Blood

• The circulatory system is made up of the heart, blood, and blood vessels.
• Blood is the fluid that flows in the circulatory system and carries substances around the body.
• For an average adult, there are about 5.5 liters of blood in their body.
• Blood is made up of a liquid called plasma and blood cells that float in this plasma.
• Blood is made up of two liquids.

  A) plasma

  B) 55

  C) blood cells

  D) 45

  
• Blood plasma carries three types of blood cells:

  A) red blood cell

  B) white blood cell

  C) platelet

  
• Blood flows around the body transporting substances from one place to another.
• Plasma is the blood fluid that surrounds blood cells and carries them along as it flows through the blood vessels.
• Plasma is mostly water and contains other substances that are dissolved in it.
• Plasma is mostly water with other substances dissolved with it: Useful substances and Waste substances.
• Useful substances dissolved in plasma are digested food. And must be transported to where it is needed in the body.
• Waste substances dissolved in plasma are carbon dioxide and urea. And must be transported to where it can be removed from the body.
• The digestive system breaks long insoluble molecules of food into small soluble molecules that the body can use. Soluble digested food diffuses from the small intestine into the bloodstream and dissolves in plasma. The digestive food is then carried to the body's cells and used in various chemical reactions.
• Plasma transports these dissolved substances between this body parts.

  A) small intestine

  B) body's cells

  C) body's cells

  D) lungs

  E) liver

  F) kidney

  
• Red blood cells are the most common type of blood cell.
• The job of red blood cell is to transport oxygen from the lungs to the body's cell, where it is used for respiration.
• Red blood cells contain haemoglobin, which contains iron that can bond with oxygen which turns red blood cells to appear color red. Which can help with oxygen transportation.
• Red blood cells has no nucleus so there is more space for haemoglobin and more oxygen. Which can help oxygen transportation.
• Red blood cells are disc-shaped with a dent on each side, creates a large surface area for gas exchange. Which can help oxygen transportation
• Red blood cells have large surface area compared to volume, so oxygen is always close to the surface. Which helps oxygen transportation.