endocrine embryology and anatomy

Question 1

thyroid embryology

Answer 1

thyroid arises from the floor of the primitive pharynx, and descends into the neck. it is connected to the tongue by the thyroglossal duct, which normally disappears but may persist as a pyramidial lobe of the thyroid. foramen cecum is the normal remnant of the thyroglossal duct. most common ectopic thyroid tissue site is the tongue

Question 2

thyroglossal duct cyst

Answer 2

presents as an anterior midline neck mass that moves with swallowing or protursion of the tongue. this is different from a persistent cervical sinuse/branchial cleft cyst, which is in the lateral neck.

Question 3

what are the layers of the adrenal cortex? what is the primary regulatory hormone from each layer? What about the medulla?

Answer 3

cortex: glomerulosa, fasciculata, reticularis. (salt: aldo; sugar: cortisol; sex: androgens).
renin/angiotensin controls aldo release; ACTH and CRH control cortisol, sex hormones
medulla: stimulated by ACh (sympathetics); releases Epi and NE

Question 4

pheochromocytoma

Answer 4

most common tumor of the adrenal MEDULLA. it makes epinephrine/norepinephrin and causes episodic HTN

Question 5

neuroblastoma

Answer 5

most common tumor of the adrenal medulla in kids; rarely causes HTN

Question 6

What hormones are similar to hCG? how do they differ?

Answer 6

alpha subunit of hCG is the same as TSH, LH, and FSH.

they differ in terms of beta subunit.

Question 7

what are the acidophils vs. basophils of the pituitary gland?

Answer 7

acidophils: GH, prolactin
basophils: B-FLAT: FSH, LH, ACTH, TSH

Question 8

What is the arrangement of cell types within the islets of langerhans?

Answer 8

alpha cells are peripheral and make glucugon; beta cells are central. delta cells are interspersed.

Question 9

CRH function in HPA; clinical notes in

Answer 9

increase ACTH, MSH (melanotropin), beta endorphin.

decreased in chronic exogenous steroid use.

Question 10

GnRH: function in HPA, regulation

Answer 10

incr. FSH and LH.

regulated by prolactin. tonic GnRH suppresses the HPA axis, pulsatile GnRH leads to fertility and puberty.

Question 11

prolactin: function in HPA; notes

Answer 11

decr. GnRH. pituitary prolactinoma causes amenorrhea and osteoporosis

Question 12

somatostatin function in HPA, regulation

Answer 12

decreases GH, TSH.

analogs are used to treat acromegaly (octreotide)

Question 13

TRH function in HPA, regulation

Answer 13

incr. TSH, prolactin

Question 14

dopamine

Answer 14

decr. prolactin.