1 / 48

Endocrine System Hormones

Endocrine System Hormones. Regulation. Hormones- chemical signals that cause a response in Target Cells. Why are hormones needed? chemical messages from one body part to another communication needed to coordinate whole body daily homeostasis & regulation of large scale changes

brendaburke
Télécharger la présentation

Endocrine System Hormones

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 Hormones

  2. Regulation • Hormones-chemical signals that cause a response in Target Cells. • Why are hormones needed? • chemical messages from one body part to another • communication needed to coordinate whole body • daily homeostasis & regulation of large scale changes • solute levels in blood • glucose, Ca++, salts, etc. • metabolism • growth • development • maturation • reproduction growth hormones

  3. Regulation & Communication • Animals rely on 2 systems for regulation • endocrine system • system of ductless glands • secrete chemical signals directly into blood • chemical travels to target tissue • target cells have receptor proteins • slow, long-lasting response • nervous system • system of neurons • transmits “electrical” signal & release neurotransmitters to target tissue • fast, short-lasting response

  4. http://www.youtube.com/watch?v=tMMrTRnFdI4 Signal Transduction Pathway model • Reception-cell signals are detected by receptors that change in shape in response to a specific stimulus. (ie: G-protein-coupled receptors and tyrosine kinase receptors • Transduction- a multistep pathway that amplifies the signal allowing a small number of signal molecules to produce a large cellular response. • Response is accomplished by two mechanisms • Increase/Decrease mRNA production • Activating existing enzyme molecules What kinds of molecules are the receptors?

  5. Regulation by chemical messengers • Neurotransmitters released by neurons • Hormones release by endocrine glands endocrine gland neurotransmitter axon hormone carried by blood receptor proteins receptor proteins Lock & Keysystem target cell

  6. Classes of Hormones • Protein-based hormones • polypeptides • small proteins: insulin, ADH • glycoproteins • large proteins + carbohydrate: FSH, LH • amines • modified amino acids: epinephrine, melatonin • Lipid-based hormones • steroids • modified cholesterol: sex hormones, aldosterone insulin

  7. How do hormones act on target cells • Lipid-based hormones (Direct Gene Activation) • hydrophobic & lipid-soluble • diffuse across cell membrane & enter cells • bind to Intracellular receptor proteins in cytoplasm & nucleus • bind to DNA as transcription factors • turn on genes • Examples include estrogen and testosterone! • Protein-based hormones (Second Messenger System) • hydrophilic & not lipid soluble • can’t diffuse across cell membrane • bind to Cell Surface Receptor proteins in cell membrane • trigger secondary messenger pathway (Signal Transduction Pathway) • activate internal cellular response • enzyme action, uptake or secretion of molecules… • Epinephrine, growth factors, etc.

  8. Action of lipid (steroid) hormones steroid hormone target cell blood S 1 S cross cell membrane protein carrier S 2 cytoplasm binds to receptor protein becomes transcription factor 5 mRNA read by ribosome S 3 plasma membrane 4 DNA mRNA 6 7 nucleus protein protein secreted ex: secreted protein = growth factor (hair, bone, muscle, gametes)

  9. Some useful terms… GTP (Guanosine-5'-triphosphate)-GTP is essential to signal transduction, particularly with G-proteins, in second-messenger mechanisms where it is converted to GDP (guanosine diphosphate) through the action of GTPases. G proteins (guanine nucleotide-binding proteins) are a family of proteins involved in transmitting chemical signals outside the cell, and causing changes inside the cell. They communicate signals from many hormones, neurotransmitters, and other signaling factors. Problems with these signal transducing proteins cause many diseases, such as diabetes, blindness, allergies, depression, cardiovascular defects, and certain forms of cancer. It is estimated that more than half of the modern drugs' cellular targets are GPCRs (G-Protein Coupled Receptors) cAMP (cyclic adenosine monophospate)is used for intracellular signal transduction, such as transferring the effects of hormones like glucagon and adrenaline, which cannot pass through the cell membrane

  10. signal-transduction pathway Action of protein hormones 1 signal proteinhormone plasma membrane P activates G-protein binds to receptor protein activates enzyme cAMP acts as 2nd messenger receptorprotein ATP transduction GTP activatescytoplasmicsignal ATP activates enzyme 2 secondary messengersystem activates enzyme cytoplasm response 3 produces an action target cell

  11. adrenal gland Ex: Action of epinephrine (adrenaline) signal 1 epinephrine activatesG protein 3 activatesadenylyl cyclase receptor protein in cell membrane cAMP GDP transduction 4 ATP 2 GTP activates protein kinase-A 5 activates GTP activates phosphorylase kinase cytoplasm releasedto blood activates glycogen phosphorylase 7 glycogen glucose 6 liver cell response

  12. Benefits of a 2nd messenger system Amplification! 1 signal Activated adenylyl cyclase receptor protein Not yet activated 2 amplification 4 amplification 3 cAMP 5 amplification GTP G protein protein kinase 6 amplification enzyme Cascade multiplier! 7 amplification FAST response! product

  13. high low Maintaining homeostasis hormone 1 lowersbody condition gland specific body condition raisesbody condition gland Negative FeedbackModel hormone 2

  14. hypothalamus hypothalamus high low Nervous System Control Feedback Controlling Body Temperature nerve signals sweat dilates surfaceblood vessels body temperature (37°C) constricts surfaceblood vessels shiver nerve signals

  15. pancreas high liver low pancreas liver Endocrine System Control Feedback Regulation of Blood Sugar islets of Langerhans beta islet cells insulin body cells takeup sugar from blood liver storesglycogen reducesappetite blood sugar level (90mg/100ml) liver releasesglucose triggershunger islets of Langerhansalpha islet cells glucagon

  16. osmoreceptors inhypothalamus increasethirst nephron nephron high JuxtaGlomerularApparatus low nephron (JGA) adrenalgland Endocrine System Control Feedback Blood Osmolarity ADH increasedwaterreabsorption pituitary blood osmolarity blood pressure increasedwater & saltreabsorption renin aldosterone angiotensinogen angiotensin

  17. Nervous & Endocrine systems linked • Hypothalamus = “master nerve control center” • nervous system • receives information from nerves around body about internal conditions • releasing hormones: regulates release of hormones from pituitary • Pituitary gland = “master gland” • endocrine system • secretes broad rangeof “tropic” hormones regulating other glands in body hypothalamus posterior pituitary anterior

  18. tropic hormones = target endocrine glands hypothalamus thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) posterior pituitary Thyroid gland anterior pituitary Kidney tubules adrenocorticotropic hormone (ACTH) oxytocin Muscles of uterus gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) melanocyte-stimulating hormone (MSH) growth hormone (GH) prolactin (PRL) Adrenal cortex Melanocyte in amphibian Mammary glands in mammals Bone and muscle Ovaries Testes

  19. The Pituitary Gland is approximately the size of a pea and hangs by a stalk from the hypothalamus in the brain. It is surrounded and protected by the “Turks Saddle” of the sphenoid bone.The pituitary is often called the “Master Endocrine Gland” The pituitary is located directly behind the bridge of the nose. It forms a link between the nervous and endocrine systems. It weighs .5 gram and secretes approximately .00001 grams of hormone a day.

  20. Characteristics of all anterior pituitary hormones: • Proteins (or peptides) • Act through second-messenger systems • Regulated by hormonal stimuli, mostly negative feedback

  21. The Pituitary has two functional lobes • Anterior pituitary—glandular tissue • Endocrine cells that synthesize and secrete hormones. • Many are Tropic Hormones which stimulate the activity of other endocrine tissue. • Posterior pituitary—nervous tissue

  22. There are six anterior pituitary hormones • Two affect non-endocrine targets • Growth hormone • Prolactin • Four stimulate other endocrine glands (tropic {turn on} hormones) • Thyroid-stimulating hormone (thyrotropic hormone) • Adrenocorticotropic hormone • Two gonadotropic hormones

  23. Growth Hormone is a general metabolic hormone • Major effects are directed to growth of skeletal muscles and long bones • Plays a role in determining final body size • Causes amino acids to be built into proteins (anabolic) • Causes fats to be broken down for a source of energy sparing glucose for blood sugar homeostasis.

  24. Abuse of Human Growth Hormone (HGH)

  25. Growth hormone (GH) disorders include: • Pituitary dwarfism results from hyposecretion of GH during childhood • Gigantism results from hypersecretion of GH during childhood • Acromegaly results from hypersecretion of GH during adulthood

  26. Prolactin (pro=for; lact= milk) (PRL) is a protein hormone that is similar in structure to GH. • Stimulates and maintains milk production following childbirth • Function in males is unknown

  27. Thyroid-Stimulating Hormone (TSH) or Thyrotropic Hormone (TH) • Influences growth and activity of the thyroid gland

  28. Regulating metabolism • Hypothalamus • TRH = TSH-releasing hormone • Anterior Pituitary • TSH = thyroid stimulating hormone • Thyroid • produces thyroxine hormones • metabolism & development • bone growth • mental development • metabolic use of energy • blood pressure & heart rate • muscle tone • digestion • reproduction tyrosine + iodine thyroxines

  29. Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine + ✗ tyrosine + iodine ✗ thyroxines

  30. Adrenocorticotropic Hormone (ACTH) • Regulates endocrine activity of the adrenal cortex to secrete glucocorticoids.

  31. Gonadotropic hormones • Regulate hormonal activity of the gonads (ovaries and testes) • Follicle-stimulating hormone (FSH) • Stimulates follicle development in ovaries. As follicles mature they produce estrogen. Eggs are readied for ovulation. • Stimulates sperm development (Spermatogenesis) in testes by acting on the cells of the seminiferous tubules. • Luteinizing hormone (LH) • Triggers ovulation of an egg in females • Stimulates testosterone production in males in the interstitial cells of the testes.

  32. Gonadotropic hormones • Regulate hormonal activity of the gonads (ovaries and testes) • Follicle-stimulating hormone (FSH) • Stimulates follicle development in ovaries. As follicles mature they produce estrogen. Eggs are readied for ovulation. • Stimulates sperm development in testes • Luteinizing hormone (LH) • Triggers ovulation of an egg in females • Stimulates testosterone production in males in the interstitial cells of the testes.

  33. The Pituitary has two functional lobes • Anterior pituitary—glandular tissue • Posterior pituitary—nervous tissue

  34. Pituitary–Hypothalamus Relationship The Hypothalamus receives information from nerves throughout the body and from other parts of the brain and initiates endocrine signals in response. Hormonal release by the pituitary is regulated by releasing and inhibiting hormones produced by the hypothalamus

  35. The Hypothalamus produces two hormones, which are transported to neurosecretory cells of the posterior pituitary through portal circulation (blood flows directly from hypothalamus to pituitary.) These hormones are stored in the posterior pituitary until they are signalled for release by the hypothalamus. The posterior pituitary is not strictly an endocrine gland, but does release hormones.

  36. Oxytocin is released in significant amounts during childbirth and in nursing women. Oxytocin stimulates contractions of the uterus during labor and intercourse and the milk ducts for breastfeeding. Pitocin (synthetic oxytocin) is frequently used to induce labor, stop post-partum bleeding, or to stimulate milk production. Oxytocin creates a feeling of well-being in mothers, which helps her to bond with a newborn. It is called the “mothering” hormone.

  37. Antidiuretic Hormone (diuresis=urine production) inhibits or prevents urine production. ADH causes the kidneys toreabsorb more water from the forming urine thereby increasing blood volume and decreasing urine output. This is accomplished by making the collecting tubules of the kidney more permeable to water, thus increasing water retention. ADH also increases blood pressure by constricting arterioles (small arteries)-sometimes called vasopressin. Alcohol inhibits ADH secretion and results in a large output of urine. The dry mouth and intense thirst of a hangover reflects the dehyrating effects of alcohol.

  38. same gene family growthhormone birds fish amphibians fatmetabolism salt &waterbalance metamorphosis& maturation growth& development Homology in hormones What does this tell you about these hormones? How could these hormones have different effects? prolactin gene duplication? mammals milkproduction

  39. The Thyroid Gland is a fairly large gland found at the base of the throat, slightly inferior to the Adam’s apple.

  40. The Thyroid Gland Consists of two lobes and a connecting isthmus (central mass).

  41. The Thyroid Gland Consists of two lobes and a connecting isthmus (central mass). Internally, the thyroid is composed of hollow structures called follicles, which store a sticky colloidal material.

  42. Internally, the thyroid is composed of hollow structures called follicles, which store a sticky colloidal material that produces calcitonin. 40x

  43. The Thyroid Gland produces two hormones… • Thyroid hormone consists of two iodine-containing hormones Thyroxine (T4) and Triiodothyronine (T3). T4 is secreted by the thyroid follicles and is converted to T3 at the target tissue. Thyroid hormone is the major metabolic hormone as it controls the rate at which glucose is burned. It is also important for normal tissue growth and development.

  44. The Thyroid Gland produces two hormones… • Calcitonin decreases blood calcium levels by causing calcium to be deposited in bones. Calcitonin acts antagonistically with parathyroid hormone, which stimulates the release of calcium from bone. Calcitonin is made in parafollicular cells found in connective tissue between follicles.

  45. Thyroid Gland Figure 9.7b 40x

  46. Goiters-thyroid gland enlarges due to lack of iodine

  47. Cretinism Caused by hyposecretion of thyroxine. Results in dwarfism during childhood

  48. Thyroid Cancer Figure 9.8

More Related