catecholamines

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catecholamines

• JP Slovak

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• Adrenal medulla
• Connected to sympathetic nervous system
• Epinephrine
• Norepinephrine
• Synthesized from tyrosine
• Cortex
• Bulk of adrenal gland
• Aldosterone (renin-angiotensin system)
• cortisol

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Introduction

• Sympathoadrenal system
• Mainly vasomotor and secretomotor
• Parasympathetic
• Nerves arise from cranial-sacral segments
• Vegetative state
• Movement of food
• ACh
• Sympathetic
• Arise from thraco-lumbar regions
• Concerned with stress response
• NE

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Receptors

• Cholinergic receptors
• Respond to Ach
• Nicotinic
• Stimulate skeletal muscle
• Autonomic neurons
• Muscarinic
• Stimulates smooth muscle
• Curare specifically blocks nicotinic
• Atropine blocks muscarinic

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Receptors

• Adrenergic receptors
• Alpha and beta
• Differ in sensitivity
• Alpha EgtNEgtISO
• Beta ISOgtEgtNE
• At high concentrations all sympahtoamines can
  stimulate both alpha and beta
• Alpha
• Arterial vasocontriction
• Beta
• Lipolytic response
• Contraction of cardiac muscle

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Receptors

• Dopaminergic
• Restricted to brain
• Vasodilation
• Inhibits release of certain neurotransmitters
• Diuresis
• Increases aldosterone release
• Stimulate PRL

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Sympathoadrenal functions

• CHO metabolism
• E stimulates hepatic glycogenolysis
• Also breakdown of muscle glycogen
• Catecholamines inhibit insulin
• Stimulate glucagon
• Fasting increases E
• Fat metabolism
• Lipolysis stimulated
• Obesity
• Ample supply of food
• Genetic predispostion
• Sedentary
• EEA

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Sympathoadrenal functions

• Protein metabolism
• Deceased release of aa
• Lactate, glycerol, glucose increased
• Thermogenesis
• Fasting and feeding stimulates SNS
• Shivering
• Muscular activity
• Piloerection controlled by SNS
• Nonshivering thermogenesis
• Brown fat
• NE injections increase brown adiopocytes
• CV
• Increase force and rate of heart
• Shunts blood during stress
• Less to skin, connective tissue, kidneys
• Dilates bronchial smooth muscle

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Adrenal Glands

• Glucocorticoids
• Affect macronutrient metabolism
• Catabolic on skeletal muscle
• Permissive actions
• Sympathoadrenal system
• Cathecholamine synthesis
• Body temp
• Role in lactognenesis
• Maintains hippocampus
• Inhibits inflammation
• General adaptation syndrome
• Alarm, resistance, exhaustion

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Aldosterone

• Control
• Muscular activity sweat
• Reduction of plasma volume
• Reduced blood flow to kidney causes renin release
• Renin causes angiotensinogen?Ag1
• Ag1 to Ag2
• Ag2 stimulates aldosterone release
• Na reabsorption
• Plasma volume increases
• Sodium Potassium Homeostasis
• Increased reabsorption by distal tubules
• More sodium reabsorbed more K secreted

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Pathophysiology

• Addisons disease
• Destruction or atrophy of adrenal glands
• Symptoms
• Weakness
• Increase in pigmentation
• Cortisol feedback to ACTH
• MSH contained within ACTH
• Weight loss
• Hypotension
• Hypoglycemia

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Pathophysiology

• Cushings
• Excessive production of glucocorticoids
• Tumor
• Symptoms
• Android shape
• May be related to insulin
• Hypertension
• Glucose intolerance
• Osteoporosis
• Polyuria
• polydipsia