Endocrine System


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Endocrine System

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Essentials of Anatomy & Physiology Fifth edition Seeley • Stephens • Tate Chapter 10 The Endocrine System
  2. 2. <ul><li>Water balance </li></ul><ul><li>Uterine contraction </li></ul><ul><li>Growth, metabolism, and milk secretion </li></ul><ul><li>Ion regulation </li></ul><ul><li>Heart rate and blood pressure regulation </li></ul><ul><li>Blood glucose control </li></ul><ul><li>Immune system regulation </li></ul><ul><li>Reproductive function control </li></ul>Functions of the Endocrine system
  3. 3. Chemical signals <ul><li>Chemical signals or Ligands </li></ul><ul><li>- Molecules released from one location that move to another location to produce a response. </li></ul><ul><li>Intracellular response – produces from one part of a cell and travel to another part of the SAME cell </li></ul><ul><li>Autocrine Paracrine </li></ul><ul><li>Neuromodulators Pheromones </li></ul>
  4. 6. Receptors Chemical signals bind to proteins and glycoproteins (RECEPTORS) Specificity – Tendency for each receptor site to bind to a specific chemical signal and not the others.
  5. 7. Membrane-bound receptors Extend across the cell membrane, with their receptor sites outside the surface of the cell membrane Responds to chemical signals that are large, and water-soluble Intracellular receptors Chemical signals DIFFUSES and bind to the intracellular receptor located at the cytoplasm or nucleus
  6. 8. <ul><li>Hormones are distributed in the blood to all parts of the body, but only its corresponding target tissue respond to each type of hormone </li></ul><ul><li>Influences target cells by chemically binding to their receptors. </li></ul><ul><li>2,000-100,000 receptors for a particular hormone </li></ul><ul><li>Hormones that pass in the blood and act on distant cells are called Circulating hormones or ENDOCRINE </li></ul><ul><li>PARACRINE - Hormones that act on neighboring cells </li></ul><ul><li>AUTOCRINE – Acts on the same cell </li></ul><ul><li>Local hormones usually are inactivated quickly </li></ul>Hormones
  7. 11. Pituitary and Hypothalamus <ul><li>Pituitary gland / Hypophysis – </li></ul><ul><li>Small gland about the size of pea </li></ul><ul><li>Rest in the depression of sphenoid bone inferior to the hypothalamus of the brain. </li></ul><ul><li>Infundibulum – Stalk connecting the pituitary gland to the hypothalamus </li></ul><ul><li>Once known as “Master Gland” </li></ul>
  8. 12. Pituitary and Hypothalamus
  9. 15. <ul><li>Growth hormone </li></ul><ul><li>Thyroid-Stimulating Hormone (TSH) </li></ul><ul><li>Adrenocorticotropic Hormone (ACTH) </li></ul><ul><li>Gonadotropins </li></ul><ul><ul><li>Leutinizing hormone (LH) </li></ul></ul><ul><ul><li>Interstitial Cell-stimulating hormone (ISCH) </li></ul></ul><ul><li>Prolactin </li></ul><ul><li>Melanocyte-Stimulating Hormone </li></ul>Hormones of the Anterior Pituitary
  10. 16. <ul><li>1. Growth Hormone </li></ul><ul><ul><li>Stimulates the growth of bones, muscles, and other organs by increasing protein synthesis. </li></ul></ul><ul><ul><li>Resist protein breakdown during periods of food deprivation </li></ul></ul><ul><ul><li>Secretion of growth hormone is controlled by 2 hormones from the hypothalamus (releasing and inhibitory hormone) </li></ul></ul><ul><ul><li>Daily peak levels during sleep, also increases during fasting and exercise </li></ul></ul><ul><ul><li>Dwarfism </li></ul></ul><ul><ul><li>Gigantism </li></ul></ul>
  11. 18. <ul><li>In gigantism - ACROMEGALY - facial features and hands become abnormally large </li></ul><ul><li>Somatomedins – Protein chemical signal which together with Growth hormone to bind to the receptors of bone and cartilage tissues to stimulate growth </li></ul>
  12. 19. <ul><li>2. Thyroid-Stimulating Hormone (TSH) </li></ul><ul><li>Binds on Membrane-bound receptors of the thyroid gland , causes to secrete thyroid hormones. </li></ul><ul><li>↑ TSH- Thyroid gland enlarges </li></ul>
  13. 20. <ul><li>3. Adrenocorticotropic Hormone (ACTH) </li></ul><ul><li>Binds on Membrane-bound receptors on the cells in cortex of adrenal glands . </li></ul><ul><li>Increases secretion of Cortisol ( hydrocortisone), which keeps the adrenal cortex from degenerating </li></ul><ul><li>Binds to melanocytes and increase skin pigmentation. </li></ul><ul><li>↑ ACTH - Darkening of the skin </li></ul>
  14. 21. 4. Gonadotropins Leutinizing hormone (LH) Interstitial Cell-stimulating hormone (ISCH) <ul><li>Binds on Membrane-bound receptors of the gonads . Regulates growth, development and of functions of gonads </li></ul><ul><li>Leutinizing hormone (LH) – Ovulation of oocytes and the secretion of estrogen and progesterone from ovaries </li></ul><ul><li>Interstitial Cell-stimulating hormone (ISCH) – stimulates interstitial cells of the testes to secrete testosterone. </li></ul><ul><li>Follicle-Stimulating Hormone – Stimulates </li></ul><ul><li>the development of follicles in the </li></ul><ul><li>ovaries and sperm cells in the testes. </li></ul>
  15. 22. 5. Prolactin <ul><li>Binds on Membrane-bound receptors in the cells of the Breast , during pregnancy and stimulates the production of milk. </li></ul>6. Melanocyte-Stimulating Hormone Binds on Membrane-bound receptors on melanocytes and causes them to synthesize melanin. ↑ ACTH - Darkening of the skin
  16. 23. <ul><li>1. Antidiuretic hormone (ADH) </li></ul><ul><li>Binds to Membrane-bound receptors and increases water reabsorption by kidney tubules. Resulting to less water lost in urine. </li></ul><ul><li>Can cause blood vessels to constrict (vasopressin) </li></ul>Hormones of the Posterior Pituitary 2. Oxytoxin Binds on Membrane-bound receptors and causes Uterine contraction and milk ejection (milk let-down)
  17. 26. <ul><li>Made up of 2 lobes connected by the isthmus </li></ul><ul><li>Located on either side of trachea, just below the larynx </li></ul><ul><li>Largest endocrine gland </li></ul><ul><li>Thyroid follicles – small spheres with walls that consist of simple cuboidal epithelium </li></ul><ul><li>Each follicle is filled with protein to which </li></ul><ul><li>thyroid hormones attached. </li></ul>Thyroid Gland
  18. 28. Thyroid Hormones <ul><li>Binds to intracellular receptors in cells and regulate the rate of metabolism in the body. </li></ul><ul><li>Participates in normal rate of growth and development. </li></ul><ul><li>Hypothyroidism </li></ul><ul><li>Infants – Cretinism - Mentally retarded and short in stature, with abnormally formed skeletal structures. </li></ul><ul><li>Adults – reduced rate of metabolism </li></ul><ul><li>sluggishness, reduced ability to perform </li></ul><ul><li>routine task. </li></ul>
  19. 29. <ul><li>Hyperthyroidism </li></ul><ul><li>Elevated rate of metabolism, extreme nervousness, and chronic fatigue. </li></ul><ul><li>Grave’s disease – bulging of the eyes (exopthalmia). </li></ul><ul><li>Thyroid gland requires iodine to synthesize thyroid hormone. </li></ul><ul><li>Iodine is taken up by thyroid follicles, hormone synthesis </li></ul><ul><li>Thyroxine / tetraiodothyronine (T4) </li></ul><ul><li>Triiodothyronine (T3) </li></ul><ul><li>Lack of iodine results in reduced T3 </li></ul><ul><li>and T4 synthesis </li></ul>
  20. 31. Grave's disease Cretinism
  21. 32. <ul><li>Embedded in posterior wall of the thyroid gland </li></ul><ul><li>Secretes parathyroid hormone (PTH) </li></ul><ul><ul><li>Regulation of blood calcium </li></ul></ul><ul><ul><li>Increases the absorption of Ca+ from the intestine by causing an increase in active vitamin D formation </li></ul></ul><ul><ul><li>Hyperparathyroidism </li></ul></ul><ul><ul><li>Elevated Blood Ca+ results in nerve and muscle less excitable, resulting in fatigue and muscle weakness </li></ul></ul><ul><ul><li>Hypoparathryroidism </li></ul></ul><ul><ul><li>Reduced Vitamin D formation. Nerves and muscles </li></ul></ul><ul><ul><li>become more excitable and produce spontaneous </li></ul></ul><ul><ul><li>action potential. Frequent muscle cramps or tetanus </li></ul></ul>Para-thyroid Gland
  22. 34. <ul><li>Hyperparathyroidism </li></ul><ul><li>Bones become soft, deformed and easily fractured </li></ul>
  23. 35. <ul><li>Adrenal Medulla – Inner part </li></ul><ul><ul><li>Epinephrine (adrenaline) </li></ul></ul><ul><ul><li>Norephinephrine </li></ul></ul><ul><li>Adrenal Cortex – Outer part </li></ul>Adrenal Glands
  24. 36. <ul><li>Adrenal Medulla – Inner part (narrow or middle) </li></ul><ul><ul><li>Secretes Epinephrine (adrenaline) and small amounts of Norephinephrine </li></ul></ul><ul><ul><li>Released in response to stimulation of Sympathetic nervous system </li></ul></ul><ul><ul><li>Fight or Flight hormones </li></ul></ul>
  25. 39. Fig. 10.18
  26. 40. <ul><li>Endocrine part consist of pancreatic islets a.k.a. “Islets of Langerhans” – has two types of cells. </li></ul><ul><li>Alpha cells – secrete glucagon </li></ul><ul><li>Beta cells – secrete insulin </li></ul><ul><li>A decline in the blood glucose below the normal range causes the nervous system to </li></ul><ul><li>malfunction (Glucose is the Nervous </li></ul><ul><li>system’s main source of energy) </li></ul>Pancreas, Insulin, Diabetes
  27. 42. <ul><li>Insulin – Released in response the elevated blood glucose levels and increased sympathetic stimulation. </li></ul><ul><li>The major target of insulin are the liver, adipose tissue, muscles, and the area of the hypothalamus that controls the appetite, satiety center. </li></ul><ul><li>Diabetes Mellitus – Result from: (1) secretion of too little insulin from pancreas, (2) Insufficient numbers of insulin receptors on target cells, and (3) defective receptors that do not respond normally to insulin. </li></ul><ul><li>Triad of Diabetes Mellitus </li></ul><ul><ul><li>Polyuria - ↑ urination </li></ul></ul><ul><ul><li>Polyphagia - ↑ food intake </li></ul></ul><ul><ul><li>Polydypsia - ↑ water intake </li></ul></ul>
  28. 43. <ul><li>(Diabetes Mellitus) </li></ul><ul><li>Hyperglycemia- Tissues cannot take up glucose effectively, causing blood glucose to become very high. </li></ul><ul><li>Polyphagia – Glucose cannot enter cells of the satiety center of the brain without insulin, the brain responds as if there were little blood glucose, resulting in exaggerated appetite. </li></ul><ul><li>Polyuria – Excess of glucose in the blood is </li></ul><ul><li>excreted in the urine, thus… </li></ul><ul><li>Polydypsia – Because of polyuria, the person </li></ul><ul><li>becomes dehydrated and thirsty, thus </li></ul><ul><li>the need to drink often. </li></ul>
  29. 46. <ul><li>Testosterone – Main sex hormone in male </li></ul><ul><li>Responsible for the growth and development of male reproductive structures, muscle enlargement, growth of body hair, voice changes and male sexual drives. </li></ul>Testes and Ovaries
  30. 47. <ul><li>Estrogen & Progesterone </li></ul><ul><li>Development of female reproductive structures and sexual characteristics </li></ul><ul><li>Enlarges the breast and distribute fat, which influences the shape of the hips, breast, and thighs. </li></ul><ul><li>Maintains menstrual cycle </li></ul>
  31. 50. <ul><li>Lies at the upper part of the thoracic cavity </li></ul><ul><li>Plays an important role in immune system </li></ul><ul><li>Thymosin – Helps in the development of T-Cells (helps protect the body against infection by foreign organism) </li></ul><ul><li>Most important in early life. </li></ul>Thymus Gland
  32. 51. <ul><li>Small pinecone-shaped structure located superior and posterior to the thalamus of the brain. </li></ul><ul><li>Melatonin – decrease secretion of LH and FSH by decreasing release of hypothalamic-releasing hormones. Acts to inhibit reproductive system </li></ul>Pineal Body
  33. 52. Thank You… Good Luck!