Endocrine system 2

Question 1

Name the six anterior pituitary hormones

Answer 1

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

Question 2

The thyroid gland consists of..

Answer 2

Follicle cells encircling follicles filled with Colloids

Question 3

What is the function of the colloids

Answer 3

They are precursors to thyroid hormones

Thyroglobulin with Iodine atoms bound to it

Question 4

What type of cells are located outside of follicles and explain their function

Answer 4

parafollicular cells, secretion of Calcitonin (regulates Ca and Phosphate balance)

Question 5

What are Thyroid hormones composed of and how are transported in the blood plasma?

Answer 5

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)

Question 6

Explain the synthesis of Thyroid hormones

Answer 6

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

Question 7

What are the functions of thyroid hormones

Answer 7

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

Question 8

Hormone disorder: Hypothyroidism

Answer 8

Myxedema, feeling cold, gaining weight, bradycardia (slow HR), decreased cardiac function due to low alpha beta receptors

Question 9

The most common cause of Hypothyroidism?

Answer 9

Hashimoto´s disease

Question 10

How is Hypothyroidism treated?

Answer 10

Levothyroxine, a supplement of thyroid hormones

Question 11

Hormone disorder: Hyperthyroidism

Answer 11

exophthalmia (thyroid eye disease), rapid HR (increased beta receptors), weight loss, high metabolic rate, decreased fertility

Question 12

The most common disease of Hyperthyroidism?

Answer 12

Grave´s disease (primary)

Question 13

What does the adrenal gland consist of?

Answer 13

Cortex (outer):
zona glomerulosa (whorles and globules) - mineralocorticoids
zona fasciculata (fascicles or bundles) - glucocorticoids
zona reticularis (network) - androgens (DHEA)

Medulla (inner): NE and epinephrine

Question 14

Meaning of Corticosteroid and Glucocorticoid?

Answer 14

Corticosteroid: A Steroid related to steroids secreted by the adrenal cortex

Glucocorticoid: affect glucose metabolism - cortisol

-

Question 15

Meaning of mineralocorticoid and Gonadocorticoid?

Answer 15

Mineralocorticoid: steroids affecting salt and water balance - aldosterone

Gonadocorticoid: produced by the adrenal cortex and affect sexual function

Question 16

What is the function of aldosterone?

Answer 16

promotes Na(+) retention in the kidney and K(+) excretion in urine

water follows Na(+), increases extracellular fluid, blood volume and blood pressure

Question 17

What is the function of Cortisol? (Glucocorticoid)

Answer 17

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

Question 18

What are symptoms of Adrenocortical insufficiency?

Answer 18

Low Na, high K(+) in plasma, low blood pressure, low blood glucose, muscle fatigue, vomiting, dehydration

Question 19

What is Cushing’s disease?

Answer 19

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)

Question 20

What is Cushing’s disease?

Answer 20

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)

Question 21

Name the osteogenic cells

Answer 21

Osteoblasts: synthesize Osteoids (95%collagen)
Osteocytes: bone cells
Osteoclasts: bone breakdown, produce acids and proteolytic enzymes, bone growth and repair

Question 22

Composition of bone matrix

Answer 22

Organic: Osteoblasts (95% collagen, 5% ground substance)
Inorganic: Minerals -> hydroxyapatite Ca(+2) and PO4

Question 23

Function of Osteoblasts

Answer 23

Synthesis of osteoid -> become osteocyts (sorrounded by mineralized bone)

Question 24

How is connection between osteocytes maintained?

Answer 24

Through canaliculi and gap junctions, so they are provided with nutrients and glucose

Question 25

Composition of compact bone

Answer 25

organized in bundles of bones: Osteon
with central and perforating canals, concentric lamellae sorrunding one bundle