Pancreas and OtherEndocrine Glands
Pancreas and other EndocrineGlands Pancreatic Islets (Islets of  Langerhans) Pineal Gland Thymus Gastrointestinal Trac...
Pancreatic Islets These structures are most common in  the body and tail of the pancreas On a microscopic level, the mos...
Pancreatic Islets
Glucagon Secreted by: Alpha cells Produced in response to a fall in blood  glucose concentrations.    ◦ Glucagon Stimula...
Insulin Secreted by: Beta cells Produced in response to a rise in  blood glucose concentrations    ◦ Promotes the entry ...
The actions of Insulin and Glucagon are               antagonistic After a meal    ◦ Insulin> Glucagon   During times of...
Pineal Gland Is found on the roof of the third  ventricle near the corpora  quadrigema, where it is encapsulated  by the ...
Pineal Gland
Pineal Gland It lacks direct nervous connection to  the rest of the brain but it is highly  innervated by the sympathetic...
Circadian Rhythms The primary center for circadian  rhythms in the body is the SCN These are Rhythms of Physiological  a...
Circadian Rhythms ◦ environmental light/dark changes are   required to synchronize this activity to a   day/night cycle  ...
Melatonin Secretion Excessive melatonin secretion in  humans is associated with a delay in  the onset of puberty. Melato...
Thymus A bilobed organ positioned in front of  the aorta and behind the manubrium  of the sternum It is relatively large...
Thymus
Thymus The Thymus secretes hormones that  help to regulate the immune system Site of production of T cells (thymus  depe...
Gastrointestinal Tract The stomach and intestine secrete a  number of hormones that act on the  gastrointestinal tract it...
Gonads   The gonads(testis and ovary) secrete    sex steroids.    ◦ Males-androgens    ◦ Females- estradiol-17β and proge...
Testis   Consists of two compartments:    1. Seminiferous tubules-which produce       sperm cells    2. Interstitial tiss...
Testis
Ovary   Estrogen is secreted by small structures    within the ovary called ovarian follicles    ◦ The ovarian follicles ...
Ovary
Placenta   It is the organ responsible for nutrient and    waste exchange between the fetus and    the mother
Placenta   It secretes:    ◦ Large amounts of estrogen and      progesterone    ◦ A number of polypeptide and protein    ...
Autocrine and Paracrine      Regulation
 Autocrine regulators-if they are  produced and act within the same  organ Paracrine regulators-if they are  produced wi...
Examples of ParacrineRegulation   Nitric Oxide-can function as a    neurotransmitter in memory processes and in    other ...
Examples of AutocrineRegulation   Cytokines- molecules that regulate    different cells of the immune system    ◦ Lymphok...
Growth factors ◦ Platelet-derived growth factor ◦ Epidermal growth factor ◦ Insulin-like growth factor*stimulate cell divi...
Prostaglandins The most diverse group of autocrine  regulators Members of a family called the  eicosanoids[molecules der...
Prostaglandins Prostaglandins of the E series (PGE)-can cause  smooth muscle to relax in the  bladder,bronchioles intesti...
Examples of ProstaglandinActions1.       Immune system-prostaglandins promote the         development of pain and fever.2....
Examples of ProstaglandinActions5.       Circulatory system- Prostacylin,a         vasodilator ,and Thromboxane A₂ ,a     ...
Inhibitors of Prostaglandin               Synthesis   Aspirin-most widely used member of a    class of drugs known as non...
Inhibitors of Prostaglandin                 Synthesis 2 isoenzyme forms of cyclo-  oxygenase:1. Type I isoform(COX1)-prod...
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Endo 5 red

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Endo 5 red

  1. 1. Pancreas and OtherEndocrine Glands
  2. 2. Pancreas and other EndocrineGlands Pancreatic Islets (Islets of Langerhans) Pineal Gland Thymus Gastrointestinal Tract Gonads and Placenta
  3. 3. Pancreatic Islets These structures are most common in the body and tail of the pancreas On a microscopic level, the most conspicuous cells in the islets are the alpha and beta cells Hormones secreted by the pancreatic islets:  Glucagon  Insulin
  4. 4. Pancreatic Islets
  5. 5. Glucagon Secreted by: Alpha cells Produced in response to a fall in blood glucose concentrations. ◦ Glucagon Stimulates the liver to hydrolyze glycogen to glucose Stimulates the hydrolysis of stored fat (lipolysis) and the consequent release of free fatty acids into the blood. ◦ This effect helps provide energy substrates during fasting when blood glucose levels decrease
  6. 6. Insulin Secreted by: Beta cells Produced in response to a rise in blood glucose concentrations ◦ Promotes the entry of glucose into tissue cells and the conversion of this glucose into glycogen and fat Insulin aids the entry of amino acids into cells and the production of cellular protein
  7. 7. The actions of Insulin and Glucagon are antagonistic After a meal ◦ Insulin> Glucagon During times of Fasting ◦ Insulin<Glucagon
  8. 8. Pineal Gland Is found on the roof of the third ventricle near the corpora quadrigema, where it is encapsulated by the meninges covering the brain The pineal gland of a child weighs about 0.2 g and is 5-8 mm long and 9mm wide ◦ This gland begins to regress at age 7 and in the adult appears as a thickened strand of fibrous tissue
  9. 9. Pineal Gland
  10. 10. Pineal Gland It lacks direct nervous connection to the rest of the brain but it is highly innervated by the sympathetic nervous system from the superior cervical ganglion Secretes melatonin ◦ Production and secretion is stimulated by activity of the Suprachiasmatic Nucleus (SCN) in the hypothalamus of the brain
  11. 11. Circadian Rhythms The primary center for circadian rhythms in the body is the SCN These are Rhythms of Physiological activity that follow a 24-hour pattern The circadian activity of the SCN is automatic
  12. 12. Circadian Rhythms ◦ environmental light/dark changes are required to synchronize this activity to a day/night cycle  Secretion of melatonin increases with darkness and peaks at the middle of the night  During the day, the neural pathways from the retina of the eyes to the hypothalamus act to depress the activity of the SCN (decreasing melatonin secretion)
  13. 13. Melatonin Secretion Excessive melatonin secretion in humans is associated with a delay in the onset of puberty. Melatonin secretion is highest in children between the ages of 1 and 5 and decreases thereafter, reaching its lowest levels at the end of puberty
  14. 14. Thymus A bilobed organ positioned in front of the aorta and behind the manubrium of the sternum It is relatively large in newborns and children and sharply regresses in size after puberty. ◦ The thymus in adults becomes infiltrated with strands of fibrous and fatty connective tissue.
  15. 15. Thymus
  16. 16. Thymus The Thymus secretes hormones that help to regulate the immune system Site of production of T cells (thymus dependent cells) In addition to providing T cells, the thymus secretes a number of hormones that are believed to be stimulate T cells after they leave the thymus
  17. 17. Gastrointestinal Tract The stomach and intestine secrete a number of hormones that act on the gastrointestinal tract itself and on the pancreas and gallbladder. The effects of these hormones coordinate the activities of different regions of the digestive tract and the secretions of pancreatic juice and bile.
  18. 18. Gonads The gonads(testis and ovary) secrete sex steroids. ◦ Males-androgens ◦ Females- estradiol-17β and progestogens
  19. 19. Testis Consists of two compartments: 1. Seminiferous tubules-which produce sperm cells 2. Interstitial tissues-contains the Leydig cells which secrete Testosterone ◦ Testosterone- is needed for the development and maintenance of the male genitalia [penis and scrotum] and the male accessory organs [prostate, seminal vesicles ,epididymis and vas deferens]
  20. 20. Testis
  21. 21. Ovary Estrogen is secreted by small structures within the ovary called ovarian follicles ◦ The ovarian follicles contain the egg cell (or ovum) and granulosa cells that secrete estrogen By about the midcycle,one of these follicles grows very large and ,in the process of ovulation,extrudes its ovum. ◦ The empty follicle under the influence of the Luteinizing hormone becomes the corpus luteum [which secretes progesterone and estradiol-17β]
  22. 22. Ovary
  23. 23. Placenta It is the organ responsible for nutrient and waste exchange between the fetus and the mother
  24. 24. Placenta It secretes: ◦ Large amounts of estrogen and progesterone ◦ A number of polypeptide and protein hormones  Human Chorionic Gonadotropin (hCG)-similar to LH  Somatomammotropin- similar in action to both growth hormone and prolactin
  25. 25. Autocrine and Paracrine Regulation
  26. 26.  Autocrine regulators-if they are produced and act within the same organ Paracrine regulators-if they are produced within one tissue and regulate a different tissue of the same organ
  27. 27. Examples of ParacrineRegulation Nitric Oxide-can function as a neurotransmitter in memory processes and in other processes can be produced by the endothelium of blood vessels ◦ Functions as the regulator previously known as endothelium-derived relaxation factor Endothelins-directly promote vasoconstriction ◦ Endothelin-1 –is produced by the epithelium of the airways Bradykinin-promotes vasodilation *endothelins and bradykinin are very important in the control of blood pressure. These are also involved in artherosclerosis
  28. 28. Examples of AutocrineRegulation Cytokines- molecules that regulate different cells of the immune system ◦ Lymphokines- cytokines produced by lymphocytes (interleukins are the specific molecules involved) Neutrophins-including nerve growth factor,guide regenerating peripheral neurons that have been injured Growth factors- promote growth and cell division in any organ*cytokines may also function as growth factors
  29. 29. Growth factors ◦ Platelet-derived growth factor ◦ Epidermal growth factor ◦ Insulin-like growth factor*stimulate cell division and proliferation of their target cells Prostaglandins
  30. 30. Prostaglandins The most diverse group of autocrine regulators Members of a family called the eicosanoids[molecules derived from the precursor arachidonic acid] ◦ Upon stimulation arachidonic acid is released from phospholipids in the cell membrane and may enter one of the two possible metabolic pathways 1. Arachidonic acid is converted by the enzyme cyclo-oxygenase into other prostaglandins 2. Arachidonic acid is converted by the enzyme lipoxygenase into leukotrienes
  31. 31. Prostaglandins Prostaglandins of the E series (PGE)-can cause smooth muscle to relax in the bladder,bronchioles intestine and unterus and the same can cause the vascular smooth muscle to contract PGF₂α -has exactly the opposite effects as PGE Thromboxane A₂- promotes clotting by stimulating platelet aggregation and vasoconstriction Prostacylin or PGI₂-has the opposite effects as Thromboxane A₂*these antagonistic effects ensure that, while clotting is promoted, the clots will not normally form on the walls of the intact blood vessels
  32. 32. Examples of ProstaglandinActions1. Immune system-prostaglandins promote the development of pain and fever.2. Reproductive system- plays a role in ovulation and corpus luteum function in the ovaries and in contraction of the uterus. ◦ Excessive prostaglandin production leads to dysmenorrhoea,endometriosis and premature labor3. Digestive system-the stomach and intestines produce prostaglandins,which are believed to inhibit gastric secretions and influence intestinal motility and fluid absorption4. Respiratory system-The leukotrienes are potent bronchoconstrictors and these compounds together with some prostaglandins may cause respiratory distress and contribute to bronchoconstriction in asthma
  33. 33. Examples of ProstaglandinActions5. Circulatory system- Prostacylin,a vasodilator ,and Thromboxane A₂ ,a vasoconstrictor play a role in blood clotting. ◦ In fetus PGE₂ is believed to promote ductus arteriosus –a short vessel that connects the pulmonary artery to the aorta fails to close after birth. It can be closed by the administration of drugs that inhibit prostaglandin sythesis6. Urinary system- Prostaglandins produced in the renal medulla cause vasodilation resulting in increased blood flow and increased excretion of water and electrolytes in the urine
  34. 34. Inhibitors of Prostaglandin Synthesis Aspirin-most widely used member of a class of drugs known as nonsteroidal anti-inflammatory drugs(NSAIDs) ◦ Other members of this class are indomethacin and ibuprofen ◦ These drugs specifically inhibit the cyclo- oxygenase enzyme that is needed for prostaglandin sythesis ◦ Inhibit inflammation but with side effects like:  Gastric bleeding  Possible kidney problems  Prolonged clotting time
  35. 35. Inhibitors of Prostaglandin Synthesis 2 isoenzyme forms of cyclo- oxygenase:1. Type I isoform(COX1)-produced in a constant fashion by cells of the stomach and kidneys and by blood platelets2. Type II isoform(COX2)-is induced in a number of cells in response to cytokines involved in inflammation ◦ Produces prostaglandins that promote
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