Biology Form 4(Chapter 10)

• Circulatory system


  A system that transports substances such as oxygen, nutrients, and waste products to and from the body's cells
• Unicellular organisms like amoeba can rely on diffusion for their transport needs because they have a small body mass and large total surface area to volume ratio
• Multicellular organisms cannot rely on diffusion alone and require a circulatory system to rapidly transport substances throughout the body
• Experiment to determine total surface area to volume ratio

  1. Prepare agar with phenolphthalein

  2. Cut agar into 3 different sizes

  3. Add sodium hydroxide solution

  4. Observe color change and calculate ratio
• As the size of an organism increases, its total surface area to volume ratio decreases
• Open circulatory system


  Invertebrates have this system with one or more muscular hearts, where the hemolymph (blood) flows directly into the body cavity (hemocoel) and bathes the cells
• Closed circulatory system


  Blood is always contained in a continuous system of blood vessels, does not mix with the interstitial fluid, and rapidly flows back to the heart
• Differences between open and closed circulatory systems

  • In open, hemolymph mixes with interstitial fluid and flows at a slower speed
  • In closed, blood does not mix with interstitial fluid and flows rapidly back to the heart
• Insect circulatory system


  • Has an open circulatory system with a heart with segmented chambers and ostia (pores) to allow hemolymph to enter
  • Hemolymph transports nutrients and hormones but not respiratory gases, which are transported in the tracheal system
• Fish circulatory system


  • Has a single, closed circulatory system with a two-chambered heart (one atrium, one ventricle)
  • Blood flows through the heart once in a complete circulation, with deoxygenated blood going to the gills and oxygenated blood going to the systemic circulation
• Amphibian circulatory system


  • Has a closed, incomplete double circulatory system with a three-chambered heart (two atria, one ventricle)
  • Mixing of oxygenated and deoxygenated blood occurs in the ventricle
  • Has a pulmo-cutaneous circuit for gas exchange in the lungs and skin, and a systemic circuit
• Blood flow in amphibian circulatory system

  1. From heart to lungs

  2. Back to heart

  3. To systemic capillaries

  4. Back to heart
• Amphibian circulatory system


  Close and incomplete double circulatory system
• Amphibian heart has 3 chambers: 2 atria, 1 ventricle</b>
• Mixing of blood happens in the ventricle


  Because amphibian heart has only 1 ventricle
• Human circulatory system


  1. Oxygenated blood from lungs flows to left atrium

  2. Deoxygenated blood from body flows to right atrium

  3. Blood from both atria enters ventricle

  4. Ventricle pumps oxygenated blood to body via aorta

  5. Deoxygenated blood from body flows to right atrium
• Human circulatory system


  Complete, closed, double circulatory system
• Two major circulations in human

  • Pulmonary circulation
  • Systemic circulation
• Pulmonary circulation


  1. Deoxygenated blood from right ventricle to lungs

  2. Oxygenated blood from lungs to left atrium
• Systemic circulation


  1. Oxygenated blood from left ventricle to body tissues

  2. Deoxygenated blood from body tissues to right atrium
• Smaller organisms have larger surface area to volume ratio
• Fish have single circulatory system, 2 heart chambers
• Humans have double circulatory system, 4 heart chambers
• Fish have lower blood pressure, slower blood flow
• Humans have higher blood pressure, faster blood flow
• Flatworms do not require specialized transport system
• Insects have tracheal system to transport oxygen
• Circulatory system


  Transports essential substances to the body cells and also transport waste products from the cells to be eliminated
• Components of the human circulatory system

  • Heart
  • Blood vessels
  • Blood
• Heart


  Pumps blood which carries vital materials required by the body and also the waste products that needs to be excreted out from the body
• Blood vessels


  Transport the blood from the system to the body cells and the blood flows in the blood vessels that function to carry substances that are needed to be transported
• Blood is only 8% of the human body and we have about 4 to 6 liters of blood on average
• Components of blood


  • Plasma (55%)
  • Cell components (45%)
• Separating blood components


  Centrifuging a sample in a centrifugal machine
• Components of whole blood

  • Red blood cells
  • White blood cells
  • Platelets
• Blood plasma


  Light yellow coloured liquid, consists of 90% water and 10% dissolved substances
• Dissolved substances in blood plasma

  • Plasma proteins
  • Dissolved gases
  • Digestive products
  • Excretory substances
  • Hormones
  • Minerals
• Plasma proteins


  Albumin required to keep viscosity and osmotic equilibrium, Antibodies (globulin) for immunization, Blood clotting factors (fibrinogen and prothrombin)
• Red blood cells


  Biconcave in shape for large surface area to volume ratio, No nucleus but contain hemoglobin which binds oxygen, Developed in bone marrow, Circulate for 120 days then destroyed in liver and spleen
• Blood is not blue, veins may appear blue due to the level of oxygen in the blood