Endocrine Glands & Feedback Loops

What are the endocrine functions of the gonads?

• Gonads = reproductive organs that produce sex cells and secrete sex hormones

  • Females: ovaries

  • Males: testes

What hormones are produced by these organs? What are their functions?

• Estrogen: Maturation of reproductive organs and secondary sex characteristics + Cause breast development and control of menstrual cycle

• Progesterone: Cause breast development and control of menstrual cycle

• Testosterone: Maturation of reproductive organs and secondary sex characteristics, production of sperm

How are hormones regulated?

Control of hormone secretion is required to regulate the amount of hormones released into the body. Often this control comes from feedback mechanisms. The thyroid feedback mechanism is a negative feedback. 

Label the steps of the feedback loop.

1. Hypothalamus secretes hormones into the pituitary

2. Pituitary secretes thyroid-stimulating hormone

3. Thyroid secretes thyroxine into blood, which increases metabolism

4. When thyroxine levels get too high, the hypothalamus is triggered to stop the impulse

What happens when endocrine glands function improperly?

Improper functioning of an endocrine gland may cause:

• Hyposecretion: not enough hormone is released

• Hypersecretion: too much hormone is released

All endocrine disorders are caused by either the hyposecretion or hypersecretion of hormones.

Summary: The endocrine system is controlled by feedback loops, like that of the hypothalamus–pituitary–thyroid system. If the glands of the endocrine system malfunction, it often results in the hypersecretion or hyposecretion of hormones.