osmoregulation

• What is negative feedback in biological systems?

  • Mechanism to restore normal conditions
  • Returns system to original state
  • Example: temperature regulation
• What is the normal body temperature in degrees Celsius?

  37 degrees C
• What does osmoregulation control in the blood?

  Water potential
• What are the two types of blood water potential deviations?

  Hypertonic and hypotonic
• What does hypertonic blood indicate?

  Too low water potential
• What does hypotonic blood indicate?

  Too high water potential
• What happens to cells in hypertonic blood?

  Cells shrivel due to water loss
• What happens to cells in hypotonic blood?

  Cells burst due to excess water
• What factors can cause hypertonic blood?

  • Excessive sweating
  • Not drinking enough water
  • High salt intake
• What factors can cause hypotonic blood?

  • Drinking too much water
  • Low salt intake
• What happens to urine when blood water potential is low?

  Urine becomes more concentrated
• What happens to urine when blood water potential is high?

  Urine becomes more dilute
• What roles do the hypothalamus and posterior pituitary gland play in osmoregulation?

  • Hypothalamus detects water potential changes
  • Produces antidiuretic hormone (ADH)
  • Posterior pituitary gland releases ADH into blood
• What triggers the hypothalamus to produce more ADH?

  Low water potential in blood
• What triggers the hypothalamus to produce less ADH?

  High water potential in blood
• What is the function of antidiuretic hormone (ADH)?

  • Increases water reabsorption in kidneys
  • Makes urine more concentrated
  • Acts on collecting ducts and distal convoluted tubule
• How does ADH affect the permeability of kidney tubules?

  Increases permeability to water
• What are aquaporins?

  Channel proteins for water movement
• How does ADH increase aquaporin presence in kidney cells?

  • Binds to receptors on kidney cells
  • Activates phosphorylase enzyme
  • Causes vesicles to fuse with cell membrane
• What happens when ADH is released into the blood?

  More water is reabsorbed into blood
• What is the overall process of osmoregulation?

  • Detect changes in blood water potential
  • Adjust ADH levels accordingly
  • Regulate water reabsorption in kidneys
  • Maintain normal blood water potential
• What is the significance of osmoregulation in homeostasis?

  Maintains constant water potential in blood
• What is the relationship between osmoregulation and negative feedback?

  • Osmoregulation is a negative feedback mechanism
  • Restores blood water potential to normal levels
  • Involves hypothalamus, ADH, and kidneys
• What are osmoreceptors responsible for?

  Detecting changes in blood water potential
• What happens to osmoreceptors when blood water potential is low?

  They shrivel and stimulate ADH production
• What happens to osmoreceptors when blood water potential is high?

  They swell and inhibit ADH production
• What is the effect of high salt intake on blood water potential?

  It can cause hypertonic blood
• What is the effect of excessive sweating on blood water potential?

  It can cause hypertonic blood