Chapter 4

• Blood


  A key part of how multicellular organisms in animals transport substances around their body
• Blood

  • Contains red blood cells
  • Contains platelets
  • Contains plasma
  • Contains white blood cells
• Red blood cells


  Doughnut-shaped cells that account for 40-45% of blood
• Platelets


  Cells that cause blood to clot, account for 1-2% of blood
• Plasma


  The liquid component of blood that accounts for around 50% of blood, transports substances
• White blood cells


  Account for about 1% of blood, fight infections
• Blood vessels


  • Arteries
  • Capillaries
  • Veins
• Arteries


  • Thickest blood vessels, carry blood away from the heart at high pressure
• Veins


  • Contain valves to prevent backflow of blood, lower pressure than arteries
• Capillaries


  • Incredibly thin, allow for easy diffusion
• Double circulatory system


  Blood enters the heart twice, goes to the lungs to become oxygenated then back to the heart to be pumped around the body
• Blood flow through the heart

  1. Enters through vena cava into right atrium

  2. Passes through valve into right ventricle

  3. Pumped to lungs via pulmonary artery

  4. Returns oxygenated from lungs via pulmonary veins

  5. Enters left atrium

  6. Passes through valve into left ventricle

  7. Pumped around body via aorta
• Heart


  • Left side is thicker to pump blood further around the body
  • Will beat around 2 billion times in a lifetime
• Pacemaker


  Artificial device that sends electrical impulses to regulate heartbeat
• Artificial heart


  Completely replaces the natural heart, very dangerous procedure
• Plant organ systems


  • Leaf
• Leaf


  • Waxy cuticle on upper surface to prevent water loss
  • Upper epidermis layer prevents water loss and provides stability
  • Palisade mesophyll layer where most photosynthesis occurs
  • Spongy mesophyll layer with air gaps for gas exchange
  • Lower epidermis with stomata that open and close to regulate gas exchange and water loss
• Xylem


  Transports water and minerals up from the roots
• Phloem


  Transports products of photosynthesis down from the leaves
• Factors affecting plant water loss

  • Wind
  • Heat
• Plant adaptations to reduce water loss

  • Fewer leaves
  • Waxy surfaces
  • Stomata only open during photosynthesis
• Potometer


  Device used to measure plant transpiration and water uptake