Developmental Aspects of the Endocrine System

Hormone-producing glands arise from

all three germ layers during embryonic development 

Effects of Environmental Pollutants

• Exposure to pesticides, industrial chemicals, arsenic, dioxin, and soil and water pollutants disrupts hormone function

• Sex hormones, thyroid hormone, glucocorticoids are all vulnerable to effects of pollutants

• Interference with glucocorticoids may help explain high cancer rates in certain areas 

• Most endocrine organs operate well until

old age

• GH levels decline with

age: accounts for muscle atrophy with age

TH declines with

age, contributing to lower basal metabolic rates

PTH levels remain fairly constant with

age

• lack of estrogen in older women makes them more vulnerable to bone-demineralizing effects of PTH

Glucose tolerance deteriorates with

age

Ovaries undergo significant changes with

age

• become unresponsive to gonadotropins; problems associated with estrogen deficiency occur

Testosterone diminishes with

age,

• effect is not usually seen until very old age