All of the following statement about a normal subject in the erect position are true EXCEPT
**Core Concept**
The question is testing knowledge of the physiological changes that occur in a normal subject in the erect position. This involves understanding the effects of gravity on blood distribution, cardiac output, and intrathoracic pressure.
**Why the Correct Answer is Right**
In the erect position, gravity causes a pooling of blood in the lower extremities. This results in a decrease in peripheral resistance and a subsequent increase in cardiac output to compensate for the decreased effective circulating volume. Additionally, the erect position increases intrathoracic pressure due to the effects of gravity on the abdominal contents.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided.
**Option B:** This option is not provided.
**Option C:** This option is not provided.
**Option D:** This option is not provided.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the erect position can lead to a decrease in effective circulating volume, which can result in a decrease in blood pressure. This is why patients are often placed in the supine position for blood pressure measurement.
**Correct Answer:**
Unfortunately, the options A, B, C, and D are not provided, so I am unable to give a correct answer.