Explanation

Extracellular signaling in animals can be carried out by:

• Endocrine signaling: This involves the release of hormones into the bloodstream, which then travel to reach distant target cells. Examples include insulin and adrenaline.
• Paracrine signaling: This involves the release of signaling molecules into the extracellular space, which then diffuse to nearby target cells. Examples include histamine and prostaglandins.
• Autocrine signaling: This involves the release of signaling molecules that bind to receptors on the same cell that produced them. Examples include autocrine growth factors.
• Juxtacrine signaling: This involves the release of signaling molecules that bind to receptors on adjacent cells. Examples include signaling through cell-cell contacts.