Anatomy of endocrine glands and thyroid Flashcards
(48 cards)
What are the pharyngeal arches lined with internally?
Endoderm
What are the pharyngeal arches lined with externally?
Ectoderm
What are the skeletal components of the pharyngeal arch formed from?
Neural crest cells
Which cleft remains open during embryological development?
Pharyngeal cleft 1
What is the boundary between the ectoderm and endoderm?
Oropharyngeal membrane
How is the pititary gland attached to the brain?
Via the infundibulum to the base of the brain. Hypothalamus is superior and optic chaismata is posterior. If the pituitary gland swells, it will place pressure on the optic chiasma.
What is the optic chiasma?
Optic nerves cross over for vision to be seen on each side
What is the midline structure located near the pituitary gland?
Optic chiasma
Where is the location of the pituitary gland?
In the sella turcica of the sphenoid bone
What are the lobes of the pituitary gland?
Adrenohypohysis which is an endocrine gland and the neurophyposis which is a neural structure.
What is the embryonic origin of the anterior lobe?
Derived from the hypophyseal diverticulum of the oral ectoderm which eventually fuses with the neuroectoderm of the infundibulum of the diencephalon.
What is the embryonic origin of the posterior lobe?
Neuroectoderm of the diencephalon infundibulum. It will fuse with the hypophyseal diverticulum to form the pituitary gland.
What is the blood supply to the pituitary gland?
Superior hypophyseal artery which is a branch of the internal carotid artery. Inferior hypophyseal artery which is a cavernous branch of the internal carotid artery.
What is the venous drainage of the pituitary gland?
Cavernosus sinus.
What is the primary capillary plexus?
Formed from branches of the superior hypohyseal artery. It is located in the medial eminence of the infundibulum which allows neurohormones secreted by the hypothalamus to travel to the adrenohypophysis without entering systemic circulation.
What is the hypothalamo-hypophyseal portal systemr?
Communication between the hypothalamus and pituitary gland via blood supply. Can travel to the primary capillary plexus in the infundibulum and then secondary capillary plexus in the adrenohypophysis.
What is the hypothalamo-hypophyseal tract?
Communciation between the paraventricular and supraoptic nuclei of the hypothalamus with the neurohypophysis via bundle of axons transmitting the neurohormones oxytocin and ADH. It is stored in the neurohypophysis.
How does the hypothalamus communicate with the adrenohypophysis?
Releases neurohormones which enter the capially bed of the medial eminence of the infundibulum called the primary capillary plexus. It travels to act on the endocrine gland adrenohypophysis to synthesise and secrete hormones which are released into the secondary capillary plexus in the adrenohypophysis and enter portal circulation.
How does the posterior lobe act?
It is a neural tissue which stores and secretes hormoens in response to electrical signals from the hypothalamus.
What is the histology of the anterior lobe of the pituitary lobe?
Highly vascularised endocrine gland with different cells. Contains somatotroph cells, gonadotrophs, corticotrophs, mammotrophs and thyrotroph.
What is the histology of the posterior lobe of the pituitary lobe?
Neural tissue which is an extension of the paraventricular and supraoptic nuclei of the hypothalamus. It contains glial like pituocytes. Cell bodies located in hypothalamus
Where is growth hormone released?
From the somatotrophin region
Where is prolactin released from?
Mammotrophin region.
Where is thyroid stimulating hormone released from?
Thyrotroph region.
