The fluid coming out of proximal convoluted tubule has a concentration of about

Options

A. 200 mosmol/liter
B. 300 mosmol/liter
C. 600 mosmol/liter
D. 1200 mosmol/liter

Answer

To find the concentration of fluid coming out of the proximal convoluted tubule (PCT), we can follow these steps:

### Step 1: Understand the Structure of the Nephron
The nephron is the functional unit of the kidney, consisting of several parts: Bowman's capsule, proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and collecting duct. Each part has a specific function in the process of urine formation.

**Hint:** Remember that the nephron is the basic structural and functional unit of the kidney, and each part plays a role in filtering blood and forming urine.

### Step 2: Identify the Role of the Proximal Convoluted Tubule
The PCT is responsible for the reabsorption of water, electrolytes, and nutrients from the filtrate back into the blood. It is highly coiled and located in the cortex of the kidney.

**Hint:** Focus on the functions of the PCT, especially its role in reabsorbing essential substances.

### Step 3: Understand the Filtration Process
In the Bowman's capsule, blood is filtered, and the filtrate that enters the PCT contains various substances, including water, electrolytes, and waste products. The concentration of this filtrate is influenced by the reabsorption processes that occur in the PCT.

**Hint:** Consider how the initial filtrate composition changes as substances are reabsorbed in the PCT.

### Step 4: Determine the Concentration of the Filtrate
The concentration of the fluid coming out of the PCT is approximately 300 milliosmoles per liter (mOsm/L). This is because the PCT is located in the cortex of the kidney, where the concentration of the filtrate is lower compared to the deeper parts of the nephron, such as the loop of Henle.

**Hint:** Remember that the concentration in the PCT is lower than in the medulla due to the reabsorption of water and solutes.

### Step 5: Conclusion
Thus, the concentration of fluid coming out of the proximal convoluted tubule is about 300 mOsm/L.

**Final Answer:** 300 milliosmoles per liter (mOsm/L).