pituitary gland

Examples of pituitary gland in the following topics:

• Hypothalamic-Pituitary Axis

  • The hypothalamus, an endocrine organ, regulates the anterior pituitary gland and transports hormones along the posterior pituitary gland.
  • The hypothalamus also synthesizes and secretes regulatory hormones that control the endocrine cells in the anterior pituitary gland.
  • The pituitary gland, sometimes called the hypophysis or "master gland," is located at the base of the brain in the sella turcica, a groove of the sphenoid bone of the skull.
  • The anterior portion of the pituitary gland is regulated by releasing or release-inhibiting hormones produced by the hypothalamus.
  • The pituitary gland is located at (a) the base of the brain and is (b) connected to the hypothalamus by the pituitary stalk.

• Humoral, Hormonal, and Neural Stimuli

  • A number of endocrine glands release hormones when stimulated by hormones released by other endocrine glands.
  • For example, the hypothalamus produces hormones that stimulate the anterior portion of the pituitary gland.
  • The anterior pituitary, in turn, releases hormones that regulate hormone production by other endocrine glands.
  • The anterior pituitary releases the thyroid-stimulating hormone (TSH), which then stimulates the thyroid gland to produce the hormones T3 and T4 .
  • The hypothalamus stimulates the anterior pituitary gland, via hormones, to release thyroid-stimulating hormone (TSH).

• Hormonal Regulation of the Reproductive System

  • Regulation of the reproductive system is a process that requires the action of hormones from the pituitary gland, the adrenal cortex, and the gonads.
  • 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.
  • In addition to producing FSH and LH, the anterior portion of the pituitary gland also produces the hormone prolactin (PRL) in females.
  • Prolactin stimulates the production of milk by the mammary glands, following childbirth.
  • GnRH, secreted by the hypothalamus, stimulates the production of FSH and LH from the pituitary gland.

• Hormonal Regulation of the Excretory System

  • The anterior pituitary is composed of glandular cells that secrete protein hormones.
  • The pituitary gland has two components: anterior and posterior.
  • The posterior pituitary is an extension of the hypothalamus.
  • The hypothalamus produces a polypeptide hormone known as antidiuretic hormone (ADH), which is transported to and released from the posterior pituitary gland.
  • If the posterior pituitary does not release enough ADH, water cannot be retained by the kidneys and is lost as urine.

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

  • Other steroid hormones include aldosterone and cortisol, which are released by the adrenal glands along with some other types of androgens.
  • Examples of amino acid-derived hormones include epinephrine and norepinephrine, which are synthesized in the medulla of the adrenal glands, and thyroxine, which is produced by the thyroid gland.
  • The pineal gland in the brain makes and secretes melatonin, which regulates sleep cycles.
  • 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.
  • This class also includes small proteins, such as growth hormones produced by the pituitary, and large glycoproteins, such as follicle-stimulating hormone produced by the pituitary .

• Hormonal Regulation of Growth

  • Body growth is controlled by growth hormone (GH), produced by the anterior pituitary, and IGF-1, whose production is stimulated by GH.
  • Growth hormone (GH), produced by the anterior portion of the pituitary gland, accelerates the rate of protein synthesis, particularly in skeletal muscle and bones.
  • Underproduction of GH in adults does not appear to cause any abnormalities, but in children it can result in pituitary dwarfism, in which growth is reduced.
  • Pituitary dwarfism is characterized by symmetric body formation.

• Hormonal Regulation of Stress

  • The adrenal glands respond to either short-term or long-term stressors by releasing different hormones that act differently on the body.
  • Stressful stimuli cause the hypothalamus to signal the adrenal medulla (which mediates short-term stress responses) via nerve impulses, and the adrenal cortex, which mediates long-term stress responses via the hormone adrenocorticotropic hormone (ACTH), which is produced by the anterior pituitary.
  • In a long-term stress response, the hypothalamus triggers the release of ACTH from the anterior pituitary gland.
  • Describe the role of the adrenal glands in the "fight-or-flight" response and the body's reaction to stress

• Thyroid Gland

  • The thyroid gland, the largest endocrine gland, is responsible for the production of the hormones T3, T4, and calcitonin.
  • The thyroid gland, one of the largest endocrine glands in the body, is located in the neck, just below the larynx and in front of the trachea .
  • It is a butterfly-shaped gland with two lobes that are connected by the isthmus.
  • Follicle cells are stimulated to release stored T3 and T4 by thyroid-stimulating hormone (TSH), which is produced by the anterior pituitary.
  • The location of the thyroid gland is in the neck below the larynx and in front of the trachea; it is the largest endocrine gland in the body, producing T3, T4, and calcitonin.

• Labor and Birth

  • This causes the cervix to stretch, sending nerve impulses to the hypothalamus, which signals for the release of oxytocin from the posterior pituitary.
  • A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin.
  • The mother's mammary glands go through changes during the third trimester to prepare for lactation and breastfeeding.
  • When the baby begins suckling at the breast, signals are sent to the hypothalamus causing the release of prolactin from the anterior pituitary, which signals the mammary glands to produce milk.

• Female Hormones

  • The stages of the ovarian cycle in the female are regulated by hormones secreted by the hypothalamus, pituitary, and the ovaries.
  • 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.
  • The endometrium begins to regrow, replacing the blood vessels and glands that deteriorated during the end of the last cycle.
  • The decrease in progesterone also allows the hypothalamus to send GnRH to the anterior pituitary, releasing FSH and LH to start the cycles again .
  • The ovarian and menstrual cycles of female reproduction are regulated by hormones produced by the hypothalamus, pituitary, and ovaries.