The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system and male secondary sex characteristics.
Testosterone causes an increase in muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks.
Estrogens, made in the ovary, most importantly estradiol, are responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics.
In mammals, progestins, which include progesterone, are primarily involved in preparing and maintaining the uterus.
Synthesis of the sex hormones is controlled by FSH and LH from the anterior pituitary.
The pineal gland, located in the brain, secretes melatonin.
Light/dark cycles control release of melatonin.
Primary functions of melatonin appear to relate to biological rhyths associated with reproduction.
Signal Transduction Pathway
Low blood glucose
Pancreas alpha cells
Glycogen breakdown, glucose release into blood
You should now be able to:
Distinguish between the following pairs of terms: hormones and local regulators, paracrine and autocrine signals.
Describe the evidence that steroid hormones have intracellular receptors, while water-soluble hormones have cell-surface receptors.
Explain how the antagonistic hormones insulin and glucagon regulate carbohydrate metabolism.
Distinguish between type 1 and type 2 diabetes.
Explain how the hypothalamus and the pituitary glands interact and how they coordinate the endocrine system.
Explain the role of tropic hormones in coordinating endocrine signaling throughout the body.
List and describe the functions of hormones released by the following: anterior and posterior pituitary lobes, thyroid glands, parathyroid glands, adrenal medulla, adrenal cortex, gonads, pineal gland.