gonadotropin-releasing hormone

Examples of gonadotropin-releasing hormone in the following topics:

• Male Hormones

  • The onset of puberty is controlled by two major hormones: FSH initiates spermatogenesis and LH signals the release of testosterone.
  • At the onset of puberty, the hypothalamus begins secreting high pulses of GnRH, or gonadotropin-releasing hormone.
  • In response, the pituitary gland releases follicle stimulating hormone (FSH) and luteinizing hormone (LH) into the male system for the first time.
  • The Sertoli cells produce the hormone inhibin, which is released into the blood when the sperm count is too high.
  • In turn, the testes production of testosterone and the hormone inhibin inhibit the release of GnRH, FSH, and LH in a negative feedback loop.

• Hormonal Regulation of the Reproductive System

  • During puberty, in both males and females, the hypothalamus produces gonadotropin-releasing hormone (GnRH), which stimulates the production and release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland.
  • These hormones regulate the gonads (testes in males and ovaries in females); they are called gonadotropins.
  • At the pituitary, GnRH stimulates the synthesis and secretion of the gonadotropins, FSH and LH.
  • FSH production is inhibited by the hormone inhibin, which is released by the testes.
  • Prolactin levels are regulated by the hypothalamic hormones, prolactin-releasing hormone (PRH) and prolactin-inhibiting hormone (PIH) (which is now known to be dopamine).

• Female Hormones

  • As with the male, the hypothalamic hormone GnRH (gonadotropin-releasing hormone) causes the release of the hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary.
  • Follicle cells produce the hormone inhibin, which inhibits FSH production.
  • Progesterone assists in endometrial re-growth and inhibition of FSH and LH release .
  • As the follicles grow, they begin releasing estrogens and a low level of progesterone.
  • This mature egg follicle may rupture and release an egg in response to a surge of LH.

• Organs with Secondary Endocrine Functions

  • Several organs with specialized non-endocrine functions possess endocrine roles, such as hormone production and release.
  • These cells release the hormone atrial natriuretic peptide (ANP) in response to increased blood volume .
  • High blood volume causes the cells to be stretched, resulting in hormone release.
  • It must be present for GnRH and gonadotropin synthesis to occur.
  • The hormone atrial natriuretic peptide (ANP), released in response to increased blood volume, is produced by endocrine cells in the heart.

• Humoral, Hormonal, and Neural Stimuli

  • The release of hormones can be triggered by changes in the blood ("humor"), by the actions of other hormones, or by neurological stimuli.
  • Hormonal stimuli refers to the release of a hormone in response to another hormone.
  • A number of endocrine glands release hormones when stimulated by hormones released by other endocrine glands.
  • The anterior pituitary, in turn, releases hormones that regulate hormone production by other endocrine glands.
  • This in turn causes the release of the hormones T3 and T4.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • The primary class of lipid hormones in humans is the steroid hormones.
  • These two hormones are released by the female and male reproductive organs, respectively.
  • Other steroid hormones include aldosterone and cortisol, which are released by the adrenal glands along with some other types of androgens.
  • The peptide hormones include molecules that are short polypeptide chains, such as antidiuretic hormone and oxytocin produced in the brain and released into the blood in the posterior pituitary gland.
  • They are then released in response to stimuli (e.g., as high blood glucose levels in the case of insulin).

• Hormone Functions

  • The endocrine system plays a role in growth, metabolism, and other processes by releasing hormones into the blood.
  • Communication between neighboring cells and between cells and tissues in distant parts of the body occurs through the release of hormones into body fluids (usually blood), which carry them to their target cells.
  • Target cells, those having a receptor for a signal, respond to a hormone when they express a specific receptor for that hormone.
  • Different tissue types may also respond differently to the same hormonal signal.
  • By releasing hormones, the endocrine system plays a role in growth, metabolism, and sexual development.

• Hypothalamic-Pituitary Axis

  • The anterior portion of the pituitary gland is regulated by releasing or release-inhibiting hormones produced by the hypothalamus.
  • These regulatory hormones can be releasing hormones or inhibiting hormones, causing more or less of the anterior pituitary hormones to be secreted.
  • Negative feedback then regulates how much of these regulatory hormones are released and how much anterior pituitary hormone is secreted.
  • The posterior pituitary itself does not produce hormones, but instead stores hormones produced by the hypothalamus, releasing them into the blood stream.
  • Describe the hormones released by the anterior posterior pituitary and their effects on the body

• How Hormones Work

  • Hormones are chemical messengers that relay messages to cells that display specific receptors for each hormone and respond to the signal.
  • A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism.
  • All multicellular organisms produce hormones; plant hormones are also called phytohormones.
  • Hormones mediate changes in target cells by binding to specific hormone receptors.
  • Cells respond to a hormone when they express a specific receptor for that hormone.

• Hormonal Responses to Food

  • The endocrine system controls the release of hormones responsible for starting, stopping, slowing, and quickening digestive processes.
  • The endocrine system controls the response of the various glands in the body and the release of hormones at the appropriate times.
  • These hormones are chemical mediators released from endocrine tissue into the bloodstream where they travel to target tissue and generate a response.
  • However, when the stomach is emptied, the acidic environment need not be maintained and a hormone called somatostatin stops the release of hydrochloric acid.
  • These hormones are released from endocrine tissue to generate specific controls in the digestion of chyme.