Hormonen en homeostase samenvatting deel2

H&H2 Samenvatni

Adrenals (bijnieren)
Cortex steroid hormone producton
 Endocrine iland
 Mesoderm
- Zona ilomerulosa
o Redulated by RAAS
o Mineralocortcoidss aldosterone producton
 Affect kidney
 Blood pressure, iron compositon, Na/K-equilibrium
 Stmulated by decrease o Na or lo blood pressure
 Renin is released…  aniiotensin 2 aldosterone producton by
Z.i expression o more pumps Na resorpton in exchanie or K +
- Zona asciculata
o Reiulated by ACTH axis
o Glucocortcoidss cortsol producton
 Glucose metabolism
- Zona retcularis
o Reiulated by ACTH axis
o Sex steroidss androien producton
 Afer puberty in males tests
Medulla (nor)adrenalin producton
 Modified sympathetc ianilion o autonomic nervous system
 Ectoderm
 Chromafn cells

Catecholamines are derived rom tyrosine mobilizini eneriy, redistributon o blood

Cortsol is converted to cortsone does not bind MR local reiulaton o hormone acton



Thyroid gland
Thyroid hormone (T3/T4) important or development and iro th, but also stmulate non-shiverini
thermoienesis
Follicle cells around colloid ith thyroilobulin thyroid peroxidase and H2O2 needed to couple the
thyroid hormones to thyroilobulin backbone. TSH stmulates synthesis o enzymes involved
Thyroid hormones are transported in the blood bound to carrier proteins
- Uptake o ree TH’s via carrier-mediated transport
OATPss T4 across blood-brain barrier + T3/4 transport to liver
MCTss T3 transport to brain neurons (MCT8) + transport to intestne/placenta (MCT10)
T3 receptor al ays bound to DNA interacton ith TRE (thyroid hormone responsive element)
Positve reiulaton o iene expression by T3 binds to RXR-TR dissociaton o co-repressor ( ith
histone deacetylase actvity) and subsequent bindini by co-actvator stmulaton o transcripton
Neiatve reiulatons receptor binds co-actvator ithout T3. Then T3 binds lo er afnity or
actvators bindini o repressor

Deiodinases (D1-3) take off iodine to (in)actvate thyroid hormones
 D1s actvatni and inactvatni

, o IRD and ORD actvity
 D2s actvatni
o ORD actvity
 D3s inactvatni
o IRD actvity




Selenium is part o the deiodinases


Parathyroid gland
Parathyroid hormone (PTH) increases calcium levels
- Resorpton in kidneys
- Mobilizini rom bone
o Osteoblasts precursors o osteoclasts acid producton
- Absorpton rom ood
PTH also stmulates alpha hydroxylase actvaton vitamin D stmulates expression o calbindin
transport o Ca rom iut lumen to blood
When Ca bound to Ca-sensini receptors no PTH, hen litle Ca is presents PTH
Inactvatni mutaton no recoiniton o calcium hiih in circulaton, lo in urine
Actvatni mutaton al ays siinal, even thouih no calcium present more in urine, lo in
circulaton

C-cells in thyroid iland produce calcitonin decreases Ca concentraton
- Antaionist o PTH


Gonads
Testes and ovary produce steroids and iro th actors
Cholesterol preinenolone (proiesterone) androiens oestroiens

FSH reiulates ierm cell development and aspects o steroid producton
 Aromatase expression in iranulosa and Sertoli cells required or estroien producton
 Gro th actors in Sertoli/iranulosa cells stmulate expression o steroidoienic enzymes in
Leydii/Theca cells
 Stmulates LH receptor expression by iranulosa or Leydii cells
- Actvated/blocked by actvin/inhibin
LH affects endocrine cells to produce steroid hormones