2.2-animal tissues, organs and systems

• What is the main function of the digestive system?

  To digest food and absorb nutrients
• What does the stomach produce to aid digestion?

  Hydrochloric acid
• What is the role of hydrochloric acid in the stomach?

  Kills bacteria and provides optimum pH
• What do the pancreas and salivary gland produce?

  Digestive juices containing enzymes
• What is the role of the small intestine in digestion?

  Absorbs soluble food molecules into bloodstream
• What does the liver produce for digestion?

  Bile
• What is the function of bile in digestion?

  Emulsifies lipids for efficient lipase action
• What is the role of enzymes in the digestive system?

  Speed up breakdown of food without being used up
• What does the large intestine absorb?

  Water from undigested food
• How does the shape of an enzyme affect its function?

  Active site is complementary to substrate
• What is metabolism?

  Sum of all reactions in a cell or organism
• What is the lock and key hypothesis of enzyme function?

  Enzyme active site and substrate are complementary
• What types of metabolic reactions do enzymes catalyse?

  • Building larger molecules from smaller ones (e.g., glucose to starch)
  • Changing one molecule to another (e.g., glucose to fructose)
  • Breaking down larger molecules into smaller ones (e.g., carbohydrates to glucose)
• How does temperature affect enzyme action?

  Increases action until denaturation occurs
• What is the optimum temperature for enzyme action?

  Around 37°
• What do carbohydrases do in the digestive system?

  Break down carbohydrates into monosaccharides
• How does pH affect enzyme function?

  Extreme pH alters active site shape
• Where are carbohydrases, proteases, and lipases produced in the body?

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

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

  Break down lipids into fatty acids and glycerol
• Where is bile made and stored in the body?

  Made by the liver, stored in gallbladder
• How are the products of digestion used?

  To build larger molecules and for respiration
• What is the role of bile in the digestive system?

  • Neutralizes hydrochloric acid from stomach
  • Emulsifies lipids to increase surface area for lipase
• What is the heart?

  An organ that pumps blood around the body
• How does the double circulatory system work?

  • One pathway: heart to lungs (gas exchange)
  • One pathway: heart to tissues
• What is the purpose of the circulatory system?

  Carries oxygen and removes waste substances
• Where does blood pumped by the right ventricle go?

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

  Body tissues
• How many chambers does the heart have?

  4 chambers
• What are the names of the heart chambers?

  Right atrium, right ventricle, left atrium, left ventricle
• Why is the double circulatory system important?

  Increases efficiency by pumping oxygenated blood at higher pressure
• Why is the wall of the left ventricle thicker?

  Pumps blood at higher pressure around the body
• What are the four main blood vessels associated with the heart?

  • Aorta: carries oxygenated blood to the body
  • Pulmonary vein: carries oxygenated blood from lungs to heart
  • Vena cava: carries deoxygenated blood from body to heart
  • Pulmonary artery: carries deoxygenated blood from heart to lungs
• What is the purpose of coronary arteries?

  Supply heart muscle with oxygenated blood
• What is the purpose of valves in the heart?

  Prevent backflow of blood
• Describe the process of blood flow through the heart.

  • Blood enters right atrium via vena cava, left atrium via pulmonary vein
  • Atria contract, forcing blood into ventricles, causing valves to shut
  • Right ventricle: blood enters pulmonary artery (to lungs)
  • Left ventricle: blood enters aorta (to body)
• What is the approximate value of the natural resting heart rate?

  70 beats per minute
• How can an abnormal heart rhythm be treated?

  Using an artificial pacemaker
• How is the heart rate controlled?

  By a group of cells in the right atrium
• What are the three types of blood vessel in the body?

  • Arteries
  • Veins
  • Capillaries