Physiology of Pituitary and Hypothalamus Flashcards
What is the embryological origin of the hypothalamus?
Ventral diencephalon
The hypothalamus is derived from the ventral part of the diencephalon during embryonic development.
What are the embryological origins of the anterior part of the pituitary gland?
Oral ectoderm
The anterior part of the pituitary gland develops from the oral ectoderm.
What are the embryological origins of the posterior part of the pituitary gland?
Neural ectoderm
The posterior part of the pituitary gland originates from the neural ectoderm.
What is Rathke’s pouch?
Upward protrusion of the oral ectoderm
Rathke’s pouch is formed during the development of the anterior pituitary and is crucial for its formation.
What do the cells of Rathke’s pouch proliferate to form?
Anterior lobe of the pituitary gland
The proliferation of cells from Rathke’s pouch leads to the formation of the anterior lobe.
How does the posterior lobe of the pituitary gland develop?
Downward growth from the ventral diencephalon
The posterior lobe develops as a result of downward growth from the ventral diencephalon.
What are the three main regions of blood supply to the hypothalamus?
- Anterior Region
- Intermediate (Tuberal) Region
- Posterior (Mammillary) Region
Which artery supplies blood to the Anterior Region of the hypothalamus?
Anterior cerebral artery and the anterior communicating artery
What artery supplies blood to the Intermediate (Tuberal) Region of the hypothalamus?
Posterior communicating artery
List the arteries that supply blood to the Posterior (Mammillary) Region of the hypothalamus.
- Posterior communicating artery
- Posterior cerebral artery
- Basilar artery
From which artery does the anterior pituitary receive blood?
Superior hypophyseal artery
The superior hypophyseal artery is a branch of the internal carotid artery.
Which artery primarily supplies the posterior pituitary?
Inferior hypophyseal artery
The inferior hypophyseal artery directly supplies the neurohypophysis.
How does the posterior pituitary receive hormones from the hypothalamus?
Directly from hypothalamic neurons
This method of hormone delivery differs from the anterior pituitary’s reliance on portal circulation.
What drains blood from the pituitary gland?
Hypophyseal veins
These veins connect to the cavernous sinus
Acidophils
Somatotrophs and Lactotrophs
Basophils
Thyrotrophs, Gonadotrophs, Corticotrophs
Chromophobes
Folliculostellate cells
Melanotrophs
TSH hormone composition
Peptide hormone
1 Alpha and 1 Beta chain
Which chain of TSH is similar to other hormones?
Alpha chain
Same as that of LH, FSH and HCG
Factors stimulating TSH release
- TRH
- Low T3, T4
- Estrogens
Factors inhibiting TSH release
- High T3, T4
- Dopamine
- Somatostatin
How does dopamine decrease TSH secretion?
Binds to pituitary D2 receptors, decreases gene transcription necessary for TSH production
How does somatostatin decrease TSH secretion?
Decreases adenylyl-cyclase activity
Decreases cAMP, thus preventing TSH release
TSH diurnal variation
Highest at night
Low during the day
