Question

Experiments by Deutsch and colleagues allowed rats to eat until they were satiated and then withdrew a few milliliters of diet from their stomach using an implanted catheter. After the withdrawal, what did the rats do?

1) ate until they became obese.
2) reported no hunger pangs.
3) showed evidence of continued short-term satiety.
4) experienced periodic feelings of hunger.
5) ate enough food to replace that withdrawn from the stomach.

Answer 1

After having food removed from their stomachs, rats continued to eat until they had replaced the withdrawn amount, showcasing their physiological need to maintain satiety as controlled by the brain's hypothalamus and gastrointestinal signals.

Step-by-step explanation:

Based on the information provided and research by Deutsch and his colleagues, when rats were allowed to eat until they were satiated and then had a small amount of food removed from their stomachs via an implanted catheter, they ate enough food to replace that withdrawn from the stomach. This behavior supports findings on physiological mechanisms of hunger and satiety which include blood glucose levels, hormonal signals like leptin from fat cells, and the stomach and intestines' role in signaling satiety to the brain. These signals are largely regulated by the hypothalamus region of the brain.

In addition, the passage of food through the gastrointestinal tract also provides satiety signals to the brain. It plays a significant role in regulating food intake by signaling when the stomach is full. This acts as a feedback mechanism to reduce hunger and encourage the sensation of satiety.

Leptin, often referred to as the satiety hormone, is secreted by fat cells and influences the regulation of appetite according to the body's fat reserves. The occurrence of leptin resistance could contribute to pathological conditions such as obesity, where despite high-fat reserves, the feeling of satiety is impaired, leading to overeating.