14.1 - Endocrinology Flashcards
Pituitary Gland
= divided into 2 parts based on embryonic origin of its tissues
1) Neurohypophysis (posterior pituitary)
- is derived from neuroectoderm
- consists of the median eminence, infundibular stalk, pars nervosa
- contains descending axons that originated in the supraoptic and paraventricular nuclei of the hypothalamus
- descending axons release ADH and oxytocin
2) Adenohypophysis (anterior pituitary)
- derived from oral ectoderm
- forms donut-shaped ring around the infundibular stalk
- consists of: pars tuberalis, pars intermedia, pars distalis
Neurohypophysis
= posterior pituitary
- derived from neuroectoderm
- consists of
1) median eminence
2) infundibular stalk
3) pars nervosa - contains descending axons that originate in the supraoptic and paraventricular nuclei of the hypothalamus
- dilated ends of axons from herring bodies –> release ADH and oxytocin
- resident glia cells = pituicytes
Where do the descending axons of the neurohypophysis originate
- in the hypothalamic supraoptic and paraventricular nuclei
Herring Bodies
= the dilated ends of the axons (descending from supra optic and paraventricular hypothalamic nuclei)
- release ADH and Oxytocin
Pituicytes
= resident glia cells of the pituitary gland
Adenohypophysis
= anterior pituitary
- derived from oral ectoderm
- forms a donut-shaped ring of tissue around the infundibular stalk - consists of:
1) pars tuberalis
2) pars intermedia
3) pars distalis
3 cell characterizations of the pars distalis
1) Acidophilis - producing:
a. growth hormone (somatotropin)
b. prolactin
2) Basophils - producing:
a. ACTH
b. TSH
c. FSH
d. LH
e. beta-endophin
3) chromophobes - not well understood
Melanocyte-stimulating hormone (MSH)
- produced by cells of pars intermedia
Thyroid gland
- contains numerous thyroid follicles = spherical accumulations of colloid composed of thyroglobulin contained by follicular cells with occasional interposed parafollicular cells (C-cells)
Thyroid follicles
= spherical accumulations of colloid
Colloid
- arranged in spherical accumulations called thyroid follicles
= composed of thyroglobulin contained by follicular cells with occasional interposed parafollicular cells (C-cells)
Thyroglobulin
- component of colloid
- colloid accumulates into spherical thyroid follicles
- is contained by follicular cells with occasional interposed parafollicular cells (C-cells)
Follicular cells
- contain thyroglobulin
- produce T3 and T4
- component of colloid
Parafollicular cells
= c-cells
- produce calcitonin
- component of colloid
Parathyroid Gland
- majority cell type = chief cell –> produces PTH
- minority cell type = oxyphil –> unknown function
Chief cell
= majority cell type in parathyroid glands
- produces parathormone (PTH)
Oxyphil cell
= minority cell type in parathyroid gland
- unknown function
Pineal Gland
- sits within the brain
- parenchymal cells = pinealocytes –> produce melatonin
- gland accumulates concretions = corpora arenacea = brain sand
Pinealocytes
= parenchymal cells of the pineal gland
- produce melatonin
Corpora arenacea
= concretion accumulations that occur in the pineal gland
- also called brain sand
Pancreas
- contains groups of endocrine cells = islets of Langerhans
- 4 cell types in the islets (decreasing frequency)
1) beta cells - produce insulin
2) alpha cells - produce glucagon
3) PP cells - produce pancreatic polypeptide
4) delta cells - produce SST
Islets of Langerhans
= groups of endocrine cells in the pancreas
- contain 4 cell types
1) beta cells
2) alpha cells
3) PP cells
4) delta cells
Beta cells
- most frequent cell type in the islets of Langerhans in the pancreas
- produce insulin
alpha cells
- second most frequent cell type in the islets of langerhans in the pancreas
- produce glucagon
PP cells
= third most frequent cell type in the islets of Langerhans in the pancreas
- produce pancreatic polypeptide
Delta cells
= fourth most frequent cell type in the islets of Langerhans in the pancreas
- produce SST
Adrenal Gland
- consists of two embryologically distinct parts
1) adrenal cortex - produces corticosteroids
- organized into 3 layers:
a. zona glomerulosa - mineralcorticoids (aldosterone)
b. zona fasciculata - glucocorticoids (cortisol)
c. zona reticularis - androgens
2) adrenal medulla - contains two types of chromatin cells
- producing epinephrie + NE
Adrenal Cortex
- produces corticosteroids
- organized into 3 layers
1) Zona glomerulosa - produces mineralcorticoids
- primarily aldosterone
2) Zona fasciculata - produces glucocorticoids
- primarily cortisol
3) Zona reticulata - produces androgens
Adrenal Medulla
- contains two types of chromatin cells
- they produce epinephrine + NE
Diffuse neuroendocrine system (DNES)
= endocrine cells occurring as minority cell types in other endodermal-derived epithelia
- are particularly important to the control of the GI and respiratory systems
- many (but not all) secrete polypeptide hormone (e.x. CCK) from amine precursors using decarboxylase enzymes –> thus are known as amine precursor uptake and ecarboxylation cells (APUD)
APUD cells
= amine precursor uptake and decarboxylation cells
- cells of the DNES that secrete polypeptide hormones from amine precursors (using decarboxylase enzymes)
