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The Brain, Neurons and Brain Chemistry

Author(s): Nancy P. Moreno, PhD, Barbara Z. Tharp, MS, and Tadzia GrandPré, PhD

A Balance of Chemicals

Our bodies’ reactions to stress are controlled by the brain. Immediate stress responses are directed through pathways in the brainstem and spinal cord to the major internal organs of the body. However, chemicals circulating in the bloodstream also help prepare the body to handle a crisis. The brain coordinates the release of these chemicals, which belong to the family of messengers known as hormones. 

Unlike the chemical messengers between neurons (neurotransmitters), hormones can have wide-reaching effects on many different body tissues at the same time. Hormones, which circulate in the bloodstream, act as messengers to the nervous system and other tissues in the body. They act only on cells that have compatible receptors. 

Hormones have many vital functions in mammals, such as regulating digestion; controlling the metabolism of sugars, proteins and fats; and regulating growth and development. Many of our most basic drives—sleeping, hunger, thirst, sex—are regulated through hormones. 

The master control system for all hormones is located within the brainstem. Known as the hypothalamus, this small structure interconnects with many regions of the brain. It is adjacent to the pituitary gland, which produces hormones that control other glands in the body. Together, the hypothalamus and the pituitary gland regulate many different body functions. 

During periods of stress, these tiny structures direct the two small adrenal glands near the kidneys to produce hormones, such as adrenaline (also called epinephrine), that prepare the body for action.

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Funded by the following grant(s)

NIH Blueprint for Neuroscience Research Science Education Award, National Institute on Drug Abuse, and NIH Office of the Director

The Learning Brain: Interactive Inquiry for Teachers and Students
Grant Number: 5R25DA033006

Science Education Partnership Award, NIH

Filling the Gaps: K-6 Science/Health Education
Grant Number: 5R25RR013454