The Pituitary Gland Flashcards
What a messenger?
A messenger, carried from the organ where they are produced to the organ which they affect by means of the blood stream
What are the types of hormones?
Peptide and steroid
What is the difference between peptide and steroid hormones?
- synthesis, storage, receptors
Label this diagram of the pituitary gland.
What is another name for the anterior pituitary gland and what did it derive from?
aka adenohypophysis
Derived from an upgrowth from the oral ectoderm of the primitive oral cavity called Rathke’s pouch
Epithelial origin
What is another name for the posterior pituitary gland and what did it derive from?
neurohypophysis
Formed from a downgrowth of the diencephalon that forms the floor of the third ventricle
Neural origin
Label this diagram of the pituitary gland.
What do hypothalamic parvocellular neurones regulate?
Anterior pituitary function
Where is the median eminence?
Base of the hypothalamus
Why does the median eminence have lots of capillaries?
They are leaky, so they allow things to flow into them so they can encounter circulation (the portal circulation)
What are hypothalamic parvocellular neurones?
Short, terminate on median eminence
Release hypothalamic releasing/inhibitory factors into capillary plexus in median eminence
These hypothalamic regulatory factors carried by portal circulation to anterior pituitary
Label this diagram of the pituitary gland.
How would you describe the anterior pituitary gland to the hypothalamus?
Anatomically distinct
What cells is the anterior pituitary gland made of?
Somatotrophs
Lactotrophs
Corticotrophs
Thyrotrophs
Gonadotrophs
How is the activity of the cells in the anterior pituitary gland regulated?
Regulated by hypothalamic releasing/inhibiting factors via hypophyseal-pituitary portal system
What are the steps of the hypothalamo-pituitary portal system?
- Axon terminals of hypothalamic neurosecretory cells release hormones (RHs and IHs) into the hypothalamo-pituitary portal system
- The RHs and IHs travel in the portal system to the anterior pituitary
- The RHs and IHs stimulate or inhibit the release of hormones (black dots) from anterior pituitary cells
- Anterior pituitary hormones leave the gland via the blood
Give an example of the hypothalamo-pituitary portal system with the regulation of thyroid hormone production.
- Axon terminals of hypothalamic neurosecretory cells release Thyrotropin Releasing Hormone (TRH) into hypothalamo-hypophysial portal system
- TRH travels in the portal system to the anterior pituitary
- TRH stimulates the release of Thyroid Stimulating Hormone (TSH) from anterior pituitary thyrotrophs
- TSH leaves the gland via the blood to travel to the thyroid gland to stimulate thyroid hormone release (thyroxine)
what hormone do somatotrophs release?
Growth hormone
What hormone do lactotrophs release?
Prolactin
What hormone do thyrotrophs release?
Thyroid stimulating hormone (TSH)
What hormone do gonadotrophs release?
Luteinising hormone (LH)
Follicle stimulating hormone (FSH)
What hormone do corticotrophs release?
Adrenocorticotrophic hormone (ACTH)