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