5 Endocrine

• Cells of organisms need to communicate with each other to regulate their development and organize growth and cell division
• Hormones act as messengers between cells, telling them what's happening elsewhere and how they should respond
• Endocrine system (Hormone system) consists of:

  • Glands located throughout the body
  • Hormones made by the glands and released into the bloodstream or the fluid surrounding cells
  • Receptors in various organs and tissues that recognize and respond to the hormones
• Hormones control many bodily processes such as:

  • Metabolism
  • Homeostasis
  • Growth and development
  • Sexual function
  • Reproduction
  • Sleep-wake cycle
  • Mood
• Endocrine glands contain cells that release their products (hormones) just outside the cells (into the extracellular fluid), which diffuse directly into the bloodstream
• Hypothalamus:

  • Links the endocrine and nervous systems together
  • Drives the endocrine system
• Pituitary gland:

  • Receives signals from the hypothalamus
  • Produces hormones like Antidiuretic hormone (ADH), Oxytocin (OT), Growth Hormone (GH), Luteinizing hormone (LH), and Follicle-stimulating hormone (FSH)
• Thyroid gland:

  • Produces Thyroid hormone (TH) which regulates metabolism and heat production
  • Produces Calcitonin (CT) which helps bone cells process calcium and add it to the bones
• Adrenal gland:

  • Located on each kidney
  • Produces hormones like Epinephrine ('adrenaline') for the "fight-or-flight response"
• Gonads:

  • Testes produce Androgens (testosterone) and develop male sex characteristics
  • Ovaries produce Estrogens and progesterone and develop female sex characteristics
• Insulin is a hormone made by the pancreas that enables the body's cells to absorb sugar (glucose) from the bloodstream for energy
• Diabetes is a complex chronic metabolic disease characterized by high fasting blood glucose with two major forms: type 1 and type 2

  • Type 1: Insulin is no longer secreted
  • Type 2: Insulin is no longer able to facilitate glucose entry into cells for energy production
• Insulin insufficiency in Type 1 diabetes is due to lack of insulin production by the pancreas beta (β) cells

  • Insulin resistance in Type 2 diabetes is due to reduced or dysregulated insulin receptor signaling
• Hemoglobin A1c test (HbA1c) assesses average glucose levels over a 2-3 month period and is used to monitor blood glucose levels in diabetics
• Pre-diabetes is defined as impaired fasting glucose and/or impaired glucose tolerance, where blood glucose is higher than normal but not high enough to meet the diagnostic criteria for type 2 diabetes
• Diabetes increases the risk of developing comorbidities and various health complications compared to non-diabetic individuals
• Genetics play a role in the risk of developing type 1 diabetes, with environmental factors like viral infections also being implicated as possible triggers for β-cell autoimmunity
• Factors that contribute to the increased risk of developing type 1 diabetes among Caucasians compared to other ethnic groups:

  • Genetic susceptibility
  • Family history
  • Certain environmental triggers
• Management of Type 1 Diabetes:

  • Insulin replacement by daily injection to maintain blood glucose levels
  • Timing and dosing of insulin, diet patterns, and activity levels to prevent hyperglycemia leading to diabetic ketoacidosis and hypoglycemia leading to diabetic coma
  • Life-long daily insulin replacement and glucose monitoring are required for type 1 diabetics
• Type 2 Diabetes:

  • Represents approximately 90-95% of all cases of diabetes
  • Insulin is still produced and secreted by the pancreas but its impact on glucose uptake is impaired
  • Elevated blood glucose occurs due to a mismatch between insulin production and the amount needed to maintain normal blood glucose levels, caused by target tissue insulin resistance
• Risk Factors for Type 2 Diabetes:

  • Obesity is the strongest modifiable predictor of type 2 diabetes
  • The cause and effect relationship between obesity and type 2 diabetes has been demonstrated in several studies
  • Compared with a body mass index (BMI) of 21 kg/m2, the relative risk of developing type 2 diabetes rises exponentially with increasing BMI
• Dietary Factors:

  • Dietary factors influence the risk of developing type 2 diabetes
  • Factors such as glycemic index, glycemic load, type of fat, type of carbohydrate, dietary fiber, and dietary additives have been investigated in experimental and epidemiologic studies
• Glycemic Index:

  • A measure of postprandial increase in blood glucose due to intake of a specific food relative to that induced by glucose
  • Ranks foods based on their glycemic impact relative to glucose
  • Glycemic index and glycemic load have been widely used in epidemiologic and clinical investigations (GL = GI x quantity of serving)
• Dietary Fiber:

  • Certain types of fiber protect against the development of type 2 diabetes
  • Soluble fiber inhibits macronutrient absorption, reduces postprandial glucose responses, and influences blood lipids beneficially
  • Primarily insoluble fiber is associated with reduced diabetes risk
• High Fructose Corn Syrup:

  • Attracts attention as a potential risk factor for insulin resistance and obesity
  • Effects include weight gain, quicker absorption compared to regular sugar, increased insulin resistance, decreased insulin sensitivity, fat production in the liver, damage to the intestinal lining, increased appetite, diabetes, and non-alcoholic fatty liver disease
• Ethnic Disparities in Type 2 Diabetes:

  • Disproportionately affects Asians, Hispanics, Native Americans, Pacific Islanders, and African Americans
  • Asians have a high risk for developing type 2 diabetes at relatively low levels of body mass due to body composition and distribution of body fat
• Metabolic Syndrome:

  • Symptoms include abdominal obesity, abnormal cholesterol levels, hypertension, insulin resistance, and a pro-inflammatory state
  • Clinical diagnosis is made when any three of these conditions exist in the same individual
• Other Approaches to Prevention:

  • Sustained glucose control is essential to prevent dangerous episodes of hyperglycemia and hypoglycemia
  • Weight loss in overweight and obese diabetic patients reduces insulin resistance
  • Individualized programs of diet and exercise for weight loss are recommended
  • Regular examinations are critical to prevent complications such as vision loss, foot issues, and other health risks
• What is a endocrine disruptors?


  natural or human made chemicals that may mimic, block or interfere with the body's hormones.
• What are the common sources of endocrine disruptors?

  bisphenol A (BPA), Dioxins
• What is hyperglycemia?

  condition with elevated blood glucose, arises when insulin is either no longer secreted (type 1) OR no longer able to facilitate glucose properly into the cells for energy production (type 2)
• Who isolated insulin in 1923?

  Frederick Banting and Charles Best
• What are the functions of the pancreas?

  a)digestive function b)controller of blood sugar levels
• What is the insulin insufficiency?

  lack of insulin production by the B-cells of the pancreas (type 1 )
• What is insulin resistance?

  reduced or dysregulated insulin receptor signaling (type 2)
• What is glucose transporter 4 (GUT-4)?


  is the gateway for insulin mediated cellualr glucose uptake
• What is hemoglobin A1c test (HbA1c)?

  used to monitor blood glucose levels, assess average glucose levels over a 2-3 month period
• Insulin and glucagon are two hormones secreted by the pancreas that act antagonistically to regulate the level of glucose in the blood to help maintain homeostasis

  
• Insulin lowers blood glucose levels and glucagon raises blood glucose levels

  
• Diabetes mellitus is a group of diseases characterized by problems in insulin production or insulin function