Microscope drawing of blood smear THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood composition Blood consists of a pale yellow fluid called plasma in which are suspended white blood cells, platelets and red cells. Centrifuged whole blood Microscope drawing of blood smear white cells red cells plasma white cells red cells If blood is centrifuged the cells precipitate leaving the plasma as a supernatant. Here is a photograph of a blood smear taken down a microscope

Microscope drawing of blood smear THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood composition Can you label the arrows? plasma Microscope drawing of blood smear Plasma transports: Carbon dioxide from the organs to the lungs Soluble products of digestion from the small intestine to other organs Urea from the liver to the kidneys Plasma contains a variety of dissolved solutes such as urea, glucose, hormones. platelet red blood cell whiteblood cell It also contains plasma proteins that remain in the blood all the time.

Microscope drawing of blood smear IGCSE BIOLOGY – 11.7 TRANSPORT THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood composition Microscope drawing of blood smear white cells White cells: Have a nucleus Form part of the body’s defence system against microbes

Microscope drawing of blood smear THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood composition Red cells Have no nucleus Microscope drawing of blood smear Are packed with a red pigment called haemoglobin In the lungs oxygen combines with haemoglobin to form oxyhaemoglobin red cells In other organ oxyhaemoglobin splits into haemoglobin +O2

Microscope drawing of blood smear THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood composition Design features of red blood cells for oxygen carriage Microscope drawing of blood smear No nucleus making more room for haemoglobin Doughnut shaped giving greater surface area for gas exchange red cells

II.7 ANIMAL TRANSPORT Platelets Blood composition THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood composition Platelets Platelets are small fragments of cells Platelets have no nucleus Platelets help blood to clot at the site of a wound platelets Light microscope photograph of a stained blood sample (X3000) Platelets are stained blue

II.7 ANIMAL TRANSPORT White blood cells The immune system THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP The immune system White blood cells If pathogens gain entry to the body 2 types of white cells attack them: lymphocyte Makes antibodies which attach to the pathogen and help disable or destroy it Produces antitoxins which neutralise any toxins produced by the pathogen phagocyte Phagocytic - engulfs the pathogen and digests it. Microscope photo of a human blood smear

II.7 ANIMAL TRANSPORT White blood cells The immune system Phagocyte. THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP The immune system White blood cells – phagocytosis and antibody action Pathogen engulfed by white cell engulfs and digests pathogens by phagocytosis Invading pathogens usually a bacteria or viruses Phagocyte. Pathogen toxin produces antibodies to attack the pathogens or their toxins Lymphoctye Pathogen or toxins produced by the pathogen antibody

II.7 ANIMAL TRANSPORT Re-infection The immune system THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP The immune system Re-infection Once they have produced antibodies against a particular bacterium or virus, white memory cells can produce them quicker, and in greater quantity if the pathogen returns, giving the person immunity against that disease Memory cells: rapid and massive antibody production Level of antibody in the blood The pathogen is eliminated but the damaging symptoms of disease will have already occurred The pathogen is eliminated before disease symptoms and dangers occur Time initial infection infection over new infection

II.7 ANIMAL TRANSPORT Vaccination The immune system THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP The immune system Vaccination Introducing a mild or dead form of the disease into a person causes the production of antibodies without the symptoms of disease HOW VACCINATION WORKS Memory cells: rapid and massive antibody production Level of antibody in the blood The pathogen is eliminated before disease symptoms and dangers occur Antibodies produced but no disease symptoms Time Vaccination with mild or dead pathogen Infection with the real virulent pathogen

II.7 ANIMAL TRANSPORT Blood clotting IGCSE BIOLOGY – 11.7 TRANSPORT THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood clotting When a blood vessel is damaged, either by a cut or other means, the blood clots for 2 reasons: To prevent leakage of blood To prevent the entry of pathogens How clotting happens: There is a protein called ___________ which circulated in the blood. At points of damage in blood vessels this protein is converted to _______, a net like protein which catches red blood cells and forms a tangle, or clot. fibrinogen A blood clot forming – the blood protein fibrin (white) acts like a net at the point of damage. It catches red blood cells and they form a clump which blocks the opening in the blood vessel fibrin

II.7 ANIMAL TRANSPORT Blood clotting IGCSE BIOLOGY – 11.7 TRANSPORT THE HEART THE IMMUNE SYSTEM II.7 ANIMAL TRANSPORT CIRCULATORY SYSTEM THE LYMPHATIC SYSTEM BLOOD AND BLOOD CELLS ROUND UP Blood clotting White blood cells move to the clot to kill bacteria of viruses entering through the point of damage white blood cell ‘puss’ a mixture of fibrin and dead white blood cells fibrin trapped red blood cell

CLICK HERE TO RETURN TO THE CIRCULATORY SYSTEM IGCSE BIOLOGY – 11.7 TRANSPORT II.7 ANIMAL TRANSPORT CLICK HERE TO RETURN TO THE CIRCULATORY SYSTEM William Harvey was born in England in 1578. In 1628 Harvey published An Anatomical Study of the Motion of the Heart and of the Blood in Animals which explained how blood was pumped from the heart throughout the body, then returned to the heart and recirculated. The views this book expressed were very controversial and lost Harvey many patients, but it became the basis for all modern research on the heart and blood vessels.

Immunity Types of immunity Natural active immunity Immune system activation due to infection Artificial active immunity (vaccination) Immune system activation by vaccination Artificial passive immunity Injection with antibodies. Used against potentially fatal and fast acting diseases e.g. tetanus antitoxin Natural passive immunity Mother’s antibodies crossing the placenta e.g. measles. Also IgA in colostrum prevents bacterial / viral growth