14.2 Lab + Lecture Notes Flashcards
Endocrine Cell
- secretes a product basal (i.e into surrounding CT)
- can occur singly (e.g. tracheal/GI epithelia)
- can be a shared FXN of another cell type
- generally have prominent basal surface
- surrounded by dense + extensive capillary network
- usually (1 exception - follicular cells of thyroid) lack a lumenal (apical) surface
Parathyroid
- most numerous cell = chief cell (sometime called principal cell)
- Oxyphil cell = minority cell type - increase in number with aging - so frequency is not the best way to recognize the cells
Thyroid
= source of hormones T3 + T4 (both incorporate iodine in structure)
- secondary funciton = sequestering + storage of iodine
- contain follicular cells = endocrine cells with an apical surface that functions in storing the iodine
Follicular cells
= endocrine cells with an apical surface (is rare occurrence)
- apical lumen forms a sealed compartemtn with iodine stored bound to thryoglobulin
- connect with each other via tight junctions - that create an apical and basal polarity to the cells
Thyroglobulin
- prominent eosinophilic material
- fills the lumen of thyroid follicle
- better to be called colloid
2 types of endocrine cells in thyroid
1) parafollicular cell = less frequent of the two
- called the C-cell
- produces calcitonin
2) ? follicular cell
Pituitary
= endocrine organ sitting at base of brain
- surrounded + protected by Sella turcica (indention in base of skull)
- derived from apposition of 2 embryonic tissues
1) Oral ectoderm –> adenohypophysis
2) Neural ectoderm –> neurohypophysis
Sella Turcica
= indentation in base of skull
- surrounds + protects the pituitary gland
Neurohypophysis
- axons of neurons seen here whose cells bodies sit in hypothalamus
- 2 products secreted by the axons are:
1) ADH
2) Oxytocin
Adenohypophysis
= collection of basal secreting cells surrounded by extensive capillary network
- 3 morphologically distinguishable parts
1) Pars distalis - comprises bulk of structure
2) Pars intermedia - lies immediately adjacent to neurohypophysis
3) Pars tuberalis - surrounding stalk of pituitary (which is itself part of neurohypophysis)
Classification of cells of adenohypophyssi
1) Acidophils
2) basophils
- hormones produced by basophils have glycogen precursors (will stain well in PAS stains)
3) Chromophobes
Pineal Gland
- sits in center of brain
= glandular tissue clustered in cords
= surround by CT that is an extension of pail tissue of brain - principle product = melatonin (inhibited by light and regulates circadian rhythms)
- has abundant capillaries
- morphologically distinguishable due to corpora arenacea
- parenchyma cell = pinealocyte
- has stromal glia cells too
Corpora arenacea
= brain sand
= unique metabolic byproduct
- accumulated throughout life as microscopic calcified particles
Pinealocyte
= parenchymal cell of pineal gland
Adrenal Gland
- unique because is endocrine organ with a layered organization
- sits above kidney (suprarenal gland)
- surrounded by capsule of CT
- outermost portion = adrenal cortex
- inner portion = adrenal medulla
- the 2 parts are from separate embryonic sources
Blood Supply/Flow in Adrenal Gland
- 3 suprarenal arteries - supply blood to gland
- 1 suprarenal vein - carries blood away
- blood flows from periphery to center
3 layers of adrenal cortex
- all layers produce steroid hormones –> called corticosteroids
- layers from outside in:
1) zona glomerulosa
2) zone fasiculata - cells have canonical appearance of steroid producing cells
- -> frothy/bubbly cytoplasm due to intracellular cholesterol
3) Zona reticularis
The amount of cholesterol in each layer of cortex depends on..
1) Whether enzyme that cleaves cholesterol (SCC) is rate-limiting step
2) Local availability of cholesterol carrier proteins (StAR)
Medullary Arteries
= long cortical arteries
= arteries that traverse the cortex