Human circularion

• Diffusion is very useful and important to move particles from a high to low concentration gradient
• in multicellular organisms diffusion is very hard to work throughout the entire organism, which is why specialized cells are required.
• The larger the object, the smaller the surface area, which means that diffusion will not occur from one side of the body to another
• •Red blood cells carry out diffusion in our body


  •Arteries take blood away from the heart and have the highest pressure
• •An artery has the thickest inner layer to withstand the high pressure


  •Capillaries give the nutrients needed to the cells. Therefore they have the thinnest layer also because the pressure is not as high.
• •Superior vena cava takes blood from the brain to the heart


  •Inferior vena cava takes blood from the body to the heart
• •Hepatic vein takes blood from the liver to the heart


  •Renal vein takes blood to the kidney•Hepatic portal vein takes blood from the stomach to the liver
• •Carotid artery takes blood to the brain


  •Aorta is the main artery
• •Pulmonary vein takes blood from lungs to the heart
• •Red blood cells (erythrocytes (Iron (III) ions (Fe3+) gives it the red color) are needed to carry oxygen around the body
• •White blood cells (leucocytes) are needed to provide protection against foreign particles in our bodies such as viruses and bacteria.
• The shape of a red blood cell is biconcave. This shape provides a high oxygen storage and surface area and allows the cells to be slightly flexible. Erythrocytes don’t have a nucleus to provide more space for oxygen to bind to hemoglobin which gives the blood its red color
• Plasma proteins are soluble proteins in blood plasma. There are three kinds:


  Albumin - makes the blood thick and viscous
• •Globulin – is the protein of which antibodies are made. This is produced by the lymph cells for destroying germs.


  •Fibrinogen – is responsible for blood clotting
• The functions of blood

  Transportation:

  •1) It carries oxygen from lungs to tissue, and carbon dioxide from tissue to the lungs•2) it carries dissolved food substances from the gut to other parts of the body•3) it carries unwanted substances, including urea, to the kidneys which get rid of them•4) it carries hormones from endocrine glands to other parts of the body•5) it carries antibodies from one part of the body to another
• Protection:

  •1) By clotting , it prevents fluid being lost from cuts and wounds•2) It protects us against disease by killing germs

  Regulation

  •1) it helps to control the amount of water in tissues•2) it helps the control the amounts of various chemical substances in the tissues•3) It helps to keep our body temperature constant by absorbing and/or losing heat at the surface of the body, and distributing it evenly around the body