Endocrine Histology Flashcards
The Neurohypophysis is the ________ lobe of the pituitary.
-Posterior
The Adenohypophysis is the _________ lobe of the pituitary.
-Anterior
What are the two Acidophils (eosinophils) of the Adenohypophysis and what do they secrete?
- Somatotropic Cell = GH
- Mammotropic Cell = Prolactin
What are the three Basophils of the Adenohypophysis and what do they secrete?
- Thyrotropic Cell = TSH
- Corticotropic Cell = ACTH
- Gonadotropic Cell = FSH & LH
What is the pars tuberalis and what kind of cells are located there?
- collar of cells around the infundibular stem
- part of the adenohypophysis
-Contains gonadotropic cells (basophilic)
Where are ADH and oxytocin synthesized? Where are they released?
- Neurons of the supraoptic and paraventricular nuclei in the hypothalamus
- released in pars nervosa (posterior pituitary)
Where is the pars nervosa located?
-posterior pituitary
What are the three Pars of the adenohypophysis?
- Pars distalis (75%)
- Pars Intermedia
- Pars tuberalis
Neurons of what nuclei influence hormone release in the anterior pituitary?
-dorsal & ventral medial and infundibulary nuclei
Neurons of what nuclei release hormones in the posterior pituitary?
Supraoptic and paraventricular nuclei
What is a Herring Body?
- Secretory material in the neurohypophysis
- Storage of secretory elements
What are Pituicytes?
-basically glial cells for the posterior pituitary
What are the principal cell types of the Thyroid gland?
- Follicular Cells
- Parafollicular cells (C-cells)
What is found on the inside of a thyroid follicle?
-colloid
Where is thyroglobulin stored?
-lumen colloid of thyroid gland
What happens to thyroglobulin?
-it is iodinated in the lumen of the follicle, forming T3 and T4. This is then secreted basally into a capillary
What does T3 do?
- increases basal metabolic rate
- stimulates mitochondiral respiration
- increases number of mitochondria and cristae
What is the embryological origin of C-cells in the thyroid?
Neural crest
What do C-cells do?
-produce and secrete Calcitonin
What are the principal cells of the Parathyroid Glands?
- Chief Cells
- Oxyphil cells
What are the parathyroid glands important for?
-calcium homeostasis
What do chief cells of the Parathyroid do?
-secrete PTH in response to low Ca levels
What do Oxyphil Cells do?
- Unknown function
- Have lots of mitochondria (eosinophilic)
- may be transitional chief cells
What is a result of hyperparathyroidism?
- multiple sites of bone deposition (bone cysts)
- Kidney stones
What is a result of Hypoparathyroidism?
- low serum calcium
- Muscle spasms and convulsions
What does the Pineal Gland do?
- regulates circadian rhythm
- secretes Melatonin in relation to light/dark cycles
What are the main cells of the Pineal Gland?
-Pinealocytes
What is the embryological origin of the cortex and medulla of the adrenal glands?
Cortex: Mesoderm
Medulla: Neural Crest
What gland regulates the Adrenal Cortex?
-pituitary
What is secreted by the Adrenal Cortex?
-steroid hormones
What is produced and secreted by the Adrenal Medulla?
-Catecholamines
What are the three zones of the Adrenal Cortex, in order of outer to inner?
- Zona Glomerulosa
- Zona Fasciculata
- Zona Reticularis
What class of hormones is produced in the Zona Glomerulosa?
-Mineralcorticoids
What class of hormones is produced in the Zona Fasciculata?
-Glucocorticoids
What class of hormones is produced in the Zona Reticularis?
-Androgens
What is the histological appearance of Adrenal Cortex cells?
foamy
(T/F) The adrenal cortical and medullary arteries are separate.
T
What is the primary Mineralcorticoid?
-aldosterone
What is the primary glucocorticoid?
-Cortisol
What is the primary Catecholamine released by the Adrenal Medulla?
Epinephrine (80%)
What is the functional cell of the Adrenal Medulla?
-Chromaffin Cells
What is PNMT (Phenylethnolamine N-methyltransferase)?
-enzyme that converts Norepinephrine to Ephinephrine in the Adrenal Medulla
What do Delta cells of the Pancreas release?
- Gastrin
- Somatostatin
- VIP
What does Somatostatin do?
-inhibits insulin and Glucagon
What do Follicular cells of the Thyroid do?
- produce Thyroglobulin and secrete apically into lumen
- Take up iodide, oxidise to iodine, and secrete apically to lumen
- Take up T4/3, secrete basally
What causes Goiter?
- thyroglobulin is produced, secreted to lumen, but never iodinated
- builds up, swelling the thyroid gland
What is Myxedema?
-adult hypothyroidism
What is Graves Disease?
-Hyperthyroidism
