Basics

• What is homeostasis?


  The maintenance of a stable internal environment
• What can changes in your external environment do?


  Affect your internal environment
• What is your internal environment?


  the blood and tissue fluid that surrounds your cells
• What does homeostasis involve?


  Control systems that keep your internal environment roughly constant (within certain LIMITS)
• why is keeping internal environment stable important?


  • vital for cells to function normally and stop cells being damaged
• Why is it particularly important to maintain the right core body temp and blood pH?


  temp and pH affect enzyme activity and enzymes control the rate of metabolic reactions
• What happens if body temp is too high eg 40 degrees?

  • enzymes may become denatured because:
  • enzymes molecules vibrate too much = breaks the hydrogen bonds that hold them in their 3D shape
  • shape of enzyme' active site changed and it no longer works as a catalyst
  • = metabolic reactions are LESS EFFICIENT
• What happens if body temp is too low?


  Enzyme activity is reduced, slowing down rate of metabolic reactions
• what happens at 37 degrees?


  The highest rate of enzyme activity happens at their optimum temp- about 37 for humans
• What happens if blood pH is TOO HIGH or TOO LOW?

  Enzymes become denatured:

  • hydrogen bonds holding them in their 3D shape are BROKEN, so the shape of the enzymes active site is changed and it no longer works as a catalyst
  • this means that metabolic reactions are less EFFICIENT
• Why is it important to maintain the right concentration of glucose in the blood?


  Because cells need glucose for ENERGY

  Blood glucose conc also affects WATER POTENTIAL OF BLOOD
• define water potential?


  the potential (likelihood) of water molecules to diffuse out of or into a solution
• What happens if blood glucose concentration is too high?


  The water potential of blood is REDUCED to a point where water molecules DIFFUSE OUT OF CELLS into the BLOOD by OSMOSIS.

  • This can cause the cells to SHRIVEL UP + DIE
• What happens if blood glucose concentration is too LOW?


  Cells unable to carry out normal activities because there is not enough glucose for RESPIRATION to provide ENERGY