Question

system physiology
practice it
what is endocrine signaling?
a type of signaling where the signal molecule acts on the same cell that released it
a type of signaling where the signal molecule acts on cells in a different tissue
when a signal molecule is released into the bloodstream to reach distant target cells
a type of signaling that involves the release of hormones into the bloodstream
a type of signaling that occurs between adjacent cells

Explanation:

Endocrine signaling is a form of cell - to - cell communication. Hormones are the signaling molecules in endocrine signaling. These hormones are secreted by endocrine glands directly into the bloodstream. The bloodstream then transports these hormones to distant target cells throughout the body. For example, the thyroid gland secretes thyroid hormones which are carried by the blood to various organs and tissues to regulate metabolism.

Answer:

When a signal molecule is released into the bloodstream to reach distant target cells.