Questions: Receptors interact with body substances. Which of the following is NOT one of those body substances? hormones neurotransmitters enzymes antigens

The answer is: enzymes.

Explanation for each option:

1. Hormones: Hormones are chemical messengers that travel through the bloodstream to tissues or organs. They interact with specific receptors on the surface of or inside target cells to exert their effects. Therefore, hormones are body substances that interact with receptors.

2. Neurotransmitters: Neurotransmitters are chemical messengers that transmit signals across a chemical synapse, such as between a neuron and another neuron, muscle cell, or gland cell. They bind to receptors on the target cell to initiate a response. Thus, neurotransmitters are body substances that interact with receptors.

3. Enzymes: Enzymes are biological catalysts that speed up chemical reactions in the body. They typically interact with substrates (the substances they act upon) rather than receptors. Therefore, enzymes are not body substances that interact with receptors.

4. Antigens: Antigens are substances that can induce an immune response, often by binding to specific receptors on immune cells, such as antibodies or T-cell receptors. Hence, antigens are body substances that interact with receptors.

Summary: Enzymes are not one of the body substances that interact with receptors, unlike hormones, neurotransmitters, and antigens.