Hypothalamus and Pituitary Flashcards
What connects the hypothalamus to the pituitary gland?
Infundibulum
How is the hypothalamus connected to the pituitary gland?
Hypothalamic communication with the pituitary gland is both neural (to the posterior pituitary) and endocrine (to the anterior pituitary), hence it’s neuroendocrine function.
What is the name of section of bone the pituitary gland is found?
Located in a pocket in the sphenoid bone (hypophyseal fossa), directly below the hypothalamus
What types of hormones are released from the hypothalamus?
Neurohormones
What types of hormones are released from the anterior pituitary?
Classic endocrine hormones
What types of hormones are released from the posterior pituitary?
Neurohormones (extension of hypothalamus)
What are the two forms of hypothalamic neurohormones?
Tropic – neurohormones secreted into capillaries travelling to anterior pituitary. Govern release of anterior pituitary hormones (can be stimulatory or inhibitory)
Non-tropic – neurohormones produced in the hypothalamus and travel to posterior pituitary (via axons of hypothalamic neurons) where they are released into blood.
Define tropic hormones
Tropic – neurohormones secreted from hypothalamus into capillaries travelling to anterior pituitary. Govern release of anterior pituitary hormones (can be stimulatory or inhibitory)
Define non-tropic hormones
Non-tropic – neurohormones produced in the hypothalamus and travel to posterior pituitary (via axons of hypothalamic neurons) where they are released into blood.
What is the action of hypothalamic tropic hormones?
All hypothalamic tropic hormones bind to receptors on anterior pituitary and stimulate/inhibit release of anterior pituitary hormones
What 7 tropic hormones are produced by the hypothalamus?
5 hypothalamic “releasing hormones”:
– Thyrotrophin Releasing Hormone (TRH)
– Corticotropin Releasing Hormone (CRH)
– Growth Hormone Releasing Hormone (GHRH)
– Gonadotrophin Releasing Hormone (GnRH)
– Prolactin Releasing Hormone (PRH)
2 hypothalamic “inhibiting hormones”
– Growth Hormone Inhibiting Hormone (GHIH) aka somatostatin
– Dopamine aka Prolactin Inhibiting Hormone (PIH)
What are the releasing hormones released by the hypothalamus?
– Thyrotrophin Releasing Hormone (TRH) – Corticotropin Releasing Hormone (CRH) – Growth Hormone Releasing Hormone (GHRH) – Gonadotrophin Releasing Hormone (GnRH) – Prolactin Releasing Hormone (PRH)
What are the inhibiting hormones released by the hypothalamus?
– Growth Hormone Inhibiting Hormone (GHIH) aka somatostatin
– Dopamine aka Prolactin Inhibiting Hormone (PIH)
What kind of hormones are the 7 hormones released by the hypothalamus?
All are peptides, except dopamine, which is an amine hormone
What is the Hypothalamo-hypophyseal portal system?
Network of tiny vessels which transfer trophic hormones from hypothalamus to anterior pituitary