Summary

The endocrine_system uses chemical messengers called hormones to regulate body functions. Major glands: pituitary_gland, thyroid_gland, parathyroid_glands, adrenal_glands, pancreas, and gonads. In aging, common patterns include lower sex_hormones and growth_hormone, slower metabolism, altered glucose_control from reduced insulin_sensitivity, and changes in stress_response and fluid balance. Older adults often show mild declines in T3_levels with stable T4_levels, and reduced renin_aldosterone. Remember that hormone shifts can affect energy, muscle, and bone_health.