exchange and transport in animals

• Exchange surfaces


  • SAIV
  • 100t hair cens
  • Large surface area and thin walls
  • Meaning diffusion across the plant into the walls can happen quickly
• Nephrons in Kidneys


  • Thin walls and very large surface area as required to efficiently reabsorb substances like water and glucose
• Gas exchange in animals

  • O2 transported to blood and CO2 to the lungs, takes place across membranes or alveoli which are covered in capillaries which supply the blood
• Small intestine


  • Alveoli surround by blood vessels with thin walls
• Factors affecting diffusion


  Concentration gradient - the greater the difference in concentration, the faster the rate of diffusion because more particles are randomly moving down the gradient than against it
• Nails growing


  • Very small and arranged in clusters creating large surface area for diffusion
  • Capillaries provide a large blood supply, maintaining a concentration gradient
  • Walls are very thin so short diffusion pathway
• Diffusion in single-celled organisms

  • Can use diffusion to transport molecules because they have relatively large surface area to volume ratio
  • Multi-cellular organisms have small surface area to volume ratio so cannot rely on diffusion alone
• Blood plasma


  Carries components (RBCs, WBCs, platelets, glucose, amino acids, urea)
• Red blood cells


  • Carry O2 to all cells, biconcave shape provides large surface area, no nucleus allowing more room for haemoglobin which binds to O2 (oxyhaemoglobin)
• White blood cells


  • Body's defence against pathogens, phagocytes digest and eat pathogens, lymphocytes responsible for antibody production (memory lymphocytes)
• Platelets


  • Help blood to clot and form scabs, no nucleus, made from small fragments of cells
• Arteries


  • From heart, elastic fibres and layers of muscle in walls make them strong, under high pressure
• Veins


  • Towards heart, lumen wide to allow low pressure blood flow, valves
• Capillaries


  • One cell thick, permeable walls
• Temperature increase means more particle movement resulting in more collisions and therefore faster diffusion rate
• Greater surface area of membrane means more space for particles to move through, resulting in faster diffusion
• Pulmonary vein


  pulmonar anen Svena
• Aorta


  left night amum
• Vena cava


  left night amum
• Atrioventricular valve


  amovenmcular valve
• Ventricle


  cept vennicle
• Septum


  A V venmae
• Aerobic respiration


  1. Uses oxygen

  2. Yields the most energy

  3. Usually in mitocondria
• Anaerobic respiration occurs when not enough O2 is available
• Anaerobic respiration yields less energy
• Cardiac output


  Volume pumped out in contraction
• Cardiac output is an exothermic reaction
• Heart rate is the number of contractions per minute
• Exchange and transport


  In animals