Flashcards in Endocrine Anatomy Deck (53):
What is the function of the endocrine system?
Regulation of metabolic activities and maintenance of homeostasis (slower and longer lasting affect than ANS).
What are the main endocrine glands?
Pineal gland, pancreas, ovary, testis, adrenal gland, thyroid gland and pituitary gland.
Where does the pituitary gland sit?
Hypophyseal fossa (deepest part of sella turcica of sphenoid bone).
What covers the pituitary gland?
A fold of dura mater called diaphragma sellae.
What sits on top of the pituitary gland?
Optic chiasma (why you can get bitemporal hemianopia with pituitary adenomas).
What connects the pituitary gland and the hypothalamus?
Pituitary stalk (Infundbulum).
What are the two parts of the pituitary gland?
Anterior lobe (adenohypohysis) and the posterior lobe (neurohypophysis).
Which of the two lobes of the pituitary are larger?
Anterior lobe (makes up 2/3rd of pituitary).
How do the two lobes differ in their connection with the hypothalamus?
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).
How does the pituitary stain?
Anterior pituitary stains dark and posterior pituitary stains lighter.
What are the three types of cells in the pituitary and how do they stain?
Chromophobes (don't stain)
What does the histology of the posterior pituitary look like?
Wavey fibres - nervous tissue.
What two hormones are secreted by the posterior pituitary?
Vasopressin and oxytocin.
What are the two acidophils?
Somatotrophs (produce GH)
Mammotrophs (produce prolactin)
What are the three basophils?
Corticotrophs (produce ACTH)
Thyrotrophs (produce TSH)
Gonadotrophs (produce FSH and LH)
What is the blood supply to the pituitary gland?
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.
At what vertebral levels does the thyroid gland lie?
C5-T1 (between thyroid cartilage and 6th tracheal ring).
Where does the isthmus lie?
Opposite the 2nd-4th tracheal rings.
What is the thyroid gland responsible for?
Secretion of thyroxine and triiodothyronine.
Which strap muscles overlie the thyroid gland?
Sternohyroid, sternothyroid and anterior belly of omohyoid.
Which two nerves supply the vocal cords?
Recurrent laryngeal nerve and external laryngeal nerve.
What is the external laryngeal nerve a branch of?
Superior laryngeal nerve.
What path does the recurrent laryngeal nerve take?
Runs between tracheo-oesophageal groove close to the inferior thyroid a.
Where does the external laryngeal nerve lie?
Close to the superior thyroid artery (anterior to the thyroid gland).
What does damage to the recurrent laryngeal nerve cause?
Hoarseness if unilateral and aphonia/difficulty breathing if bilateral.
What does damage to the external laryngeal nerve lead to?
Hoarsness and inability to produce high pitched noises.
What is the arterial supply to the thyroid gland?
Superior thyroid artery (from 1st branch of ECA)
Inferior thyroid artery (from branch of subclavian)
What is the venous drainage of the thyroid gland?
Superior and middle thyroid veins drain into IJV.
Inferior thyroid vein drains into brachiocephalic vein.
Where does lymph from the thyroid gland drain?
Mostly into deep cervical group.
Hormones in thyroid glands are stored in cavities known as what? What cells are these cavities surrounded by?
Secretory cells - follicular cells.
Within the follicles of the thyroid gland, what are the hormones bound to?
What is the substance in the follicles referred to as?
What colour is colloid stained?
What stains stain clear in thyroid gland histology?
Parafoliicular/C cells - these secrete calcitonin.
How many parathyroid glands are there? Where are these located?
4 - on the lateral half of the posterior surface of each of the thyroid lobules (external to the thyroid fibrous capsule).
The superior parathyroids are at the level of what other structure?
Are the positions of the parathyroid glands always the same?
No - variable in different people
What is the arterial supply to the parathyroid glands?
Predominantly the inferior thyroid arteries.
What is the venous drainage of the parathyroids lands?
Veins draining the thyroid into the IVJ.
What are the two types of cells composing the thyroid gland and what are their functions?
Chief cells - secretory cells, stain light.
Oxyphils - function unknown, stain dark.
May also see clear cells - adipocytes (fatty deposits normal with age).
What is the function of the parathyroid glands?
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.
Where are the suprarenal glands located?
Upper poles of each kidney. They are enclosed in separated from kidney by means of a capsule.
How are the suprarenals peritonised?
What does the outer cortex of the suprarenals develop from?
What does the inner medulla of the suprarenals develop from?
What is the arterial supply to the suprarenals?
Suprarenal arteries (3 pairs of arteries (superior, middle, inferior that arise from inferior phrenic arteries, the aorta and the renal arteries)).
What is the venous drainage of the suprarenals?
Suprarenal vein that drains into IVC on right side and left renal vein on left side.
What are the three layers of the cortex of the adrenal glands and what does each layer synthesise?
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.
What does the medulla secrete? What does it appear like histologically?
Appears as large ovoid chromatin cells which secrete catecholamines (E/NE).
How is the pancreas peritonised?
Retroperitoneal apart from tail.
What are the four different cells types in the pancreas and what do each secrete?
Alpha - glucagon.
Beta - insulin.
Delta - somatostatin.
F-cells - pancreatic polypeptide.
What part of the pancreas stains poorly on H&E?
Islets of Langerhans.