Blood Sugar Levels

• sugar in the blood is in the form of glucose
• all cells need a constant supply of glucose
• energy is released from glucose molecules by cellular respiration
• glucose + oxygen -> carbon dioxide + water + energy
• Liver:

  • high blood sugar level
  • glucose converted into glycogen (glycogenesis) -> stimulated by insulin
  • glycogen stored in liver but cannot be used in the body
  • low blood sugar level
  • glycogen converted into glucose (glycogenolysis) -> stimulated by glucagon
  • glycogen stored in the liver has a role of conversion and maintaining homeostasis
  • glycogen in muscle cells provides glucose requirement for physical activity
• glycogen stored in the liver has only a short term energy supply (approx. 6 hours). If energy is required, it will use energy stored in muscle then adipose tissue
• High Blood Sugar Levels: storing of glucose

  • occurs in liver, skeletal muscle, adipose cells
  • storage of glucose
  • glucose -> glycogen = glycogenesis
  • glucose -> fats = lipogenesis
  • hormone = insulin
• Low Blood Sugar Levels: release of glycogen to glucose

  • liver, adipose cells
  • releasing of glucose after conversion
  • glycogen -> glucose = glycogenolysis
  • lipids -> glucose = lipolysis
  • amino acids -> glucose = gluconeogenesis
  • hormone = glucagon
• pancreas:

  • secretes insulin (Beta cells, high BSL) and glucagon (Alpha cells, low BSL) by Islets of Langerhans
• High BSL >9mmol/L

  Normal BSL = 4-8mmol/L

  Low BSL < 3.9mmol/L
• Fasting Blood glucose test:

  diabetes = 10-17mmol/L = >125mg/dL

  pre-diabetes = 7-8.2mmol/L = 100-125mg/dL

  normal = 4-6mmol/L = 70-99mg/dL
• Fasting Blood Glucose Test

  A) Normal

  B) Pre-diabetic

  C) Diabetic

  
• Fasting blood glucose test of diabetic:

  • begins in high range
  • spikes very high
  • takes over 6 hours to plateau
  • plateau is still in high range
• Adrenal cortex role in blood sugar levels:

  • ACTH secreted from anterior pituitary
  • releases cortisol which regulates carbohydrate metabolism
  • stimulates conversion of glycogen to glucose (glycogenolysis)
  • stimulates protein breakdown in muscles and converts amino acids to glucose in the liver (gluconeogenesis)
  • increases BSL
• Adrenal Medulla role in blood sugar levels:

  • stimulates release of adrenaline and noradrenaline
  • stimulates breakdown of glycogen in liver and release glucose (glycogenolysis)
  • stimulates production of lactic acid from glycogen in muscle cells, then lactic acid can be used by the liver to manufacture glucose
  • increase BSL
• Negative feedback loop of high blood glucose

  Stimulus:

  • Increased BSL

  Receptor:

  • pancreas (beta cells)

  Modulator:

  • islets of langerhans (beta cells)

  Effector:

  • beta cells secrete insulin
  • liver
  • skeletal muscles

  Response:

  • uptake of glucose to glycogen in liver (glycogenesis)
  • uptake of glucose into adipose cells (lipogenesis)

  Feedback:

  • decrease in BSL
  • homeostasis of 90mg/100mL
• Negative Feedback loop of low blood glucose

  Stimulus:

  • decreased BSL

  Receptor:

  • pancreas (alpha cells)
  • adrenal cortex and medulla

  Modulator:

  • Islets of Langerhans (alpha cells)

  Effector:

  • alpha cells secrete glucagon
  • liver
  • skeletal muscles

  Response:

  • liver converts glycogen back to glucose -> glycogenolysis
  • new glucose molecules formed from amino acids -> glycogenesis and fats -> lipolysis

  Feedback:

  • increase BSL
  • homeostasis 90mg/100mL