Chapter 7 ( Endocrine ) Flashcards
Hormones action through activation of Tyrosine kinase ?
Insulin
IGF-1
Growth hormone
Prolactin
Steroid hormones ?
Glucocorticoids Aldosterone Testosterone Estrogen Progesterone Thyroxin Vitamin D
Hormones action through IP3 mechanism ?
ADH ( V1 receptors ) Alpha-1 receptors GnRH GHRH TRH Angiotensin ll Oxytocin
Hormones action through cAMP mechanism ?
ADH ( V2 receptors ) Beta- 1,2 receptors Alpha-2 receptors Glucagon ACTH LH FSH TSH HCG MSH CRH PTH Calcitonin
The only peptide hormone thats bound to protein carrier ?
IGF-1
Monomer and dimer tyrosine kinase receptors ?
Monomer : receptors for Nerve growth factor
Dimer : receptors for Insulin and IGF
Tyrosine kinase-associated receptor ?
Receptor for Growth Hormone
Hormones derived from Proopiomelanocortin (POMC) ?
ACTH
MSH
Beta-lipotropin
Beta-endorphin
How somatomedins (IGF) inhibit the secretion of growth hormone ?
Directly by acting on the anterior pituitary and indirectly by stimulating the release of somatostatin from hypothalamus
Direct actions of growth hormone ?
1- diabetogenic ( decrease glucose uptake into cells )
2- increase lipolysis
3- increase protein synthesis
4- increase production of IGF
Actions of growth hormone vis IGF ?
Increase protein synthesis in chondrocytes ( linear growth ) , in muscles ( lean body mass ) , most organs ( organ size )
Actions of prolactin ?
1- stimulates milk production
2- stimulates breast development
3- inhibits ovulation ( by decreasing GnRH )
4- inhibits spermatogenesis
Primary origin of ADH ?
Supraoptic nuclei in the hypothalamus
Factors increase and decrease ADH secretion ?
1- factors increase : Increased osmolarity Volume contraction Pain , nausea , hypoglycemia Nicotine , opiates , antineoplastic drugs
2- factors decrease : Decreased osmolarity Ethanol Alpha-agonists ANP
Primary origin of oxytocin ?
Paraventricular nuclei of the hypothalamus
Oxytocin medical uses ?
To induce labor
To reduce postpartum bleeding
Inhibitors of Na-I cotransport ?
Thiocyanate
Perchlorate anions
Inhibitor of thyroid peroxidase enzyme ?
Propylthiouracil
T3 action in the anterior pituitary ?
Down regulates TRH receptors
Organs that BMR not controlled by thyroid hormones ?
Brain
Gonads
Spleen
21 carbon steroids ?
Progesterone
Deoxycorticosterone
Aldosterone
Cortisol
19-carbon steroids ?
Have androgenic activity , are precursors to the estrogens
Dehydroepiandrosterone
Androstenedione
18-carbon steroids ?
Have estrogenic activity
Oxidation of the A ring ( aromatization ) to produce estrogen occurs in the Ovaries and Placenta
Location of the CRH containing neurons ?
Paraventricular nuclei in the hypothalamus
ACTH action in the adrenal cortex ?
Stimulating cholesterol desmolase which convert cholesterol to Pregnenolone which is the precursor for the other steroids
Also ACTH up regulates its own receptors
Anti-inflammatory effects of glucocorticoids ?
1- induce the synthesis of Lipocortin which inhibits Phospholipase A2
2- inhibits the production oh Interleukin and inhibits proliferation of T lymphocytes )
3- inhibit the release of histamine and serotonin
Phospholipase A2 function ?
Liberates Arachidonate from membrane phospholipids , providing the precursor for prostaglandins and interleukins synthesis
Mechanism of the permissive action of cortisol to catecholamines ?
Upregulates alpha-1 receptors on arterioles
Difference between primary and secondary immunodeficiency ?
Decreased ACTH in secondary : no hyperpigmentation
Normal aldosterone level in secondary : no volume contraction, hyperkalemia, metabolic acidosis
Delta cells of the pancreas secrets which hormones ?
Somatostatin
Gastrin
Solfonylurea drugs mechanism ?
Closes K channels in beta cells of pancreas —-> depolarization —-> open Ca channels —-> increase intracellular Ca —-> secretion of insulin
Factors regulating glucagon secretion ?
1- Factors increase secretion : Decrease blood glucose Increase blood amino acids CCK Norepinephrine Epinephrine Acetylcholine
2- factors decrease secretion : Increase blood glucose Insulin Somatostatin Fatty acids , ketoacids
Factors regulating insulin secretion ?
1- factors increase secretion : Increase blood glucose Increase blood amino acids Increase blood fattyacids Glucagon GIP Acetylcholine
2- factors decrease secretion Decrease blood glucose Somatostatin Norepinephrine Epinephrine
How serum magnesium regulates PTH secretion ?
Mild decreases in serum Mg stimulate PTH secretion
Severe decreases in serum Mg inhibit PTH secretion
Laboratory sign of resorption of the organic matrix of bone ?
Increased hydroxyproline excretion
Pseudohypoparathyroidism ?
Type la-Albright hereditary osteodystrophy
Caused by defective Gs protein in the kidney and bone which causes end organ resistance to PTH .
Hypocalcemia and hyperphosphatemia not correctable by administration of PTH
Familial hypocalciuric hypercalcemia mechanism ?
Inactivating mutationsof the Ca sensing receptors that regulate PTH secretion
Factors that increase 1-alpha hydroxylase activity in the kidney ?
Decreased serum Ca
Increased PTH level
Decreased serum phosphate
Vitamin D dependent Ca-binding protein in the intestine name ?
Calbindin D-28K
Medical uses of calcitonin
Ttt of Hypercalcemia Osteoporosis Paget’s disease of the bone Marker of medullary carcinoma of the thyroid
Hormones secreted by the testes ? By which cells ?
Testosterone by Leydig cells
Anti-Mullerian hormone by Sertoli cells
5alpha-reductase inhibitor ?
Finasteride
Which nuclei of hypothalamus secrets GnRH ?
Arcuate nuclei
FSH and LH functions in male ?
FSH acts on Sertoli cells to maintain spermatogenesis
LH acts on Leydig cells to promote testosterone synthesis
Testosterone and dihydrotestosterone cause differentiation of which organs ?
Testosterone : epididymis , vas deferens and seminal vesicle
Dihydrotestosterone : penis , scrotum and prostate
Major placental estrogen ?
Estriol
Why ovulation is suppressed during lactation ?
Because prolactin has the following effects :
Inhibits hypothalamic GnRH secretion
Inhibits action of GnRH on the anterior pituitary
Antagonizes the actions of LH and FSH on the ovaries
