Hormone pathway: Metabolism (thyroid stimulating hormone)

• Increases metabolic rate by regulating T3 and T4, TSH indirectly boosts energy consumption. Essential for normal growth and maturation, especially of the nervous system
• Stimulus: Low levels of T3 and T4 
• Low levels of T3 and T4 are registered by the hypothalamus
• Hypothalamus: releases thyrotropin releasing hormone (TRH)
• Pituitary: secretes TSH, which acts on the thyroid gland to increase T3 and T4 production
• Response: increase in T3 and T4 hormones
• Feedback: High levels of T3 and T4 inhibit TRH and TSH production, maintaining hormonal balance