Hypothalamus and Pituitary gland Flashcards
What hormones are produced by the hypothalamus? Where are they release and where do they travel?
Oxytocin and vasopressin (ADH) are released by the neurones in the posterior pituitary which originate in the hypothalamus. These are peptide neurohormones. Unlike all the other hypothalamic hormones these hormones do not act on the anterior pituitary.
All the other hormones synthesised by the hypothalamus are tropic hormone which act on the anterior pituitary. Growth hormone releasing hormone-GHRH Corticotropin releasing hormone- CRH Thyrotropin releasing hormone- TRH Gonadotrophin releasing hormone- GnRH Prolatcin releasing hormone- PRH
Growth hormone inhibiting hormone- GHIH (somatostatin)
Dopamine - PIH (Prolactin inhibiting hormone)
(Remember R comes before S in the alphabet so Releasing hormones come before stimulating hormones, so releasing hormones are produced by the hypothalamus)
Describe the difference between the anterior and posterior pituitary glands.
The AP is a true endocrine gland where as the PP is neurotissue, as it is an extension of the hypothalamus.
What is the AP otherwise known as?
Adenohypophysis
What is PP otherwise known as?
Neurohypophysis
What connects the hypothalamus to the AP?
Hypothalamo-hypophyseal portal system of capillaries
What is the point at which hypothalamic hormones enter the portal system called?
b
What is hyporesponsiveness?
Can be caused by alterations to the receptor, disordered post receptor events,failure of metabolic activation of hormone or antagonistic effects.
What does permissive mean?
The presence of one hormone enhances the effect of another.
What is an antagonistic effect?
The presence of one hormone reduces the effect of another- e.g. Growth hormone impairs insulin effects (so reduces glucose uptake).
What is the name of the hypothalmic neurons which release the neurohormones in the PP?
Magnocellular neurons
