Flashcards in Endocrine - Embryology and Anatomy Deck (43)
Describe thyroid development
Thyroid diverticulum arises from floor of primitive pharynx, descends into the neck.
How is thyroid diverticulum connected to the tongue?
What is the pyramidal lobe of thyroid?
Persistent thyroglossal duct
What is the foramen cecum of thyroid?
Normal remnant of thyroglossal duct
Most common ectopic thyroid tissue site
Describe thyroglossal duct cyst
Anterior midline neck mass that moves with swallowing or pertrusion of the tongue
How is thyroglossal duct cyst different from a brachial cleft cyst?
Brachial cleft cyst - persistent cervical sinus
Lateral neck (vs midline for thyroglossal duct cyst)
Describe fetal adrenal gland
Consists of an outer adult zone and inner active fetal zone.
Adult zone is dormant during early fetal life but begins to secrete cortisol late in gestation.
What controls cortisol secretion in the fetus?
ACTH and CRH from fetal pituitary and placenta
Role of cortisol in the fetus
Fetal lung maturation and surfactant production
What are the embryologic derivatives of the adrenal cortex and medulla?
Cortex - mesoderm
Medulla - neural crest
What are the layers of adrenal gland?
Medulla (Chromaffin cells)
Primary regulatory control and secretory products of: Zona glomerulosa
Regulation: Renin-Angiotensin-Aldosterone System
Primary regulatory control and secretory products of: Zona fasciculata
Regulation: ACTH and CRH
Secretion: glucocorticoids (cortisol)
Primary regulatory control and secretory products of: Zona reticularis
Regulation: ACTH and CRH
Secretion: sex steroids (androgens)
Primary regulatory control and secretory products of: Adrenal medulla (Chromaffin cells)
Regulation: Pre-ganglionic sympathetic fibers (acetylcholine)
Secretion: Catecholamines (Epi, NE)
What is the most common tumor of adrenal medulla in adults? And in children?
How are they different?
Pheochromocytoma causes episodic hypertension; Neuroblastoma does not
Describe adrenal gland drainage
Left adrenal -> Left adrenal vein -> Left renal -> IVC
Right adrenal -> Right adrenal vein -> IVC
Same as left and right gonadal veins
What are the embryologic derivatives of anterior and posterior pituitary?
Anterior pituitary (Adenohypophysis): oral ectoderm (Rathke's pouch)
Posterior pituitary (neurohypophysis): neuroectoderm
Function of posterior pituitary gland
Secretes vasopressin and oxytocin made in hypothalamus and shipped to posterior pituitary through neurophysins (carrier proteins)
Function of anterior pituitary gland
Secretes FSH, LH, ACTH TSH, prolactin, GH, melanotropin (MSH)
Describe structure of TSH, LH, FSH, hCG
Alpha and Beta subunit
Alpha: common to all
Beta: determines hormone specificity
How do pituitary acidophils appear on histology and what do they make?
How do pituitary basophils appear on histology and what do they make?
FSH, LH, ACTH, TSH
Describe organization of islets of langerhans
Alpha cells in periphery
Beta cells central
Delta cells interspersed
What are the different cell types of islets of langerhans and what do they secrete?
What does the islets of langerhans arise from?
Structure of insulin
Alpha and Beta chains connected by sulfur bonds
Describe insulin secretion in the pancreatic beta-cell
1. Glucose enter cell
2. Glycolysis increases ATP/ADP ratio
3. ATP closes ATP-sensitive K+ channels
4. Depolarization of cell
5. Influx of Ca2+ through voltage-gated Ca2+ channels
6. Exocytosis of insulin granules into blood vessel