Download Adrenal hormones

Adrenal hormones
Why stress about it?
Adrenal gland
• Really two separate glands
• Cortex- Outer not essential to life
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Produces 3 categories of steroids
mineralocorticoids -aldosterone
Glucocorticoids-cortisol, corticosterone
Sex steroids
• Medulla- (inner) essential to life
– Produces catecholamines epinepherine+norepinepherine
Origin of Adrenal tissue and hormones
• Steroids produced from mesodermally derived tissue
• Cortex and gonads- derived from mesoderm
• Medulla- derived from and develop with sympathetic ganglia
Macroscopic anatomy
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Cortex and medulla regions only applicable to mammals
Non mammals have medulla or cortex like regions
Suprarenal or intrerrenal glands
Chromafin tissue-medullary like tissue that produces catecholamines found in the abdomen
Regulation
• Medulla is regulated totally by nerves
• Cortex is regulated totally by ACTH
Microscopic anatomy
• Mammals cortex - 3 regions
– Zona glomerulosa
– Zona faciculata
– Zona reticularis
• Z.G. produces mineralocorticoids and new cortical cells - can regenerate if
damaged.
• All three layers produce glucocorticoids
– Z.F. and Z.R. produce the sex steroids.
Microscopic anatomy
• Medulla- contains lots of blood vessels and sinusoids.
• Contains chromaffin tissue (produces catecholamines)
• Regulation of the medulla is nervous.
Hormone Chemistry
• Cathecholamines
• Epinepherine, norepinepherine, DOPA
• Catechol-aromatic ring with alanine
• Found in adrenal medulla,nervous tissue both sympathetic and
parasympathetic systems
• Precursors are phenylalanine - tyrosine- 3,4 DH Dopa- 3,4 DH, dopamine
Metabolism
• Liver, Kidney, and Target Tissue
• COMT, MOA-breakdown catecholamine
• Not avidly bound. Short 1/2 life
Functions Of Catecholamines
• Provide responses to acute and chronic stress -Fight or flight- adrenal
medulla and Sympathetic NS
• Massive CNS Stimulation-Anxious- Alert- Attentive
• Quick stimulation of muscles, increase reflexes/strength
Cardiovascular System
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Raise Heart Rate-epinephrine increase
Cardiac Output- epinephrine increase
Blood Pressure-epinephrine no effect, norepinephrine increase
Peripheral Resistance-dilates skeletal muscle epinephrine-norepinephrine
causes vasoconstriction
Metabolic Effects
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Fat Mobilization-(both) provide free fatty acids as energy source
Major Diabetogenic Hormone
Proteins
Caloriogensis
Epinephrine and norepinephrine work together
Clinical applications of catecholamines
Treat Anxiety, depression or mood disorders
 agonists -epinepherine analogs
Catecholamine Regulation
Adrenal Cortex
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Steroid Synthesis- all come from acetate and cholesterol
C-18 Estranes (estrogens)
C-19 Androstanes (Androgens)
C-21 Pregnanes (progest, mineralcorticords, glucocorts
Adrenal Cortex
• Steroid Synthesis - emphasis on adrenal production
• Two Important Synthetic Steroids - Dexamethasone, and Prednisone
Pathways of adrenal steroidogenesis
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Cholesterol
Pregnenolone
Progesterone
Deoxycorticosterone
Corticosterone
18-hydroxycorticosterone
Aldosterone
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Mineralocorticoids
17 hydroxypregnenalone
17 hydroxyprogesterone
11 deoxycortisol
Cortisol
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Glucocorticoids
Adrenal Cortex
• Adrenogenital Syndrome- alteration in one of these enzyme systems.
Blocking of hydroxlases in corticosterone pathway results in orderly or
over production of other pathways (androgens surge)
• Glucocorticoids are 90% bound
• Aldosterone is mainly free
• Liver and Kidney primary targets
Quiz
Discuss the factors that regulate the secretion of catecholamines.
Function of Adrenal Cortex Hormones
• Mineralocorticoids
– Aldosterone- regulates H2O and electrolyte balance (osmoregulation)
– Active uptake of Na+ and H2O occurs
– Mammals- Kidney tubules, Sweat, Salivary, Intestinal glands
Regulation of adrenal cortical hormones
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Indirect influence from sympathetic nervous system
Decrease in Na/Increase in K - raise aldosterone
Decrease in ECF ( blood loss or dehaydration Triggered by angiotensin II
Stress, anxiety, trauma
Regulation of cortex
• Chemical
– Aldosterone, renin, Angiotensin I, II
• Neural
– Hardwiring to the JGA
• Metabolites
– K/Na
• Chronotropic
– Elevated day/lowered night
Functions of Glucocorticoids
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Primary effect is as metabolic regulator
Maintain carbohydrate levels to supply the CNS
Produce hyperglycemia
Dec. uptake by non-essential tissues
Stimulate gluconeogenesis
Functions of Glucocorticoids
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Catabolize protein providing AA’s for gluconeogenesis
Immunosuppressive
Anti inflammatory,anti allergenic
Catabolic to skeletal muscle
Weakens bones (collagen)
Inc. RBC’s and Platelets dec. WBC’s
Regulation of glucocorticoids
• Neural
– Emotional stress, physical wounds, bacterial infection
• Chemical (diagram)
Regulation of glucorticoids
General Adaptation Syndrome
• Stress responses
– Specific- heat-sweat, cold-shiver
– Nonspecific- same no matter what the stimulus is but the degree can vary
• Selye
– Non specific stress elicits the following responses:
General Adaptation Syndrome
• Alarm reaction- fight or flight response,muscles tense, HR and BP
increase
• Resistance or adaptation-nervous and endocrine systems deal with
stressor. dangerous if longterm.
• Exhaustion-resistance drops, immunity suppression, depletion of energy
reserves, stress related disease.
General adaptation Syndrome
General Adaptation Syndrome
General Adaptation Syndrome