Endocrine System Dr. Motamedi 2017

Transcription

1 Endocrine System

2 The Endocrine System I. General Overview II. III. Basic Anatomy Control of the endocrine system

3 Messenger Molecules Cells must communicate with one another to coordinate cell processes within tissues and to maintain homeostasis. Cell-to-cell communication is carried out via messenger molecules.

4 Four methods of cell-to-cell communication are found in the human body, ranging from direct to remote communication.

5 I. A General Overview ES (endocrine system) and homeostasis Anatomy Endocrine glands, cells, neurosecretory cells Hormones Target cells ES as a Control System Hormone + target = change in cell function (return to homeostasis)

6 ES and Homeostasis Homeostasis

7 Feedback Mechanisms Stimulus change in homeostatic environment signal sent to CNS Response signal sent from CNS produce effect body returns to homeostasis

8 Basic ES cont. ES and NS = 2 main control systems of body Endocrine organs located throughout body Actions mediate all tissues Control of ES through feedback mechanisms

9 C. Hormones Chemical messenger Secreted by endocrine gland Specific to target Activate cellular change Different chemical types

10 Three types of chemical signals are used for cell-to- cell communication.

11 Hormone + Receptor

12 Protein/Peptide Hormones Hydrophilic Large Can't fit through membrane Second messenger mechanism of action Most hormones Example: Insulin

13 1 The hormone binds to a receptor on the plasma membrane of a target cell (extracellular fluid) peptide or amino acid-derived hormone (first messenger) 2 Hormone receptor binding activates an enzyme that catalyzes the synthesis of a second messenger, such as cyclic AMP cyclic AMPsynthesizing enzyme ATP (cytoplasm) receptor cyclic AMP (second messenger) plasma membrane active enzyme product 4 The activated enzymes catalyze specific reactions inactive enzyme reactant 3 The second messenger activates other enzymes nuclear envelope (nucleus)

14 Steroid Hormones Small Hydrophobic/Lipophilic Travel in blood w/carrier Cytoplasmic or nuclear receptors Change protein synthesis Example: estradiol

15 steroid hormone 1 A steroid hormone diffuses through the plasma membrane (extracellular fluid) 2 The hormone binds to a receptor in the nucleus or to a receptor in the cytoplasm that carries it into the nucleus 3 The hormone receptor complex binds to DNA and causes RNA polymerase to bind to a nearby promoter site for a specific gene plasma membrane ribosome hormone receptor DNA 5 The mrna leaves the nucleus, then attaches to a ribosome and directs the synthesis of a specific protein product mrna RNA polymerase 4 RNA polymerase catalyzes the transcription of DNA into messenger RNA (mrna) new protein gene (cytoplasm) nuclear envelope (nucleus)

16 Amine Synthesized from a single amino acid Melatonin from tryptophan Thyroid hormone from tyrosine Catecholamines (EPI) from tyrosine

17 Hormone + Receptor

18 Where Do Hormones Made?

19 The H-P-A Hypothalamic-Pituitary Axis Most feedback loops run through this axis HPA mediates growth, metabolism, stress response, reproduction.

20 Why is the Hypothalamus so Important? Secretes regulatory homones RH (releasing hormons) RIH (releasing inhibition hormons) "Directs" pituitary

21 Role of the Hypothalamus The thalamus receives sensory information, relays some to the hypothalamus. Hypothalamus monitors the body for temperature, ph, other conditions. Hypothalamus signals pituitary gland if conditions need to be corrected.

22 Role of the Pituitary The pituitary is the master gland that signals other glands to produce their hormones when needed. The anterior lobe of the pituitary receives signals from the hypothalamus, and responds by sending out the appropriate hormone to other endocrine glands. The posterior pituitary receives oxytocin or antidiuretic hormone (ADH) from the hypothalamus, relays them to the body as necessary.

23 STIMULUS Hypothalamus Releasing Hormone (Release-Inhibiting Hormone) Pituitary Stimulating Hormone Gland Hormone Target

24 1. Posterior Pituitary Hormones Manufactured in Hypothalamus, released from Post. Pit. Oxytocin Target = smooth ms. Uterus and Breast (&brain) Function = labor and delivery, milk ejection ADH Target = kidneys Function = water reabsorption

25 hypothalamus 1 Neurosecretory cells of the hypothalamus produce releasing and inhibiting hormones 1 Neurosecretory cells of the hypothalamus produce oxytocin and ADH 2 Releasing or inhibiting hormones (green circles) are secreted into capillaries feeding the anterior lobe of the pituitary blood flow pituitary (anterior lobe) endocrine cell capillary bed 3 Endocrine cells of the anterior pituitary secrete hormones (red squares) in response to releasing hormones; the pituitary hormones enter the bloodstream blood flow 2 Oxytocin and ADH (blue triangles) are secreted into the blood via capillaries in the posterior pituitary pituitary (posterior lobe) capillary bed

26 2. Anterior Pituitary Hormones HORMONE TARGET FUNCTION Thyroid (TSH) Stimulating Thyroid gland TH synthesis & Release Growth (GH) Many tissues growth Adrenocortico- Tropin (ACTH) Adrenal cortex Cortisol release (androgens) Prolactin (Prl) Breast Milk production Follicle (FSH) Gonads Egg/sperm prod. Luteinizing (LH) Gonads Sex hormones

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28 Pituitary Hormones Pituitary Hormone Follicle-stimulating hormone Lutenizing hormone Thyroid-stimulating hormone Adrenocorticotropic hormone Melanocyte-stimulating hormone Growth hormone Antidiuretic hormone Oxytocin Functions Stimulates egg maturation in the ovary and release of sex hormones. Stimulates maturation of egg and of the corpus luteum surrounding the egg, which affects female sex hormones and the menstrual cycle. Stimulates the thyroid to release thyroxine. Causes the adrenal gland to release cortisol. Stimulates synthesis of skin pigments. Stimulates growth during infancy and puberty. Signals the kidney to conserve more water. Affects childbirth, lactation, and some behaviors.

29 Endocrine Hormones Gland Hormones Functions Thyroid Thyroxine Regulates metabolism Calcitonin Inhibits release of calcium from the bones Parathyroids Parathyroid hormone Stimulates the release of calcium from the bones. Islet cells (in the pancreas) Insulin Glucagon Decreases blood sugar by promoting uptake of glucose by cells. Increases blood sugar by stimulating breakdown of glycogen in the liver. Testes Testosterone Regulates sperm cell production and secondary sex characteristics. Ovaries Estrogen Stimulates egg maturation, controls secondary sex characteristics. Progesterone Prepares the uterus to receive a fertilized egg. Adrenal cortex Epinephrine Stimulates fight or flight response. Adrenal medulla Glucocorticoids Aldosterone Testosterone (in both sexes) Part of stress response, increase blood glucose levels and decrease immune response. Regulates sodium content in the blood. Adult body form (greater muscle mass), libido. Pineal gland Melatonin Sleep cycles, reproductive cycles in many mammals.

30 Basic Structure of Feedback Loop Environmental Stimulus Stimulates Control Center (Brain-hypothal.) Hypothalamic hormones stim. Pituitary Pituitary hormone stim. Target area Target area produces change Change acts negatively or positively on the cycle.

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33 Pars nevrosa (posterior hypophysis) Pars distalis (anterior hypophysis)

34 Pars distalis (anterior hypophysis)

35 Pars distalis (anterior hypophysis) Acidophil cell chromophobe cell basophile cell

36 Pars distalis (anterior hypophysis) Acidophil cell

37 Pars nevrosa (posterior hypophysis)

38 Thyroid gland

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42 گواتر آنطور که عموم مردم تصور میکنند به معنی کمکاری تیروئید نیست بلکه تنها معنی بزرگشدن غده تیروئید را میدهد. گواتر از نظر شکلی به دو نوع منتشر و ندولر تقسیم میشود در نوع منتشر تمام غده تیروئید به میزان تقریبا یکسان رشد میکند و بزرگ میشود درحالیکه در نوع ندولر تیروئید هم در نگاه و هم در لمس توسط پزشک به صورت غده غده درمیآید. از نظر کارکرد گواتر به سه نوع کمکار پرکار و ساده تقسیم میشود: در نوع اول یعنی گواتر کمکار غده تیروئید هم بزرگ شدهاست هم به میزان کافی هورمون تولید نمیکند. در نوع دوم تیروئید هم بزرگ است و هم بیشتر از نیاز طبیعی بدن هورمون تولید میکند که به آن پرکاری تیروئید میگویند. در نوع سوم گواتر که به آن گواتر ساده میگویند و نسبت به دو نوع دیگر شیوع بیشتری دارد اگرچه تیروئید بزرگ است ولی چون میزان تولید هورمون در حد طبیعی نگه داشته شده است و از نظر بالینی هیچ عالمتی برای فرد ایجاد نمیکند به آن گواتر ساده میگویند.

43 Follicles Of thyroid T3-T4 Tirocalsitonin

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45 The follicular cells Manufacture the glycoprotein component of thyroglobulin and secrete it into the follicle. Change iodide ( ion I ) into iodine ( I ) and secrete it into the follicle (Pendrin pump) where it combines with the glycoprotein spontaneously to form thyroglobulin. At need, it break down the long thyroglobulin molecule into smaller T3 and T4 and releases it into the bloodstream.

46 C-cells (Para follicular cell) These cells lie between follicles within the thyroid gland. They are inobvious in humans with a slightly paler staining nucleus. Their purpose is production and release of calcitonin. Calcitonin has the opposite effect to parathormone - it reduces the action of osteoclasts and increases activity of osteoblasts. It is produced in response to calcium levels alone..

47 Blood Calcium

48 Adrenal Gland Adrenal gland located a top kidney Outer part = cortex Secretes Cortisol (stress), Androgens, Aldosterone (electrolytes) Inner part = medulla Secretes EPI & NEPI

49 Adrenal Gland

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52 Adrenal gland Cortex zona glomeruloza zona fasciculata zona reticularis medulla

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54 Cortex 1.zona glomeruloza Mineralocorticoid Aldestron (Natrium and potassium balance) 2. zona fasciculata Glucocotricoid Corton (control sugar, fat and proteins metabolism) In liver increase glucose synthesis and blood sugar It is controls by ACTH hormones of distal hypophysis. 3. zona reticularis Androgens

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56 Capsule cortex(glomerulosa fasiculata reticularis layer) medullae

57 Capsule cortex(glomerulosa)

58 Lamina Fasiculata sinusoid

59 Capsule cortex(glomerulosa fasiculata)

60 cortex( reticularis layer) medullae reticular layer