Big Idea: Animals use various chemicals to send signals within their bodies. Rather than grouping them by what they look like, we classify them based on their job.

• What Are They? Tiny chemical messengers made by special cells and then sent around the body via blood.

• From Where? From glands! There are two types

  • Endocrine glands: Directly release hormones into the bloodstream.
  • Exocrine glands: Use a duct to move their secretions.

• Target and Effect: These messengers don't just go anywhere; they have a specific destination called target cells. Here's the twist - only cells with the right receptors will understand the hormone's message!

• How long do they stay? They can hang around for hours. Unlike a quick text, hormones are more like a long, heartfelt email.

• Real-world Example: When you're hungry, a hormone called insulin helps your body use or store sugar. Also, ever wondered why some guys have deeper voices? Thank testosterone for that!

• What Are They? They're the Uber drivers of the nervous system, carrying messages across a tiny gap called a synapse between two neurons.

• The Process: One neuron (presynaptic) sends a neurotransmitter, and the one across the gap (postsynaptic) picks it up.

• Duration: Imagine the fastest thing ever! Now speed it up. That’s how quickly neurotransmitters work - gone in a flash! Unlike the long visit from hormones, these guys bounce in and out real quick.

• Real-world Example: Feeling thrilled on a roller coaster? Thank dopamine for that rush!