Endocrine Anatomy

Question 1

What is the function of the endocrine system?

Answer 1

Regulation of metabolic activities and maintenance of homeostasis (slower and longer lasting affect than ANS).

Question 2

What are the main endocrine glands?

Answer 2

Pineal gland, pancreas, ovary, testis, adrenal gland, thyroid gland and pituitary gland.

Question 3

Where does the pituitary gland sit?

Answer 3

Hypophyseal fossa (deepest part of sella turcica of sphenoid bone).

Question 4

What covers the pituitary gland?

Answer 4

A fold of dura mater called diaphragma sellae.

Question 5

What sits on top of the pituitary gland?

Answer 5

Optic chiasma (why you can get bitemporal hemianopia with pituitary adenomas).

Question 6

What connects the pituitary gland and the hypothalamus?

Answer 6

Pituitary stalk (Infundbulum).

Question 7

What are the two parts of the pituitary gland?

Answer 7

Anterior lobe (adenohypohysis) and the posterior lobe (neurohypophysis).

Question 8

Which of the two lobes of the pituitary are larger?

Answer 8

Anterior lobe (makes up 2/3rd of pituitary).

Question 9

How do the two lobes differ in their connection with the hypothalamus?

Answer 9

Anterior - receives trophic hormones from the hypothalamus. Communication via hypothalamo-hypophyseal portal system (2 capillary beds in series).

Posterior - has a neural connection with hypothalamus and releases neurohormones produced by hypothalamus (axons go down pituitary stalk and end on capillaries).

Question 10

How does the pituitary stain?

Answer 10

Anterior pituitary stains dark and posterior pituitary stains lighter.

Question 11

What are the three types of cells in the pituitary and how do they stain?

Answer 11

Acidophils (pink)
Basophils (purple)
Chromophobes (don’t stain)

Question 12

What does the histology of the posterior pituitary look like?

Answer 12

Wavey fibres - nervous tissue.

Question 13

What two hormones are secreted by the posterior pituitary?

Answer 13

Vasopressin and oxytocin.

Question 14

What are the two acidophils?

Answer 14

Somatotrophs (produce GH)

Mammotrophs (produce prolactin)

Question 15

What are the three basophils?

Answer 15

Corticotrophs (produce ACTH)
Thyrotrophs (produce TSH)
Gonadotrophs (produce FSH and LH)

Question 16

What is the blood supply to the pituitary gland?

Answer 16

From branches of ICA - superior hypophyseal artery and the inferior hypophyseal artery.

Superior hypophyseal artery enters substance of hypothalamus and breaks into capillaries (hypophyseal portal system). These capillaries supply the anterior lobe.

The inferior hypophyseal artery supplies the posterior lobe.

Question 17

At what vertebral levels does the thyroid gland lie?

Answer 17

C5-T1 (between thyroid cartilage and 6th tracheal ring).

Question 18

Where does the isthmus lie?

Answer 18

Opposite the 2nd-4th tracheal rings.

Question 19

What is the thyroid gland responsible for?

Answer 19

Secretion of thyroxine and triiodothyronine.

Question 20

Which strap muscles overlie the thyroid gland?

Answer 20

Sternohyroid, sternothyroid and anterior belly of omohyoid.

Question 21

Which two nerves supply the vocal cords?

Answer 21

Recurrent laryngeal nerve and external laryngeal nerve.

Question 22

What is the external laryngeal nerve a branch of?

Answer 22

Superior laryngeal nerve.

Question 23

What path does the recurrent laryngeal nerve take?

Answer 23

Runs between tracheo-oesophageal groove close to the inferior thyroid a.

Question 24

Where does the external laryngeal nerve lie?

Answer 24

Close to the superior thyroid artery (anterior to the thyroid gland).

Question 25

What does damage to the recurrent laryngeal nerve cause?

Answer 25

Hoarseness if unilateral and aphonia/difficulty breathing if bilateral.

Question 26

What does damage to the external laryngeal nerve lead to?

Answer 26

Hoarsness and inability to produce high pitched noises.

Question 27

What is the arterial supply to the thyroid gland?

Answer 27

Superior thyroid artery (from 1st branch of ECA) | Inferior thyroid artery (from branch of subclavian)

Question 28

What is the venous drainage of the thyroid gland?

Answer 28

Superior and middle thyroid veins drain into IJV. | Inferior thyroid vein drains into brachiocephalic vein.

Question 29

Where does lymph from the thyroid gland drain?

Answer 29

Mostly into deep cervical group.

Question 30

Hormones in thyroid glands are stored in cavities known as what? What cells are these cavities surrounded by?

Answer 30

Follicles. | Secretory cells - follicular cells.

Question 31

Within the follicles of the thyroid gland, what are the hormones bound to?

Answer 31

Glycoproteins.

Question 32

What is the substance in the follicles referred to as?

Answer 32

Colloid.

Question 33

What colour is colloid stained?

Answer 33

Pink

Question 34

What stains stain clear in thyroid gland histology?

Answer 34

Parafoliicular/C cells - these secrete calcitonin.

Question 35

How many parathyroid glands are there? Where are these located?

Answer 35

4 - on the lateral half of the posterior surface of each of the thyroid lobules (external to the thyroid fibrous capsule).

Question 36

The superior parathyroids are at the level of what other structure?

Answer 36

Cricoid cartilage.

Question 37

Are the positions of the parathyroid glands always the same?

Answer 37

No - variable in different people

Question 38

What is the arterial supply to the parathyroid glands?

Answer 38

Predominantly the inferior thyroid arteries.

Question 39

What is the venous drainage of the parathyroids lands?

Answer 39

Veins draining the thyroid into the IVJ.

Question 40

What are the two types of cells composing the thyroid gland and what are their functions?

Answer 40

Chief cells - secretory cells, stain light. Oxyphils - function unknown, stain dark. May also see clear cells - adipocytes (fatty deposits normal with age).

Question 41

What is the function of the parathyroid glands?

Answer 41

Secretion of PTH (stimulates conversion of inactive vitamin D3 into calcitonin) and increases bone resorption of calcium and phosphates (stimulate osteoclasts) and kidneys to reduce urinary excretion of Ca and increase phosphate excretion. Regulated by plasma calcium levels.

Question 42

Where are the suprarenal glands located?

Answer 42

Upper poles of each kidney. They are enclosed in separated from kidney by means of a capsule.

Question 43

How are the suprarenals peritonised?

Answer 43

Retroperitoneal.

Question 44

What does the outer cortex of the suprarenals develop from?

Answer 44

Mesoderm.

Question 45

What does the inner medulla of the suprarenals develop from?

Answer 45

Neuroectoderm.

Question 46

What is the arterial supply to the suprarenals?

Answer 46

Suprarenal arteries (3 pairs of arteries (superior, middle, inferior that arise from inferior phrenic arteries, the aorta and the renal arteries)).

Question 47

What is the venous drainage of the suprarenals?

Answer 47

Suprarenal vein that drains into IVC on right side and left renal vein on left side.

Question 48

What are the three layers of the cortex of the adrenal glands and what does each layer synthesise?

Answer 48

Zona glomerulosa (thin) - organised into little glomeruli. Secretes mineralocorticoids. Zona fasiculata (thick) - straight vertical cords. Secretes glucocorticoids. Zona reticularis (thin) - wavey organisation. Secretes sex hormones.

Question 49

What does the medulla secrete? What does it appear like histologically?

Answer 49

Appears as large ovoid chromatin cells which secrete catecholamines (E/NE).

Question 50

How is the pancreas peritonised?

Answer 50

Retroperitoneal apart from tail.

Question 51

What are the four different cells types in the pancreas and what do each secrete?

Answer 51

Alpha - glucagon. Beta - insulin. Delta - somatostatin. F-cells - pancreatic polypeptide.

Question 52

What part of the pancreas stains poorly on H&E?

Answer 52

Islets of Langerhans.

Question 53

Pancreatic ducts are composed of what type of epithelium?

Answer 53

Type layers of either cuboidal or columnar epithelium.