ADRENAL CORTEX AND GLUCOCORTICOIDS I
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Tuesday, June 14, 2022 ADRENAL GLAND DR.NILESH KATE. M.D. ASSOCIATE PROFESSOR, DEPARTMENT OF PHYSIOLOGY,
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Transcript of ADRENAL CORTEX AND GLUCOCORTICOIDS I
Monday, May 1, 2023
ADRENAL GLAND
DR.NILESH KATE. M.D.
ASSOCIATE PROFESSOR,DEPARTMENT OF PHYSIOLOGY,
OBJECTIVES Physiological anatomy Development. Functional layers.
Macro Micro
Zones Hormones Biosynthesis of steroid hormones. Glucocorticoids normal levels. Transport & metabolism. Mechanism of action of steroid.
INTRODUCTION Among most
important and vital endocrine organ.
Small bilateral yellowish retroperitoneal organ.
Lies just above kidney in gerota’s fascia.
PHYSIOLOGICAL ANATOMY
Right adrenal is triangular, related to upper pole Right kidney
Left adrenal is crescent shaped, related to upper and medial part Left kidney
Size : 3 - 6cm long, Weight : 3-5 gm app Width : 2-3 cm
Adrenal gland -- General considerations
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Cortex – 80 to 90 % of gland
Secretes cortisol hormones
Medulla – 10 to 20 %
Secretes Catecholamine.
Development. Adrenal cortex –
Mesoderm derivatives. In fetal life – comprises outer Neocortex &
inner Fetal cortex Fetal cortex degenerates & neocortex
enlarges & differentiates into 3 layered adrenal cortex.
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Development.(cont…) Adrenal medulla
Neuroectodermal cells Represents enlarged & specialized
sympathetic ganglion. Develops from the neural crest.
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FUNCTIONAL ANATOMY. Position.
Above each kidney. Covered by
connective tissue capsule.
2 parts- Outer cortex Inner medulla.
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SUPRARENAL GLAND.(MACROSCOPIC)
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MICROSCOPIC(HISTOLOGICAL)
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Zona glomerulosa (1/5TH)Inverted U shaped
Zona fasiculata (3/5TH)Sinusoids between columns
Zona reticularis (1/5TH)Compactly arranged cords of cells
ADRENAL GLAND
HORMONES OF ADRENAL CORTEX
ZONA GLOMERULOSA –Mineralocorticoids – AldosteroneDeoxycorticosterone
ZONA FASCICULATA – Glucocorticoids – cortisol or hydrocortisoneCorticosterone.
ZONA RETICULARIS –Sex steroids.– androgen Oestrogen & progesterone .
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GLUCOCORTICOIDS Characteristics features.
Cortical cells – large smooth ER. High amount of lipids mainly cholesterol in
ester form. Also vitamin C. All hormones steroid hormones. CPPP Ring 17 hydroxy-corticosteroids 17 ketosteroids.
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O
HO
CH2OH
C O
OH
CORTISOL MOLECULAR STRUCTURE
Cyclo-Pentano-Perhydro-Phenantherene Ring
BIOSYNTHESIS OF STEROID HORMONES
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Synthesis of hormones.
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PLASMA LEVELS Diurnal variations –
10 – 25 μg % (avg 14 μg %) Rate of secretions of cortisol
15 mg/day normally 300 – 400 mg/day under stress.
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TRANSPORT Cortisol.
Bound form (90%) CBG (α 2) – Glycoprotein called Transcortin. Albumin (10 %)
Free form (10%) Responsible for physiological actions.
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Inter relationship between free & bound form
TRANSCORTIN – normal plasma conc. 3 mg%
Binding capacity – 20 μg / dl. Synthesized in liver. Increased by oestrogen - pregnancy. liver cirrhosis , nephrosis & multiple
myeloma.
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METABOLISM & EXCRETION. Major pathway – cortisol & cortisone
Conjugated & excreted in urine.
Cortol glucoronide & cortolone glucoronide.
Minor pathway – conversion to 17-ketostroid conjugated to sulphate & excreted in urine,
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EXCRETION. In 24 hr urine
0.03 mg – free cortisol 5 mg – tetrahydrocortisol glucoronide &
cortol glucoronide 3 mg -- tetrahydrocortisone glucoronide &
cortolone glucoronide 6 mg – as 17-ketosteroids. 7 mg – unidentified metabolite. TOTAL – 22 mg.
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AVERAGE PLASMA LEVELS- (ADRENAL CORTICAL HORMONES)
Hormones PlasmaConcentrationmicro g’/dl
Daily secretion
14.0 10Corticosterone 0.4 3Aldosterone 0.006 0.15Dehydroepian-drosterone 175.0 20.0
(mg)
Cortisol
MECHANISM OF ACTION.
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CORTICOADRENAL REGULATION
REGULATION OF SECRETION OF CORTISOL
StressStress
Hypothalamus-CRHHypothalamus-CRH
Ant Pituitary-ACTHAnt Pituitary-ACTH
HH-Portal SystemHH-Portal System
REGULATION OF SECRETION OF CORTISOLHYPOTHALMO-HYPOPHYSEAL PORTAL SYSTEM
CortisolCortisolReleasingReleasingHormoneHormone
ACTHACTH
OBJECTIVES Physiological anatomy Development. Functional layers.
Macro Micro
Zones Hormones Biosynthesis of steroid hormones. Glucocorticoids normal levels. Transport & metabolism. Mechanism of action of steroid.
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