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Endocrine System

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  1. Endocrine System for copying

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

  4. Steroid 2 types of hormones Peptide 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

  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. Negative Feedback 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. hyperthyroidism • excessive secretion of thyroid hormones

  12. 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

  13. thymus • upper thorax, posterior to sternum • largest in infants, decreases as we age • produces: thymosin – programs T cells

  14. 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+

  15. pancreas • Insulin • protein • reduces blood glucose by increasing entry of glucose into cells/making glycogen in hepatocytes • regulated by blood glucose levels • Glucagon • protein • raises blood glucose by acting on glycogen stores in liver • regulated by blood glucose levels

  16. testes • paired oval organs suspended in scrotum • site of: • spermatogenesis • production of androgens: • Testosterone major one • made by interstitial cells/stimulated by FSH & LH • produces male 2◦ sex characteristics in puberty • promotes growth & maturation of reproductive system organs • increases libido

  17. ovaries • paired, almond-shaped organs in pelvic cavity • produce ova • release: estrogens & progesterone • begin functioning in puberty in response to anterior pituitary gonadotrophins

  18. estrogens • Estrone &Estradiol made by follicle where ova is maturing • stimulate: • development of 2◦ sex characteristics • work with progesterone to prepare uterine lining for implantation • help maintain pregnancy & prepare breasts to lactate(those estrogens made in placenta)

  19. progesterone • made &secreted by corpus luteum • acts with estrogen to prepare uterine lining for implantation • quiets uterine muscle during early pregnancy • helps prepare breasts for lactation

  20. placenta • produces hCG (human Chorionic Gonadotropin) • stimulates corpus luteum of ovary to continue producing estrogens and progesterone so lining of uterus does not slough off (like in menstruation) • turns pregnancy tests + • by 3rd mo pregnancy placenta produces estrogen & progesterone (ovaries become inactive rest of pregnancy) • also produces hPL (human placental lactogen) works w/E & P in preparing breasts for lactation

  21. Posterior Pituitary Pituitary disorders Anterior Pituitary Giantism: hypersecretionhCG during chidhood abnlincrese in length of long bones hypersecretionhCG in adulthood  acromegaly (epiphyseal plates sealed) see thickening of bones of hands, face & thickening of skin on brow Diabetes Insipidus: defects in ADH excrete large volumes of urine  dehydration & thirst (bed-wetting in children) can die w/in 2 days from the dehydration

  22. Thyroid gland disorders • Hypothyroidism: • Cretinism: congenital hypothyroidism • severe mental retardation if not tx’d • most states require testing new borns • Myxedema:adults • hallmark:edema of facial tissues, slow HR, low body temp, sensitivity to cold, dry skin & hair, muscle weakness

  23. Thyroid gland disorders • Graves Disease • most common form of hypothyroidism • 7 – 10 x more common in females • autoimmune disorder: autoantibodies that mimic TSH  causes thyroid to grow & make thyroid hormones • signs: enlarged thyroid, exophthalmos • tx: surgical excision of all or part of thyroid or use of antithyroid drugs to block synthesis of hormones

  24. goiter • enlarged thyroid • could be associated with hypo- or hyperthyroidism, or euthyroidism (normal level of hormones) seen when intake of iodine too low

  25. Adrenal Gland disorders • Cushing’s Syndrome: • hypersecretion of cortisol • caused by tumors that secrete • cortisol (in adrenal cortex) • ACTH  stimulates more cortisol production in adrenal cortex • muscle wasting  spindly arms & legs, “moon” face, “buffalo hump” red face • ~80% have hypertension

  26. Adrenal gland disorders • Addison’s Disease: • hyposecretion of glucocorticoids & aldosterone • most are autoimmune: antibodies cause adrenal cortex destruction or block binding of ACTH to its receptors • TB can destroy adrenal cortex • symptoms: (after 90% of cortex destroyed) mental lethargy, anorexia, N/V, wt loss, hypotension, hypoglycemia, muscular weakness

  27. Pancreatic islet disorders • Diabetes mellitus: (honey-sweetened) • inabillity to use or produce insulin • 4th leading cause death in USA • blood glucose levels high  glucosuria • 3 polys: polyuria, polydipsia, polyphagia

  28. Diabetes Mellitus • Type 1: autoimmune abys destroy beta cells • mostly develops <20 yrs old • most common in northern European heritage • cells starved for glucose so switch to breaking down fatty acids  ketone production  ketoacidosis  untx’d  death • transport of lipids from adipocytes  plaque formation in walls of arteries = atherosclerosis • excess glucose attaches to proteins in lens  catarracts • small vessel disease: blindness, kidney failure, amputation of toes  legs, impotence

  29. Diabetes Mellitus Treatment • self-monitoring of blood glucose levels  injections of insulin • Diet: • 45 – 50% carbohydrates • <30% fats Exercise

  30. Type 2 Diabetes • non-insulin-dependent diabetes (NIDDM) • more common (90% of all cases) • typically occurs in obese people > 35 yrs old • #s children diagnosed increasing • many control it with diet, exercise, wt loss • oral hypoglycemic drugs • stimulates secretion of insulin from beta cells