- Hormones are chemical messengers that travel in the blood to activate target cells
- They are carried in the blood plasma to other parts of the body, but they only affect target cells
- They are released directly into the blood
- Hormones are secreted by various glands
- Hormones tend to have long-lasting effects
- They travel at the "speed of blood"
The Pituitary Gland
- secretes many important hormones…