Chapter 1: Overview of the Endocrine System
2. Hormones and Their Roles
- Hormones are chemical messengers synthesized by specialized glands or cells, released into and travel through the bloodstream to target organs, where they modulate various functions such as growth, metabolism, reproduction, and mood.
- They act on target cells with specific receptors to a particular hormone, influencing:
- Metabolism (e.g., insulin, thyroid hormones)
- Growth, development and aging (e.g., growth hormone, sex steroids)
- Sexual differentiation (sex steroids)
- Reproductive processes (e.g., estrogen, testosterone)
- Behavior: courtship, mating, maternal behavior
- Local effects on specific organs;
o development of the follicle
o uterine changes (menstrual cycle)
o maintenance of pregnancy
o initiation of labor
o milk secretion and ejection
- Homeostasis (e.g., ADH, aldosterone). Major homeostatic variables controlled by the endocrine system:
- Temperature
- Nutrients
- Oxygen
- Pressure
- Ion concentrations
- pH
- Toxic chemicals