chapter 4

• What is the primary function of the heart?

  Pumps blood around the body
• What type of muscle tissue is the heart made from?

  Cardiac muscle tissue
• Which artery supplies oxygen to the heart?

  Coronary artery
• What does the right ventricle do?

  Pumps blood to the lungs
• What is the function of the pulmonary vein?

  Brings oxygenated blood from the lungs
• What does the left ventricle do?

  Pumps blood around the body
• What is the function of the pulmonary artery?

  Takes deoxygenated blood to the lungs
• What does the vena cava do?

  Brings deoxygenated blood into the heart
• What is the function of the aorta?

  Carries oxygenated blood around the body
• How is heart rate controlled?

  By a group of cells in the right atrium
• What is the role of artificial pacemakers?

  Control irregular heartbeats
• What are the main types of blood vessels and their functions?

  • Arteries: carry blood away from the heart (high pressure)
  • Veins: carry blood to the heart (low pressure)
  • Capillaries: connect arteries and veins, facilitate exchange
• What is the structure of arteries?

  Thick, muscular, and elastic walls
• Why do arteries have a small lumen?

  To withstand high pressure
• What is the structure of veins?

  Thin walls with valves
• Why do veins have valves?

  To stop blood flowing the wrong way
• What is the structure of capillaries?

  One cell thick walls
• Why are capillaries one cell thick?

  To provide a short diffusion distance
• What is the human circulatory system described as?

  • A double circulatory system
  • Blood passes through the heart twice for each circuit
• What happens in the lungs during gas exchange?

  Oxygen diffuses into the blood
• What are the four main components of blood?

  Red blood cells, plasma, platelets, white blood cells
• What is the function of red blood cells?

  Bind to oxygen and transport it
• What is the function of plasma?

  Transports substances and blood cells
• What is the function of platelets?

  Form blood clots to prevent infections
• What is the function of white blood cells?

  Defend the body against pathogens
• Why is a leaf considered an organ?

  Contains many tissues for photosynthesis
• How is the upper epidermis of a leaf adapted for its function?

  Transparent to allow light to pass through
• What is the function of guard cells?

  Control the opening and closing of stomata
• What is transpiration?

  Movement of water from roots to leaves
• What is the purpose of transpiration?

  Provide water to keep cells turgid
• What factors affect the rate of transpiration?

  • Temperature
  • Humidity
  • Wind speed
  • Light intensity
• How does temperature affect transpiration?

  Higher temperatures increase the rate
• How does humidity affect transpiration?

  Lower humidity increases the rate
• How does wind speed affect transpiration?

  More wind increases the rate
• How does light intensity affect transpiration?

  Higher light intensity increases the rate
• What is translocation in plants?

  • Movement of dissolved sugars from leaves
  • Provides energy for respiration, growth, and storage
• What is the function of xylem?

  Transport water and minerals from roots
• What is the function of phloem?

  Transport dissolved sugars from leaves
• What adaptations do xylem vessels have?

  Made of dead cells, no end walls
• What is the purpose of stomata?

  Allow gas exchange in plants