2.3 Cell Transport

• The immediate environment of a cell is the extracellular fluid or tissue fluid. It allows a continual exchange of materials into and out of the cell
• when body systems work together to ensure that the cellular environment is kept constant is called homeostasis. Kept at constant temperature and constant concentration
• Substances that all cells require : glucose and oxygen. It produces carbon dioxide, water and energy which need to be removed
• the cell membrane is represented through a fluid mosaic model because it is made up of many different molecules and is constantly changing position
• main structure of membrane is formed from phospholipid molecules which are lipid molecules containing a phosphate group.
• phospholipids are arranged in two layers known as a bilayer. Phospholipid head which is hydrophilic (loves water) and a tail that is hydrophobic (hates water)
• fluid mosaic model

  A) Bilayer

  B) Extracellular fluid

  C) phospholipid

  D) hydrophilic head

  E) hydrophobic tails

  F) hydrophilic head

  G) cytoplasm