Histology - Endocrine System

Front 1

1.Describe the three possible scenarios in which endocrine secretion happens (gland is a separate entity with exclusive endocrine functions; the gland is a scattered mass of tissue amid exocrine components; the gland is actually unicellular or behaves as such).

Back 1

Gland is a separate entity with exclusive endocrine functions: most of the ones we know by name: thyroid, parathyroid, adrenal, etc.
Scattered tissue amidst exocrine components: islets of Langerhans, Leydig cells at the testis, interstitial cells of the kidney, etc.
Unicellular gland: enteroendocrine cell in the intestine and respiratory tract.

Front 2

1.Acidophils are further divided into: ____________________ that secrete growth hormone, and ______________________, that secrete prolactin.

Back 2

Somatotropes, lactotropes

Front 3

1.Basophils are further divided into: _________________ that secrete thyrotropic hormone; ________________ that secrete follicle-stimulating hormone and luteinizing hormone; and __________________ that secrete adrenocorticotropic hormone.

Back 3

Thyrotropes, Gonadotropes, Corticotropes

Front 4

1.What cells contribute to the production of the melanocyte-stimulating hormone?

Back 4

POMC

Front 5

1.The two hypothalamic nuclei that create the neurohyphophysis are the _____________________ nucleus, from which ____________________ hormone comes, and the _____________________ nucleus, from which _______________ comes.

Back 5

Supraoptic, Antidiuretic, paraventricular oxytocin

Front 6

1.What are the Herring bodies?

Back 6

Both hormones travel toward the nerve terminalis binded to neurophysin (neurophysin 1 for oxytocin, neurophysin 2 for antidiuretic hormone), where their accumulations can be seen with the light microscope (Herring bodies).

Front 7

1.What are the pituicytes?

Back 7

Pituicytes – they resemble glial cells and lack of secretory activities.

Front 8

1.Describe a thyroid follicle.

Back 8

Follicle: Anatomofuncional unit. It consists of simple cuboidal epithelium in the shape of a spheroid, whose centre is made of colloid.

Front 9

1.What is the function of the parafollicular cells?

Back 9

Cuboidal cells (lower when inactive, higher when active). Microvilli.

The colloid has thyroglobulin, enzymes, and here the thyroid hormones are kept.

Secrete the thyroid hormones T3 and T4 {target: many organs}

Front 10

1.In the parathyroid most cells are ________ cells and secrete ___________ while the less abundant cells are those round, big, bright cells whose function is still somewhat undefined, known as ____________________, and that appear between the ____ and ____ birthday. As the gland ages, the number of associated adipocytes will increase.

Back 10

Chief cells, parathyroid hormone, oxyphils, 5th and 7th

Front 11

1.What part of the suprarenal is under the hyphophysis control?

Back 11

cortex

Front 12

1.How is the adrenal cortex divided?

Back 12

1.Zona glomerulosa: External, accounts for 15% of the cortical volume. The cells create a glomerulus-like pattern.

2.Zona fasciculata: 78% of the cortical volume. Large cells (sometimes called spongiocytes) arranged in parallel chords.

Zona reticularis: Makes 7% of the cortex volume. Network of anastomosing chords facing the adrenal medulla.

Front 13

1.What organelle is quite developed in the cells of the adrenal cortex?

Back 13

Smooth ER

Front 14

1.What are the secretions of the adrenal and how are they related to the layers of the cortex?

Back 14

1.Mineralocorticoids
1.Aldosterone and deoxycorticosterone – zona glomerulosa

2.Glucocorticoids
Cortisol (hydrocortisone), cortisone and corticosterone – zona fasciculata and reticularis

3.Gonadocorticoids
Few amounts of dehydroepiandrosterone, other androgens, estrogen and progesterone – zona reticularis

Front 15

1.What are the secretions of the adrenal medulla?

Back 15

Anastomosing chords of polyhedral cells surrounded by capillary vessels that secrete epinephrine and norepinephrine.

Front 16

1.What system exerts its control over the adrenal medulla?

Back 16

Medulla related with the sympathetic autonomous nervous system.

Front 17

1.What is the chromaffin reaction and why it is important?

Back 17

Chromaffin reaction: Granules of cells that secrete epinephrine or norepinephrine react with potassium bichromate, getting a brown colour. Although not important for the recognition of the adrenal medulla (we precisely know where it is) it is helpful to identify cells that belong to the chromaffin system and their neoplastic derivatives, as happens with pheochromocytoma.

Front 18

1.What is the chromaffin system? Name its largest portion.

Back 18

Chromaffin system

Scattered groups of cells similar to the ones of the suprarenal medulla.
Mostly retroperitoneal.
More abundant at birth (they are fetal remnants of the migration of adrenal medulla cells) and later they decline, but don’t disappear.
Largest one is the para-aortic bodies of Zuckerkandl.
Secrete epinephrine and norepinephrine.

Front 19

1.What is the function of the pineal?

Back 19

Secretion: melatonin. Might play a role in suppressing the (start of the) gonadal function, hence stopping puberty up to the moment it is supposed to start.

Front 20

1.What are the cells of the pineal?

Back 20

1.Pinealocytes: Irregular cytoplasm with bulbous endings near blood vessels.

Glial cells: They resemble astrocytes.

Front 21

1.Describe the acervuli or corpora arenacea.

Back 21

Acervuli: main characteristic helpful to identify the organ. AKA as corpora arenacea or brain sand. [HINT: in normal conditions, just two organs have calcareous concretions: the pineal and the prostate]

Front 22

1.What are the Langerhans islets?

Back 22

Spheroidal groups of cells distributed amidst the exocrine pancreas, more common toward the tail of the organ.

Front 23

1.Describe the functions of the cells of the Langerhans islets, particularly Alpha, Beta and Delta cells.

Back 23

1.Alpha, Beta and Delta cells.
1.Alpha: 20 % of the cells, at the periphery of the islet, secrete glucagon.

2.Beta: 70 % of the cells, at the centre of the islet, secrete insulin.

Delta: 5 % of the cells, not evenly distributed, mostly at the centre and where alpha and beta cells intertwine. They secrete somatostatin.