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The endocrine system

The endocrine system. Honors Anatomy & Physiology. Endocrine vs nervous system. act together to coordinate body’s activities both: use chemical messengers to communicate cell to cell major function: homeostasis endocrine : slower response time

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The endocrine system

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  1. The endocrinesystem Honors Anatomy & Physiology

  2. Endocrine vs nervoussystem • act together to coordinate body’s activities • both: • use chemical messengers to communicate cell to cell • major function: homeostasis • endocrine: slower response time • hormones transported thru circulatory system • target cells (any cell with hormone receptor) anywhere in body • nervous: quicker conduction of signals • neurotransmitters • act on cells close by

  3. Glands • no ducts • secretions released and diffuse into blood capillaries • have ducts • secretions released onto surface • example: sweat glands, salivary glands Endocrine Exocrine

  4. 2 types of hormones • bind to protein receptors in cell membranes (do not enter cell) • receptor-hormone activate enzyme in cytoplasm  series of reactions result in cell response • enter cell & bind to receptor in cytoplasm or nucleus • Activates transcription of gene  protein produced • generally action slower than peptide hormone Peptide Steroid

  5. Endocrine system

  6. hypothalamus • part of brain • secretes “releasing” hormones that act on pituitary gland • axons that store the 2 posterior pituitary hormones end there

  7. Pituitary gland • 2 lobes: posterior & anterior

  8. negativeFeedback Inhibition

  9. Thyroid Gland • stimulated by TSH • secretes thyroxin (T4) and triiodothyronine (T3) • (-) feedback inhibition • both have similar effects on target cells

  10. hypothyroidism • Thyroid produces too little hormone • several causes: Hashimoto’s autoimmune/ lack of Iodine in diet  goiter (enlargement of thyroid due to increased TSH stimulation • Symptoms: • Adults: lethargy, weight gain, anovulatory cycles • Infants:cretinism: dwarfism, low IQ, failure to reach sexual maturity

  11. Goiter

  12. hyperthyroidism • excessive secretion of thyroid hormones

  13. Parathyroid Glands • 4 small glands embedded in posterior surface of thyroid gland • secrete: parathyroid hormone (PTH) • regulated by serum Ca++ levels • actions: • stimulates removal of Ca++ from bone • increases kidney tubules reabsorption of Ca++ • activates vit D which enhances Ca++ absorption from food

  14. Adrenal gland

  15. Adrenal Cortex • outer layer • produces 2 kinds of steroid hormones • Glucocorticoids • major 1 – cortisol: • reduces swelling by inhibiting immune system/ raises serum glucose (stimulates liver to make glucose from proteins or lipids • Mineralocorticoids • major 1- aldosterone • acts on kidney to promote absorption of Na+ & excretion of K+

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