Key Definitions
Adrenaline: A hormone produced by the adrenal glands in response to stress or danger; prepares the body for the fight-or-flight response by increasing heart rate, breathing rate, and blood glucose.
Thyroxine: A hormone produced by the thyroid gland that controls the basal metabolic rate; regulated by negative feedback involving TSH from the pituitary gland.
Adrenal glands: A pair of endocrine glands located above the kidneys; produce adrenaline in response to stress signals from the nervous system.
Thyroid gland: An endocrine gland in the neck that produces thyroxine; controlled by TSH from the pituitary gland via negative feedback.
Fight-or-flight response: The physiological response to perceived threat; triggered by adrenaline to prepare the body for rapid physical action.
Metabolic rate: The speed at which chemical reactions take place in the body's cells; controlled in the long term by thyroxine.
Negative feedback: A control mechanism in which the body's response to a change acts to reverse or oppose that change, maintaining a stable internal condition.