1. Hormones attach to receptors on cells to trigger responses. Cells can up-regulate or down-regulate receptor production.
2. The document discusses different types of hormones including amino acids, proteins, steroids, and fatty acids. It also covers how hormones are deactivated after use.
3. The hypothalamus monitors the body's status and triggers hormone release from the pituitary gland, which then signals other endocrine glands to release their hormones.