Negative Feedback

• Where are the adrenal glands located and what do they do?

  At the top of the kidneys, during times of fear or stress, the adrenal glands produce the hormone adrenaline which is released into the blood. One of the main effects of adrenaline is to increase the heart rate, this means that more oxygen and glucose are delivered in the blood to the brain and muscles. Both oxygen and glucose are needed for aerobic respiration, this prepares the body to either fight or run away.
• Where are the thyroid glands located and what do they do?

  Found in the base of the neck and releases the hormone thyroxine which has two main effects. Firstly it stimulates the body's basal metabolic rate (thyroxine makes the body's chemical reactions take place at a faster rate). Secondly thyroxine plays an important role in growth and development. The level of thyroxine in the blood is controlled by negative feedback.
• What is negative feedback?

  If the level of a hormone falls, events are triggered which cause the level of hormone to increase. If the level of a hormone is too high, events are triggered to bring it back down. This is called a negative feedback cycle.
• What negative feedback cycles are there in the body?

  In the control of blood glucose and in the menstrual cycle.