Endocrine Flashcards
Where does the thyroid gland develop?
thyroid diverticulum arises from floor of primitive pharynx, descending into neck. It is connected to tongue by thyroglossal duct which norally disappears but may persist as pyramidal lobe of thyroid.
What is the normal remnant of the thyroglossal duct?
foramen cecum
What is the most common site of ectopic thyroid tissue?
tongue - lingual thyroid
How does a thyroglossal duct look like?
an anterior midline neck mass that MOVES w/ swallowing. Make sure you remove it b/c it can get infected
Tell me about the 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.
- Cortisol secretion is controlled by ACTH and CRH from fetal pituitary and placenta.
Why is cortisol necessary for the fetus?
- responsible for fetal lung maturation and surfactant production
What is the embryonic derivative of the adrenal cortex and medullar?
- cortex = mesdoerm
- medulla = neural crest
What is produced in the adrenal medulla?
it’s stimulated by pregangionlic sympathetic fibers to make catecholamines via chromaffin cells
What is produces in the adrenal cortex?
- Renin-Angiotensin activates Zone Glomerulosa to make Aldosterone
- ACTH, hypothalamic CRH stimulates Zone Fasciculata to make cortisol and some sex hormone
- ACTH, hypothalamic CRH stimulates Zona Reticularis to make sex hormones
How do the adrenal glands drain?
- Left adrenal –> left adrenal vein – > left renal vein –> IVC
- Right adrenal –> right adrenal vein –> IVC
What is the most common tumor of the adrenal medullar for an adult?
pheochromcytoma
What is the most common tumor of the adrenal medulla in kids?
neuroblastoma
What is stored in the posterior pituitary? (neurohypophysis)
- secretes ADH and oxytocin
- remember derived from neuroectoderm
What is released from the anterior pituitary? (adenohypophysis)
Secretes FSH, LH, ACTH, TSH, prolactin, GH, MSH
- Remember derived from oral ectoderm (Rathke’s pouch)
There are some hormones who have alpha and beta subunits. What are they and what is the importance of the subunits?
- FSH, LH, TSH, bhCG
- all the alpha subunits are the same
- the Beta subunits determines hormone specificity
What are the acidophilic hormones?
GH, prolactin
What are the basophilic hormones?
FSH, LH, ACTH, TSH
What makes up the endocrine pancreas?
- alpha cells- make glucagon
- beta cells- make insulin
- delta cells- make somatostatin
- islets of langerhans are made up of peripheral alpha cells w/ central beta cells and interspersed delta cells
What are all the hormones involved in the HP and HPA axis?
- TRH –> TSH and prolactin
- Dopamine inhibits prolactin
- CRH –> ACTH, MSH, beta-endorphin
- GHRH –> GH
- Somatostatin inhibits GH, TSH
- GnRH –> FSH, LH
- Prolactin inhibits GnRH
What is the precursor molecule for ACTH?
-POMC which also contains sequences for other hormonal peptides. eg MSH and beta-endorphin
Where is somatostatin made?
throughout the GI Tract notably by delta cells in pancreas and GI mucosa
- also made by nervous system
What effect do somatostatin have?
- decrease endocrine and exocrine secretions
- decrease splanchnic blood flow
- decrease GI motility and gallbladder contraction
What are the clinical uses of somatostatin? eg octreotide
- pituitary excess - acromegaly, thyroitropinoma, ACTH secreting tumor
- GI endocrine excess: ZE syndrome, carcinoid syndrome, VIPoma, glucagonoma, insulinoma
- Need to decrease splanchnic circulation : portal HTN and bleeding peptic ulcers, esophageal varicies
What is the function of prolactin?
- stimulates milk production in breast
2. inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release