Red Blood Cells (SQA National 5 Biology): Revision Note

Structure & function of red blood cells

• Red blood cells are specialised cells that carry oxygen to respiring cells

• They are adapted for this function in three key ways:

  • Red blood cells are packed with haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin

  • They have no nucleus, which allows more space for haemoglobin to be packed in

  • Red blood cells have a biconcave disc shape, which means they are thinner in the middle than at the edges

    • This shape gives them a larger surface area to volume ratio, allowing oxygen to diffuse in and out quickly and efficiently