1 / 67

The Endocrine S ystem

The Endocrine S ystem . Contributes to: control of growth, development, reproduction, behaviour , energy metabolism, and water balance By: Secreting hormones To control Organ and tissue functions. Endocrine System.

morwen
Download Presentation

The Endocrine S ystem

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. The Endocrine System • Contributes to: • control of growth, development, reproduction, behaviour, energy metabolism, and water balance • By: • Secreting hormones • To control • Organ and tissue functions

  2. Endocrine System • A system of ductless secretory organs (glands) located in various parts of the body • Include • Pineal • Anterior/posterior pituitary • Thyroid • Parathyroid • Thymus • Adrenal • Islets of Langerhans, • Ovaries • Testes • Main function • Secrete hormones directly into the blood or extracellular fluid

  3. Hypothalamus • Is not a gland but a region of the brain • Part of the nervous system • Very important for function of endocrine system • Produce neurohormones that stimulate or inhibit production of other hormones in the pituitary gland

  4. Hormones of The Hypothalamus • Thyrotropin-releasing hormone (TRH) • Stimulates release of thyroid-stimulating hormone (TSH) • Gonadotropin-releasing hormone (GnRH) • Stimulates release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) • Growth hormone-releasing hormone (GHRH) • Stimulates release of growth hormone (GH) • Corticotropin-releasing hormone (CRH) • Release of adrenocorticotropic hormone (ACTH) • Somatosin • Inhibits the release of growth hormone (GH) • Dopamine • Inhibits the release of thyroid-stimulating hormone (TSH)

  5. Hormones: Maintaining Homeostasis • Chemical management system for the body • Chemicals produced by cells in one part of the body that regulate the processes of cells in another part of the body • Chemical messengers • act on cells from another part of the body • Local regulators (paracrine) • act on nearby cells • Self regulators (autocrine) • cells that produce chemicals to stimulate their own cellular processes

  6. Tropic vs Non-Tropic Hormones • Tropic Hormones • Target endocrine glands • Nontropic Hormones • Target cells, tissues, and organs

  7. Hormones • Produced and secreted by cells, tissues and organs that compose the endocrine system (glands) directly into the blood or extracellular fluid • Hormones are circulated throughout the body • Only target cells will respond to specific hormones • Hormones are broken down by enzymes in target cell, liver or kidneys where they are reused or excreted

  8. Hormones • Secreted in an inactive form –prohormones • Prohormones are converted by target cells or by enzymes in the blood to an active form • Angiotensinogen → angiotensin

  9. Hormones • Protein hormones • Consist of AA (3 to 200 in length) • Usually hydrophilic (water soluble) • Diffuse well through blood • Cannot pass through lipid bilayer • Steroid hormones • Derived from cholesterol • Not water soluble • Usually encased with protein (protein carrier) to travel through blood • Pass easily through lipid bilayer

  10. Hormone Mechanisms • Water-Soluble • Cannot pass membrane • Bind to receptor molecules in the cell membrane • Signal is activated • Secondary messenger is activated (cAMP – cyclic adenosine monophosphate) • Change is caused inside cell • Acts in the cytosol or the nucleus • Regulate protein production, ion channels • Activation of protein kinases • Glucagon • Breakdown of glycogen into glucose

  11. Controlling Blood Glucose Levels

  12. Hormone Mechanisms • Lipid-Soluble • Can pass membrane (lipid) • Bind to receptors inside a cell (cytosol or nucleus) • Turn on or off an action of a specific gene • Changes amount of protein that is synthesized by cell • Aldosterone • Increase sodium absorption → increases water retention → increase blood pressure

  13. Major Features of Hormone Mechanisms • Only the cells that contain surface or internal receptors for the hormones respond to the hormones • Once bound to their receptors, hormones produce a response by turning cellular processes on or off. They do this by altering the proteins that are functioning in or produced by the cell • Hormones are effective in very small concentrations because of the amplification that occurs in both the surface and internal receptor mechanisms • The response to a hormone differs among target organs and among species

  14. Hormones: Negative Feedback Mechanisms • Secretion of hormones are regulated by negative feedback mechanisms • Hormones inhibit other hormones • Multiple hormones can be secreted at a time

  15. The Pituitary Gland • The Master Gland • Produces hormones that control most of the other glands in the endocrine system • Made up of anterior lobe and posterior lobe • Links endocrine system to nervous system via portal vein (hypothalamus) • Influenced by hypothalamus • Releasing hormones/inhibiting hormones

  16. 2. portal vein • 4. anterior pituitary gland • 5. hypophyseal vein • 6. posterior pituitary gland • 8. pituitary stalk • 9. capillary network • 10. neurons • 11. neurosecretory cells • 12. hypothalamus

  17. Anterior Pituitary Gland • Major hormones secreted into the bloodstream • Tropic • Growth hormone (both) • thyroid-stimulating hormone • adrenocorticotropic hormone • follicle-stimulating hormone • luteinizing hormone • Nontropic • Prolactin • Melanocyte-stimulating hormone

  18. Prolactin • Promote milk production in mammary glands • Suckling on nipple causes stimulus • Regulated by dopamine • Too much • Hyperprolactinaemia • Too little • Hypoprolactinaemia

  19. Growth hormone • Cell division, protein synthesis, bone growth • Release of growth hormone stimulates release of IGF in liver (insulin growth factor) that stimulates these functions • Conversion of glycogen to glucose, fats to fatty acids – regulates levels in blood • Stimulates cells to take up FA, AA and limits muscle cells to take up glucose

  20. Growth hormone • Underproduction • Dwarfism • Heart disease, increased fat • Cause • Genetic, benign tumour on pituitary gland • Overproduction • Acromegaly – body tissues get larger over time • Gigantism – excessive production of growth hormone • Cause • Benign tumour on pituitary gland

  21. Thyroid-stimulating hormone • Controls production of the thyroid hormones • Underproduction • Hyperthyroidism • Cause • Thyroid is producing too much thyroid hormone • Overproduction • Hypothyroidism • Cause • Thyroid if producing too much thyroid hormone

  22. Adrenocorticotropic hormone • Controls production of cortisol, adrenaline, noradrenaline • Underproduction • Cushing’s syndrome • Cause • Steroid medication, tumour of pituitary gland • Overproduction • Cushing’s disease • Addison’s disease (loss of function of cortex of adrenal gland) • Cause • Adenoma (non-cancerous tumour) in the pituitary gland • Autoimmunity

  23. Follicle-stimulating hormone/luteinising hormone • Puberty development/function of the gonads (testes/ovaries) • Sex steroid production • Germ cell production (sperm/eggs) • Underproduction • Incomplete development at puberty • Infertility • Overproduction • Turner syndrome (female is missing entire/parts of x chromosome) • Kallmann’s syndrome (failure to start/complete puberty) • Cause • Testicular/ovarian failure,

  24. Melanocyte-stimulating hormone • Causes darkening in humans by releasing melanin in the skin and hair and eyes • Specialized cells called melanocytes release melanin • Protects from UV rays • Overproduction • Increase production of melanin • Cause • Prolonged exposure to sun or skin tanning • Underproduction • Lack of skin pigmentation • Loss of natural protection from UV rays and sun • Cause • Damage to pituitary glands

  25. Posterior pituitary gland • Stores and releases 2 major hormones into the bloodstream • Antidiuretic hormone (vasopressin) • oxytocin • These hormones are produced by the hypothalamus and stored here

  26. Antidiuretic Hormone (vasopressin) • Causes distal convoluted tubule to become permeable to water • Helps maintain water balance • Overproduction • Kidneys retain too much water • Underproduction • Kidneys excrete too much water

  27. Oxytocin • Contraction of the womb • Lactation • Overproduction • Not clear • Underproduction • Linked to autism

  28. Thyroid gland • Located in the front of the throat and shaped like a bow tie • Secretes • Thyroxine (T₄) • calcitonin

  29. Thyroxine (T₄) • Prohormone (inactive) • Active form is triiodothyronine • Contains 4 iodine atoms • Regulates body’s metabolic rate, heart and digestive function, muscle control, brain development, maintenance of bones • Overproduction • Thyrotoxicosis – too much thyroxine in bloodstream recognized by goitre • Causes • Hyperthyroidism • Graves Disease • Underproduction • Hypothyroidism • Causes • Autoimmune diseases, poor iodine diet

  30. Calcitonin • Reduces levels of Calcium (Ca²⁺) in the blood stream • Opposes the action of parathyroid hormone • Overproduction • No apparent effect on body • Underproduction • No apparent effect on body

  31. Parathyroid gland • 4 spherical glands (size of a pea) located on each side of the posterior surface of the thyroid gland • Secretes • Parathyroid hormone

  32. Parathyroid hormone • Stimulates enzymes in kidneys to convert vitamin D into calcitrol increasing absorption of Ca²⁺ and phosphates from food • Underproduction • Muscle cramps • Osteoporosis • Overproduction • Kidney stones

  33. Pineal gland • Located near the centre of the brain • Secretes • melatonin • Secretion of melatonin is controlled by circadian rhythm (biological processes that fluctuate on a 24 hour timetable) • Helps to synchronize biological clock (jet lag, sleep disorders) • Melatonin also produced in retina of the eye • Overproduction • Reduced core body temperature • Underproduction • No apparent effect on the body

  34. Adrenal glands • Consist of two regions • Adrenal medulla • contains highly modified neuro-secretory neurons 2. Adrenal cortex • contains non-neural endocrine cells

  35. Adrenal medulla • Secretes • Epinephrine, nor-epinephrine • These chemicals can act as hormones or neurotransmitters (transmit nerve signals to brain) • Part of the “fight or flight” response

  36. Epinephrine • Released when body encounters stresses • Increase heart rate • glycogen and fat breakdown • Major blood vessels dilate (increase blood flow) • Blood vessels in skin constrict (chills and sweating) • Increase in blood pressure • Reduces water loss • Digestive system slows • Used to counter anaphylaxis

  37. Adrenal cortex • Secretes • Aldosterone, cortisol

  38. Glucocorticoids • Cortisol – Helps raise blood glucose levels using three mechanisms • Stimulate synthesis of glucosefrom fats and proteins • Reduce glucose uptake by the body cells except in the central nervous system • Promote breakdown of fats and proteins into fatty acids and amino acids as alternative fuels

  39. Mineralocorticoids • Aldosterone • Increase amount of sodium /water reabsorption in bloodstream • Increase amount of potassium removal in urine • Increase blood pressure • Overproduction • High blood pressure, low potassium, alkaline blood • Causes • Adrenal tumour • Underproduction • Addison’s disease, low blood pressure

  40. Regulating blood sugar • Occurs automatically in our body • Pancreas – contain both exocrine and endocrine glands • Exocrine • secretes digestive enzymes into the small intestine • Endocrine • Islets of Langerhans - Secretes insulin (beta cells) and glucagon (alpha cells)

  41. Insulin/Glucagon • Regulate the ability of most tissues in the body to metabolize fuel substances (glucose, fats, proteins)

  42. Insulin • Secreted by beta cells • Lower blood glucose levels by • Acts on skeletal muscles, liver cells, adipose tissue (fat) to uptake glucose • In the Liver • Lowers fatty acid levels • promotes fatty acid uptake and storage in adipose tissue • Inhibits breakdown of fats into fatty acids • Lowers amino acid levels • Promotes protein synthesis • Inhibits breakdown of proteins

  43. Glucagon • Secreted by alpha cells • Increase blood glucose levels by • Stimulating breakdown of glycogen into glucose • Stimulates breakdown of fats into fatty acids • Stimulates breakdown of proteins into amino acids • Stimulate cells to use amino acids and non-carbohydrates to synthesize glucose

  44. Glucose levels throughout the day

  45. Unstable levels of glucose • Hyperglycemia (above 200mg/dL of blood) • Blood glucose levels are too high • (norm 115-200mg/dL) • Symptoms • Frequent urination, sugar in the urine, vision problems, fatigue, weight loss • Hypoglycemia (below 70mg/dL of blood) • Blood glucose levels are too low • (norm 70-115mg/dL) • Symptoms • Nervousness, cold sweats, hunger, headaches, weakness

  46. Diabetes • High glucose levels in the blood caused by problems with insulin production • Symptoms • Frequent urination, increased thirst/appetite • Classified into 3 different types • Type 1 • Type 2 • Gestational

More Related