Endo: Histology Flashcards
Hormones travel via _________ to reach their target organs
Hormones travel via the blood to reach their target organs
The pituitary is located within what bony structure?
Sella turcica
What is the embryologic origin of the anterior pituitary?
Posterior pituitary?
Anterior: Oral ectoderm called Rathke’s pouch
Posterior: outgrowth of hypothalamus (neuroectoderm)
What hormones are produced by the anterior pituitary?
FLAT PiG
- FSH
- LH
- ACTH
- TSH
- PRL
- GH
What cells produce Growth Hormone?
FSH and LH?
- Somatotrophs made growth hormone
- Gonadotrophs make FSH and LH
Name the location and function of each:
Pars distalis, nervosa, intermedia, tuberalis
- Anterior pituitary
- Pars distalis: hormone producing cells
- Pars intermedia: secretes melanocyte stimulating hormone
- Pars tuberalis: collar of cells around infundibulum that contains blood flow
- Posterior pituitary
- Pars nervosa
Describe the blood flow of the anterior pituitary
Internal carotid artery -> superior hypophyseal arteries -> capillaries within hypothalmus median eminence -> vessels within pars tuberalis -> capillaries in anterior pituitary -> hypophyseal veins
Describe the blood flow of the posterior pituitary
(3 vessels)
- Fed by artery of trabecula and inferior hypophseal artery
- Drained by hypophyseal veins
What is another name for posterior pituitary? (2)
Neurohypophysis
Pars nervosa
What 2 substances are released by posterior pituitary?
Where are these substances made?
Vasopression (ADH) and oxytocin
Made in hypothalamus. Stored and released from posterior pituitary
What cells in the thyroid make thyroid hormones?
What cells in the thyroid make calcitonin?
Epithelial cells surrounding the colloid (follicular cells) make thyroid hormones
Scattered C cells make calcitonin
Describe the thyroid’s blood supply
- Supply: Inferior thyroid artery (thyrocervical trunk) and superior thyroid artery (from external carotid)
- Drainage: Inferior thyroid vein (to subclavian vein) and superior thyroid vein (to jugular vein)
What is the effect of calcitonin?
Calcitonin downregulates osteoclasts, decreasing calcium release from bones
Describe the overall production of thyroid hormones.
What effect does TSH have?
- Iodine gets transported into colloid
- Thyroglobulin within colloid gets iodinated on tyr residues
- Follicular cells take up thyroglob/I and convert it into T3, T4
- Thyroglobulin is a large protein that gets iodinated and modified to make thyroid hormones
- TSH stimulates synthesis of thyroglobulin
What three cell types are present in the parathyroid?
Which cells makes parathyroid hormone?
- Chief cells: produe PTH
- Oxyphil cells
- Adipose cells
Where is PTH made?
What does it do?
PTH is made by chief cells of parathyroid
PTH increases osteoclast activity and calcium uptake in GI tract/kidney (increases serum calcium)
What are the three adrenal cortex layers?
What is made in each?
-
Zona glomerulosa: makes aldosterone, mineralocorticoids
- outermost
- Zona fasiculata: makes cortisol
-
Zona reticularis: makes androgens
- innermost
From outside: GFR, gets sweeter the deeper you go (Salt -> sugar -> sex)
What regulates the adrenal cortex?
Granulosa controlled by Renin-Angiotension system
Fasiculata and reticularis controlled by ACTH
What is made in the adrenal medulla?
Epi and norepi
Where are steroid hormones v peptide hormones made?
Steroid hormones are made in the adrenal cortex
Peptide hormones are made in the adrenal medulla
Describe the role of neurons in the anterior and posterior pituitary
- Anterior: Neurons in hypothalamus secrete releasing factors into portal circulation
- Posterior: Neurons with cells bodies in hypothalamus end in the posterior pituitary itself. Herrig bodies release the granules of hormones
What are pituiocytes?
Astroglial (support cells) that surround the neurons within the posterior pituitary
Describe blood flow in the adrenal gland
- Supply: suprarenal artery
- Branches into short and long cortical arteries
- Drainage: Suprarenal vein
What is pictured?
Left is anterior pituitary
Right is posterior pituitary (less blood supply)
