2.2

• What is the main function of the digestive system?

  To digest food and absorb the nutrients obtained from digestion.
• What is the role of the pancreas and the salivary gland in the digestive system?

  They produce digestive juices containing enzymes.
• What is the role of the stomach in the digestive system?

  Produces hydrochloric acid to kill bacteria and provide an optimum pH for protease enzyme function.
• What is the role of the small intestine in the digestive system?

  The small intestine is the site where soluble food molecules are absorbed into the bloodstream.
• What is the role of the liver in the digestive system?

  Produces bile which emulsifies lipids and allows lipase to work more efficiently.
• What is the role of the large intestine in the digestive system?

  Absorbs water from undigested food, producing faeces.
• What is the role of enzymes in the digestive system?

  Enzymes act as biological catalysts that speed up the breakdown of food without being used up.
• How does the shape of an enzyme affect its function?

  Enzymes have a specific active site that is complementary to their substrate.
• What is metabolism?

  The sum of all the reactions in a cell or an organism.
• What types of metabolic reactions do enzymes catalyse?

  • Building larger molecules from smaller molecules (e.g., glucose to starch)
  • Changing one molecule to another (e.g., glucose to fructose)
  • Breaking down larger molecules into smaller molecules (e.g., carbohydrates to glucose)
• What is the lock and key hypothesis of enzyme function?

  The shape of the enzyme active site and the substrate are complementary, allowing them to bind together to form an enzyme-substrate complex.
• How does temperature affect enzyme action?

  Increasing temperature up to a certain point increases enzyme action, but beyond that, the enzyme becomes denatured.
• How does pH affect enzyme function?

  The optimum pH for most enzymes is 7, and extreme pH levels can alter the shape of the active site, affecting enzyme activity.
• Where are carbohydrases, proteases, and lipases produced in the body?

  • Carbohydrases: Amylase (salivary gland and pancreas), Maltase (small intestine)
  • Proteases: Pepsin (stomach), others (pancreas and small intestine)
  • Lipases: Pancreas and small intestine
• What is the role of carbohydrases in the digestive system?

  Carbohydrases break down carbohydrates into monosaccharides and disaccharides.
• What is the role of proteases in the digestive system?

  Proteases break down proteins into amino acids.
• What is the role of lipases in the digestive system?

  Lipases break down lipids into fatty acids and glycerol.
• How are the products of digestion used?

  They are used to build larger molecules such as carbohydrates and proteins, and glucose is used in respiration.
• Where is bile made and stored in the body?

  Bile is made by the liver and stored in the gallbladder.
• What is the role of bile in the digestive system?

  Bile neutralizes hydrochloric acid and emulsifies lipids to increase the surface area for lipase action.
• What is the heart?

  An organ that pumps blood around the body.
• What is the purpose of the circulatory system?

  It carries oxygen and other useful substances to bodily tissues and removes waste substances.
• How does the double circulatory system work?

  • One pathway carries blood from the heart to the lungs for gas exchange.
  • Another pathway carries blood from the heart to the tissues.
• Where does blood pumped by the right ventricle go?

  To the lungs.
• Where does blood pumped by the left ventricle go?

  To the body tissues.
• Why is the double circulatory system important?

  It makes the circulatory system more efficient by allowing oxygenated blood to be pumped at a higher pressure.
• How many chambers does the heart have and what are they called?

  4 - right atrium, right ventricle, left atrium, left ventricle.
• Why is the wall of the left ventricle thicker?

  It has to pump blood at a higher pressure around the whole body.
• What are the four main blood vessels associated with the heart?

  • Aorta (left): carries oxygenated blood from the heart to the body.
  • Pulmonary vein (left): carries oxygenated blood from the lungs to the heart.
  • Vena cava (right): carries deoxygenated blood from the body to the heart.
  • Pulmonary artery (right): carries deoxygenated blood from the heart to the lungs.
• What is the purpose of valves in the heart?

  To prevent the backflow of blood.
• What is the purpose of coronary arteries?

  They supply the heart muscle with oxygenated blood.
• Describe the process of blood flow through the heart.

  • Blood enters the right atrium via the vena cava and the left atrium via the pulmonary vein.
  • The atria contract, forcing blood into the ventricles and causing valves to shut.
  • After the ventricles contract, blood is pumped out of the heart.
• What is the purpose of valves in the heart?

  Prevent the backflow of blood
• What is the purpose of coronary arteries?

  Coronary arteries supply the heart muscle with oxygenated blood.
• Describe the process of blood flow through the heart.

  • Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
  • The atria contract, forcing blood into the ventricles and causing valves to shut.
  • After the ventricles contract, blood in the right ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricle enters the aorta (to the body).
• What is the approximate value of the natural resting heart rate?

  70 beats per minute
• How is the heart rate controlled?

  Heart rate is controlled by a group of cells in the right atrium which act as a pacemaker.
• How can an abnormal heart rhythm be treated?

  Irregular heart rhythms can be treated using an artificial pacemaker.
• What are the three types of blood vessel in the body?

  • Arteries
  • Veins
  • Capillaries
• How are arteries adapted for their function?

  Arteries have a thick muscle layer and a thick elastic layer to withstand high pressure.