Blood

• Blood consists of red blood cells, white blood cells, platelets and plasma
• Composition of human blood

  A) plasma

  B) red blood

  C) white blood

  D) platelets

  
• Components of the Blood Table

  A) biconcave discs

  B) nucleus

  C) protein haemoglobin

  D) large

  E) big

  F) nucleus

  G) structures

  H) functions

  I) fragments

  J) straw

  K) liquid

  
• You need to be able to identify red and white blood cells in photomicrographs and diagrams

  • Red blood cells have a concave disc shape with no nucleus
  • White blood cells are usually round in shape with a nucleus
• • Blood micrograph

  A) red blood

  B) white blood

  C) platelet

  
• Plasma is important for the transport of carbon dioxide, digested food (nutrients), urea, mineral ions, hormones and heat energy
• Red blood cells transport oxygen around the body from the lungs to cells which require it for aerobic respiration

  • They carry the oxygen in the form of oxyhaemoglobin
• White blood cells defend the body against infection by pathogens by carrying out phagocytosis and antibody production
• Platelets are involved in helping the blood to clot
• Platelets are fragments of cells which are involved in blood clotting and forming scabs where the skin has been cut or punctured

  • Blood clotting prevents continued / significant blood loss from wounds
• Scab formation seals the wound with an insoluble patch that prevents entry of microorganisms that could cause infection

  • It remains in place until new skin has grown underneath it, sealing the skin again
• White blood cells are part of the body’s immune system, defending against infection by pathogenic microorganisms

  • There are two main types, phagocytes and lymphocytes
• Phagocytes - carry out phagocytosis by engulfing and digesting pathogens

  A) multi-lobed nucleus

  B) cell membrane

  C) bacterial pathogen

  D) engulfed

  E) phagocyte

  F) phagocytosis

  G) granules

  H) digestive

  I) enzymes

  J) phagosome

  K) digestive enzymes

  L) bacteria

  
• Phagocytosis

  • Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
  • Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
  • They can be easily recognised under the microscope by their multi-lobed nucleusand their granular cytoplasm
• Lymphocytes

  • Produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens
  • They can easily be recognised under the microscope by their large round nucleuswhich takes up nearly the whole cell and their clear, non-granular cytoplasm
• Platelets are fragments of cells which are involved in blood clotting and forming scabs where the skin has been cut or punctured

  • Blood clotting prevents continued / significant blood loss from wounds
  • Scab formation seals the wound with an insoluble patch that prevents entry of microorganisms that could cause infection
  • It remains in place until new skin has grown underneath it, sealing the skin again
• How the blood clotsHow the blood clots

  A) broken

  B) vessel wall

  C) red blood

  D) soluble fibrinogen proteins

  E) insoluble fribin

  F) platelets release chemicals

  G) blood clot

  H) activated platelets

  
• When the skin is broken (i.e. there is a wound) platelets arrive to stop the bleeding and a series of reactions occur within the blood plasma

  • Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot
  • The clot eventually dries and develops into a scab to protect the wound from bacteria entering
• Erythrocytes - red blood cells
• Lymphocytes and phagocytes - white blood cells
• Lymphocytes

  • produce antibodies and antitexins
  • can turn into memory cells
  • there are two types: B cells and T cells (kills infected cells)
  • ribosomes make antibiodies
• Erythrocytes

  • carries oxygen
  • biconcave disc for more surface area
  • no nucleus for more surface area
  • flexible fit
• Phagocytes

  • detect pathogens and engulfs them
  • digests pathogens
  • has a lobed nucleus
• Platelets

  • causes clotting and forms a scab
• Plasma

  • transports nutrients - protein, electrolytes, urea, CO2, glucose
  • made up of liquids