Adrenal Gland Functional Histology Two parts1)Adrenal Cortex • Aldosterone(mineralocorticoid) Angiotensin II •the cortisol (glucocorticoids) and •androgenic hormones (Dehydroepiandrosterone). ACTH 2) Adrenal medulasecretes the catecholamine hormones, • adrenaline (epinephrine) • Noradrenaline (norepinephrine) Adrenal Morphology Zona glomerulosa Zona fasciculata Zona reticularis Aldosterone Glucocorticoids Androgens Blood supply of the adrenal 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 – mineralocorticoidsaldosterone Na+ and K+ balance(RAA System) Hypothalamus CRH Anterior Pituitary ACTH (minor) Angiotensin II K+ Adrenal Cortex (Zona Glomerulosa) Aldosterone Hypersecretion • Tumor in the Zona glomerulosa/primary/conn`s syndrome or increased renin secretion/secondary hyperaldosteronism. Effects:• Increased extracellular fluid volume • Hypertension • Hypokalemia – Muscle weakness, arrhythmias 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 CRH Anterior Pituitary ACTH Adrenal Cortex (Zona Fasciculata Zona Reticularis) Cortisol / Androgens Energy glucose Action of Insulin ?? General cell Fatty acids glycerol glucose Amino Acids glycogen Liver lipolysis Protein breakdown Adipose Cells Muscle 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 CRH Anterior Pituitary ACTH Adrenal Cortex (Zona Fasciculata Zona Reticularis) Cortisol Cortisol Hypersecretion Cushing’s Disease – cortisol excess due to hypersecretion of pituitary ACTH 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 Metabolic effects• liver glucose output • (+ insulin) fat deposition in trunk, face and upper back • Muscle wasting and weakness • Impaired glucose tolerance, insulinresistant 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 Disease Metabolism • 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 androgensdehydroepiandrosterone. Hypersecretion lack of 21- or 11-hydroxylase activity in the adrenal cortex leads to the preferential formation of adrenal androgensCongenital adrenal hyperplasia. • Females (adrenogenital syndrome) – ADULTS-Masculine characteristics (hair, voice, enlarged clitoris, muscles) virilization – INFANTS- Female Pseudohermaphroditism. • Males – Will induce pubertal effects Adrenal Medulla Autonomic Nervous System Pre-ganglionic neuron Adrenal Medulla Chromaffin cell Epinephrine/Norepinephrine Synthesis of the two major adrenal medulla hormones :- Tyrosine Epinephrine(80-90%) Tyrosine hydroxylase Cortisol Dopa ACTH PNMT Dopamine Dopamine β-hydroxylase Norepinephrine(10-20%) Epinephrine Secretory granule Chromaffin cell PNMT- phenylethanolamine-N-methyltransferase Chromaffin Cell ACh Na+ Vesicles containing Epinephrine and Norepinephrine Release of Epi and Norepi via exocytosis N Ca2+ Transport and Circulation of Medullary Hormones ~ 50% travel loosely bound to albumin Half-life of between 10-100 seconds, very short Vm • The adrenal medullapheochromocytes, 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 pheochromocyte s -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 STRESS Hypothalamus ANS/ Adrenal Medulla PituitaryAdrenal Cortex cortisol Release of catecholamines HR & BP Blood glucose Metabolic rate Bronchodilation Short-term response glucocorticoids Protein b/down Fat b/down Immune supression mineralocorticoids BP Long-term response