Endocrine micro anatomy Flashcards
What is an Endocrine gland?
No connection to epithelial surface and release products into blood stream so high vascular network
What is an Exocrine gland?
maintain contact with surface and secrete directly into surface
What tissue does the posterior and anterior pituitary grow from?
Posterior = neural tissue (downward invagination of brain) Anterior = buccal cavity (cheek of mouth), connection to mouth breaks off
What is the invagination of the buccal cavity to form the anterior pituitary called?
Rathke’s pouch
What is the part of the sphenoid bone that the pituitary glands sits in called?
Sella Turcica
What is the division between the anterior and posterior pituitary called?
Pars Intermedia (technically part of anterior lobe)
What is the connection between the hypothalamus and posterior pituitary called
Infundibulum
What is the sheath which forms around the infundibulum called?
Pars Tuberalis
What are the three parts of the anterior pituitary?
- Pars Tuberalis
- Pars intermedia
- Pars Distalis
What are the two parts of the posterior pituitary?
- Pars Nervose
- Infundibular stalk
What cells make up posterior and anterior pituitary?
Posterior = neurones (doesn't make its own cells) anterior = glandular cells (makes its own cells)
What are the two types of cells which can be seen on staining of the anterior pituitary?
Chromophils (brightly stained)
Chromophobes (Pale staining)
What are the two types of chromophils?
Basophils (stained darker so more granular content)
Acidophils (stained red, less mature versions of basophils)
What are the five cell types of the anterior pituitary and what hormone do they secrete?
Somatotrophs - growth hormone Mammotrophs - prolactin Corticotrophs - adrenocorticoids Thyrotrophs- thyroid-stimulating hormone Gonadotrophs - FSH and LH
Which which hormone do the nuclei in the hypothalamus secrete?
Supraoptic - ADH
Paraventricular - Oxytocin
Where in the posterior pituitary are the hormones stored?
Herring bodies (dilations of the axon)
Describe histology of posterior pituitary?
- Herring bodies - dilation of axon bodies
- Pituicytes - support cells
- highly vascular
Where is the thyroid located?
anterior and lateral surface of trachea spanning from C5 to T1
What is the structure of the thyroid?
- Two lobes connected by central band of thyroid tissue
- Highly vascular
- superior to parathyroid
Where are the parathyroid glands and what do they do?
Four glands posterior to the thyroid which are needed for calcium regulation
- without which muscles would go into tectonic failure
What are the cell types that make up the thyroid follicle?
Follicular cells (epithelial cells which surround lumen) Parafollicular cells (also called C cells)
What do Follicular cells do?
- Produce T3 and T4
- which regulate cell and tissue metabolic rate, heat production and influence body growth and Development
What do Parafollicular cells do?
- Regulate calcium levels
- Calcitonin decreases blood calcium by decreasing reabsorption by osteoclasts and increasing bone formation by osteoblasts
What is found in lumen of follicles?
Colloid which stores thyroglobulin and inactive T3 and T4
What can amount of colloid tell you about the thyroid?
Lots of colloid = overactive thyroid
Little colloid = underachieve thyroid
What hormone stimulates release of thyroid hormone from follicle?
TSH from thyrotrophs of anterior pituitary
Describe location and structure of adrenal glands?
Location: embedded in perinatal fat superior to kidneys
Structure: central medulla surrounded by a cortex, adrenal glands are surrounded by a layer of connective tissue also
What are the cells which make up the medulla?
Neural crest cells
Describe cells of Zona Glomerulosa?
circular pyramidal or columnar cells which secrete aldosterone
Describe cells of Zona Fasciculata?
Large columnar cells which contain lots of fat droplets (cholesterol) which secrete aldosterone so controlled by ACTH
Describe cells of Zona Reticularis?
small netlike arrangement of cells which secrete androgens
What is the GEP?
- Gastrointestinal Enteroendocrine Pancreatic system
- Clusters or individual endocrine cells (i.e. hormone secreting) within the GI or pancreas
What are the four cells in the Islets of Langerhan?
Alpha secrete glucagon
Beta secrete insulin
Delta secrete somatostatin
F cells secrete pancreatic polypeptide
Function of GEP cells?
Secrete hormones which control gut function
Give examples of GEP cells?
Gastrin - stimulates gastric acid secretion
Cholecystokinin - stimulates gall bladder contraction
Motilin - stimulates gastric and intestinal motility
Secretin - stimulates pancreatic enzyme secretion and inhibits gastric acid secretion
What blood vessel brings hypothalamic hormones to the anterior pituitary?
Superior hypophyseal artery
What blood vessel brings Trophic hormones into the circulation?
Hypophyseal vein
