The hypothalamus is a part of the brain that regulates many bodily functions, including hunger, thirst, and temperature. One of the ways that it helps regulate these functions is by secreting hormones through its connection with the pituitary gland. Let’s take a look at how the hypothalamus control pituitary secretion!
The hypothalamus controls pituitary gland secretion in two ways:
The pituitary gland secretes several hormones into the blood to control other hormone production. The hypothalamus controls the pituitary gland in two ways:
- By controlling the secretion of releasing and inhibiting hormones into the secondary capillary system, which connects the hypothalamus and anterior pituitary.
- By direct nervous stimulation via sympathetic nerves.
By controlling the secretion of releasing and inhibiting hormones into the secondary capillary system, which connects the hypothalamus and the anterior pituitary.
The hypothalamus also controls the secretion of releasing and inhibiting hormones into the secondary capillary system, which connects the hypothalamus and the anterior pituitary. This secondary capillary system carries blood to both tissues.
The anterior pituitary gland releases its hormones in response to its stimulation or in response to stimulation from other parts of your brain, including those that control it directly. For example, when your hypothalamus detects that you’re thirsty or hungry, it secretes a hormone called vasopressin or oxytocin. These hormones travel through this special pathway and reach their target cells, releasing them into your bloodstream by exocytosis (releasing contents outside cells).
The hormones travel through the bloodstream and reach their target cells. This process is called endocytosis, in which the cell membrane engulfs and surrounds the hormone. Then, once inside the cell, the hormone travels to another area for release into its appropriate location.
By direct nervous stimulation via sympathetic nerves.
In addition to its endocrine role, the hypothalamus plays a central role in regulating anterior pituitary secretion. It does so by secreting and releasing hormones that send signals to the anterior pituitary and directly stimulating it with sympathetic nerves.
These axons project from neurons of the hypothalamic paraventricular nucleus (PVN) to release acetylcholine onto their targets, which are also located in this region. The main effectors of these neurons are gonadotropes; they contain receptors for gonadotropin-releasing hormone (GnRH). This hormone binds to these receptors, then triggers them to release luteinizing hormone-releasing hormone (LHRH), which causes gonadotropin secretion from thyrotropes and corticotropes.
The hypothalamus has other areas that also play key roles in regulating anterior pituitary secretion. The median eminence is a portion of the hypothalamus that contains capillaries and blood vessels, and it receives axons from neurons in the PVN. These neurons release vasopressin-releasing peptide (VIP), which signals through receptors on these capillaries to cause vasopressin release into the bloodstream.
The PVN is also where neurons release corticotropin-releasing hormone (CRH), which signals through receptors on the capillaries to stimulate ACTH release. The arcuate nucleus contains neurons that release agouti-related peptide (AgRP) and neuropeptide Y (NPY), stimulating appetite and increasing metabolism.
The paraventricular nucleus contains neurons that release gonadotropin-releasing hormone (GnRH), which then stimulates the anterior pituitary to secrete luteinizing hormone-releasing hormone (LHRH). LHRH triggers the production of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
The hypothalamic–pituitary–adrenal axis is a series of interactions between the hypothalamus, pituitary gland, and adrenal cortex that control reactions to stress. This system is often colloquially referred to as the HPA axis or HPAA.
The hypothalamus controls pituitary secretion through various mechanisms. It can stimulate the release of hormones from the anterior lobe and inhibit other hormones’ release. The hypothalamus is rich in receptors for many different hormones and nutrients, which allows it to be responsive to a wide range of factors that might affect hormone levels in your body.