II. Anatomy
- Anatomy Images
- Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
- Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
- Adrenal Gland is a flat, triangular organ that sits atop each Kidney
- Adrenal Gland is without ducts
- Adrenal Gland is divided into two distinct anatomical and physiologic components
- Adrenal Medulla is a modified sympathetic Ganglion releasing Sympathomimetic agents (epineprine, Norepinephrine)
- Adrenal Cortex generates inter-related steroid Hormones (mineralcorticoids, Glucocorticoids and androgens)
III. Physiology
- Physiology Images
- Adrenal Medulla (sympathetic agent synthesis)
- See Sympathetic Nervous System
- See Alpha Adrenergic Receptor
- See Beta Adrenergic Receptor
- Inner structure of the Adrenal Gland
- Functions as a sympathetic Ganglion that releases Sympathomimetics in response to stressors
- Epinephrine
- Primary Adrenal Medulla released Catecholamine (more than Norepinephrine)
- Alpha Adrenergic Agonist Effects
- Vasoconstriction (increased Systemic Vascular Resistance and Blood Pressure)
- Increases Vital Organ Perfusion (myocardial perfusion, cerebral perfusion)
- Decreases Non-Vital Organ Perfusion (splanchnic, intestinal, renal and skin perfusion)
- Beta 1 Adrenergic Agonist Effects (at physiologic doses)
- Increases myocardial contractility
- Increases Heart Rate
- Beta 2 Adrenergic Agonist Effects
- Relaxes Bronchial Smooth Muscle (bronchodilation)
- Stimulates Gluconeogenesis, lipolysis and glycogen breakdown
- Norepinephrine
- Neurotransmitter for all other postganglionic sympathetic Neurons
- Potent Alpha 1 Adrenergic ReceptorAgonist Effects
- Potent arterial and venous Vasoconstriction
- Beta 1 Adrenergic ReceptorAgonist Effects
- Similar potency to Epinephrine
- Increases myocardial contractility
- No Beta 2 Adrenergic Receptor Activity
- Adrenal Cortex (steroid Hormone synthesis from Cholesterol)
- See Steroid Hormone Pathway
- Outer structure of the Adrenal Gland
- Mineralcorticoids (esp. Aldosterone)
- See Sodium and Water Homeostasis
- Increases Sodium retention and Potassium excretion
- Increases water reabsorption from Kidney
- Glucocorticoids (esp. Cortisol)
- Mobilizes available energy sources (Glucose, fats, Amino Acids)
- Increases Serum Glucose by stimulating liver Gluconeogenesis and glycogenolysis
- Increases serum Fatty Acids by promoting lipolysis of adipose Triglyceride stores
- Increases blood Amino Acids by breaking down Proteins (outside liver)
- Antiinflammatory activity
- Inhibit Histamine release
- Inhibit Lymphocyte production
- Stabilize MacrophageLysosomes
- Increases gastric acid production
- Mobilizes available energy sources (Glucose, fats, Amino Acids)
- Androgens
IV. Pathophysiology
- Aldosterone
- Cortisol
- Androgens
- Epinephrine and Norepinephrine (Adrenal Medulla)
V. References
- Goldberg (2014) Clinical Physiology, Medmasters, Miami, p. 132-46