transport systems

• Blood


  Transports materials around the body and helps to protect against diseases
• Body fluids


  • Plasma
  • Cells
• Plasma


  Makes up 55% of the total composition of blood, 90% water, contains digested food, antibodies, hormones, urea & plasma proteins
• Blood components


  • Red blood cells - Transport oxygen & carbon dioxide
  • White blood cells - Ingest pathogens & produce antibodies
  • Platelets - Involved in blood clotting
• Red blood cells


  Also known as erythrocytes
• Erythrocyte life cycle


  1. Produced in the bone marrow

  2. Found in the blood vessels for 3-4 months

  3. Dead red blood cells go to the liver & spleen, iron is recycled
• Red blood cell


  • Biconcave shape
  • No nucleus
  • Binds with oxygen to form oxy-haemoglobin
• Carbon dioxide in the blood

  1. Carbon dioxide dissolves in the blood - plasma and cytoplasm of red blood cells

  2. Red blood cells produce an enzyme (carbonic anhydrase) which helps the reaction of carbon dioxide and water

  3. Carbonic acid (H2CO3) is also found as bicarbonate ions (HCO3-) when dissolved
• White blood cells


  Also known as leucocytes, help to fight against pathogenic organisms
• Types of white blood cells

  • Phagocytes
  • Lymphocytes
• Phagocytes


  1. Can move out of capillaries into tissues

  2. Collect at the site of an infection and engulf (by phagocytosis) and digest harmful bacteria and microbes

  3. Physically attack foreign microbes

  4. Dead white blood cells and microbes form pus
• Lymphocytes


  1. Produce antitoxins that neutralise poisonous chemicals released by bacteria

  2. Produce antibodies (proteins) that fit onto an antigen on the bacterium or virus

  3. Chemically attack foreign microbes

  4. Antibodies work by lock & key, are very specific, stick to the microbes and cause them to burst or glues them together
• Platelets


  Also known as thrombocytes, smallest cellular component of the blood, made up of small cell fragments, made in the bone marrow, responsible for clotting of the blood to stop wounds bleeding
• Blood clotting

  
  

  Prothrombin--> thrombokinase ----> thrombin. Fibrinogen ---->thrombin ---> fibrin
• Haemophilia


  Inability of the blood to clot, factor VIII is absent so fibrin cannot form, blood loss is significant
• Arteries


  Carry blood away from the heart, usually to another organ, have a thicker wall made of muscle and elastic fibres, have a smaller lumen, do not have valves
• Veins


  Carry blood to the heart, coming from another organ, have a thinner wall of muscle and elastic fibres, have a larger lumen, have semi-lunar valves to prevent backflow of blood
• Capillaries


  Connect arteries to veins, usually found at an organ, provide a large surface area for diffusion of substances
• Heart


  • It is an organ (made of different tissues) that pumps blood through the body
  • It is made of cardiac muscle that is able to work without getting tired
  • It has four chambers - two atria (top) and two ventricles (bottom)
  • Its left and right sides are divided by a septum (=wall) - the left deals with oxygenated blood, while the right deals with deoxygenated. This is important to prevent mixing of oxygenated and deoxygenated blood
  • One atrium and ventricle found on each side
• Blood Flow through the Heart

  1. Deoxygenated blood from the rest of the body enters the right atrium through the vena cava

  2. The right atrium contracts, pushing the blood to the right ventricle

  3. The right ventricle contracts (tricuspid valve closes) and blood is pushed out of the heart through the pulmonary artery

  4. Deoxygenated blood goes to the lungs, becomes oxygenated, and returns to the left atrium via the pulmonary vein

  5. The left atrium contracts, pushing the blood to the left ventricle

  6. The left ventricle contracts (bicuspid valve closes) and blood is pushed out of the heart through the aorta

  7. Oxygenated blood goes to the rest of the body

  8. Body organs use up the oxygen and send the now deoxygenated blood back to the heart via the vena cava
• Cardiac Cycle


  The rhythm of heart beats, very regular - between 50 and 75 beats per minute in adult humans, affected by exercise, excitement, fright, age, gender, general health
• Cycles of Contraction


  1. Atria

  2. Ventricles
• Lymphatic System


  Major functions: Collection of excess tissue fluid (and formation of lymph), Return of leaked fluid to cardiovascular system, Production of immune system proteins - lymphocytes present, Transport of digested lipids from small intestinal lacteals
• Removal of Excess Tissue Fluid

  1. Tissue fluid leaves the arteriole end

  2. The fluid that never makes it back to the capillaries is picked up by the lymph vessel

  3. Lymph drains in the subclavian vein and returns to the blood circulatory system
• Production of lymphocytes which kill and filters off any pathogens
• Absorption of fat molecules that are too large to pass through a capillary, returned to the blood circulatory system through the subclavian vein