2 Adrenal Gland Anatomy was first described in 1563. Is located above (or attached to) the upper pole of the kidney.Is pyramidal in structure and weighs ~ 4 g.Consists of the adrenal cortex and adrenal medullaActivities are regulation of fluid volume and stress response
5 Adrenal CortexIs divided into 3 zones in the adult gland: Zona Glomerulosa, Zona Fasciculata, Zona Rericularis.Is divided onto 4 zones in the fetal gland.The three zones of the permanent cortex constitutes only 20% of the fetal gland’s size. The remaining zone (fetal cortex) comprises up to 80% of gland’s size during fetal life.
6 Adrenal Cortex: Steroid Hormone Production Aldosterone, sex hormones, cortisolSynthesized from cholesterol–steroid ring
8 Cortisol and Chronic Stress Prolonged exposure to high cortisol levels can lead to break down of muscle, excessive epinephrine release, hyperglycemia, weakening of bone, destruction of the immune system, inhibition of reproductive function, and other complications.
9 Cortisol Effects: Body Responses to Stress Permissive effect on glucagonMemory, learning and moodGluconeogenesisSkeletal muscle breakdownLipolysis, calcium balanceImmune depressionCircadian rhythms
14 Permissive Effects of Cortisol on Development Cortisol is required for normal development:- permissive role in final maturation of many organs- required for synthesis of digestive enzymes, surfactant- required for skeletal growth in children
15 Mechanisms of Cortisol Action The actions of cortisol are mediated through the glucocorticoid receptor.Intracellular receptor in steroid receptor superfamily.Stimulates transcription of target genes by interaction of bound receptor with GRE in 5’ flanking region.Inhibits transcription of some genes by interaction of receptor with AP1 (jun/fos dimer), decreasing AP1-mediated gene expression.AP1transcriptionGRcortisolAP1site
17 Cortisol Effects: Body Responses to Stress to living
18 Control of Cortisol Secretion: Feedback Loops External stimuliHypothalamicAnterior PituitaryAdrenal cortexTissues
19 Cortisol: Role in Diseases and Medication Use as immunosuppressantHyperimmune reactions (bee stings)Serious side effectsHypercortisolism (Cushing's syndrome)Tumors (pituitary or adrenal)Iatrogenic (physician caused)Hypocortisolism (Addison's disease)
20 Aldosterone Exclusively synthesized in Z. Glomerulosa Essential for life.Promotes sodium retention and Potassium elimination by the kidney.Expands ECF volume
22 Aldosterone: Role in Diseases Complete failure to secrete aldosterone leads to death (dehydration, low blood volume).Hyperalsdosterone states: Contribute to hypertension associated with increased blood volume.
23 Adrenal Medulla: A Modified Sympathetic Ganglion Sympathetic stimulationCatecholamine release to bloodEpinephrineNorepinephrineTravel to:Multiple targetsDistant targets
24 Adrenal Medulla: A Modified Sympathetic Ganglion
25 Mechanism: Norepinephrine Release and Recycling
26 Review of Efferent Pathways: Motor and Autonomic
27 Catechalomines: Activity Stimulates the “fight or fight” reactionIncreased plasma glucose levelsIncreased cardiovascular functionIncreased metabolic functionDecreased gastrointestinal and genitourinary function