HIST Pituitary, Thyroid & Adrenal Glands Workshop - Week 11 Flashcards
Describe process of ant pit hormone secretion
For anterior pit. hormones, stimulating hormones are synthesised in the hypothalamus & secreted into capillaries -> travels via veins into ant. pituitary -> stimulate cells to synthesise & secrete hormones -> enter bloodstream.
Describe process of post pit hormone secretion.
For posterior pit. hormones, hormones are synthesised in the hypothalamus -> travel via axons of the neurons which create them -> stored in ends of the axons in the post. pituitary - > later released into capillaries to travel to post. pituitary.
Somatotrophs are found in what endocrine organ, release what hormone, are under what hypothalamic control & have what action?
Ant pit. GH. GHRH (releasing) & SRIF (somatostatin inhibiting). Growth promotion.
Thyrotrophs are found in what endocrine organ, release what hormone, are under what hypothalamic control & have what action?
Ant pit. TSH. TRH, SRIF. Secretion of thyroid hormones.
Corticotrophs are found in what endocrine organ, release what hormone, are under what hypothalamic control & have what action?
Ant pit. ACTH. CRH, AVP. Secretion of cortisol.
Lactotrophs are found in what endocrine organ, release what hormone, are under what hypothalamic control & have what action?
Ant pit. Prolactin. TRH (Thytrophin-releasing hormone), dopamine - inhibitory. Milk secretion.
Gonadotrophs are found in what endocrine organ, release what hormone, are under what hypothalamic control & have what action?
Ant pit. FSH, LH. GnRH. Production of gametes, secretion of sex steroids.
Post pit synthesises & secretes what hormones?
ADH & oxytocin.
What 2 classes of hormones does the adrenal cortex synthesise?
Protein & steroid hormones.
Adenohypophysis
Ant pit.
Pars distalis
Ant pit.
Pars nervosa
Post pit.
Neurohypophysis
Post pit.
How do hormones produced in the hypothalamus travel to the ant pit?
Hormones produced in hypothalamus pass through capillaries -> portal venous system -> capillaries @ ant pit where hormone will finally be released into the bloodstream.
How do hormones produced in the hypothalamus travel to the post pit?
Post pit consists of nerve fibres from the hypothalamus, their terminals, being in close association with capillaries. Post pit hormones are peptides, which are synthesised in the hypothalamus, then bound to carrier proteins and stored in granules in the axon terminals until discharged by exocytosis.
What tissue is the ant pit derived from?
Oral ectoderm (epithelial organ).
What tissue is the post pit derived from?
Nervous tissue.
What are the main cells composing the ant pit gland? How are these cells arranged?
Secretory cells. Often arranged in clumps/cords.
What hormones does the thyroid gland synthesise and how are these created - what critical mineral/element is required and from where is this sourced?
Makes & stores hormones - T3 & T4. These hormones can be stored for months in colloid tissue (which also includes iodinated glycoprotein, thyroglobulin), until release post signal.
What epithelial cells surround follicular cells?
Simple cuboidal/simple squamous cells.
What is the inner layer of stromal cells surrounding a follicle called? What is their function?
Thecal cells. Secrete steroid precursors.
What receptors do thecal cells have?
LH receptors.
What is an immature follicle termed?
Primordial follicle.
What cells are the main steroid producing cells of the testis? Where are they found? What hormones do they respond to? What steroids do they mainly synthesise? Where are these steroids secreted?
Leydig cells. Interstitial tissue (space btw seminiferous tubules). Respond to LH from the ant pit. Smooth ER characteristic of these cells to support testosterone synthesis. Testosterone secreted into lymphatics.
2 x regions of the adrenal gland
Inner medulla & outer cortex.
What are the main cells of the inner adrenal medulla? What is their main function? What cells are they derived from? How are they usually arranged?
Chromaffin cells - modified symp post-ganglionic neurons. Derived from neural crest cells. Synthesise & store A & NA. Nests & cords.
What 2 x classifications of hormones does the adrenal cortex synthesise?
Protein & steroid hormones.
What are the 3 x layers of the adrenal cortex?
- Zonula glomerulosa – synthesises & secretes mineralcorticoids (e.g., aldosterone) to regulate fluid.
- Zonula fasiculata – synthesise glucocorticoids (e.g., cortisol) w foamy appearance histologically due to high presence of lipid droplets required to synthesise these hormones.
- Zonula reticularis – synthesise weak androgens (e.g., DHEA – precursor of testosterone).
Remember: GFR & salt, sugar, sex.
What hormones are produced by the endocrine pancreas?
Insulin & glucagon.
How many parathyroid glands are there usually? What is the function of these glands?
- Secretes parathyroid hormones strongly regulating Ca2+ homeostasis.
What kind of hormone is Vit D classified as?
Steroid.
What kind of hormone is insulin classified as?
Peptide hormone.
