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The Human Endocrine System

The Human Endocrine System. Chemical Signals. Pheromones Chemical signals that work at a distance between individuals A woman’s axillary extract can alter another woman’s menstrual cycle Hormones Chemical signals that work At a distance between organs, or Locally between adjacent cells.

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The Human Endocrine System

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  1. Hormones & the Endocrine System

  2. The Human Endocrine System

  3. Chemical Signals • Pheromones • Chemical signals that work at a distance between individuals • A woman’s axillary extract can alter another woman’s menstrual cycle • Hormones • Chemical signals that work • At a distance between organs, or • Locally between adjacent cells

  4. Target Cell Concept

  5. Action of Hormones • Hormones • Chemical signals produced by one cell that regulate the metabolism of other cells • Steroid Hormones • Can cross cell membranes • Peptide Hormones • Most bind to receptor in plasma membrane • First Messenger • Causes internal release of cAMP • Second Messenger

  6. Peptide Hormone

  7. Steroid Hormone

  8. Human Endocrine System • Endocrine glands • Ductless glands that secrete hormones directly into the bloodstream • Most endocrine hormones are peptides • Only gonads and adrenal cortex produce steroid hormones • Effects of hormones are moderated in two ways • Negative feedback opposes release • Antagonistic hormones oppose each other’s actions

  9. Hypothalamus and Pituitary Gland • Hypothalamus regulates internal environment • Acts through autonomic system • Also controls glandular secretions of pituitary gland • Posterior Pituitary • Antidiuretic Hormone (ADH) • Controlled by negative feedback • Oxytocin • Controlled by positive feedback • Anterior Pituitary • Hypothalamus controls by producing • Hypothalamic-releasing hormones, and • Hypothalamic-inhibiting hormones

  10. Hypothalamus and the Pituitary

  11. Anterior Pituitary Hormones • Anterior pituitary hormones that affect other glands: • Thyroid-Stimulating Hormone (TSH) • Adrenocorticotropic Hormone (ACTH) • Gonadotropic Hormones • Anterior pituitary hormones that do NOT affect other glands • Prolactin (PRL) • Melanocyte-Stimulating Hormone (MSH) • Growth Hormone (GH)

  12. Effect of Growth Hormone

  13. Acromegaly

  14. Thyroid Glands • Composed of large number of follicles filled with • Triiodothyronine (T3), and • Thyroxine (T4) • Thyroid hormones increase metabolic rate • Thyroid-induced abnormalities • Simple goiter - Poor hormone production • Cretinism - Poor thyroid development • Myxedema - Hypothyroidism • Exophthalmic goiter - Hyperthyroidism

  15. Simple Goiter

  16. Cretinism

  17. Calcitonin • Regulates blood calcium level (in part) • Secreted by thyroid gland when blood calcium level rises • Brings about deposit of calcium in the bones • Low calcium level in blood stimulates the release of parathyroid hormone (PTH) • Parathyroid hormone causes • Phosphate level in blood to decrease, and • Calcium level in blood to increase • Insufficient production of parathyroid hormone leads to tetany

  18. Regulation of Blood Calcium Level

  19. Adrenal Glands • Paired – One sits atop each kidney (ad-renal) • Each consists of outer cortex and inner medulla • Inner portion, the adrenal medulla • Produces • Epinephrine, and • Norepinephrine • Short-term response to stress (fight or flight) • Outer portion, adrenal cortex • Produces • Mineralocorticoids, and • Glucocorticoids • Long-term response to stress

  20. Adrenal Glands

  21. Glucocorticoids • Cortisol • Raises blood glucose level • Promotes breakdown of muscle proteins to amino acids • Promotes metabolism of fatty acids • Counteracts inflammatory response

  22. Mineralocorticoids • Aldosterone • Promotes two renal functions: • Absorption of sodium, and • Excretion of potassium • Renin-angiotensin-aldosterone system • Raises blood pressure • Angiotensin II constricts arterioles • Aldosterone causes kidneys to reabsorb sodium (causing water retention) • Atrial natriuretic hormone (ANH) is antagonistic to aldosterone

  23. Regulation ofBlood Pressure and Volume

  24. Addison Disease

  25. Cushing Syndrome

  26. Pancreas • Made up up exocrine and endocrine tissue • Endocrine Portion of the Pancreas: • Consists of pancreatic islets • Produce and secrete • Insulin • Secreted during high blood glucose level • Stimulates uptake of glucose by cells • Glucagon • Secreted during low blood glucose level • Stimulates liver to break down glycogen • Exocrine Portion of the Pancreas: • Secretes enzymes and buffers into intestine

  27. Regulation of Blood Glucose Level

  28. Other Endocrine Glands • Gonads • Testes • Produce testosterone • Secondary sex characteristics • Ovaries • Produce estrogen and progesterone • Reproduction • Secondary sex characteristics

  29. The Effects of Anabolic Steroid Use

  30. Other Endocrine Glands • Pineal Gland • Produces melatonin • Involved in Circadian rhythms • Thymus Gland • Secrete thymosins • Aid in differentiation of lymphocytes • Prostaglandins • Produced within cells • Not distributed in blood

  31. Melatonin Production

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