Lifestyle & Risk

• What essential substances do animals require to survive?

  Oxygen and carbon dioxide
• How do small organisms meet their transport needs?

  Through diffusion due to large surface area
• What happens to the surface area to volume ratio as organism size increases?

  It decreases
• Why does diffusion become insufficient in larger organisms?

  Because diffusion distance increases and metabolic rate rises
• What do larger organisms have to transport substances?

  A mass transport system
• What are the features of a mass transport system?

  1. A network to move through (e.g., vessels)
  2. A medium for movement (e.g., blood)
  3. Controlled direction for substance movement
  4. Maintenance of speed through heart contraction
• What type of molecule is water?

  A polar molecule
• Why is water considered a polar solvent?

  It can dissolve many biological molecules
• What do hydrogen bonds between water molecules create?

  Cohesion and adhesion
• What is the significance of water's high heat specific capacity?

  It minimizes temperature fluctuations in living things
• What do arteries carry?

  Oxygenated blood to body tissues
• Why do arteries have a small lumen?

  To maintain high blood pressure
• What is the function of smooth muscle in arteries?

  To control diameter through contraction and relaxation
• What do veins carry?

  Deoxygenated blood to the lungs
• Why do veins have a large lumen?

  To minimize resistance to flow
• What is the structure of capillaries?

  Very small with a narrow lumen
• What is the purpose of the thin endothelium in capillaries?

  To maintain a short diffusion distance
• What are the components of the heart and cardiac cycle?

  1. Four chambers: right/left atria, right/left ventricles
  2. Four main blood vessels: pulmonary vein, aorta, vena cava, pulmonary artery
  3. Atrioventricular valves: mitral and tricuspid
  4. Semilunar valves: pulmonary and aortic
  5. Tendinous chords prevent valve inversion
  6. Septum prevents blood mixing
  7. Coronary arteries supply blood to cardiac muscle
  8. Cardiac muscle is thicker on the left side
• What occurs during atrial systole?

  Atria contract, forcing blood into ventricles
• What happens during ventricular systole?

  Ventricles contract, closing atrioventricular valves
• What occurs during cardiac diastole?

  Atria and ventricles relax, decreasing pressure
• What is atherosclerosis?

  The hardening of arteries due to plaque
• What causes atheroma formation?

  Damage to the endothelium and inflammatory response
• What is the result of plaque build-up in arteries?

  Narrowing of the artery and restricted blood flow
• What are the risk factors for atherosclerosis?

  • Genetics
  • Age
  • Diet
  • Gender
  • High blood pressure
  • High cholesterol levels
  • Smoking
  • Physical inactivity
  • Obesity
• How can the risk of cardiovascular disease be reduced?

  By stopping smoking and exercising regularly
• What is thrombosis?

  Blood clotting to prevent blood loss
• What triggers the conversion of prothrombin to thrombin?

  Thromboplastin released from platelets
• What does thrombin catalyze?

  The conversion of fibrinogen into fibrin
• What forms the blood clot?

  A network of fibrin trapping platelets and red blood cells
• What is energy balance?

  The balance of calories consumed and burned
• What happens if more calories are burned than consumed?

  It leads to weight loss
• How is BMI calculated?

  • Divide body mass in kilograms by height in metres squared
  • Compare the value to a chart for classification

  
• What does a BMI value below 18 indicate?

  Underweight
• What does a waist-to-hip ratio above 1 suggest?

  A health risk for heart disease
• What are carbohydrates made of?

  Carbon, hydrogen, and oxygen
• What are the types of saccharides?

  • Monosaccharides: simple sugar monomers
  • Disaccharides: two monosaccharides
  • Polysaccharides: many monosaccharides
• What does a value below 18 indicate in BMI?

  Individual is underweight
• What does a value above 30 indicate in BMI?

  Individual is obese
• How is waist-to-hip ratio used in health assessment?

  Determines risk of heart disease