A client with chronic osteoarthritis is troubled by knee pain. Which pathophysiological process is contributing to the pain?

Disseminated intravascular coagulation (DIC) is a serious condition characterized by widespread activation of coagulation throughout the body, leading to both thrombosis and hemorrhage. Here's why option C is the correct choice:

A) Glucosuria and lethargy:

Glucosuria (presence of glucose in the urine) and lethargy are not typical findings associated with DIC. Glucosuria may indicate diabetes mellitus or renal dysfunction, while lethargy can result from various causes but is not specific to DIC.

B) Frothy urine and anorexia:

Frothy urine may indicate proteinuria, which can occur in conditions such as nephrotic syndrome, but it is not a characteristic finding of DIC. Anorexia (loss of appetite) is a nonspecific symptom that can occur in many conditions but is not directly related to DIC.

C) Hematuria and hemoptysis:

Correct. Hematuria (blood in the urine) and hemoptysis (coughing up blood) are common manifestations of DIC. In DIC, widespread activation of the coagulation cascade can lead to microthrombi formation in small blood vessels, resulting in tissue ischemia and bleeding. Hematuria and hemoptysis can occur due to bleeding from the urinary tract or respiratory system, respectively, as a result of DIC-induced coagulopathy.

D) Polyuria and productive cough:

Polyuria (excessive urination) and productive cough (cough with production of sputum) are not specific findings of DIC. Polyuria may occur in conditions such as diabetes mellitus or diuretic use, while productive cough can be seen in respiratory infections or chronic lung diseases but is not directly related to DIC.

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.