Pituitary Flashcards
Another name for the pituitary gland
Also known as the hypophysis
What does the pituitary do
It releases hormones produced by the hypothalamus which either inhibit or stimulate other organs to release their hormones.
Structure of the pituitary gland
Pea-sized structure made up of 2 lobes, each of which has different functions
Where is the pituitary gland located
Situated in a bony hollow beneath the base of the brain. This bony hollow is called the sella turcica or the pituitary fossa.
Where is the Hypothalamus located
It is situated in the brain at the base of the optic chiasm (posterior to the orbits, where the optic nerves partially cross)
Hypothalamus function
It acts as a collecting centre for information about with the internal environment of the body and uses much of this information to regulate the secretion of the hormones produced by the pituitary gland.
hypothalamic-pituitary axis
hypothalamus is actually attached to the pituitary gland via a stalk-like structure.
Made from the hypothalamus and pituitary gland
Why is the sella turcica important for skull x-rays
his is an important feature for radiographers – we check there is no rotation of this on lateral skull x-rays and on a lateral cervical spine x-ray also. This can be enlarged or eroded which may indicate certain pathologies.
Its where the pituitary gland sits
Anterior pituitary (one lobe of the pituitary. Alternative name, origin and how is it connected to the hypothalamus
Adenohypophysis
Glandular epithelium
Vascular
Posterior pituitary (one lobe of the pituitary. Alternative name, origin and how is it connected to the hypothalamus
Neurohypophysis
Nervous tissue
Neural
Posterior pituitary, how does it work
Hormones are synthesised in the hypothalamus, travel down neurons to the posterior pituitary where they are released into the blood stream. Two of these neurohormones (hormones secreted by neurons) are secreted by the posterior pituitary, these are anti-diuretic hormone (ADH) and oxytocin. (posterior pituitary is an extension of hypothalamus)
What is the feedback loop for the Posterior pituitary
Positive feedback loop
What is the feedback loop for the The Anterior Pituitary
negative feedback loop
The Anterior Pituitary, how does it work
The release of hormones from the anterior pituitary is under the control of the hypothalamus and many of these hormones are released with a diurnal rhythm as environmental stimuli (such as day/night or sleep patterns) influence the hypothalamus.
The hypothalamus controls the hormonal output of the anterior pituitary via releasing and inhibiting hormones that are secreted into local blood vessels that connect the hypothalamus to the anterior pituitary. These hormones act on the anterior pituitary controlling the release of its hormones into the blood stream.
Several hypothalamic-pituitary hormones are termed trophic, meaning that they exert their effects on other endocrine glands, influencing hormone release elsewhere in the body. An example of this is thyroid-stimulating hormone (TSH) released by the anterior pituitary that causes the release of thyroid hormone by the thyroid gland.
What is the Optic Chiasm
The optic chiasm, or optic chiasma, is the part of the brain where the optic nerves cross and is therefore of primary importance to the visual pathway. It is located at the base of the brain inferior to the hypothalamus, and approximately 10 mm superior to the pituitary gland within the suprasellar cistern.
