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Adrenal Gland

Adrenal Gland. 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 medulla Activities are regulation of fluid volume and stress response.

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Adrenal Gland

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  1. Adrenal Gland

  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 medulla Activities are regulation of fluid volume and stress response

  3. The Adrenal Gland: Anatomy

  4. Adrenal Histology

  5. Adrenal Cortex • Is 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, cortisol • Synthesized from cholesterol–steroid ring

  7. Adrenal Cortex: Steroid Hormone Production

  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 glucagon • Memory, learning and mood • Gluconeogenesis • Skeletal muscle breakdown • Lipolysis, calcium balance • Immune depression • Circadian rhythms

  10. The General Adaptation Syndrome

  11. The General Adaptation Syndrome

  12. The General Adaptation Syndrome

  13. 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

  14. AP1 cortisol AP1 site 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. transcription GR

  15. Hormone Effects on Gene Activity Cortisol

  16. Cortisol Effects: Body Responses to Stress toliving

  17. Control of Cortisol Secretion:Feedback Loops • External stimuli • Hypothalamic • Anterior Pituitary • Adrenal cortex • Tissues

  18. Cortisol: Role in Diseases and Medication • Use as immunosuppressant • Hyperimmune reactions (bee stings) • Serious side effects • Hypercortisolism (Cushing's syndrome) • Tumors (pituitary or adrenal) • Iatrogenic (physician caused) • Hypocortisolism (Addison's disease)

  19. Aldosterone • Exclusively synthesized in Z. Glomerulosa • Essential for life. • Promotes sodium retention and Potassium elimination by the kidney. • Expands ECF volume

  20. Regulation of Aldosterone Secretion

  21. 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.

  22. Adrenal Medulla: A Modified Sympathetic Ganglion • Sympathetic stimulation • Catecholamine release to blood • Epinephrine • Norepinephrine • Travel to: • Multiple targets • Distant targets

  23. Adrenal Medulla: A Modified Sympathetic Ganglion

  24. Mechanism: Norepinephrine Release and Recycling

  25. Review of Efferent Pathways: Motor and Autonomic

  26. Catechalomines: Activity • Stimulates the “fight or fight” reaction • Increased plasma glucose levels • Increased cardiovascular function • Increased metabolic function • Decreased gastrointestinal and genitourinary function

  27. Activity of Epinephrine

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