Thyroid, Parathyroid and Adrenal Flashcards
Cell types of thyroid
- Follicular
2. Parafollicular (aka clear cells)
Follicular cell appearance
Cuboidal epithelium with microvilli on apical edge
Held together by tight junctions
Parafollicular cell appearance
Isolated clusters beside follicle
Larger and paler
Produce calcitonin
Phases of thyroid cels
Endocrine and storage phase
Storage phase of follicular cells
Synthesize and secrete thyroglobulin which is stored in lumen of follicle
Endocrine phase of follicular cells
- Stored thyroglobulin is taken up by follicular cells
- Broken down to active thyroid hormone
- Released into blood
Most abundant thyroid hormone
T4 (thyroxine) → prohormone
Less abundant thyroid hormone
T3 (triiodothyronine) → active
T4 is activated by what cells?
- Liver
- Kidney
- Muscle
Thyroid hormone function
Increase metabolic rate and mitochondrial respiration
Colloid
Made up of thyroglobulin (glycoprotein) → storage phase
Cell types of parathyroid
- Chief cells (principle)
2. Oxyphil cells
Oxyphil cells are found in?
Human, ox, horse
Chief cells produce?
PTH to raise blood Ca
Parenchyma of adrenal gland includes?
Fine reticular fibers and trabeculae from capsule
3 regions of adrenal cortex
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
Zona glomerulosa is stimulated by?
Angiotensin
Not ACTH from the pituitary
Zona glomerulosa produces?
Mineralcorticoids (esp. aldoserone) to increase blood Na
Widest zone of adrenal cortex
Zona fasciculata
Cells of zona fasciculata
Spongiocytes
Spongiocyte appearance
Polyhedral with foamy cytoplasm (contains SER and lipid inclusions)
Zona reticularis
Closely packed cells → produces some weak androgens and some glucocorticoids
Zona fasciculata is stimulated by ___ to produce ____
ACTH to produce glucocorticoids
Adrenal medulla are made up of?
Chromaffin cells
