Transport of Nutrients, Gases and Other Molecules

• The gas exchange specifically happens in the alveoli within the lungs. The mechanism for the exchange of gases between the alveoli and the blood in the capillaries is diffusion.
• The major system responsible for the distribution and pumping of the blood is the circulatory system.
• There are two major circulatory loops namely:

  • the systemic circulation, and
  • the pulmonary circulation.
• Blood


  transports dissolved substances around the body including hormones, water, sugar, proteins, minerals and vitamins, and waste substances such as carbon dioxide and urea
• Transport Materials Through Blood

  • through the plasma
  • red blood cells
• Transport of Materials via Blood Plasma

  • The absorbed nutrients in the digestive system are directly dissolved in the plasma for immediate transport.
  • Hormones are secreted by the hormonal organs into the blood which mix directly to the plasma
  • Waste materials like excess salts and urea are also transported by the blood through incorporation to plasma.
• Red blood cells

  • are round and flat cells with an indentation in the center like doughnuts without a hole.
  • transport materials at maturity. Within an RBC, an oxygen-carrying protein, hemoglobin is highly abundant.
• Hemoglobin

  • The iron-containing protein present in the red blood cells.
  • It carries oxygen and carbon dioxide to the different parts of the body.
• Hemoglobin in Red blood cell

  • The heme group binds oxygen tightly when the concentration of oxygen is very high and quickly releases it when the concentration is low.
• RBC Diagram

  A) Red Blood Cell

  B) Hemoglobin

  C) Oxygen Molecule

  
• • When hemoglobin is loaded with oxygen, it can be referred to as oxyhemoglobin. It is characterized by a bright red color.
• • Deoxyhemoglobin is the form of hemoglobin without oxygen that is purple to bluish.