Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
32 Cards in this Set
- Front
- Back
|
Endocrine Glands - Epithelial cells secrete what? Name 4 of them. Where do these secretions go?
|
-Epithelial cells secrete Hormones:
1) Proteins/Glycoproteins (thyroglobulin) 2) Steroids (aldosterone, Mineralocorticoids) 3) Catecholamines - small MWT, highly (epinephrine) 4) Peptides (gastrin) -Secretions into Systemic Circulation |
|
|
Epithelial cells associated closely with what and how?
|
-Epithelial cells associated closely with Fenestrated Capillaries.
-Fenestrated capillaries have transmural pores facilitating transfer into the systemic circulation |
|
|
What exactly regulate hormone secretion?
|
Feedback loops regulate hormone secretion
Autoregulatory system i. Change in physiological state detected ii. Endocrine gland turned off |
|
|
Pituitary Gland - which other glands does it regulate? 2 components? has extension of what?
|
-Master regulatory gland for endocrine system. Regulates all of the other glands
-Has two components - adenohypophysis and neurohypophysis -Is a complex gland with small projection of the hypothalamus (neurohypophysis) |
|
|
Thyroid Gland Histology (part I) - consists of closed cysts called?, the epithelial cells found here secrete what, which was originally stored as what?
|
-Consists of large number of closed cysts called Follicles.
-Follicular epithelial cells secrete Thyroglobulin |
|
|
Thyroid Gland Histology (part II) - what triggers the release of what cleavage product of thyroglobulin, follicles held together by what and surrounded by what
|
-TSH (made in pituitary) triggers release of cleavage product of thyroglobulin called Thyroxine
-Follicles held together by delicate CT domain that also forms capsule. -Follicles surrounded by fenestrated capillaries that receive thyroxine |
|
|
Parafollicular (C-) cells of Thyroid Gland - secrete what, which is the antagonist of what?
|
-Scattered, rounder, pale cells with larger, more lightly stained nuclei, either among follicular epithelial cells or adjacent to follicles
-Secrete Calcitonin, an antagonist of parathormone -Parathormone – crucial regulator of serum calcum, made by the parathyroid gland |
|
|
Thyroglobulin Synthesis and Storage - what is it? what does it contain? what is it stored as and where?
|
-Thyroglobulin is a high MW glycoprotein containing iodinated amino acids.
-Thyroglobulin stored as Colloid in lumen of follicles |
|
|
Thyroglobulin Synthesis and Storage - how is it synthesized?
|
-Follicular epithelial cells take up amino acids, sugars, and iodide from capillaries on basal surface and synthesize TG through (in order) RER, Golgi apparatus, and secretory vesicles into the lumen
|
|
|
Role of TSH - TSH comes from where? When TSH is secreted into blood and reaches thyroid follicles, what 2 things does it do? What is released as a result into capillaries?
|
-Thyroid-Stimulating Hormone (TSH) comes from adenohypophysis of pituitary gland
-When TSH is secreted into blood and reaches thyroid follicles, it stimulates uptake of thyroglobulin from stored colloid and cleavage of iodinated amino acids from thyroglobulin. -These iodinated amino acids - thyroxine (T3 and T4) are then released into capillaries |
|
|
Differences between normal and TSH-stimulated follicular cell?
|
Normal:
i. Taking up constitutents ii. Synthesizing thyroglobulin iii. Secreting thyroglobulin into lumen TSH-Stimulated: i. Surface projections engulf thyroglobulin (Follicular cells have large surface projections to take TG in endocytose) ii. Lysosomes fuse with endocytic vesicle *iii. Thyroglobulin broken to make T3/T4, Thyroxine iv. Secreted into the basal surface |
|
|
Feedback loop for Thyroid Function - When serum thyroxine is low and needs to be increased...
|
-When serum thyroxine is low, TRH is secreted by neurohypophysis
-TRH causes TSH secretion from adenohypophysis -TSH then causes increase in Thyroxine levels -Increased thyroxine then shuts off TRH secretion so TSH secretion and thyroxine secretion fall -Negative feedback loop system – when too much thyroxine present in blood, TRH secretion is shut off, preventing TSH secretion, preventing an increase in thyroxine levels -Thyroxine levels increase with hydrolysis of thyroglobulin -This system maintains homeostatic level of thyroxine |
|
|
Parathyroid/Thyroid Relations - How many parathyroids are there? Where are they in relation to the thyroid? Do they share the same blood supply?
|
-There are normally 4 parathyroids (2 superior and 2 inferior)
-Located outside capsule of thyroid -Posterior surface of thyroid -Parathyroid is histologically distinct from thyroid gland and has distinct blood supply |
|
|
Parathyroid Histology - what type of cells make up most of the parathyroid parenchyma? What do they secrete? Acidophilic or Basophilic? What are found between these cells (2)?
|
Chief cells make up most of parathyroid parenchyma. These are basophilic granular epithelial cells that secrete Parathormone (PTH).
CT elements (fibroblasts and adipocytes) and fenestrated capillaries between nests and cords of chief cells |
|
|
Parathyroid Histology - what type of cells make up the rest of the parathyroid parenchyma? Acidophilic or Basophilic?
|
Oxyphil cells are rest of parenchyma. These are acidophilic epithelial cells, probably effete (worn-out) chief cells
|
|
|
What is the relationship between osteoperosis and the parathyroid hormones?
|
More adipose tissue invades the glands with aging because function declines over time- responsible for osteoporosis
|
|
|
Function of parathyroid glands - regulate levels of what by secreting what and how?
What is the antagonist of PTH and does the normal system of Calcitonin/PTH work with or without intervention of the pituitary gland? |
-They regulate Serum Calcium by secreting PTH from parathyroid chief cells
-When serum calcium falls, PTH triggers osteocytic osteolysis and mobilization of calcium from bone martix by binding on receptors of osteocytes, osteoclasts -Calcitonin from C-cells in thyroid is an antagonist of PTH. The normal system of Calcitonin/PTH opposing balance works without intervention of the pituitary gland |
|
|
High levels of PTH lead to what 4 things?
|
i. Increase in serum calcium
ii. Osteoporosis because of resorption of calcium from bone iii. Breakable bones iv. Kidney stones from the heightened serum levels of calcium |
|
|
Tumors of chief cells in parathyroid can lead to what 2 things?
|
Tumors of chief cells in parathyroid can lead to chronic bone decalcification and osteoporosis
|
|
|
Basic Organization of Adrenal Glands - where are they, what 2 parts do they have and what do each of these 2 parts consist of and secrete?
|
-Paired structures on superior pole of each kidney
-Each has an outer shell of Cortex and an inner core of Medulla -Cortex has conspicuous morphological and functional Zones and secretes Steroids -Medulla has neurons and modified neuron-like cells that secrete Catecholamines (epinephrine and norepinephrine). The medulla is a highly modified autonomic ganglion that secretes nuerotransmitters. Cortex and medulla are separate morphologically, functionally, and in their embryologic origin |
|
|
Blood Flow Through Adrenal Glands - 3 sets of blood vessels and what hormone(s) each transports
|
-Medullary Arteries pass directly from capsule to Adrenal Medullary Veins - fast bypass of cortex to get medullary catecholamines into blood quickly. Catecholamines secreted by medulla are used quickly and acutely, such as in the fight or flight response- rapid response to life threatening dangers.
-Cortical Capillaries (sinusoids) pass over cortical tissue to get cortical steroids into medulla and systemic circulation. Steroids secreted by cortex work slowly but surely -> released into a slower moving blood circulation of cortical capillaries. |
|
|
Innervation of the endocrine cells
|
Cells that synthesize hormone are embedded deep in gland, so mechanism for quick release comes from innervation of the same endocrine cells that produce the adrenaline-> immediate release into systemic circulation
|
|
|
Adrenal Cortex - 3 layers and their secretions
|
-Superficial: Zona Glomerulosa - mineralocorticoids, e.g., aldosterone; steroids affect kidneys, salt metabolism
-Middle (thickest): Zona Fasciculata - glucocorticoids, e.g. cortisone; steroids regulate carbohydrate metabolism -Deepest: Zona Reticularis (adjecent to adrenal medulla)-sex steroids, e.g., dehydroepiandosterone; steroids metabolized in gonads -“Salt, sugar, sex, the deeper it goes the better it gets.” GFR - Girlfriend |
|
|
Cortical Zonation - Zona glomerulosa
|
Zona glomerulosa, cells in glomeruli surrounded by glomerular capillaries.
|
|
|
Cortical Zonation - Zona fasciculata
|
Zona fasciculata, cells in long radially arranged plates and cords with capillaries running parallel to cords. Abundant vacuoles laden with cholesterol esters- foamy appearance in H&E. Cholesterol esters in vacuoules are precursors for steroids
|
|
|
Cortical Zonation - Zona reticularis
|
Zona reticularis, cells in reticular cords surrounded by anastomosing network of capillaries
|
|
|
All three layers sensitive to...
|
All three layers sensitive to ACTH- Corticotropin
|
|
|
Fine Structure of Adrenal Cortex - 3 structures
|
-Have abundance of SER where one finds some enzymes for steroid biosynthesis
-Have Lipid Vacuoles (stored cholesterol esters - steroid precursors)- especially zona fasciculata -Have Mitochondria With Tubular Cristae where other steroid synthesis enzymes are found. Tubular cristae in mitochondria unique to cells of steroid synthesis |
|
|
Adrenal Medulla - contain two kinds of parenchymal _______ cells; what does each kind possess?; surrounded by numerous blood vessels carrying _________ ; Connection between brain and body?
|
-Contains two kinds of parenchymal Chromafffin Cells
-Surrounded by numerous blood vessels carrying Catecholamines into systemic circulation -One kind has very electron dense granules of Norepinephrine -Other kind has less electron dense granules of Epinephrine -Scattered Ganglionic Cells and preganglionic sympathetic nerve fibers - Connection between brain and body: synapse of sympathetic nerve fibers on ganglionic cells that release neurotransmitters, ganglionic cells appear as little neurons |
|
|
Islets of Langerhans - what are they and in what cells are they found? What are the 4 different cells found in these islets and what do each of them secrete?
|
-Islands of endocrine tissue among exocrine pancreatic acinar cells
*Alpha cells-secerete glucagon-20%, peripheral *Beta cells secrete insulin-80%, central -Delta cells produce gastrin and somatostatin -F cells secrete pancreatic polypeptide |
|
|
Diffuse Endocrine Cells
|
-Widely distributed in GI and respiratory tract
-Also called enteroendocrine or APUD cells -Secrete wide variety of regulatory peptides and catecholamines/hormones |
|
|
Gonadal Endocrine Cells - abundant where, similar in morphology to what cells, what are the male and female sex steroids and what do they do?
|
-Abundant in ovary (estrogens) and testes (andogens)
-Similar in morphology to adrenal cortical cells secreting steroids -Estrogens- female sex steroids- regulate female reproductive cycle -Andogens- male sex steroids- regulate spermatogenesis, “bar fights” -Morphology of cells also similar between sexes- a lot of SER, lipid vacuoles, mitochondria with tubular cristae |
