The Pituitary Gland COPY Flashcards
What is the role of the hypothalamus and the pituitary in the endocrine system?
Principal organisers
What connects the hypothalamus and the pituitary?
The infundibulum
What is the connection between the hypothalamus and the posterior pituitary?
Neural
What is the connection between the hypothalamus and the anterior pituitary?
Endocrine
What is the role of the hypothalamus?
The integrating system of a huge amount of stimuli
What type of hormones are released by the anterior pituitary?
Classic endocrine hormones
Released in response to a tropic hormone binding to a receptor on the anterior pituitary
What are the 5 tropic “releasing hormones” released by the hypothalamus that act on the anterior pituitary?
Thyrotrophin releasing hormone (TRH)
Corticotrophin releasing hormone (CRH)
Growth hormone releasing hormone (GHRH)
Gonadotrophin releasing hormone (GnRH)
Prolactin releasing hormone (PRH)
What are the 2 inhibiting hormones released by the hypothalamus?
Growth hormone inhibiting hormone (somatostatin)
Dopamin (inhibits prolactin)
What is the hypothalamo-hypophyseal portal system?
Network of tiny vessels that transfer hormones from the hypothalamus to the anterior pituitary
Where are the hormones from the hypothalamus released into the hypothalao-hypophyseal circulation?
At the median eminence
What is the anterior pituitary also known as?
Adenohypophysis
What hormones are released by the adenohypophysis?
Thyroid stimulating hormone
Adrenocorticotrophic hormone
FSH
LH
GH
Prolactin
What is the target of thyroid stimulating hormone and what does it cause?
Thyroid
Release thyroxine (therefore is a tropic hormone)
What is the target and effect of adrenocorticotropic hormone?
Adrenal glands
Cortisol release
What is the function of LH?
Regulation of sexual function (direct effect)
Sex hormone release (tropic effect)
What is the effect of GH?
Liver
Release of IGF1 (tropic effect)
Tissue metabolism (direct effect)
What is the effect of prolactin?
Stimulates milk production
How is the hypothalo-hypophyseal pathway controlled?
Feedback control
What is the short feedback loop?
The pituitary’s secretions inhibiting the hypothalamus
What is the long feedback loop?
Target cells secretions inhibiting the hypothalamus
What is secreted by the posterior pituitary?
Vasopressin
Oxytocin
In what cells are oxytocin and ADH synthesised?
Magnocellular neurones
Where do magnocellular axons project to?
The posterior pituitary
It’s actually these that secrete into the bloodstream therefore neuroendocrine.
