Endocrine

Insulin function

Binds insulin receptors (tyrosine kinase activity), inducing glucose uptake (carrier-mediated transport) in insulin-dependent tissue & gene transcription. Anabolic effects of insulin: Increase glucose transport in skeletal muscle & adipose tissue

Adrenal Cortex

Derived fr mesoderm GFR corresponds with Salt (Na+), Sugar (glucocorticoids) & Sex (androgens) "The deeper you go, the sweeter it gets"

Adrenal medulla

Derived fr neural crest

Endocrine pancreas cell types

Isles of Langerhans are collections of alpha, beta, & delta endocrine cells. Islets arise fr pancreatic buds. alpha = glucagon (peripheral); beta= insulin (central); delta = somatostatin (interspersed) *Ins*ulin (beta cells) *ins*ide

Adrenal gland drainage

Left adrenal gland -> left adrenal vein ->left renal vein -> IVC Right adrenal gland -> right adrenal vein -> IVC

Pheochromocytoma

Most common tumor of adrenal medulla in adults Episodic HTN

Neuroblastoma

Most common tumor of adrenal medulla in children. Rarely causes HTN

Insulin Synthesis

Preproinsulin (synthesized in RER) -> cleavage of "presignal" -> proinsulin (stored in secretory granules) -> cleavage of proinsulin -> exocytosis of insulin & C-peptide equally. Insulin & C-peptide increased in insulinoma, whereas exogenous insulin lacks C-peptide.

Insulin source

Released fr pancreatic beta cells.

Anterior pituitary (adenohypophysis)

Secretes FSH, LH, ACTH, TSH, prolactin, GH, melanotropin (MSH). Derived fr oral ectoderm (Rathke pouch). alpha subunit - hormone SU common to TSH, LH, FSH, & hCG beta subunit - determines hormone specificity Acidophils - GH, prolactin *B-FLAT*: Basophils - FSH, LH, ACTH, TSH *FLAT PiG*: FSH, LH, ACTH, TSH, Prolactin, GH

Posterior pituitary (neurohypophysis)

Secretes vasopressin (ADH) & oxytocin Made in hypothalamus & shipped to posterior pituitary via neurophysins (carrier proteins). Derived fr neuroectoderm.

Thyroid development

Thyroid diverticulum arises fr floor of primitive pharynx & descends into neck. Connected to tongue by thyroglossal duct, which normally disappears but may persists as pyramidal lobe of thyroid. Foramen cecum is normal remnant of thyroglossal duct. Most common ectopic thyroid tissue site is tongue. Thyroglossal duct cyst presents as an anterior midline neck mass that moves w swallowing / protrusion of tongue (vs. persistent cervical sinus leading to branchial cleft cyst in lateral neck)