Hormones and Homeostasis
Endocrine glands release chemical messengers (hormones) that help regulate function throughout the body. Sometimes these glands fail to respond to normal feedback loops, resulting in a disruption of homeostasis. For example, the pituitary gland, located in the brain, secretes human growth hormone. If cells in the gland produce too much of this hormone, a person will continue to grow far above average height. The result is a condition known as gigantism (top left image).
If the cells produce too little of the hormone, a person will grow to far less than average height. This condition is known as dwarfism (top right image).