Which one of the following is incorrect statement?

Options

A. The site of actual diffusion of gases between blood and atmospheric air is called exchange part of lungs.
B. Inspiration is initiated by the contraction of diaphragm and internal inter-costal muscles.
C. A healthy man inspire or expire approximately 6000 to 8000 ml of air per minute.
D. About 97 percent oxygen is transported by RBC in the blood.

Answer

To determine which statement is incorrect, let's analyze each option provided in the question step by step.

### Step 1: Analyze the first statement
**Statement:** The actual site of the diffusion of gases between the blood and the atmospheric air is called the exchange part of the lungs.

**Analysis:** This statement is correct. The exchange of gases (oxygen and carbon dioxide) occurs in the alveoli of the lungs, which is indeed referred to as the exchange part of the lungs.

### Step 2: Analyze the second statement
**Statement:** Inspiration is initiated by the contraction of diaphragm and internal intercostal muscles.

**Analysis:** This statement is incorrect. During inspiration, the diaphragm contracts and moves downwards, while the external intercostal muscles contract to raise the rib cage. The internal intercostal muscles are primarily involved in expiration, not inspiration.

### Step 3: Analyze the third statement
**Statement:** A healthy man inspires or expires approximately 6000 to 8000 ml of air per minute.

**Analysis:** This statement is correct. A healthy adult typically has a tidal volume (the amount of air inhaled or exhaled in one breath) of about 500 ml, and with normal breathing rates, the total volume can reach approximately 6000 to 8000 ml of air per minute.

### Step 4: Analyze the fourth statement
**Statement:** About 97% of the oxygen is transported by the RBCs in the blood.

**Analysis:** This statement is correct. Approximately 97% of oxygen in the blood is carried by red blood cells (RBCs) bound to hemoglobin, which is essential for oxygen transport.

### Conclusion
After analyzing all the statements, the incorrect statement is the second one: "Inspiration is initiated by the contraction of diaphragm and internal intercostal muscles."

### Final Answer
The incorrect statement is: **Inspiration is initiated by the contraction of diaphragm and internal intercostal muscles.**

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