Endocrine 2 Flashcards
What is the function of hormones T3 and T4?
act on all cells of the body to increase
a. basal metabolic rate
b. maturation processes
c. CNS activity
Which TH is more biologically active? How is it converted?
T3(5-10x more active)
T4 is converted to either T3 or rT3 (not active, little made) by the removal of iodine atom. liver converts some plasma T4 into T3
What proteins are responsible for transport of thyroid hormones in the blood?
thyroxin-binding globin and albumin (less)
The action of thyroid hormones is calorigenic effect, fuel metabolism, nervous system, cardiovascular system and sympathetic effect? what is the sympathetic effect?
upregulation of beta-adrenergic receptors
-increased responsiveness to catcholamines
When T3 and T4 (90% in this form) is released into capillaries what is recycled for reuse?
thyroglobulin not released in circulation and Iodine recycled
How are hormones stored in thyroid?
2-3 month supply in colloid
90% iodine stored in thyroid
What does TSH stimulate. List 5
- size of follicular cells
- # of organelles
- thyroglobulin, T3 and T4 synthesis
- thryoglobulin breakdown via receptor-mediated endocytosis
- T3 and T4 release
Parafollicular cells secret what polypeptide. What is its function. What controls this secretion. Is it dependent on pituitary control?
secretes calcitonin
function: lowers Ca2+ in plasma
control of secretion by feedback of calcium
independent from Pituitary control and TSH
what cell produces PTH? What is the function of Parathyroid hormone?
Chief cells
function : maintains Ca2+, P(O4)-3 &Mg2+
-stimulates vitamin D which is essential for calcium absorption
Where does muscarinic and nicotinic receptors found?
M: smooth, cardiac muscle and glands
N: motor end plate of skeletal muscle, sympathetic and parasympathetic ganglia and adrenal medulla
What are the structural differences between the Zona glomerulosa, zona Fasciculata, zona reticularis of the adrenal cortex?
ZG: large pyramidal cells with small dense nuclei with few lipid droplets in cytoplasm
-cells arranged in arches.
ZF: cells arranged in cords, large cells -filled with large lipid droplets and foamy appearance
both abundant in SER and many mitochondria ZR:cells arranged in a meshwork pattern -small cell-less lipid -lipofuscin pigment -nuvlear pycnosis
zona glomerulosa is responsible for a secretion of what mineralocorticoid? What does its function promote and where does the action take place?
aldosterone: increases Na+ absorption with water to increase blood pressure, decreases K+ and H+ released in urine.
- promotes NA retention
- DCT and CT of kidney and controlled by renin and angiotensin.
zona fasciculata is responsible for secretion of what glucocorticoid? How? and what is the function of this type of glucocorticoid?
cortisol
Increase stress-> increase ACTH->increase cortisol production
function:
- more sensitive to NE for smooth muscle
- carbohydrate metabolism
- decrease in glucose utilization
- increase blood glucose levels*
- gluconeogesis*
- protein catabolism
- FA mobilization from adipose tissue
- Anti-inflammatory
- prolonged high cortisol levels can cause muscle weakness
Zona reticularis responsible for what product
androgens (DHEA)
DHEA-S
ACTH stimulates
- cells of the zona fasciculata and reticularis
- synthesis and release of glucocorticoids
- increase in cell size and # of organelles
What are the 4 factors that regulate aldosterone? and how much does it increase?
- increase in potassium in ECF (greatly)
- increased in angiotensin 2 in ECF (greatly)
- increased Na+ ECF (slightly)
- ACTH (little effect)
What is the mechanism of aldosterone secretion?
angiotensiogen->uses renin to cleave angiotensinogen to produce angiotensin 1->ACE to stimulate angiotensin 2
If cortisol synthesis is blocked what happens to ACTH and androgen?
Production increase in both
ACTH stimulates both zona fasciculata and reticularis to produce___.
androgens.
ACTH increase both cortisol and DHEA-S
DHEA-S does not negatively feedback on ACTH-feedback on ACTH feedback to GnRH neurons mean?
puberty-androgen level increase without increase in cortisol
What are the structural characteristics of adrenal medulla?
large ovoid cells in irregular cords around capillaries
- well-developed golgi
- dense core and homogeneous secretory granule
- chromaffin cells
What are the origin of adrenal medulla?
homologous with post-ganglionic neurons of sympathetic system
What are the hormones produces of adrenal medulla?
catcholamines,
80% epinephrine, 20% NE
What in the role of Epinephrine for metabolism and emergency situations?
Glycogenolysis- increase plasma glucose
CS: increase CO
RS: Increase O
SM: increase ATP
What in the role of NorEpinephrine for metabolism and emergency situations?
- maintain normal BP
- increase in NE can lead to increase BP such as situations in heart attacks and hemorrhaging.
- no metabolic effects
What controls NE and E secretion?
hypoglycemia stimulates E secretion
-neural via sympathetic innervation
Alpha cells . What color stain. What does it secrete? and how is the secretion controlled?
acidophillic, 20%
- secrete glucagon (hyperglycemic factor)
- causes increase of blood glucose via glycogenolysis.
control of secretion: low blood glucose levels, low FA levels, sympathetic and parasympathetic NS stimulate glucagon production
What hormones increase blood glucose levels?
cortisol, epinephrine, T3, T4, and GH
Beta cells. What color stain. What does it secrete? what happens to fat and AA uptake?
-basophilic stain (75%) larger than alpha cells
-secrete insulin (only hypoglycemic hormone)
to reduce blood glucose levels (storage in liver and skeletal muscles)
-storage of fat-cell permeability for glucose increase
-AA uptake and protein synthesis- increase plasma AA
how is the secretion controlled for beta cells?
-high blood glucose levels, high blood FA levels, arginine, gastrin, CCK, secretin, glucagon, parasympathetic NS stimulate insulin production
What inhibits insulin production?
sympathetic NS
What type of cells don’t take up glucose?
cells in Nervous system
Delta cells. stain. secretion
5%, don’t stain with normal stain, secrete somatostatin (GHIH)- decreases insulin and glucagon production; inhibits alpha and beta secretion
