Endocrine system 2 Flashcards
Name the six anterior pituitary hormones
Gonadotropins -> FSH and LH -> Ovaries/testes -> sexual hormones
GHRH (+), SS (-) -> Growth hormone -> Bone, liver, muscle, adipose -> IGF-1
TRH -> TSH -> Thyroid -> T3,T4
DA (-) -> PRL -> Breast (milk production)
CRH corticotropin releasing h.(+) -> ACTH -> aldosterone, DHEA
The thyroid gland consists of..
Follicle cells encircling follicles filled with Colloids
What is the function of the colloids
They are precursors to thyroid hormones
Thyroglobulin with Iodine atoms bound to it
What type of cells are located outside of follicles and explain their function
parafollicular cells, secretion of Calcitonin (regulates Ca and Phosphate balance)
What are Thyroid hormones composed of and how are transported in the blood plasma?
Thyroxine - T4: 2 Tyrosine molecules with 4 bound iodine atoms
Triiodothyronine - T3: 2 Tyrosine molecules with 3 bound iodine atoms (3-4 times more potent)
bound to thyroxine-binding globulin (TBG)
Explain the synthesis of Thyroid hormones
I(-) is transported with Na(+) into follicle cells -> Thyroglobulin is synthesized in follicle cells
Thyroglobulin and I(-) are transported into the lumen of follicles ->
I(-) is oxidized (lose an electron) and attached to tyrosine of Thyroglobulin
-> coupling of tyrosin rings to produce T3 or T4 precursor (Colloid T3, T4 bound to Thyrosinglobulin)
-> TSH stimulates endocytosis of the colloid back into the follicle, where the endosome fuses with a lysosome - proteases in lysosome cleaves off the protein part -> T3, T4 are secreted out of cell into blood
What are the functions of thyroid hormones
increased metabolic rate
increased calorigenesis (heat) production
permissive effects (hormone A works when hormone B is present) via catecholamines (NE, Epi, Dop,..) –> sympathomimetic (mimics smyp): increase alpha and beta receptors, increase of HR and force to contract
Growth and development: production of growth hormone and CNS developmenmt
Hormone disorder: Hypothyroidism
Myxedema, feeling cold, gaining weight, bradycardia (slow HR), decreased cardiac function due to low alpha beta receptors
The most common cause of Hypothyroidism?
Hashimoto´s disease
How is Hypothyroidism treated?
Levothyroxine, a supplement of thyroid hormones
Hormone disorder: Hyperthyroidism
exophthalmia (thyroid eye disease), rapid HR (increased beta receptors), weight loss, high metabolic rate, decreased fertility
The most common disease of Hyperthyroidism?
Grave´s disease (primary)
What does the adrenal gland consist of?
Cortex (outer):
zona glomerulosa (whorles and globules) - mineralocorticoids
zona fasciculata (fascicles or bundles) - glucocorticoids
zona reticularis (network) - androgens (DHEA)
Medulla (inner): NE and epinephrine
Meaning of Corticosteroid and Glucocorticoid?
Corticosteroid: A Steroid related to steroids secreted by the adrenal cortex
Glucocorticoid: affect glucose metabolism - cortisol
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Meaning of mineralocorticoid and Gonadocorticoid?
Mineralocorticoid: steroids affecting salt and water balance - aldosterone
Gonadocorticoid: produced by the adrenal cortex and affect sexual function
What is the function of aldosterone?
promotes Na(+) retention in the kidney and K(+) excretion in urine
water follows Na(+), increases extracellular fluid, blood volume and blood pressure
What is the function of Cortisol? (Glucocorticoid)
Maintenance of blood glucose, anti-inflammatory, fetal lung development
The effect of Glucocorticoids is to raise blood glucose:
stimulate protein catabolism
AA uptake in the liver to make glucose
stimulate triglyceride catabolism in adipose tissue
Sacrificing protein to make glucose in liver
What are symptoms of Adrenocortical insufficiency?
Low Na, high K(+) in plasma, low blood pressure, low blood glucose, muscle fatigue, vomiting, dehydration
What is Cushing’s disease?
Cushing disease: (primary if adrenal, secondary if pituitary)
EXCESSIVE Glucocorticoids
high blood pressure
redistribution of fat
muscle wasting
poor wound healing
Osteoporosis
Striae (strech marks, no collagen)
What is Cushing’s disease?
Cushing disease: (primary if adrenal, secondary if pituitary)
EXCESSIVE Glucocorticoids
high blood pressure
redistribution of fat
muscle wasting
poor wound healing
Osteoporosis
Striae (stretch marks, no collagen)
Name the osteogenic cells
Osteoblasts: synthesize Osteoids (95%collagen)
Osteocytes: bone cells
Osteoclasts: bone breakdown, produce acids and proteolytic enzymes, bone growth and repair
Composition of bone matrix
Organic: Osteoblasts (95% collagen, 5% ground substance)
Inorganic: Minerals -> hydroxyapatite Ca(+2) and PO4
Function of Osteoblasts
Synthesis of osteoid -> become osteocyts (sorrounded by mineralized bone)
How is connection between osteocytes maintained?
Through canaliculi and gap junctions, so they are provided with nutrients and glucose
Composition of compact bone
organized in bundles of bones: Osteon
with central and perforating canals, concentric lamellae sorrunding one bundle
