Adrenal medulla

2.  The adrenal medulla, which constitutes 28%
of the mass of the adrenal gland, is made up
of interlacing cords of densely innervated
granule-containing cells that abut on venous
sinuses
 Made of chromaffin cells – 2 types
 Contains granules - 2 types
 Paraganglia cells

3.  The adrenal medulla is in effect a
sympathetic ganglion
 The cells secrete when stimulated by the
preganglionic nerve fibers
 Innervated by splanchnic nerves
 prepare the body for emergencies, the "fight-
or-flight" responses

5.  Adrenalin (epinephrine)
 Noradrenalin (norepinephrine)
 Dopamine

7.  Fight or flight reactions
 Pre-ganglionic ativation
 Exo-cytosis of granules mediated by ca
influx
 Physiological and psychological stimuli such
 Pain , anxiety , trauma , hypovolemia ,
hypoglycemia , hypothermia, severe
exercise , emotional stimulus

9. Table 1. Classification of Adrenergic Hormone
Receptors
Receptor Agonists
Second
Messenger
G protein
alpha1 (1) E>NE IP3/Ca2+; DAG Gq
alpha2 (2) NE>E  cyclic AMP Gi
beta1 (1) E=NE  cyclic AMP Gs
beta2 (2) E>>NE  cyclic AMP Gs
E = epinephrine; NE = norepinephrine
 Alpha adrenergic receptors - NE ,E – major
stimulatory (except intestine)
 Beta adrenergic receptors - E – major
inhibitory ( except myocardium)

10.  Alpha 1 , 2
 Beta 1, 2 ,3
 Up regulation
 Down regulation
 Adrenalin – alpha 1,2 . Beta 1, 2 ,3
 Nor-adr – alpha 1,2 . Beta 1 , poor beta
activity

12.  Metabolism –o2 consumption co2 production
Carbohydrate Metabolism
Gluconeogenesis , glycogenolysis , glycogenesis , insulin
inhibition , glucagon secretion , ACTH secretion
Lipid Metabolism – lipolysis thro’ HSL
 Heart - beta 1
 Cns – alertness , anxiety , tremors - beta
 Blood vessel – blood pressure
 Respiration – beta 2

13.  Skin –arrector pili
 Urinary Bladder And GIT
 Eyes –alpha - pupilary dilation , beta produces relaxation
of ciliary muscle
 Blood – increases rbc , coagulability
 Skeletal muscle – contraction , increase blood supply ,
glycogeneolysis
 Smooth muscle - splenic capsule
shpincters
dilator pupillae
uterus
arrector pili

14.  Relaxation in non sphicteric gi muscles
 Urinary bladder
 Bronchioles
 Kidney – renin secretion
 Sweat glands
 Lacrmal glands
 Salaivary glands

15.  Insulin , somatostatin
 Glucagon
 Thyroxin , t4 – t3 enhancement
 TRH
 Renin secretion

16.  Acute sympathetic stimulation
 Chronic sympathetic stimulation
 ACTH – increases enzymes of catechol
 Cortisol - PNMT
 Epinephrine
 Exposure to cold
 Hypoglycemia

17.  Produced by adrenal medulla and
dopaminergic neurons
 Vasoconstriction
 Dilatation in mesentery
 Increase in heart rate and BP

18.  Endocrine hypertension
 Anxiety
 Chest pain
 Fever
 Headache
 Hyperglycemia
 Nausea and vomiting
 Polyuria , glucosuria
 Palpitations
 Sweating
 Tachycardia
 Wt loss
 Test for pheochromocytoma