Adrenal Gland Functional Histology. Two parts- 1)Adrenal Cortex Aldosterone(mineralocorticoid) the...
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Transcript of Adrenal Gland Functional Histology. Two parts- 1)Adrenal Cortex Aldosterone(mineralocorticoid) the...
Adrenal Gland Functional Histology
Two parts-1)Adrenal Cortex • Aldosterone(mineralocorticoid)
•the cortisol (glucocorticoids) and
•androgenic hormones(Dehydroepiandrosterone).
ACTH
Angiotensin II
2) Adrenal medula-secretes the catecholamine hormones, • adrenaline (epinephrine) • Noradrenaline (norepinephrine)
Adrenal MorphologyZona glomerulosa Aldosterone
Zona fasciculata Glucocorticoids
Zona reticularis Androgens
Blood supply of theadrenal glands.
connective tissue capsule (Cap)
Outer zona glomerulosa (G) -mineralocor-ticoids.
The middle zona fasciculata (F) has linearly arranged cells that secrete glucocorticoids.
The inner zona retuclaris (R) cells form a cell network and secrete weak androgens.
inner medulla (M).
• cells of the adrenal cortex -abundance of mitochondria, lipid and smooth endoplasmic reticulum- steroid secreting cells.
• Zona glomerulosa cells -rounded in clusters
• zona glomer-ulosa –mineralocorticoids- aldosterone Na+ and K+ balance(RAA System)
Hypothalamus
Anterior Pituitary
CRH
Aldosterone
ACTH (minor)
Adrenal Cortex (Zona Glomerulosa)
Angiotensin II K+
Hypersecretion
Effects:-• Increased extracellular fluid volume • Hypertension • Hypokalemia
– Muscle weakness, arrhythmias
• Tumor in the Zona glomerulosa/primary/conn`s syndrome or increased renin secretion/secondary hyperaldosteronism.
Hyposecretion
• Primary/Addisons disease• Hyperkalemia • Hyponatremia • Decreased extracellular fluid volume
– Shock addisonian crisis.–
• Zona fasciculata (B) cells -cords or plates usually one – two cell thick separated by sinusoidal capillaries.
• Secrete glucocorticoids, - cortisol, - carbohydrate metabolism.
• Rounded nuclei and a vacuolated cytoplasm.
Hypothalamus
Anterior Pituitary
CRH
Cortisol / Androgens
ACTH
Adrenal Cortex (Zona Fasciculata Zona Reticularis)
Adipose Cells
lipolysis
Fatty acids glycerol
Muscle
Protein breakdown
Amino Acids
Liver
glucose
glucose
General cell
glycogen
Energy
Action of Insulin
??
Other effects
• Modulates behaviour and mood • Maturation of the fetus • Role in parturition????? • Modifies and controls both inflammatory
and immune responses • Important in stress response•
Inflammation
• Anti-inflammatory – Stabilizes lysosomes – capillary permeability – WBC migration & phagocytosis – decreases fever
• Helps repair after the event
Hypothalamus
Anterior Pituitary
CRH
Cortisol
ACTH
Adrenal Cortex (Zona Fasciculata Zona Reticularis)
Cushing’s Syndrome - a myriad of problems associated with cortisol excess
• Cortisol Hypersecretion Causes – Long-term corticosteroid medication – Pituitary adenoma – Ectopic ACTH syndrome (eg lung tumors) – Adrenal tumors-Primary
Cushing’s Disease – cortisol excess due to hypersecretion of pituitary ACTH
Cortisol Hypersecretion
Metabolic effects-
• liver glucose output • (+ insulin) fat deposition in trunk, face and
upper back • Muscle wasting and weakness • Impaired glucose tolerance, insulin-
resistant DM, glucose uptake by tissues
Others
• Suppression of immune system • Hypertension • Mineralocorticoid activity
– Hypokalemia – ECF
• Skin/connective tissue – Easy to bruise – Striae formation – Poor wound healing
Hyposecretion-Addison’s DiseaseMetabolism
• liver glucose output and glycogen storage
• lipolysis • Muscle weakness
– glycogen stores • Hypoglycemia
– Modified insulin response
Pigmentation in Addison's disease
ACTH• 39 amino acids • Synthesized in corticotrophs of AP • Half-life of ~ 10 minutes
pro-opiomelanocorticotrophin (POMC)
Beta- lipotropin(β –LPH)
a-melanocyte-stimulating hormone (a-MSH)
• zona reticularis -smallest of the secretory cells of the adrenal cortex
• irregular network of branching cellular cords surrounded by blood vessels and connective tissue.
• Zona reticularis -weak androgens- dehydroepiandrosterone.
Hypersecretion
• Females (adrenogenital syndrome)– ADULTS-Masculine characteristics (hair,
voice, enlarged clitoris, muscles) virilization– INFANTS- Female Pseudohermaphroditism.
• Males – Will induce pubertal effects
lack of 21- or 11-hydroxylase activity in the adrenal cortex leads to the preferential formation of adrenal androgens-Congenital adrenal hyperplasia.
Adrenal Medulla
Autonomic Nervous System
Adrenal Medulla
Pre-ganglionic neuron
Epinephrine/Norepinephrine
Chromaffin cell
Tyrosine
Dopa
DopamineDopamine β-hydroxylase
Norepinephrine(10-20%)
Epinephrine(80-90%)
EpinephrineSecretory granule
Tyrosine hydroxylase
PNMT
Chromaffin cell
PNMT- phenylethanolamine-N-methyltransferase
ACTH
Cortisol
Synthesis of the two major adrenal medulla hormones :-
Chromaffin Cell
N
ACh
Ca2+
Vesicles containing
Epinephrine and
Norepinephrine
Release of Epi and
Norepi via exocytosis
Na+ Vm
Transport and Circulation of Medullary Hormones~ 50% travel loosely bound to albuminHalf-life of between 10-100 seconds, very short
• The adrenal medulla- pheochromocytes, and large venous structures.
• Two distinct classes of medullary cells
• Distinguished from each other - secretory granules.
• Medullary cells -larger and large caliber veins are located in the medulla.
• The pheochromocytes -stained with chromic salts.
• The cells take on a yellow brown color and are called chromafin cells.
Chromaffin cells
• modified post-ganglionic sympathetic neurons that lack dendrites and axons
• secreted in response to intense emotional reactions and stresses placed on the individual.
Sympathetic ganglion cells
round or polygonal with prominent nuclei
Pheochromocytoma
• Hypersecretion of medullary hormones – Usually due to tumor
• unregulated burst of c/a release • • Get sudden symptoms associated with
excess catecholamines – Esp. on stress or postural changes
Hypothalamus
ANS/ Adrenal Medulla
Release of catecholamines
Pituitary-Adrenal Cortex
mineralocorticoidsglucocorticoids
cortisol
HR & BP Blood glucose Metabolic rate Bronchodilation
BPProtein b/down Fat b/down Immune supression
Short-term response Long-term response
STRESS