What is a hormone? Multiple Choice: O a chemical released from a nerve cell that affects nearby cells across a synapse O a chemical released from an endocrine gland that affects target cells without entering the bloodstream O a chemical found in the blood that catalyzes the destruction of ingested toxins and foreign substances O a chemical excreted from sweat gland that signals other individuals about the physiological status of the body O a chemical regulator secreted from an endocrine gland that travels through the bloodstream to affect target cells

A chemical regulator secreted from an endocrine gland that travels through the bloodstream to affect target cells

Explanation:

Hormones are the chemicals that serve as signaling molecules and regulate activities of their respective target cells. Hormones are secreted by ductless endocrine glands. Being ductless glands, they release hormones directly into the bloodstream. Therefore, hormones travel through the bloodstream to reach their target cells. Binding of receptors present on or in the target cells is followed by signal transduction and generation of a cellular response.

For example, the insulin hormone is released into the bloodstream by the pancreas. The hormone stimulates the uptake of glucose by liver and muscle cells (the target cells).

A chemical regulator secreted from an endocrine gland that travels through the bloodstream to affect target cells