LEC. 31: ADRENAL, PANCREAS, OTHER ENDOCRINE TISSUES

• Adrenal glands


  Sits on top of kidneys
• Adrenal gland structure


  • Outer: Adrenal cortex
  • Inner: Adrenal medulla
• Adrenal cortex


  Secretes corticosteroids, glandular tissue
• Adrenal medulla


  Nervous tissue, part of the sympathetic nervous system, secretes epinephrine & norepinephrine
• Mineralocorticoids (zona glomerulosa)


  Hormone: Aldosterone, Regulated by renin-angiotensin-aldosterone mechanism, blood ion levels, ACTH
• Mineralocorticoid mechanism and effects

  Acts on mineralocorticoid receptors in kidney tubules, Stimulates reabsorption of Na+ & water, Secretion of K+, Increases blood volume and BP
• Glucocorticoids (zona fasciculata)


  Hormone: Cortisol, Responds to stress (stimulated by ACTH), Promotes gluconeogenesis, fat breakdown, amino acid utilization
• Gonadocorticoids (zona reticularis)


  Hormone: Weak precursor & Androgens, Converted into testosterone and estrogens in reproductive organs
• Atrial natriuretic peptide


  Produced by cardiac muscle cells in atria, Opposes aldosterone, Lowers BP, Increases sodium excretion
• Diabetes mellitus


  Metabolic diseases prolonged by high blood sugar, Sugars cannot be used as fuel, Fats are used instead, Causes lipidemia
• Signs of diabetes mellitus

  • Polyuria: Huge urine output
  • Polydipsia: Excessive thirst
  • Polyphagia: Excessive hunger & food consumption
• Type 1 diabetes


  Hyposecretion of insulin
• Type 2 diabetes


  Hypoactivity of insulin
• Elevated blood glucose levels

  Interferes with nitric oxide production, Results in narrow blood vessels, Increased risk of heart attack, stroke, retinopathy, tissue necrosis
• Fatty acid metabolism in diabetes

  Results in the formation of ketone bodies
• Ketosis


  Metabolic state reached during faster or low-carb diet, Stressed body = ketone bodies produced faster than tissues can metabolize
• Ketoacidosis


  Build-up of ketones in blood, Ketones are acidic, Causes hyperpnea, Disrupted heart activity & oxygen transport, Possible coma and death if untreated
• Pancreas


  Contains both endocrine and exocrine glands
• Pancreatic islet cells


  • Alpha cells: Produce glucagon
  • Beta cells: Produce insulin
• Glucagon


  Increases amount of sugar in blood, Targets liver to promote glycogenolysis, gluconeogenesis, Release glucose into the blood
• Insulin


  Decreases blood sugar levels, Enhances membrane transport of glucose to body cells, Promotes glycogenesis, inhibits glycogenolysis & gluconeogenesis
• Ovaries


  Produce estrogen, progesterone, low levels of testosterone, Responsible for secondary sex characteristics and reproductive organ maturation/function
• Testes


  Produce testosterone and low levels of estradiol, Responsible for secondary sex characteristics, Influences maturation and functioning of reproductive organs
• Placenta


  Secretes estrogens, progesterone, human chorionic gonadotropin (hCG), Acts on uterus to influence pregnancy
• Pineal gland


  Located in the roof of the 3rd ventricle of the brain, Major secretory product: Melatonin (derived from serotonin)
• Melatonin functions

  Affects timing of puberty, Regulates day/night cycles (circadian rhythms), Influences physiological processes (body temp., sleep, appetite)