Hormones and Homeostasis

• What is the endocrine system made up of?

  Glands that secrete hormones
• How do hormones affect target cells?

  They bind to specific receptors on cells
• How do the effects of hormones compare to the nervous system?

  Hormonal effects are slower and longer-lasting
• What is the pituitary gland often referred to as?

  The 'master gland'
• What does the pituitary gland secrete in response to?

  Body conditions
• What is the role of some hormones secreted by the pituitary gland?

  To stimulate other glands to release hormones
• What is adrenaline produced by?

  The adrenal glands
• When is adrenaline produced?

  In times of fear or stress
• What effect does adrenaline have on the heart rate?

  It increases the heart rate
• What does adrenaline boost the delivery of to the brain and muscles?

  Oxygen and glucose
• What is the purpose of adrenaline in the body?

  To prepare the body for 'flight or fight'
• What is thyroxine produced by?

  The thyroid gland
• What does thyroxine increase?

  The metabolic rate
• What does thyroxine control in young animals?

  Growth and development
• How is thyroxine regulated?

  By negative feedback
• Key Point

  Enzymes from glands like the salivary glands pass into tubes called ducts. Endocrine glands are sometimes called ductless glands, because the hormones pass into the blood.
• What organ monitors and controls blood glucose concentration?

  Pancreas
• What happens when blood glucose concentration is too high?

  The pancreas releases more insulin
• What does insulin do to glucose in the blood?

  It causes glucose to move into cells
• What is excess glucose converted to in liver and muscle cells?

  Glycogen
• What occurs when blood glucose concentration is too low?

  The pancreas releases glucagon
• What does glucagon stimulate in the body?

  Conversion of glycogen back to glucose
• What causes Type 1 diabetes?

  Insufficient insulin production by pancreas
• What is a consequence of Type 1 diabetes?

  Uncontrolled high blood glucose levels
• How is Type 1 diabetes normally treated?

  Monitoring blood sugar and injecting insulin
• What causes Type 2 diabetes?

  Body cells lose ability to respond to insulin
• What is a risk factor for Type 2 diabetes?

  Obesity
• How can Type 2 diabetes often be treated?

  Carbohydrate-controlled diet and exercise
• What do people with Type 2 diabetes often need to take?

  Drugs to control blood sugar levels
• How does insulin affect blood glucose levels in Type 1 diabetes?

  It stimulates liver to convert glucose to glycogen
• Why is there little effect of insulin in Type 2 diabetes?

  Cells do not respond to insulin
• Key Point

  Type 1 diabetes cannot be treated by controlling the diet. Type 2 diabetes is not normally treated with insulin.