Cards (143)

  • The cells of all living organisms need a constant supply of reactants for metabolism, such as oxygen and glucose
  • What are two examples of reactants required for metabolism?

    Oxygen and glucose
  • Single celled organisms can gain the reactants for metabolism from their surroundings and the molecules can diffuse to all parts of the cell quickly due to short diffusion distances
  • Why can molecules diffuse into all parts of a single celled organism quickly?
    It has short diffusion distances
  • Large organisms have large diffusion distances due to their low surface area to volume ratio, meaning that the time taken to diffuse metabolites into every cell in the body would be too long.
  • Why do larger organisms have large diffusion distances?
    They have a low surface area to volume ratio, and the metabolite would have to diffuse through many layers of cells
  • Why do smaller organisms have short diffusion distances?
    They have a large surface area to volume ratio
  • Larger organisms have developed mass transport systems connected to their exchange surfaces
  • Why have larger organisms developed mass transport systems?
    Their surface area to volume ratio makes them unable to diffuse substances directly from their surroundings into their cells
  • What is mass transport?
    The bulk movement of gases or liquids in one direction, usually via a system of vessels and tubes
  • What are the benefits of mass transport?
    It helps to bring substances quickly from one exchange site to another, and also helps to maintain the diffusion gradients at exchange sites and between cells and their fluid surroundings
  • Mass transport of substances ensure effective cell activity by keeping the immediate fluid environment of cells within a suitable metabolic range
  • What is an example of a mass transport system?
    The circulatory system
  • The circulatory system is a mass transport system as the one way flow of blood within the blood vessels carries essential nutrients and gases in bulk to all the cells of the body
  • What are the two types of circulatory systems?
    Closed and open
  • What is a closed circulatory system?
    The blood is pumped around the body and is always contained within a network of blood vessels
  • What is an open circulatory system?
    Blood is not contained within blood vessels but is pumped directly into body cavities
  • What type of circulatory system do humans have?
    A closed double circulatory system
  • How does a double closed circulatory system work?
    In one complete circuit of the body, the blood passes through the heart twice
  • What are the two different parts of the human circulatory system?
    systemic and pulmonary
  • What is the pulmonary circulatory system?
    The right side of the heart pumping deoxygenated blood to the lungs for gas exchange
  • What is the systemic circulatory system?
    The left side of the heart pumping oxygenated blood at high pressure around the body, which allows a lot of it to be transported quickly
  • Why is the blood pumped at a high pressure in the systemic circulatory system?
    It allows lots of oxygenated blood to be transported quickly
  • What is the heart?
    A hollow, muscular organ located in the chest cavity that pumps blood around the body
  • Where is the heart located?
    In the chest cavity
  • Why is the heart described as a double pump?
    The right side pumps blood to the lungs and the left side pumps blood to the body, meaning that blood flows through the heart twice
  • How many chambers are in the heart?
    Four
  • What are the four chambers of the heart?
    The left atrium, the left ventricle, the right atrium and the right ventricle
  • The left and right sides of the heart are separated by a wall of muscular tissue called the septum
  • What is the septum separating the left and right atria called?
    The interatrial septum
  • What is the importance of the septum in the heart?

    It ensures that the blood doesnt mix between the left and right sides of the heart
  • What is the importance of valves?

    They keep blood flowing forward in the right direction, and stop it from flowing backwards
  • Valves maintain the correct pressure in the chambers of the heart
  • When do valves in the heart open?

    When the pressure of blood behind them is greater than the pressure of the blood in front of them
  • When do the valves in the heart close?

    When the pressure in-front of them is greater than the pressure behind them
  • What are the valves separating the atria and ventricles called?

    Atrioventricular valves
  • What are the valves separating the atria and blood vessels called?

    Semilunar valves
  • What are the four main blood vessels connected to the heart called?
    The aorta, vena cava, pulmonary artery and pulmonary vein
  • What is the pulmonary artery?

    An artery connected to the right ventricle, which carries deoxygenated blood to the lungs where its oxygen is replenished and carbon dioxide is removed
  • What is the aorta?

    An artery connected to the left ventricle and carries oxygenated blood to all parts of the body (except the lungs)