jueves, 5 de mayo de 2011

Hypothalamus and pituitary gland

The hypothalamus is a portion of the brain located in its lower central part. The hypothalamus is the primary link between the endocrine and nervous systems. Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary.
Pituitary Gland
The pituitary gland is about the size of a pea and is attached the hypothalamus by a thin stalk at the base of the brain, shown in Figure. The pituitary gland is considered the most important part of the endocrine system. It's often called the "master gland" because it makes hormones that control several other endocrine glands called tropic hormones. The pituitary hormones regulate homeostasis.
Both of the lobes are under the control of the hypothalamus so the production and secretion of pituitary hormones can be influenced by factors such as emotions and seasonal changes.
The pituitary gland consists of two components:

The anterior pituitary (front lobe), makes many important hormones:
Among the hormones it produces are:

  • Growth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body's handling of nutrients and minerals

  • Prolactin, which activates milk production in women who are breastfeeding

  • Thyrotropin, which stimulates the thyroid gland to produce thyroid hormones

  • Corticotropin, which stimulates the adrenal gland to produce certain hormones

  • Gonadotropin, which stimulates the gonades (ovaries or testes)
Most of these hormones are released under the influence of chemicals from the hypothalamus.
The posterior pituitary (rear lobe), releases two hormones:

  • oxytocin which triggers the contractions of the uterus that occur during the labour and delivery process.

  • antidiuretic hormone (ADH) which helps control body water balance through its effect on the kidneys and urine output.
Oxytocin creates a positive feedback loop. During the labor and delivery process, when the cervix dilates the uterus contracts. Uterine contractions stimulate the release of oxytocin from the posterior pituitary, which in turn increases uterine contractions. This positive feedback loop continues until the baby is born.
Eventually this video will help you to learn the endocrine functions ( you don't need to pay attention to how hyphotlamus stimulates the pituitary gland):

No hay comentarios:

Publicar un comentario