Labster Logo

Hormonal feedback

The body uses a variety of mechanisms to keep hormone levels tightly regulated. A critical mechanism is using feedback loops in which a hormone, such as estrogen, feeds back to control its own production. This can be either a positive or a negative feedback loop.

In a negative feedback loop, a stimulus, such as a hormone or a neurotransmitter, causes the release of a product, such as estrogen. When the product reaches a certain level in the bloodstream, it signals to the hypothalamus and anterior pituitary to stops further release of the stimulating hormone or neurotransmitter and thereby leads to reduced levels of the product. For example, testosterone, progesterone and estrogen impact the hypothalamus and anterior pituitary production of GnRH, FSH and LH, via negative feedback to reduce their own production.

The positive feedback loop is the opposite loop. A product signals to produce more of the stimulating hormone or neurotransmitter which causes a continuous increase of the product.

Some of the hormones that act in these ways are seen highlighted in orange in the figures below.

Female reproductive feedback loops:

This diagram shows how hormones control the female reproductive cycle through feedback loops. At the top, the hypothalamus releases a hormone called the Gonadotropin-releasing hormone (GnRH). This hormone signals the anterior pituitary gland to release two more hormones — Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH). These hormones travel to the ovaries, where they trigger the production of estrogen and progesterone. These ovarian hormones then act on the uterus, helping prepare it for a possible pregnancy. The system is controlled by two types of feedback loops. A positive feedback loop increases hormone release when estrogen levels rise. A negative feedback loop slows down hormone release when the levels become too high. Together, these feedback loops keep the hormonal cycle balanced and coordinate communication between the hypothalamus, the pituitary gland, and the ovaries.

Male reproductive feedback loops:

This diagram shows how hormones regulate the male reproductive system through feedback loops. At the top, the hypothalamus releases Gonadotropin-releasing hormone (GnRH), which stimulates the anterior pituitary gland. The anterior pituitary then releases two hormones — Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH). FSH acts on the Sertoli cells, while LH acts on the Leydig cells, both found in the testes. The Sertoli cells produce inhibin, and the Leydig cells produce testosterone. The testosterone provides negative feedback to the hypothalamus and pituitary gland, helping to reduce further hormone release when levels are high. Overall, the diagram shows how the hypothalamus, pituitary gland, and testes communicate through hormones to regulate sperm production and testosterone levels.