Endocrine Histology Flashcards
Anterior v. posterior pituitary: embyrological origin
- *Anterior pituitary** forms from roof of mouth
- is an endocrine glandular origin
Posterior pituitary comes from diencephalon & is connected to the brain
Hypophysis- what is is? blood supply?
It’s the hypothalamus + pituitary
Very tiny blood supply: very sensitive to blood loss
Superior hypophysial and inferior hypophysial arteries
Acidophils v. basophils in the pituitary
Acidophils make peptides
Basophiles make glycoproteins
How do you identify the product of each cell?
Not just H&E – use immunohistochemistry
Anterior pituitary: what does it make?
Acidophils:
Somatotropesmake growth hormone
Lactotropes make prolactin
Basophils:
Corticotropes make ACTH
Gonadotropes make FSH, LH
Thyrotropes make TSH
Stores everything in granules in the cells!
Growth hormone
Made in anterior pituitary by somatotrophs (acidophils)
Works though IGF-1 (insulin growht factor 1) which is produced by hepatocytes
IGF-1 stimulates growth of long bones by stimulating hypertrophy of chondrocytes at epiphysial plates
Made in the first 2 hours of sleep
Prolactin
Made by acidophils in anterior pituitary
Dopamine inhibits its secretion
Suckling during lactation = stimulus for its secretion
FSH
Made by basophils of anterior pituitary
Acts on follicular cells of overy & sertoli cells of testis
GnRH from actuate nucleus of hypothalamus stimulates its secretion
LH
Made by basophils of anterior pituitary
Acts on corpus luteum of ovary to make progesterone & leydig cells of testis to make testosterone
GnRH from actuate nucleus of hypothalamus stimulates its secretion
TSH
Made by basophils of anterior pituitary
Binds receptors in plasma membrane of thyroid follicular epithelial cells –> T4 –> T3
TRH upregulates
T3 does negative feedback
POMC
Pro-opiolmelanocortin
Made by basophils in aterior hypophysis & other tissue in the body
Leads to ACTH and beta-lipotrophic hormone in pituitary
ACTH
Adrenocorticotrophic hormone
Made by basophils of anterior pituitary
CRH –> ACTH –> acts at adrenal gland to make cortisol, androgesn, and angiotensin II
Posterior pituitary: what does it make?
ADH and Oxytocin
Posterior pituitary: what is its structure?
Pituicites: astrocyte-like glial cells that surround and retract axons
Unmyelinated axons: hormones from the nucelus travel down this and empty into the capillaries
Herring body= where the hormone empties into the capillary
Capillaries are fenestrated
Which hormones does the thyroid make?
Follicular cells make TH & store it in the colloid
Parafollicular cells make calcitonin & stores it in granules in the cell
Where does the thyroid store TH? How does it do this?
In colloid lakes = extracellular
Epithelial cells surround colloid = both exocrine & endocrine
Takes in iodine from capillary lumen & receives signal from hormones in capillary on basolateral surface
Makes thyroglobulin in the cell –> exits & is iodinized in the colloid –> becomes T4 –> comes back into cell & is cleaved into T3 –> exits into capillary lumen
What cell types are in the parathyroid & what do they make?
Chief cells make PTH, which upregulates osteoclasts, decreases renal excretion of Ca via increased renal tubular reabsorption, increases renal excretion of phosphate, and increases absorption of Ca in GI
Oxyphils are there - unclear what it does
Adrenal glands: what cells and what do they make?
Medulla: makes epinephrine and norepineprhine
Cortex:
Zona glomerulose = outermost, makes aldo
Zona fasiculata = makes cortisol
Zona reticularis = makes weak androgens
What is Sheehan’s syndrome?
Infarction of the pituitary following acute blood loss
Symptoms include:
- low TSH –> weight gain & difficulty with thermal regulation
- low prolactin –> inability to lactate
- low ACTH –> low androgens –> loss of pubic & axillary hair
- low TSH and ACTH –> low blood pressure
- fatigue from low TSH, ACTH, FSH, LH
Which hormones are suppressed during starvation? Upregulated?
What corrects this imbalance?
HPG (hypothalmic-pituitary-gonadal) and HPT (thyroid) are suppressed
HPA (adrenal) are upregulated
Giving leptin corrects this (byproduct of fat breakdown)
Which hormones levels vary in a pulsatile pattern?
Growth hormone: varies during sleep
Cortisol: lowest at midnight, highest at 8 am
Why do you not get your period when you’re breastfeeding?
Prolactin inhibits gonadotropin secretion
