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The Endocrine System
 

The Endocrine System

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    The Endocrine System The Endocrine System Presentation Transcript

    • The Endocrine System
      • Controls many body functions
        • exerts control by releasing special chemical substances into the blood called hormones
        • Hormones 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 System
      • Exocrine glands - transport their hormones to target tissues via ducts.
      • Endocrine Emergencies:
        • from common:
          • Diabetes
          • to 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 System
      • The Pituitary Gland is divided into 2 areas, which differ
        • structurally 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 System
      • And even more…
        • luteinizing hormone ( LH )
        • prolactin
      • Let’s go over these one at a time...
      • Posterior Pituitary
        • Oxytocin (the natural form of pitocin)
          • stimulates gravid uterus
          • causes “let down” of milk from the breast.
        • ADH (vasopressin) causes the kidney to retain water.
    • The Endocrine System
      • Anterior Pituitary
        • Primarily regulates other endocrine glands
        • rarely a factor in endocrinological emergencies
        • TSH stimulates the thyroid gland to release its hormones, thus  metabolic rate
      • Anterior Pituitary…
        • Growth hormone ( GH )
          •  glucose usage
          •  consumption of fats as an energy source
        • ACTH stimulates the adrenal cortex to release its hormones
        • FSH & LH stimulates maturation & release of eggs from ovary.
    • The Endocrine System
      • The Thyroid Gland
        • lies 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 System
      • Calcitonin , when released, lowers the amount of calcium in the blood.
      • Inadequate levels of thyroid hormones = hypothyroidism, or Myxedema.
      • Myxedema symptoms:
        • Facial bloating
        • weakness
        • cold intolerance
        • lethargy
        • altered mental status
        • oily skin and hair
        • TX: replacement of thyroid hormone.
    • The Endocrine System
      • Increased thyroid hormone release causes hyperthyroidism, commonly called Graves’ disease.
        • Signs and symptoms:
          • insomnia, fatigue
          • tachycardia
          • hypertension
          • heat intolerance
          • weight loss
        • Long term hyperthyroidism:
          • Exopthalmos
            • bulging of the eyeballs (picture Barbara Bush)
          • In severe cases - a medical emergency called thyrotoxicosis can result.
    • The Endocrine System
      • Parathyroid Glands
        • small, pea-shaped glands, located in the neck near the thyroid
        • usually 4 - number can vary
        • regulate 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 System
      • Pancreas
        • a key gland located in the folds of the duodenum
        • has both endocrine and exocrine functions
        • secretes several key digestive enzymes
      • Islets of Langerhans
        • specialized tissues in which the endocrine functions of the pancreas occurs
        • include 3 types of cells:
          • alpha (  )
          • beta (  )
          • delta (  )
        • each secretes an important hormone.
    • The Endocrine System
      • Alpha (  ) 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 System
      • Beta 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 System
      • Adrenal Glands
        • 2 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 System
      • The Adrenal Cortex secretes 3 classes of hormones, all steroid hormones:
        • gluticocorticoids mineralocorticoids
        • androgenic hormones
      • One at a time…
        • gluticocorticoids:
        • accounts for 95% of adrenal cortex hormone production
        •  the level of glucose in the blood
        • Released in response to stress, injury, or serious infection - like the hormones from the adrenal medulla.
    • The Endocrine System
      • Mineralocorticoids:
        • work to regulate the concentration of potassium and sodium in the body.
      • Prolonged  in adrenal cortex hormone results in Cushing’s Disease.
      • Signs & Symptoms of Cushing’s Disease:
        •   in blood sugar levels
        • unusual body fat distribution
        • rapid mood swings
    • The Endocrine System
      • And - if there is an  in mineralocorticoids as well
        • A 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:
          • dysrhythmias
          • coma
          • death
        • usually results from a tumor - TX? Removal of tumor.
    • The Endocrine System
      • Gonads and Ovaries :
        • the endocrine glands associated with human reproduction.
        • Female ovaries produce eggs
        • Male 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 manufacture
          • estrogen
          • protesterone
    • The Endocrine System
      • Estrogen and Progesterone have several functions, including sexual development and preparation of the uterus for implantation of the egg.
      • Testes:
        • located in the scrotum
        • produce sperm for reproduction
        • manufacture testosterone -
          • promotes male growth and masculinization
        • Controlled by anterior pituitary hormones FSH and LH.
    • The Endocrine System
      • Endocrine Emergencies:
      • Diabetes Mellitus
        • one 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 disease
        • stroke
        • kidney disease
        • blindness
    • The Endocrine System
      • Pathophysiology of Diabetes:
      • Glucose Metabolism
        • Glucose (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 are
        • proteins
        • fats
      • Most sugars in the human diet are complex and must be broken down into simple sugars: glucose, galactose and fructose - before use.
    • The Endocrine System
      • Breakdown 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 doesn’t readily diffuse through the cell membrane.
    • The Endocrine System
      • Glucose must pass into the cell by binding to a special carrier protein on the cell’s surface.
        • Facilitated diffusion - doesn’t 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.