interstitium, which creates the osmotic gradient necessary for urine concentration. The loop of Henle achieves this through countercurrent multiplication, where the descending limb allows passive reabsorption of water, while the ascending limb actively pumps out sodium and chloride ions. This creates an osmotic gradient that allows for further water reabsorption in the collecting ducts, leading to concentrated urine.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A) Deficiency of factors VIII or IX.
Hemophilia is a genetic disorder characterized by deficient or defective clotting factors, specifically factors VIII (hemophilia A) or IX (hemophilia B). These clotting factors are essential for the formation of stable blood clots. Therefore, if hemophilia is present, the deficiency of factors VIII or IX can lead to impaired clot formation and prolonged bleeding.
B) Diminished amount of vitamin K:
Vitamin K deficiency can lead to impaired blood clotting due to inadequate synthesis of clotting factors in the liver. However, hemophilia is specifically associated with deficiencies in factors VIII or IX, not vitamin K.
C) Decreased amount of platelets:
Platelets play a crucial role in primary hemostasis and initial platelet plug formation at the site of vascular injury. While decreased platelet count or dysfunction can lead to bleeding disorders such as thrombocytopenia or platelet function disorders, hemophilia specifically involves deficiencies in clotting factors, not platelets.
D) Missing factors V and VII:
Factor V and VII are other clotting factors involved in the coagulation cascade, but they are not deficient in hemophilia. Hemophilia is specifically characterized by deficiencies in factors VIII (hemophilia A) or IX (hemophilia B).
Correct Answer is B
Explanation
The clinical manifestations described in the scenario, including lethargy, difficulty talking, hypertension (blood pressure of 146/122 mm Hg), and elevated urine specific gravity (1.055), are indicative of Syndrome of Inappropriate Antidiuretic Hormone (SIADH). Here's a breakdown of the rationale:
A) Hyposecretion of Antidiuretic Hormone (ADH):
Hyposecretion of ADH would result in decreased levels of ADH, leading to increased urine output (polyuria) and low urine specific gravity. This condition is known as diabetes insipidus, characterized by excessive thirst and dilute urine. The elevated urine specific gravity in the scenario is inconsistent with diabetes insipidus. Therefore, this option is incorrect.
B) Syndrome of Inappropriate Antidiuretic Hormone (SIADH):
Correct. SIADH is a condition characterized by excessive release of antidiuretic hormone (ADH) from the posterior pituitary gland, leading to water retention, dilutional hyponatremia, and concentrated urine. The elevated urine specific gravity (1.055) in the scenario indicates concentrated urine, consistent with SIADH. Additionally, lethargy and difficulty talking are common neurological manifestations of hyponatremia, which can occur as a result of water retention in SIADH. The client's hypertension is likely a compensatory response to hyponatremia-induced cerebral edema. Therefore, SIADH is the most likely diagnosis in this context.
C) Hypopituitarism:
Hypopituitarism refers to deficient production of one or more pituitary hormones, which can lead to a variety of endocrine abnormalities depending on which hormones are affected. While it is possible for hypopituitarism to cause hyponatremia, the other clinical manifestations described in the scenario are not typically associated with this condition. Additionally, the elevated urine specific gravity is not consistent with hypopituitarism-induced hyponatremia. Therefore, this option is less likely.
D) Septic shock:
Septic shock is a life-threatening condition characterized by severe hypotension and tissue hypoperfusion due to systemic infection. While septic shock can cause altered mental status, hypotension (not hypertension), and oliguria (not concentrated urine), it is not typically associated with elevated urine specific gravity. Therefore, septic shock is not the most likely diagnosis in this context.
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