Endocrine System
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Endocrine System






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Endocrine System 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.