Adrenal Cortex

Adrenal Cortex

Prof. K. Sivapalan

08-01-14 Adrenal Cortex. 2

Structure of Adrenal Cortex.

• Histology-• zona glomerulosa.• zona faciculata• zona reticulata.


Structure of Steroid Hormones.


Classification of steroids

• Mineralocorticoids- aldesteron• Glucocorticoids- cortizol• Sex hormones• androgens • estrogens


Mechanism of Action of Steroids.

• Transport- bound to globulin- Transcortin.• Binds to receptors in cytozol, transported

to Nucleus and act on transcription.• Direct action on membrane and enzymes.


Glucocorticoids.

• Half-life- 60-90 minutes


Effects on Carbohydrarte Metabolism.

• In Liver, increases gluconeogenesis. – Increase transport of AA into cells of liver.– Gluconeogenic enzymes increased in liver.– Entry of AA into other tissues prevented.

• Reduces glucose utilization by cells.• The above changes are not seen in Heart,

Brain, and red cells.• Increases blood glucose level.


Effects on Protein Metabolism.

• Reduce protein synthesis.• Increase catabolism of cellular protein.• Reduce RNA in muscles and lymphoid

tissue.• Increase blood Amino acids.• Increase protein synthesis in liver, plasma

proteins.


Effects on Fat Metabolism.

• Increased lypolysis from adipose tissue in limbs.

• Fat storage increased in face and trunk.• Increased plasma FFA.


Other Effects of Glucocorticoids.

• Permissive action:– Catacholamines- calorigenesis, lypolytic

action, pressure responses, bronchodilation.– Glucagon- same as above.

• Vascular reactivity:– Smooth muscle tone requires steroids.– Capillaries require steroids for normal

permeability [absence increases permeability]• Essential for life.


Other Effects of Glucocorticoids

• Nervous system:– Reduction results in personality changes- irritability,

apprehension and inability to concentrate.– Electroencephalogram changes: slower than normal A

rhythm.– Increase results in reduced threshold for convulsions.

• Water Metabolism:– Deficiency leads to inability to excrete water.

Increased ADH and reduced GFR observed which are repaired by glucocorticoids only.


Other Effects of Glucocorticoids

• Bone- reduce protein matrix and causes osteoporosis.

• Blood and Immunity:– Increased RBC, nutrophils, platelets.– Reduced eosinophils, basophils, lympho cytes and all

immune responses at high doses.– Use as anti-inflammatory drug.

• Resistance to stress:– High levels of corticoids needed to cope with stressful

conditions. [Essential for life]


Effects of Mineralocorticoids.

• Half life- 20 minutes.• Distal tubule of kidney- sodium absorption

in exchange of potassium and hydrogen. Blood volume cannot be maintained without this action.

• *Essential for life.• Similar action seen in sweat glands,

salivary glands and gastric glands.


Effects of Sex Hormones

• Secretion increases at puberty.• Androgens are responsible for acne in

males and females. • All other actions done by sex hormones

secreted by testis and ovary.


Regulation of secretion.

• Corticotrophin Releasing hormone [CRH] stimulates ACTH which stimulates glucorticoids.

• Renin- angeotensin system regulates aldesteron secretion.


Effect of Hypophysectomy

• Zona glomeruloza is not affected.

• Other two zines atrophic.


Diurnal Variation of Secretion.


Other factors that stimulate CRH

• Trauma- nociceptive pathways• Emotion- lymbic system

– Emotional stresses, fear, anxiety, apprehension

• Baro receptors throw Nucleus Tractus Solitarius inhibit.


Stimuli that increase aldesteron secretion.

• Glucorticoid also increased,– Surgery.– Anxiety.– Physical trauma.– Haemorrhage.

• Glucocorticoid unaffected:– High potassium intake.– Low sodium intake.– Inferior vena cava constriction in throax.– Standing.– Secondary to congestic cardiac failure, cirrhosis,

nephrosis.


Adreno Cortical Insufficiency.

• Acute- adrenal crisis:– Head ache, lassitude, confusion,

restlessness, vomiting, abdominal or costo-vertibral pain, circulatory collapse, unconsciousness, death.

• Chronic- Addison’s disease.– Mineralocorticoid insufficiency alone is rare.– Mixed insufficiency is common.


Addison’s disease.

• Weakness and fatigability.• Weight loss and dehydration.-

– Increased sodium excretion, water diuresis, reduced appetite and GIT function.

• Hypotension and small heart- dizziness, syncopal attacks.

• GIT- reduced acid secretion, reduced motility.• Nervousness and mental symptoms.• Precipitation of crisis in stress.• Pigmentation- depends on the cause.


Pigmentation due to ACTH.


Hyper Aldesteronism.

• Primary hyper aldesteronism-– tumor- Conn’s Syndrom.

• Secondary Aldesteronism-– Cardiac failure, renal disease, cirrhosis.

• Hypokalaemia.• Slight increase in ECF and blood volume.• Slight increase in plasma sodium.• Hypertension.


Hyper Adrenalism- Cushings Disease.

• Redistribution of fat-• Moon face.• Fat pads of neck.• Pendulous abdomen.• Buffalo hump.• Striae in skin.• Thin extremities.


MOON Face.Same person before and after treatment.Twin sisters with and without moon face.


Other Features of Increased Glucocorticoids.

• Red face- polycythaemia.• Thin skin, wasting of muscles, osteoporosis-

weakness and backache.• Poorly healing wounds.• Systolic hypertension- sodium retention,

angeotensin increase or direct effect.• Diabetes mellitus.• Mood changes- increased appetite, insomnia,

euphoria, toxic psychosis.• Hypokalaemia- mineralocorticoid action.• Hirsutism- increased androgens.


Effects if increased Androgens.

• Female fetus- male type of genitalia.• Male fetus- facilitated development of genitalia.• In childhood- stimulation of growth but early

closure of epiphysis and short stature.• Prepubertal boys- precautious puberty without

testicular development.• Adult male- no significant changes.• Pubertal and adult females- male features.

Adrenal Cortex

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