homeostasis

• What is homeostasis?

  The maintenance of a constant internal environment through corrective mechanisms and negative feedback.
• What is negative feedback?

  a mechanism by which a deviation from normal levels causes the body to counteract the change and restore to normal levels
• What are the steps involved in negative feedback?

  1. Change in internal environment (Stimulus)
  2. Receptor detects the change
  3. Control centre triggers corrective mechanisms
  4. Corrective mechanism removes the stimulus
  5. Internal environment returns to normal condition/set-point
  6. Receptor stops corrective mechanism once set-point is reached
• What are some factors controlled by homeostasis?

  Temperature, blood water potential, blood pressure, blood pH, blood CO2 concentration, blood glucose concentration, and water content in urine.
• What is an endocrine gland?

  A ductless gland that secretes hormones directly into the bloodstream.
• How does insulin affect blood glucose levels?

  Insulin increases the permeability of liver and muscle cells to glucose, decreasing blood glucose levels.
• What is the role of glucagon in blood glucose regulation?

  Glucagon converts glycogen to glucose in the liver, increasing blood glucose levels.
• What are the differences between insulin and glucagon?

  • Insulin:
  • Released when blood glucose is high
  • Targets liver and muscles
  • Decreases blood glucose levels
  • Glucagon:
  • Released when blood glucose is low
  • Targets liver only
  • Increases blood glucose levels
• What condition is diabetes mellitus?

  It is the condition where the body is unable to maintain blood glucose levels within the normal range.
• What characterizes Type I diabetes?

  The pancreas cannot produce enough insulin and it develops at a young age.
• What characterizes Type II diabetes?

  Target organs lose sensitivity to insulin and it develops at an older age, linked to an unhealthy lifestyle.
• What are common symptoms of diabetes mellitus?

  Persistent high blood glucose, glucose in urine, frequent urination, dizziness, fatigue, unexpected weight loss, and slow healing of wounds.
• What are some risk factors for diabetes?

  Obesity, age, family history, unhealthy blood lipid levels, and a sedentary lifestyle.
• What are the prevention strategies for diabetes?

  • Exercise regularly
  • Maintain a healthy body weight
  • Eat a balanced, healthy diet low in calories and high in fiber
• What are the treatment options for diabetes?

  • Type 1: Insulin injections
  • Type 2:
  • Control blood glucose levels
  • Diet lower in carbohydrates
  • Regular exercise
  • Medication if condition worsens
• What is osmoregulation?


  The process of controlling the water potential and solute concentrations in blood to maintain constant water potential in the body
• How does osmoregulation work?

  It works by negative feedback to restore the set-point of blood water potential.
• What are osmoreceptors?

  Cells in the hypothalamus that detect changes in blood water potential.
• What is the role of Antidiuretic Hormone (ADH)?

  ADH is secreted by the pituitary gland in response to changes in blood water potential.
• What happens to ADH secretion when water potential decreases?

  • Osmoreceptors detect decreased water potential
  • Pituitary gland secretes more ADH
  • Collecting ducts become more permeable to water
  • More water is reabsorbed into the blood
  • Urine becomes less dilute/more concentrated
• What happens to ADH secretion when water potential increases?

  • Osmoreceptors detect increased water potential
  • Pituitary gland secretes less ADH
  • Collecting ducts become less permeable to water
  • Less water is reabsorbed into the blood
  • Urine becomes more dilute/less concentrated
• What does sweat contain?

  Sweat contains water, salts (mainly sodium chloride), and small amounts of urea.
• What is the function of adipose tissue?

  Adipose tissue reduces heat loss through the skin as it is a poor conductor of heat.
• How does negative feedback relate to temperature regulation?

  Negative feedback involves detecting changes in internal environment and triggering corrective mechanisms to restore the set-point.
• What are the responses to changes in internal temperature?

  • **M**etabolic Rate: Increases when too cold, decreases when too hot
  • **A**rterioles in the skin: Constrict when too cold, dilate when too hot
  • **S**weat Glands: Secrete less sweat when too cold, more sweat when too hot
  • **S**hivering: Begins when too cold, does not occur when too hot
• What happens to metabolic rate when the body is too cold?

  Metabolic rate increases.
• What happens to arterioles in the skin when the body is too hot?

  Arterioles in the skin dilate.
• What is the effect of sweating when the body is too hot?

  More sweat is secreted, leading to more evaporation and loss of latent heat.
• What is the relationship between temperature and shivering?

  Shivering begins when the body is too cold.
• How do you remember the response of arterioles in the skin to temperature changes?

  When it is cold, arterioles in the skin constrict.
• stimulus

  the change in the internal environment
• receptors

  detect the stimulus and sends signals to the control centre
• corrective mechanism

  brings about the reverse effect of the stimulus
• what is a hormone?

  a chemical substance that is secreted by the endocrine gland in minute quantities which is transported in the blood to target organs where it exerts its effect