4.2.2.3 blood

• What type of tissue is blood?

  Blood is a tissue
• What are the primary functions of blood in animals?

  Transport of substances and defense against disease
• What are the four main components of blood in humans?

  • Plasma: 55%
  • White blood cells: 4%
  • Platelets: 4%
  • Red blood cells: 41%
• What is the primary function of red blood cells?

  Transport oxygen from lungs to tissues
• What pigment do red blood cells contain?

  Haemoglobin
• Why do red blood cells have no nucleus?

  To provide more space for haemoglobin
• What advantage do small and flexible red blood cells provide?

  They can squeeze through narrow capillaries
• What are platelets?

  Cell fragments involved in blood clotting
• What do platelets release during blood clotting?

  Blood clotting enzymes
• What happens when a wound is detected by platelets?

  They form a net to stop blood loss
• How do platelets help prevent infections?

  By stopping blood from leaving the body
• What is the primary function of white blood cells?

  Protect the body from infection
• What is the size comparison of white blood cells to other blood cells?

  They are the biggest type of blood cell
• What type of nucleus do white blood cells have?

  They have a lobed nucleus
• Why can white blood cells reach invading pathogens?

  They can squeeze through small blood vessels
• What is plasma?

  The liquid that carries dissolved substances
• What waste product does plasma carry from respiration?

  Carbon dioxide
• What is another waste product carried by plasma?

  Urea
• What nutrients does plasma carry that are needed by the body?

  Glucose for respiration
• What other substances does plasma carry?

  Hormones