Endocrine System - Abnormalities
Introduction
The endocrine system has an ongoing important role in embryonic, fetal and postnatal development as well as maintainance of homeostasis and reproductive function. There exists a complex interaction between the maternal and fetal endocrine system during development and failure for fetal endocrine development has a cascading effect on many other developing systems. There are additional pages covering abnormalities of specific endocrine organs.
In addition to many genetic effects, we now know that there are many potential environmental factors which can impact upon development.
The endocrine system resides within specific endocrine organs and both organs and tissues with other specific functions. Epithelia (ectoderm and endoderm) form the majority of the “ductless” endocrine glands like gastrointestinal and skin associated “ducted” glands. Differentiation of several also organs involves a epithelial/mesenchye interaction, seen in repeated in many differentiation of many different tissues. The endocrine glands produce hormones, which are distributed by the vascular system to the many body tissues, subsequently these organs are richly vascularized.
Hormones are recognised by either cell surface receptors (modified amino acids, peptides, proteins) or cytoplasmic/nuclear receptors (steroids). Hormones “orchestrate” responses in other tissues, including other endocrine organs, and these overall effects can be similar or different in different tissues. In addition, these hormone effects (like music) can be rapid, slow, brief, diurnal, or long-term. Hormone effects can be mimicked, stimulated, and blocked by therapeutic drugs, nutritional and environmental chemicals.
The human fetus is dependent upon endocrine development for hormones, which support normal development. Peripheral endocrine glands (thyroid, pancreas, adrenals, gonads) form early in the second month from epithelial/mesenchye interactions and differentiate into the third month. The fetus also has a unique hormonal system that combines not only its own developing endocrine system, but also that of the placenta (More? see Placenta notes) and maternal hormones.
Abnormal endocrine development/function can impact on many different systems. For example, insufficient maternal dietary iodine impacts on fetal thyroid gland thyroid hormone production, which in turn can lead to abnormal neural development. Alternatively, we now know many environmental and therapeutic chemicals have a wide range of effects on the endocrine system.
Sex hormones from the gonads have significant effects prenatally and postnatally, specifically at puberty with a role to play in male/female biological maturity and have wide actions throughout the body.
