1 / 62

Endocrine System

This guide covers the definitions of hormones, their regulation of processes like growth and metabolism, various endocrine glands, chemistry of hormones, hormone secretion control, and specifics about the pituitary and thyroid glands.

lexiss
Download Presentation

Endocrine System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Endocrine System Glands and Hormones

  2. Definitions • Hormones are chemicals regulators, secreted into the blood, that affect the functioning of other cells • These “other cells” are called target cells • Hormones are specific for certain targets because hormones bind to specific receptors of target cells

  3. Hormones Regulate • Growth • Metabolism • Fluid and electrolyte • Acid-base balance • Reproduction • Blood pressure

  4. Endocrine Glands and Tissues • Secrete hormones Examples • Pituitary gland (hypophysis) • Thyroid gland • Parathyroid glands • Adrenal glands • Pancreas • Gonads • Endocrine tissues within other organs

  5. Chemistry of hormones • Compounds that act as hormones are: • Steroids (derived from cholesterol) • Amines (derived from a single amino acid) • Peptides (smaller chains of amino acids) • Proteins (polypeptide chains of amino acids) • Glycoproteins (protein/carbohydrate complex)

  6. Hormone Secretion Stimulus Gland ----------------Hormone Hormone secretion Blood Receptor------------ Action Target cell

  7. Control of Secretion • Negative feed back • Stimulus is decreased or inhibited by some factor such as concentration of hormone • Attempts to maintain normal levels of secretion • Positive feed back • Stimulus for secretion is increased or exaggerated

  8. Specific Glands

  9. Pituitary Gland (Hypophysis) • Small gland connected to hypothalamus • Two parts • Anterior pituitary (adenohypophysis) • Posterior pituitary (neurohypophysis) hypothalamus ---------infundibulum posterior pituitary--------- -------anterior pituitary

  10. Pituitary Gland • Posterior pituitary derived from neural brain tissue and connects to hypothalamus by the stalk-like hypothalamic hypophyseal tract • Anterior pituitary from ectodermal tissue in the roof of embryonic mouth. -----------------------infundibulum

  11. Pituitary Gland • Posterior pituitary secretes two hormones • Hormones produced by hypothalamus and placed in posterior pituitary for secretion • Anterior pituitary largest part • Produces and secretes most of the hormones • Under direct control of hypothalamus • Hypothalamus secretes releasing and inhibiting hormones that reach anterior pituitary through hypophyseal portal circulation.

  12. Hormones of the Posterior Pituitary • Oxytocin (OT) • Target tissues are smooth muscles of reproductive system of both sexes • Actions in female • Labor (uterine) contractions • Release of milk from mammary glands (milk letdown) • Actions in male • Contraction of smooth muscle in reproductive tissue

  13. Hormones of Posterior Pituitary • Antidiuretic Hormone (ADH) (vasopressin) • Target tissues are kidneys, sweat glands and arterioles • Actions • Causes kidneys and sweat glands to conserve water • Causes vasoconstriction of arterioles

  14. Hormones of Anterior Pituitary • Human Growth Hormone (hGH) • Targets all cells especially skeletal and muscle tissue • Actions • Promotes secretion of insulin-like growth factors (IGFs) within target tissues • IGFs increase: -rate of cell division for growth -protein synthesis needed for growth -use of fat for energy • Results in growth to adulthood and maintenance of skeleton and muscles in adults

  15. Hormones of the Anterior Pituitary Human Growth Hormone Imbalances • Pituitary dwarfism caused by hyposecretion in children and adolescents resulting in small body • Giantism caused by hypersecretion in infants and children resulting in height of over 8 feet • Acromegaly caused by hypersecretion in adults resulting in distorted facial features

  16. Giantism

  17. Acromegaly

  18. Hormones of Anterior Pituitary • Thyroid stimulating hormone (TSH) • Targets thyroid gland • Stimulates secretion of the thyroid hormones • Adrenocorticotropic Hormone (ACTH) • Targets Adrenal cortex • Stimulates secretion of glucocorticoids from adrenal glands

  19. Hormones of Anterior Pituitary • Prolactin (PRL) • Targets mammary glands • Stimulates milk production in mammary glands in concert with other hormones • Gonadotropins • Follicle Stimulating Hormone (FSH) and • Luteinizing Hormone (LH) • Target the ovaries and testes (gonads) • Control female and male reproductive physiology

  20. Control of Secretion of Anterior Pituitary Hormones • Secretion Stimulated by releasing hormones (RH’s) from hypothalamus through hypophyseal portal system • Secretion suppressed by inhibiting hormones (IH’s) from hypothalamus through hypophyseal portal system • All controlled by negative feedback

  21. Thyroid Gland • Large butterfly-shaped gland in neck below voice box (larynx) • Has Two lobes connected by an isthmus --------left lobe right lobe----- ------------isthmus thyroid follicle-----

  22. Histology of Thyroid • Composed of many follicles filled with jelly-like (colloidal) thyroglobulin protein • Thyroid hormones T3 and T4 synthesized by follicle cells and stored in combination with thyroglobulin Thyroglobulin with T3 and T4

  23. Thyroid Hormones • T3 short for triiodothyronine • T4 short for tetraiodothyronine (thyroxine)

  24. Thyroid Hormones • Formed by addition of iodine to the thryroglobulin • 3 & 4 stands for number of iodines

  25. Secretion of T3 & T4 • Synthesis and secretion stimulated by anterior pituitary hormone TSH • Portion of stored thyroglobulin taken in from colloid by follicles cells • Colloid digested by lysosomes releasing T3 & T4 • T3 & T4 enter blood, combine with transport proteins and are transported to target cells

  26. Synthesis and Secretion of T3 & T4 Figure 18.11 in text

  27. Target Cells and Actions of T3 & T4 • Actions • ATP production by mitochondria (aerobic cell respiration) • Normal growth • Control by negative feedback

  28. Thyroid and Negative Feedback • Increase in blood levels of T3 & T4 etc. • Release of thyrotropin releasing hormone (TRH) inhibited • Release of thyroid stimulating hormone (TSH) inhibited • Secretion of T3 & T4 decreases

  29. Imbalances of T3 & T4 • Thyroid dwarfism (Cretinism) • Too little secretion of thyroid hormones during fetal development and infancy. • Severe forms of mental and physical retardation in the newborn. • Retardation is reversible if hormonal replacement therapy is started during the first four months of life.

  30. Imbalances of T3 & T4 • Hypothyroidism (in adults) • Too little T3 & T4 • Symptoms • MR • bradycardia • BT • lethargy • goiter • weight gain • cold intolerance • myxedema

  31. Imbalances of T3 & T4 • Hyperthyroidism (in adults) • Too much T3 & T4 • Grave’s disease most common form • Symptoms • MR • tachycardia • BT • anxiety & irritability • goiter • Exophthalmia (exophthalmos) • heat intolerance • weight loss

  32. Imbalances of T3 & T4 • Endemic goiter and iodine deficiency • Insufficient dietary iodine to make T3 & T4 • Endemic means localized or regional • Lack of negative feedback from T3 & T4 causes over stimulation and overgrowth of the thyroid gland. • Goiter results (enlarged thyroid gland)

  33. Thyroid Disorders Exophthalmia Endemic Goiter

  34. Control of Blood Calcium • Calcitonin (CT) from thyroid lowers blood calcium by adding it to bones • Parathyroid hormone from parathyroid glands (small pea-shaped gland embedded in back of thyroid) increases blood calcium by removing it from bones

  35. Adrenal Glands • Located on top of kidneys • Gross Anatomy • Enclosed by capsule • Outer cortex • Inner medulla

  36. Structure of Adrenal Gland

  37. Histology of Adrenal Glands • Cortex with three zones • Secrete steroid hormones called corticoids • Outer (glomerular) zone • Cells in globular clusters • Secretes mineralocorticoids • Middle (fascicular) zone • Cells form vertical elongated bundles • Secrete glucocorticoids

  38. Histology of Adrenal Glands • Inner (reticular) zone • Cells form irregular, net-like pattern • Secrete some sex steroids in both sexes • More important in females • Affects female sex drive • Produces some estrogens • Secretion stimulated by ACTH

  39. Corticoids • Mineralocorticoids: glomerular zone • Aldosterone most important • Regulates blood sodium, potassium and acid • Regulation affects fluid & electrolyte homeostasis

  40. Corticoids • Glucocorticoids from fascicular zone • Principle one is cortisol • Actions include • Response to stress by • Glucose formation from fats and protein • Conversion of excess glucose to glycogen for storage in liver • use of fat for energy assures glucose availability for brain

  41. Corticoids • Glucocorticoid actions • Reduce inflammation • Various steroids including cortisol, cortisone, and synthetic steroids used medically to reduce inflammation • Control is by negative feedback

  42. Imbalances of Glucocorticoids • Addison’s disease • Insufficient glucocorticoids • Lack of energy • Weight loss • Inability to resist stress • John F. Kennedy had it

  43. Imbalances of Glucocorticoids • Cushing’s Disease • Excessive glucocorticoids • Muscle wasting • Fat redistribution • Spindly arms & legs • Large abdomen with stretch marks • Rounded face • Fatty hump between shoulders

  44. Addison’s Disease – President Kennedy Before SteroidTreatment During SteroidTreatment

  45. Cushing’s Syndrome After Before

  46. Adrenal Medulla • Develop from same tissue as the sympathetic nervous system • Chromaffin cells receive direct innervation from sympathetic nervous system • Sympathetic stimulation increases hormone secretion by adrenal medulla • Hormones are sympathomimetic • effects mimic those of sympathetic NS • cause fight-flight behavior

  47. Hormones of Adrenal Medulla • Catecholamines • epinephrine and norepinephrine • (adrenaline & noradrenaline) • Targets – most cells • React quickly to stress by: • heart rate and strength • blood flow to skeletal muscles, heart and brain • Dilation of airways • fuel for energy • blood pressure

  48. Pancreas • Large leaf-shaped gland • Located in the curve of small intestine and extend to the spleen • Both endocrine and exocrine • Endocrine part secretes hormones • Exocrine part secretes digestive enzymes

  49. Anatomy of Pancreas • Five inches long, consists of head, body & tail • Most cells produce digestive enzymes • Endocrine cells in pancreatic islets produce hormones

  50. Cell Organization in Pancreas • Exocrine acinar cells surround a small duct • Endocrine cells secrete near a capillary

More Related