Questions: Hailey is babysitting her 2-year-old nephew for the first time. While her back is turned, he touches his index finger to the pan she just took out of the oven. He pulls his finger away quickly, and a few seconds later begins to scream. Why does it take longer for him to scream than to pull away his finger? The hand-withdrawal reflex involves only the spinal cord, so it takes time before the information about pain reaches the brain. It takes longer to sense something than to understand the consequences of an action. He knew he would get in trouble if he started screaming, so he held it in as long as he could. His parasympathetic system was activated to arouse him, which stifled his vocal reaction.

The answer is the first one: The hand-withdrawal reflex involves only the spinal cord, so it takes time before the information about pain reaches the brain.

Explanation for each option:

1. The hand-withdrawal reflex involves only the spinal cord, so it takes time before the information about pain reaches the brain.

   • This is correct. The reflex action to pull the finger away from the hot pan is a spinal reflex, which means it is processed by the spinal cord and does not require input from the brain. This allows for a rapid response to prevent further injury. The sensation of pain, however, is processed by the brain, which takes a bit longer to occur, hence the delay in the scream.

2. It takes longer to sense something than to understand the consequences of an action.

   • This is incorrect. The sensation of pain is typically immediate, but the understanding of consequences is a cognitive process that involves the brain. The delay in screaming is not due to understanding consequences but rather the time it takes for the pain signal to reach the brain.

3. He knew he would get in trouble if he started screaming, so he held it in as long as he could.

   • This is incorrect. A 2-year-old child is unlikely to have the cognitive ability to suppress a scream due to fear of getting in trouble. The delay is due to the physiological process of pain signal transmission.

4. His parasympathetic system was activated to arouse him, which stifled his vocal reaction.

   • This is incorrect. The parasympathetic system is responsible for rest and digest functions and would not be involved in stifling a vocal reaction to pain. The sympathetic nervous system is more likely to be involved in a stress response, but it does not stifle vocal reactions.

In summary, the delay in the scream is due to the time it takes for the pain signal to travel from the site of injury to the brain, whereas the reflex to pull the finger away is processed by the spinal cord for a quicker response.