Final answer:
Hormones serve as chemical signals between cells and stimulate a wide range of nonspecific defenses. For example, Adrenaline (Epinephrine) and Noradrenaline (Norepinephrine) mediate the "fight or flight" response, increasing heart rate and mobilizing energy. Hence, option (a) is correct.
Step-by-step explanation:
The chemical signals that serve as chemical signals between cells and stimulate a wide range of nonspecific defenses are hormones. Hormones are secreted by endocrine glands and travel through the bloodstream to target cells. They play a crucial role in regulating various physiological processes and can also coordinate the immune response.
Hormones travel through the bloodstream and bind to specific receptors on target cells, influencing their function. The endocrine system, together with the nervous system, helps maintain homeostasis by controlling processes such as metabolism, growth and development, immune function, mood, and reproduction.
For example, Insulin regulates blood glucose levels by promoting the uptake of glucose into cells. Adrenaline and Noradrenaline stimulate the "fight or flight" response, increasing heart rate and mobilizing energy in case of excited and fearful situations. Thyroid Hormones (T3 and T4) regulate metabolism and energy production.