Adrenal Gland Functional Histology. Two parts- 1)Adrenal Cortex Aldosterone(mineralocorticoid) the cortisol (glucocorticoids) and androgenic hormones.

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