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Endocrine

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  • The Endocrine SystemControls many body functionsexerts control by releasing special chemical substances into the blood called hormonesHormones affect other endocrine glands or body systems

    Derives its name from the fact that various glands release hormones directly into the blood, which in turn transports the hormones to target tissues via ducts.

  • The Endocrine SystemExocrine glands - transport their hormones to target tissues via ducts.

    Endocrine Emergencies:from common:Diabetesto the unusual:Thyrotoxicosis

  • The Endocrine System

    Consists of several glands located in various parts of the body.

    Pituitary gland: a small gland located on a stalk hanging from the base of the brain - AKA

    The Master Gland Primary function is to control other glands.Produces many hormones.Secretion is controlled by the hypothalamus in the base of the brain.

  • The Endocrine SystemThe Pituitary Gland is divided into 2 areas, which differstructurally and functionally each area has separate types of hormone production.

    The two segments are:Posterior Pituitary:produces oxytocin and antidiuretic hormone (ADH)Anterior Pituitary:produces thyroid-stimulating hormone (TSH)growth hormone (GH)adrenocorticotropin (ACTH)follicle-stimulating hormone (FSH)

  • The Endocrine SystemAnd even moreluteinizing hormone (LH)prolactin

    Lets go over these one at a time...

    Posterior PituitaryOxytocin (the natural form of pitocin)stimulates gravid uteruscauses let down of milk from the breast.ADH (vasopressin) causes the kidney to retain water.

  • The Endocrine SystemAnterior PituitaryPrimarily regulates other endocrine glandsrarely a factor in endocrinological emergenciesTSH stimulates the thyroid gland to release its hormones, thus metabolic rate

    Anterior PituitaryGrowth hormone (GH) glucose usage consumption of fats as an energy sourceACTH stimulates the adrenal cortex to release its hormonesFSH & LH stimulates maturation & release of eggs from ovary.

  • The Endocrine SystemThe Thyroid Glandlies in the anterior neck just below the larynyx.Two lobes, located on either side of the trachea, connected by a narrow band of tissue called the isthmus.Sacs inside the gland contain colloid

    Within the colloid are the thyroid hormones:thyroxine (T4)triiodothyronine (T3)When stimulated (by TSH or by cold), these are released into the circulatory system and the metabolic rate.C cells within the thyroid produce the hormone calcitonin.

  • The Endocrine SystemCalcitonin, when released, lowers the amount of calcium in the blood.Inadequate levels of thyroid hormones = hypothyroidism, or Myxedema.

    Myxedema symptoms:Facial bloatingweaknesscold intolerancelethargyaltered mental statusoily skin and hairTX: replacement of thyroid hormone.

  • The Endocrine SystemIncreased thyroid hormone release causes hyperthyroidism, commonly called Graves disease. Signs and symptoms:insomnia, fatiguetachycardiahypertensionheat intoleranceweight loss

    Long term hyperthyroidism:Exopthalmosbulging of the eyeballs (picture Barbara Bush)In severe cases - a medical emergency called thyrotoxicosis can result.

  • The Endocrine SystemParathyroid Glandssmall, pea-shaped glands, located in the neck near the thyroidusually 4 - number can varyregulate the level of calcium in the body

    produce parathyroid hormone - level of calcium in blood

    Hypocalcemia can result if parathyroids are removed or destroyed.

  • The Endocrine SystemPancreasa key gland located in the folds of the duodenumhas both endocrine and exocrine functionssecretes several key digestive enzymes

    Islets of Langerhansspecialized tissues in which the endocrine functions of the pancreas occursinclude 3 types of cells:alpha ( )beta ()delta ()each secretes an important hormone.

  • The Endocrine SystemAlpha () cells release glucagon, essential for controlling blood glucose levels.When blood glucose levels fall, cells the amount of glucagon in the blood .

    The surge of glucagon stimulates the liver to release glucose stores (from glycogen and additional storage sites).Also, glucagon stimulates the liver to manufacture glucose -gluconeogenesis.

  • The Endocrine SystemBeta Cells () release insulin (antagonistic to glucagon). Insulin the rate at which various body cells take up glucose. Thus, insulin lowers the blood glucose level.

    Insulin is rapidly broken down by the liver and must be secreted constantly.Delta Cells () produce somatostatin, which inhibits both glucagon and insulin.

  • The Endocrine SystemAdrenal Glands2 small glands that sit atop both kidneys.

    Each has 2 divisions, each with different functions.

    the Adrenal Medulla secretes the catecholamine hormones norepinephrine and epinephrine (closely related to the sympathetic component of the autonomic nervous system).

  • The Endocrine SystemThe Adrenal Cortex secretes 3 classes of hormones, all steroid hormones:gluticocorticoids mineralocorticoidsandrogenic hormones

    One at a timegluticocorticoids:accounts for 95% of adrenal cortex hormone production the level of glucose in the bloodReleased in response to stress, injury, or serious infection - like the hormones from the adrenal medulla.

  • The Endocrine SystemMineralocorticoids:work to regulate the concentration of potassium and sodium in the body.Prolonged in adrenal cortex hormone results in Cushings Disease.

    Signs & Symptoms of Cushings Disease: in blood sugar levelsunusual body fat distributionrapid mood swings

  • The Endocrine SystemAnd - if there is an in mineralocorticoids as wellA serious electolyte imbalance will occur due to the potassium excretion by the kidney, which results in hypokalemia.

    Sodium can also be retained by the kidney, resulting in hyponatremia.Causes: dysrhythmiascomadeathusually results from a tumor - TX? Removal of tumor.

  • The Endocrine SystemGonads and Ovaries:the endocrine glands associated with human reproduction.Female ovaries produce eggsMale gonads produce sperm both have endocrine functions.

    Ovaries:located in the abdominal cavity adjacent to the uterus.Under the control of LH and FSH from the anterior pituitary they manufactureestrogenprotesterone

  • The Endocrine SystemEstrogen and Progesterone have several functions, including sexual development and preparation of the uterus for implantation of the egg.

    Testes:located in the scrotumproduce sperm for reproductionmanufacture testosterone -promotes male growth and masculinizationControlled by anterior pituitary hormones FSH and LH.

  • The Endocrine SystemEndocrine Emergencies:Diabetes Mellitusone of the most common diseases in North America. insulin secretion by the Beta () cells of the islets of Langerhans in the pancreas.

    Complications of Diabetes:contributes to heart diseasestrokekidney diseaseblindness

  • The Endocrine SystemPathophysiology of Diabetes:Glucose MetabolismGlucose (dextrose) is a simple sugar required by the body to produce energy.Sugars, or carbohydrates, are 1 of 3 major food sources used by the body.

    The other 2 major food sources areproteinsfatsMost sugars in the human diet are complex and must be broken down into simple sugars: glucose, galactose and fructose - before use.

  • The Endocrine SystemBreakdown of sugars is carried out by enzymes in the gastro intestinal system.As simple sugars, these are absorbed from the GE system into the body.More than 95% enter the body as glucose.

    To be converted into energy, glucose must first be transmitted through the cell membrane. BUT - the glucose molecule is large and doesnt readily diffuse through the cell membrane.

  • The Endocrine SystemGlucose must pass into the cell by binding to a special carrier protein on the cells surface. Facilitated diffusion - doesnt use energy. The carrier protein binds with the glucose and carries it into the cell.

    The rate at which glucose can enter the cell is dependent upon insulin levels.Insulin serves as the messenger - travels via blood to target tissues.Combines with specific insulin receptors on the surface of the cell membrane.