Hypothalamus, pituitary and thyroid function Flashcards
Describe the anatomy of the hypothalamus, the posterior pituitary and the anterior pituitary
The hypothalamus sends neurones from the hypothalamus to form a posterior pituitary, which releases nueropeptides like oxytocin and ADH. The anterior pituitary is very close but not apart of the brain.
Describe the process of the transmission of a hormone from the hypothalamus to the anterior pituitary.
The neurones in the hypothalamus send axons to the median eminence. Therre is no BBB there,, so the hormones enter the portal vessels. They then bind to their complementary receptors.
State the 5 hormones released from the hypothalamus
TRH (Thyrotropin releasing hormone) Prolactin CRF (Corticotrophin releasing factor) GnRH (Gonadotrophin releasing hormone) GHRH (Growth hormone releasing hormone)
State the 6 hormones released from the anterior pituitary
TSH (Thyroid stimulating hormone) ACTH (Adrenocorticotrophin Hormone) LH (Luteinising Hormone) FSH (Follice Stimulating Hormone) GH( Growth Hormone )
Name 2 inhibitory molecules that affect the release of hormones and state the systems they target
Somatostatin halts GH/TRH
Dopamine halts Prolactin release
Starting at the hypothalamus, describe how LH and FSH are released
Hypothalamus - Releases GnRH via median eminence and portal vessels to the anterior pituitary. The anterior pituitary releases LH and FSH via gonadotrophs.
Describe the complications that arise in children that lack FSH or LH and suggest how this can be solved.
These children will not be able to undergo puberty and may lose their reproductive function. GnRH, FSH and LH can be used to manipulate reproductive function, as they are even used in IVF.
Starting at the hypothalamus, describe how GH is released
Hypothalamus - Releases GHRH via median eminence and portal vessels to the anterior pituitary. The anterior pituitary releases GH via somatrophs.
State what happens if individials have a lack of GH
These individuals tend to have short statures. This can be treated by GH treatment.
State what happens if individials have excess GH
Too much growth hormone may result in giantism.
What is acromegaly?
Too much growth hormone in adults- usually do to a pituitary adenoma (a type of cancer). Somatotrophs produce extra GH resulting in the ones in the face, fusing together.
Starting at the anterior pituitary, describe how prolactin is released
The anterior pituitary releases prolactin via mammotrophs. Too much prolactin in males can result in gynaecomastia.
Starting at the hypothalamus, describe how TSH is released
Hypothalamus - Releases TRH via median eminence and portal vessels to the anterior pituitary. The anterior pituitary releases TSH via thyrotrophs.
Describe the histology of the thyroid
The thyroid is composed of smaller components known as thyroid follicles. These are balls of epithelial cells that surround proteinaceous (non-cellular) colloid where the thyroid hormones are sent.
How much more potent is T3 than T4?
10x