Thyroxine is made by the thyroid gland in the neck. It controls the metabolic rate, which is how fast the reactions in the body's cells happen. Thyroxine is also needed for normal growth and development.
Thyroxine level is kept steady by negative feedback. If the level in the blood falls below normal, the pituitary gland releases more TSH (thyroid stimulating hormone). TSH makes the thyroid gland release more thyroxine, so the thyroxine level rises. When the level is high, the pituitary releases less TSH, so the thyroid makes less thyroxine. In negative feedback the response reverses the original change and brings the level back to normal.
Adrenaline is made by the adrenal glands, which sit above the kidneys. It is released in frightening or stressful situations and prepares the body for fight or flight. Adrenaline makes the heart beat faster and breathing quicker, so more blood carrying oxygen and glucose reaches the muscles. It also makes the liver release glucose into the blood and widens the pupils.
