Regulation of Water Content in the Human Body

Importance of Water in the Body

• Water constitutes about 60% of body weight.
• Vital for normal functioning and life.
• Important to control water content in the blood to prevent cell damage.

Osmosis and Cell Impact

• High Water Concentration in Blood: Water moves into body cells by osmosis which may cause cells to burst if too much water is absorbed.
• Low Water Concentration in Blood: Water moves out of cells into the blood, causing cells to shrink.

Role of Kidneys and Brain

• Kidneys: Work with the brain to regulate bodily water content by controlling water and salt reabsorption.
• ADH (Antidiuretic Hormone):
  • Controls water reabsorption in kidney nephrons.
  • Makes nephron collecting ducts more permeable for more water reabsorption into the blood.
• Brain's Role:
  • Monitors water content in the blood.
  • Instructs pituitary gland to secrete ADH based on the body's needs.

Factors Affecting Blood Water Concentration

• Drinking lots of water increases blood water content.
• Sweating reduces blood water content.
• Eating salty foods reduces blood water content.

Negative Feedback System

• Decrease in Blood Water Content:
  • Brain receptor detects low water content.
  • Coordination center organizes response.
  • Pituitary gland releases more ADH.
  • More water reabsorbed from kidneys, producing concentrated urine.
  • Blood water content returns to normal.
• Increase in Blood Water Content:
  • Brain detects high water content.
  • Pituitary gland releases less ADH.
  • Less water reabsorbed, producing dilute urine.
  • Blood water content returns to normal.

Implications for Healthcare

• Medicines and illnesses can affect body water regulation.
• Pharmacists and healthcare workers must understand this process to manage patient care effectively.