BLOOD

Blood volume is usually about 5 litres per person. Blood is made of various types of different cells floating or bathed in a liquid-plasma. Blood cells live for about 4 months Blood has various functions….

Functions of Blood TRANSPORT. PROTECTION. REGULATION: Carries nutrients/ dissolved food substances Carries oxygen to cells Removes carbon dioxide/ waste Involved in carrying hormones and antibodies Provides clotting factors when injured Contains white blood cells to help fight disease Regulates the amount of chemical substances in the tissues Helps maintain body temperature Controls the amount of fluid in the tissues

Components of Blood Red blood cells (main type - erythrocytes): Round donut shape or disc shaped The shape increases the surface area and they can take up more oxygen NO Nucleus Filled with haemoglobin (makes it look red) White blood cells (leukocytes which fight infection) No haemoglobin DO have Nucleus Form part of the immune system which kills unwanted microorganisms Divided into 2 different types: Phagocytes: engulf and eat invaders Lymphocytes: make antibodies to disease Blood also contains platelets, involved in clotting

How does blood carry out some of the functions?? Carrying oxygen via haemoglobin: A red respiratory pigment carried in the red blood cells Contains iron – a lack of iron or low haemoglobin results in anaemia Combines with oxygen to form oxyhaemoglobin

Functions cont… Removing carbon dioxide: CO2 produced by cellular respiration ~ remember Combines with water to form carbonic acid and therefore lowers blood pH This means it can only be carried in small amounts 23% combines to form carbaminohaemoglobin, while the rest is transported in plasma as hydrogen carbonate ions.

NOTE You may have heard of carbon monoxide, this is what is produced by the car exhaust – it is dangerous because it is taken up by the red blood cells quicker than oxygen (300x) as the haemoglobin thinks it is similar. It then means that the oxygen cant be taken up and we will die! See pg. 141-142 and pg. 157

Blood cells are produced in bones – red marrow at the ends of the long bones, and in flat bones like ribs, skull and pelvis Platelets are fragments of cells and are involved in preventing blood loss and clotting: - Plasma proteins are also involved in clotting. - Albumen makes the blood viscous and thick - Globulin destroys the germs and is involved with the antibodies - Fibrinogen clots the blood.

Blood Transfusions People receive blood transfusions for various reasons They sometimes involve just using plasma, not whole blood Serum is plasma with the fibrinogen removed A large loss of blood which may result in a transfusion being required is called a haemorrhage The blood given must be compatible with the persons blood receiving the transfusion (same blood group) If its not compatible the blood clumps together, forming clots and leads to death.

Haemorrhage If someone haemorrhages the body goes into a clotting process: The platelets come and make the wound sticky Fibrinogen starts to be produced and then thrombin comes along to convert it to fibrin Fibrin forms long sticky threads which attach to the leaky vessel wall and forms a web This catches the red blood cells and forms the clot NOTE: without clotting factors someone can bleed to death. Have you heard of haemophilia??