Multiple choice

When a person changes position from standing to lying down, which one of the following occurs?

  1. Heart rate increases and settles at a higher level.

  2. Venous return to the heart rises immediately.

  3. Cerebral blood flow becomes more than that in standing position and settles at a higher level.

  4. Decrease in blood flow to the lung apex.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When changing from standing to lying down, gravity no longer pulls blood downward into the legs, so venous return to the heart increases immediately. Heart rate may transiently decrease due to increased baroreceptor firing, not increase. Cerebral blood flow is relatively stable in both positions due to autoregulation. Pulmonary blood flow distribution becomes more uniform in the supine position.

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