Anatomy Flashcards
What forms the pancreas embryologically?
The endoderm.
2 buds extend from the primitive duodenum at the junction of the foregut and midgut and fuse to form the pancreas and biliary system.
What cells in the islets of langerhans produce what hormone?
B: Insulin
A: Glucagon
D: Somatostatin.
What forms the adrenal glands embyologically?
Cortex: Mesodermal from urogenital ridge.
Medulla: Derived from ectodermal neural crest cells as it is part of sympathetic NS.
Describe general anatomy of the adrenal glands?
Paired organ Retroperitoneal 5-8g Superior to kidney Anatomically and functionally divided into an outer cortex and inner medulla.
Name and describe the layers of the adrenal cortex?
Zona Glomerulosa: Outer, produces aldosterone, discontinuous. Cells are arranged in ball shapes.
Zona Fasiculata: 80% of cortex, cytoplasm is lipid rich, makes glucocoritcoids and androgens. Cells are arranged as columns and capillaries run between plates.
Zona Reticularis: Network of cells.
What does the adrenal medulla produce?
Part of sympathetic NS and produces adrenaline and noradrenaline (5:1).
Part of fight or flight response.
What suspends the pituitary gland?
A stalk called the infundibulum?
Describe the location of the pituitary gland?
In a depression of the sphenoid bone called the sella turcica.
What is the adenohypophysis?
Anterior pituitary
What is the neurohypophysis?
Posterior pituitary.
What is the embryological origin of the anterior pituitary?
A dorsal outgrowth of the pharynx (endoderm).
What is the embryological origin of the posterior pituitary?
The diencephlon (neuroectoderm).
Name the cell types of the anterior pituitary, what they secrete and what is the function?
- Somatotophs - growth homone (targets body tissue to increase protein synthesis and cartilage growth etc).
- Lactotrophs - prolactin (targets breast for lactogenesis).
- Thyrotrophs - Thyroid stimulating homone (Acts on follicular cells to produce T3/4.
- Gonadotrophs - FSH and LH (act on gonads for follicle maturation/stimulates leydig cells to produce testosterone).
- Corticotrophs - Adenocorticotrophin(acts on adrenal cortex to cause cortisol synthesis), lipotropin and melanocyte stimulating hormone.
Which cells in the ant pit are acidophils/basophils?
Acidophils - lactotrophs and somatotrophs (stain lighter)
Basophils - thyrotrophs, gonadotrophs and corticotrophs.
Describe the general structure of the anterior pituitary?
Irregular cords of secretory cells with fenstrated capillaries to allow rapid transport and exchange of blood/hormone passage to the hypophysealportalsystem.
What does the posterior pituitary secrete?
ADH and Oxytocin.
What forms the thyroid gland embryologically? When does this occur?
It is an endodermal downgrowth of the thyroglossal duct from the foramen caecum posterior to the tongue.
Happens week 5-7.
What connects the 2 lateral lobes of the thyroid?
The isthmus.
Describe the CT covering of the thyroid.
Has a collagenous capsule which projects inwards to form septa seperating lobes to lobules. The septa has blood vessels.
What cell type is found in the thyroid follicular cells?
Simple cuboidal when inactive, but become columnar when active.
What is found in the lumen of a thyroid follicle?
Colloid which contains thyroglobulin.
What other cell type is found in the thyroid gland? What is its function?
Parafollicular C cells around the follicle.
They secrete calcitonin which acts to lower blood calcium (stimulates osteoblasts, renal secretion).
Describe arterial supply to the thyroid gland?
Superior thyroid from the external carotid.
Inferior thyroid from the thyrocervical trunk from the subclavian artery.
Describe venous drainage of the thyroid?
Superior and middle thyroid veins to the IJV.
Inferior thyroid veins to the brachiocephalic vein.
Describe the location of the parathyroid glands?
2 superior and 2 inferior glands on the posterior aspect of the thyroid gland.
Where are the parathyroid glands derived from embryologically?
Superior: 4th brachial cleft and descend with thyroid.
Inferior: 3rd brachial cleft and descend with thymus.
What is the arterial supply to the parathyroid glands?
Inferior thyroid arteries.
Venous drainage of the parathyroid glands?
Parathyroid veins to thyroid plexus.
Name the cell types of the parathyroid glands and their function?
Cheif cells: Contains PTH granules to increase serum calcium.
Oxyphil cells:
Water-clear cells: Cheif cells with pools of glycogen.
What nerves run behind the thyroid gland?
External laryngeal
Recurrant laryngeal.
