Question

Why nicotine increases the heart rate. How would the addition of nicotine affect the homeostasis in Daphnia and humans? (please answer in a short paragraph)

Answer 1

Nicotine causes constriction (narrowing) of the blood vessels thus limiting the amount of oxygen reaching the organs in the body. This constriction if remains constant overtime can lead to stiffening of the blood vessels eventually. In order to receive more oxygen, the heart rate may increase. The decrease in the amount of oxygen may also lead to enlargement of the heart. These changes in structure and function of the blood vessels and the heart leads to increase in blood pressure and heart rate.

The addition of nicotine affects homeostasis to a great extent. Exposure to nicotine from cigarette smoke especially can alter brain feeding regulation to reduce appetite through both energy homeostatic and reward mechanisms. This leads to a negative energy state which is characterized by reduced energy intake and increased energy expenditure. This is how homeostasis affects humans and daphnia.