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ENDOCRINOLOGY

ENDOCRINOLOGY

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ENDOCRINOLOGY

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  1. ENDOCRINOLOGY

  2. The Endocrine Glands & their Hormones Basic principles in hormone actions: Many effects of one hormone are antagonized by another hormone This helps maintain HOMEOSTASIS

  3. The Endocrine Glands & their Hormones Pineal Gland -Main hormone secreted MELATONIN -Role Melatonin --Mammals : Regulate reproductive activity in response to environmental light cycles e.g. Some mammals mate in summer (lot of light), while others mate in winter (low light).

  4. The Endocrine Glands & their Hormones Thyroid Gland -Produces 3 main hormones -Triiodothyronine (T3) -Thyroxine (T4) Regulate body metabolism and are important in bone growth and maturation of the brain -Congenital lack of thyroid hormones: Cretinism. -Calcitonin Acts by reducing calcium levels

  5. The Endocrine Glands & their Hormones Parathyroid Gland -Parathyroid Hormone Raises Blood Calcium (antagonize Calcitonin) This hormone acts on bone, kidney and the gut

  6. The Endocrine Glands & their Hormones Thymus Gland -Thymosin : Stimulates the production of Lymphocytes -Thymostatin : Inhibits the production of Lymphocytes Thymus : Important for the neonatal production of antibodies Thymus : Gland being at the center of endocrine, neural, and immune systems

  7. The Endocrine Glands & their Hormones Heart -Granular cells in the heart muscle secrete Atrial Natriuretic Factor (ANF) ..ANF : Regulates blood pressure, blood volume, and excretion of water, sodium and potassium ..ANF : Also a neuropeptide in the brain

  8. The Endocrine Glands & their Hormones Gastrointestinal Hormones -The mucosa of the GI tract secretes a dozen PEPTIDE hormones 3 most important: 1. Secretin : Secreted in the small intestine Stimulates the secretion of pancreatic bicarbonate and has other functions on digestion 2. Gastrin: Secreted in the walls of stomach Stimulate hydrochloric acid secretion stimulate pancreatic enzyme secretion 3. Cholecystokinin : Secreted in the small intestine Stimulate gall bladder contraction Stimulate pancreatic enzyme secretion

  9. The Endocrine Glands & their Hormones Pancreas Endocrine cells in the pancreas secrete 2 major types of hormones 1. Insulin : Secreted in response to increase in blood glucose levels ; So insulin LOWERS glucose levels by INCREASING glucose UPTAKE in cells where it is stored as glycogen. 2. Glucagon : Increases blood glucose levels by stimulating the conversion of glycogen to glucose in the liver.

  10. A parte : Insulin & Diabetes Insulin & Diabetes Diabetes : Hyperglycemia, ie. Elevated Blood Sugar 2 Types : The distinction is based upon whether the blood sugar problem is caused by insulin deficiency (Type 1) or insulin resistance (Type 2) Type 1- Insulin Deficiency : There is not enough insulin produced by the pancreas so the patient must inject insulin on a daily basis Type 2 - Insulin Resistance : There is plenty of insulin but the cells of the body are resistant to its action so, increase in blood sugar This form is controlled by a strict diet

  11. The Endocrine Glands & their Hormones Adrenal Glands 2 parts : Medulla & Cortex Adrenal Cortex : 3 categories of steroid hormones 1. Mineralocorticoids 2. Glucocorticoids 3. Sex Steroids Adrenal Medulla 1. Adrenaline 2. Noradrenaline

  12. The Endocrine Glands & their Hormones Adrenal Cortex Influence sexual differentiation and bodily changes during puberty Androgen Estrogen Stress Hormone, converts stored proteins to carbohydrate during stress. Antiinflammatory and Immunosuppressive functions. If there is a sodium deprivation, Aldosterone is secreted and acts to increase reabsorption of sodium ions (NA+) in the kidneys salivary glands, and sweat glands.

  13. The Endocrine Glands & their Hormones Adrenal Medulla Adrenaline : Released following stress due to environmental extremes; Increases heart rate and blood glucose levels so, increases the amount of work the muscles can do (FLIGHT) Noradrenaline : As Adrenaline, act as a NT in the brain Periphery; increase blood pressure and constrict blood vessels (noradrenaline, stress, and heart disease…)

  14. The Endocrine Glands & their Hormones Gonads ; Testes The male gonads : produces Androgens Primary androgen = TESTOSTERONE Other androgen : Dihydrotestosterone Androstenedione Testosterone : Important for masculinization Control of sperm production Development of male sexual characteristics Activation of sexual and aggressive behaviors

  15. The Endocrine Glands & their Hormones Gonads ; Ovaries 2 major classes of hormones ESTROGENS PROGESTINS Primary ESTROGEN : Estradiol others : Estriol Estrone Synthetic estrogens : Birth control pills Estrogens : -Development of sexual characteristics at puberty -Influence metabolic rate -Influence sexual and maternal behavior

  16. The Endocrine Glands & their Hormones Gonads ; Ovaries PROGESTIN : Progesterone -Stimulates breast and uterine enlargement at puberty & during menstrual cycle -Maintains pregnancy (inhibits menstrual cycle during pregnancy) Other hormone released at the end of pregnancy : Relaxin Acts to prepare the birth canal. Estrogen and Progesterone act in synergy.

  17. The Endocrine Glands & their Hormones Placenta -Hormones secreted by the fertilized egg (Used in pregnancy tests) Human Chorionic Gonadotropin (HCG) Act by keeping progesterone high at the beginning of a pregnancy Human Placental Lactogen (HPL) Stimulates the mammary glands to begin to secrete milk

  18. PART II The Pituitary Gland & its Hormone Also called the HYPOPHYSIS

  19. The Pituitary Gland & its Hormone -Attached to the HYPOTHALAMUS -Secretion of the pituitary hormones is regulated by hypothalamus -HYPOTHALAMIC-PITUITARY connection

  20. The Pituitary Gland & its Hormone ANATOMY -3 parts --> Anterior Lobe -pars distalis --> Intermediate Lobe -pars intermedia --> Posterior Lobe -pars nervosa (“neural” cells) direct extension of the hypothalamus ADENOhypophysis NEUROhypophysis

  21. The Pituitary Gland & its Hormone PVN SON -Neuroscretory Cells -Paraventricular nucleus (PVN) -Supraoptic nucleus (SON) -Hormones secreted -OXYTOCIN -VASOPRESSIN AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Neurohypophysis

  22. The Pituitary Gland & its Hormone PVN SON OXYTOCIN & VASOPRESSIN -Are really HYPOTHALAMIC hormones -OXYTOCIN : 2 main functions --> promotes uterine contractions --> stimulates milk ejection from mammary glands during lactation AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Neurohypophysis

  23. The Pituitary Gland & its Hormone PVN SON -VASOPRESIN : --> Antidiuretic hormone --> Raises blood pressure --> promotes water reabsorption by kidneys --> centrally : may promote memory - Binding proteins for both oxytocin & vasopressin --> Neurophysins AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Neurohypophysis

  24. The Pituitary Gland & its Hormone ADENOHYPOPHYSIS (ANTERIOR) Mechanism for release of hormones True endocrine gland because release hormone in the bloodstream (hypophysal portal system) AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  25. The Pituitary Gland & its Hormone 1. Neurosecretory cells of the hypothalamus release their hormones at the median eminence 2. Hormones circulate in bloodstream 3. Carried to the adenohypophysis 4. Stimulates secretion of other hormones from the adenophysis 5. These hormones are then released in the bloodstream to reach their target cells. Median eminence

  26. The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones 1. Growth Hormone (GH) (also called ‘somatotropin’) …’tropic’=stimulating effect GH = promotes growth in almost all body cells A lot of attention for degenerative disease….. -Alzheimer -Parkinson -Anti-Aging etc. AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  27. The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones 2. Adrenocorticotropic Hormone ACTH Role : Stimulates synthesis and release of glucocorticoid hormones ‘Hypothalamic-pituitary-adrenal axis’ 1970’s : Role of memory ….little problems….. AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  28. The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones 3. Thyroid Stimulating Hormone TSH Role : Stimulates the synthesis and release of thyroxine (T4) and triiodochyronine (T3) from the thyroid. AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  29. The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones 3 last hormones= ….gonadotropic hormones 4. Follicle stimulating hormone (FSH) Role : In both sexes, promotes the development of reproductive cells (gametes) and promotes secretion of gonadal hormones Males : stimulates sperm production Females : stimulates growth of primary follicle of ovary AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  30. The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones 3 last hormones= ….gonadotropic hormones 5. Luteinizing hormone (LH) Role : Female : Stimulates ovulation and formation of progesterone- secreting cells Males : Stimulates cells that secrete androgens (e.g. testosterone) AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  31. The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones 3 last hormones= ….gonadotropic hormones 6. Prolactin (PRL) Role : Initiates milk synthesis in mammary glands Other functions related to growth & parental behavior Interaction with serotonin also (important in depression) AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  32. The Pituitary Gland & its Hormone Non traditional hormone from the adenohypophysis --> beta-endorphin Derivative from POMC POMC : synthesized in the pars distalis and pars intermedia Broken down into ACTH, MSH & beta-endorphins by enzymes AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Adenohypophysis

  33. The Pituitary Gland & its Hormone Beta-Endorphin : Role to play in --> Analgesia --> Learning and Memory --> Psychiatric diseases --> Feeding, Thermoregulation, --> Blood pressure --> also called the ‘drug of the jogger’…..

  34. The Pituitary Gland & its Hormone Pars Intermedia : Not present in adult humans but present in fetal humans and mammals Synthesize the hormone called Melanocyte stimulating hormones which acts in amphibian to change skin color…. .. AXONS Attaches the hypothalamus to the pituitary. Also called the Infundibulum Pars Intermedia