1. keep constant
   1. controlled automatically
   2. blood plasma
      1. tissue fluid
      2. leak from capillaries
      3. baths body cells
   3. Bodily Levels
2. Ion
   1. Kidneys
      1. removes excess from blood
         1. urine
            1. water loss
      2. Location
         1. Location 2
   2. sodium (Na+)
   3. food
      1. absorbed into blood
      2. excess ion
         1. remove from body
   4. sweat
      1. ion loss
3. blood sugar
   1. food
      1. carbohydrate
         1. glucose (sugar type)
            1. into blood from gut
   2. normal metabolism
      1. removes glucose
   3. vigorous exercise
      1. removes much more glucose
   4. insulin
      1. adding reduces blood sugar
      2. Diabetes (type 1)
         1. too little insulin produced
4. Water
   1. In
      1. food
      2. drink
   2. loss
      1. skin
         1. sweat
      2. lungs
         1. breath
      3. urine
         1. kidneys
   3. conditions
      1. cold day & no exercise
         1. not sweat
         2. more urine
            1. dilute
            2. pale colour
      2. hot day & lots exercise
         1. sweat more
         2. less urine
            1. concentrated
            2. deeper colour
         3. breath out more
5. Temperature
   1. brain control
      1. personal thermostat
      2. blood temperature
         1. in brain
      3. skin temperature
         1. skin receptors
   2. enzymes
      1. better at 37C
         1. optimum operating temperature
6. Sports drinks
   1. electrolytes
      1. lost in sweat
      2. sodium
   2. carbohydrates
      1. energy boost