The Pituitary Gland and the Hypothalamus Flashcards
What is the name given to the depression in the skull where the pituitary gland sits?
Sella turcica
In the body of which cranial bone is this?
Sphenoid bone
1 = Hypothalamus
2 = Pituitary gland
3 = Optic chiasm
4 = Thalamus and 3rd ventricle
5 = Sphenoid sinus
How is the optic chiasm related to the pituitary gland?
Optic chaism is located anterior to the pituitary stalk
Which fibres from the optic nerve, nasal or temporal, cross over to the opposite side at the chiasm?
Temporal
What therefore would the resultant visual field defect be due to pituitary gland enlargement?
Bitemporal hemiopia
The pituitary gland which is connected to the hypothalamus by the pituitary stalk consists of?
An anterior lobe (pars anterior/adenohypophysis) and a posterior lobe (pars nervosa/neurohypophysis).
Which is the larger of the two lobes?
Anterior lobe
Which of the two lobes is glandular and manufactures numerous hormones?
Anterior lobe
What is the function of the posterior lobe
Stores hypothalamic hormones for later release into circulation. Diurectic hormone and oxytocin
How does the anterior and posterior pituitary lobes stain?
Anterior pituitary is dark staining while the posterior pituitary is pale
Label the pituitary lobes
Identify three types of cells
Acidophilic- make all hormones of anterior pituitary except ones that stimulate a few things (which stain pink)
Basophilic- make ACTH, TSH and others (which stain light purple)
Chromophobic – hate colour so that’s why they are called this. Don’t secrete anything(which do not take up much stain and therefore appear pale
What hormone(s) do the posterior cells secrete
Oxytocin and ADH
What are the 2 classes of acidophil?
Somatotrophs
Mammotrophs
What are the secretory products of the 2 acidophil?
What is their target?
Somatotrophs- Growth hormone
General but a major target is the chondrocytes in epiphyseal growth plates. Promotes growth
Mammotrophs- Prolactin
Mammary gland- Milk producing tissue
What are the 3 classes of basophils?
Corticotrophs
Thyrotrophs
Gonadotrophs
What are the 3 secretory products of basophils and their target?
Corticotrophs- ACTH, MSH. Trophic- general action- promote growth and secretory activity in other endocrine glands. ACTH- Target is the corticosteroid cells of the adrenal cortex. MSH- Melanocytes
Thyrotrophs. TSH. Targets follicular epithelial cells of the thyroid gland
Gonadotrophs- FSH, LH. FSH- Follicular cells of ovaries, to promote growth of follicles, or the Sertoli cells of the testes to promote spermatogenesis. LH- Developing follicles- promotes ovulation. Or Leydig cells of testes- promotes secretion of adrogens aiding in spermatogenesis
The arterial blood supply of the pituitary gland is form what?
The superior hypophyseal artery and inferior hypophyseal artery
The superior hypophysial artery enters into the substance of the hypothalamus before breaking up into capillaries (the hypophysial portal system). These capillaries then supply the anterior pituitary gland.
The inferior hypophysial artery supplies the posterior pituitary gland.
How does the hypothalamus communicate with the anterior pituitary?
Through releasing and inhibiting hormones- delivered through blood vessels in infundibulum
How does the hypothalamus communicate with the posterior pituitary?
Contains end of nerve cells coming from the hypothalamus
What is the venous drainage of the pituitary gland through?
Hypophyseal veins into the cavernous sinus
