endocrine physiology the adrenal gland 2 dr. khalid al-regaiey
TRANSCRIPT
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Endocrine Physiology
The Adrenal Gland2
Dr. Khalid Al-Regaiey
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• Produced by the fasciculata and reticularis layers of the adrenal cortex
• Glucocorticoids (cortisol): recognized early to increase plasma glucose levels:
• Mobilization of amino acids from proteins
• Enhance liver gluconeogenesis
• Target tissues: most body tissues
Glucocorticoids
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• CRH from hypothalamus is the major regulator of ACTH secretion
• ADH is also a potent ACTH secretagogue
• ACTH from anterior pituitary stimulates cortisol synthesis and secretion
• CRH (and ACTH) are secreted in pulses
• The greatest ACTH secretory activity occurs in the early morning hours and diminish late in the afternoon.
Glucocorticoids (cont.)
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HPA Axis
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Primary and secondary hypersecretion of cortisol
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Circadian rhythm of cortisol secretion
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Actions of Glucocorticoids
• Metabolic response to fasting:
• Gluconeogenesis from amino acids (increased expression of the enzymes)
• Mobilization of stored fat (activation of HSL) and its use in β-oxidation and the production of ketone bodies
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Anti-inflammatory Effects of GC• Glucocorticoids are used to alleviate
inflammation
• Inhibit production of prostaglandins and leukotrines (mediate inflammation)
• This occurs via stimulation of an inhibitor of phospholipase A2, which is needed for PG synthesis
• Decrease the inflammation reaction by decreasing permeability of capillary membranes, reducing swilling
• They also reduce effects of histamine
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Suppression of Immune System
• When administered in high doses, GC can:
• Suppress antibody formation
• Kill immature T and B lymphocytes
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Glucocorticoids and Stress:
• Without GCs, the body cannot cope with even mild stressors
• Fat & glucose metabolism
• Maintenance of the vascular response to norepinephrine
• Effects on CNS
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Cushing’s Syndrome
• Cushing’s syndrome results from continued high glucocorticoid levels
• 3rd - 6th decade, 4 to1 females
• Causes:
• pharmocologic
• pituitary adenoma 75-90%
• adrenal adenoma, carcinoma
• ectopic ACTH
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Cushing’s SyndromeSigns:
• Fat is deposited in the body trunk (central obesity)
• Buffalo hump
• Moon facies (subcutaneus fat in cheeks and submandibular)
• Purple striae
• Blood-glucose levels rises chronically, causing adrenal diabetes
• May cause beta cells to die
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• Purple striae
Cushing’s Syndrome
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• treatment based on cause
Cushing’s Syndrome
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Adrenocortical insufficiency
• primary causes, ie. Addison’s disease
• autoimmune disease, tumors, infection, hemorrhage, metabolic failure, ketoconazole
• secondary causes
• hypopituitarism, suppression by exogenous steroids
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Adrenocortical insufficiency
• symptoms, signs
• fatigability, weakness, anorexia, nausea, weight loss, hyperpigmentation, hypotension, women loss of axillary and pubic hair
• can lead to severe volume depletion and shock
• Reduced cortisol results in poor blood glucose regulation
• Patient cannot cope with stress
• Adrenal crisis: asthenia, severe pains in the abdomen, vascular collapse….
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• treatment
• glucocorticoid replacement, mineralocorticoid replacement
Adrenocortical insufficiency
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• Produced by the fasciculata and reticularis layers of the adrenal cortex
• Most gonadocorticoids secreted are androgens mainly dehydroepiandrosterone (DHEA)
• Androgens contribute to:
• The onset of puberty
• The appearance of secondary sex characteristics
• Sex drive in females
Gonadocorticoids (Sex Hormones)