Bio2

• Gas exchange


  One of the most important parts of a living organism's daily routine, essential for keeping the organism alive
• Gas exchange in animals

  Waste product-carbon dioxide is removed from most animal system and replaced by oxygen for "cellular respiration" that has been absorbed from the air through breathing
• Gas exchange in plants

  By-product of photosynthesis-oxygen is released into the air and replaced with carbon dioxide, an essential ingredient for photosynthesis

  
• Gas exchange is responsible for producing oxygen as well as carbon dioxide in the air
• Both plants and animals; meaning all living organisms exchange gases
• Gas exchange in plants

  • Plants obtain the gases they need through their leaves
  • They require oxygen for respiration and carbon dioxide for photosynthesis

  
• Gas exchange in plant leaves

  1. Gases diffuse into the intercellular spaces of the leaf through pores, which are normally on the underside of the leaf - stomata

  2. Stomatal opening and closing depend on changes in the turgor of the guard cells

  3. When water flows into the guard cells by osmosis, their turgor increases, and they expand

  4. Due to the relatively inelastic inner wall, the guard cells bend and draw away from each other, so the pore opens

  5. If the guard cells loose water the opposite happens and the pore closes
• Respiration in plants


  Occurs throughout the day and night, providing the plant with a supply of energy

  
• Carbon dioxide from plant respiration


  Can be used directly by the plant during photosynthesis

  
• During the day, photosynthesis

  Can be going 10 or even 20 times faster than respiration (depending on light intensity), so the stomata must stay open so that the plant has enough carbon dioxide, most of which diffuses in from the external atmosphere

  
• Gas exchange in animals

  • Usually through specialized organs such as lungs in "mammals, reptiles, birds and adult amphibians", gills in fish, and tracheae in insects
  • All organs for gas exchange must be kept moist by the body to be able to function
  • They receive the carbon dioxide from the blood and release it into the air and gather oxygen from the air and supply it into the blood
• Animals with different gas exchange organs

  • Mammals, birds, reptiles have lungs
  • Fish have gills
  • Insects have tracheae
  • Earthworms exchange gases directly through their skin
• Lungs


  • Air-filled spaces and because of that they are moist and spongy
• Terrestrial arthropods


  • Have a series of openings called spiracles at the body surface
  • Spiracles open into tiny air tubes called tracheae, which expand into fine branches that extend into all parts of the arthropod body
• Human and animal respiratory system

  • Includes airways, lungs, and blood vessels
  • The muscles that power your lungs are also part of the respiratory system
  • Allows you to talk and to smell
  • Brings air to body temperature and moisturizes it to the humidity level your body needs
  • Delivers oxygen to the cells in your body
  • Removes waste gases, including carbon dioxide, from the body when you exhale
  • Protects your airways from harmful substances and irritants

  
• Food and oxygen are transported to all the cells in the body for respiration and growth. Waste products are transported from the cells to organs that excrete them
• Transport system in plants

  • Flowering plants have well-developed transport system called vascular system
  • The vascular system is composed of pipe-like vessels called xylem and phloem vessels
• Xylem


  • Transports water to the tip of the leaves
  • Transports water and minerals upwards from the roots

  
• Phloem


  Transports glucose made in the leaves to other parts of the plant
• Transpiration


  1. Water on the surface of spongy and palisade cells (inside the leaf) evaporates and then diffuses out of the leaf

  2. Transpiration is the process by which water evaporates from the leaves, therefore causing more water to be drawn up from the roots
• Plants have adaptations to reduce the excessive loss of water
• Transport systems in animals

  • Unicellular organisms rely on simple diffusion for transport of nutrients and removal of waste
  • Multicellular organisms have developed more complex circulatory systems
• Open circulatory system


  • Blood vessels transport all fluids into a cavity
  • When an animal moves, the blood inside the cavity moves freely around the body in all directions
  • The blood bathes the organs directly, thus supplying oxygen and removing waste from the organs
  • Blood flows at a very slow speed due to the absence of smooth muscles

  
• Animals with open circulatory systems

  • Most invertebrates (crabs, insects, snails, etc.)
• Closed circulatory systems


  • Blood never leaves the blood vessels
  • Blood is transferred from one blood vessel to another continuously without entering a cavity
  • Blood is transported in a single direction, delivering oxygen and nutrients to cells, and removing waste products

  
• Single circulatory system


  • The heart pumps deoxygenated blood to the gills where it gets oxygenated
  • Oxygenated blood is then supplied to the entire fish body, with deoxygenated blood returned to the heart

  
• Double circulatory system


  • Animals have a four-chambered heart
  • The right atrium receives deoxygenated blood from the body and the right ventricle sends it to the lungs to be oxygenated
  • The left atrium receives oxygenated blood from the lungs and the left ventricle sends it to the rest of the body

  
• Animals with double circulatory systems


  • Most mammals, including humans
• Closed circulatory systems


  Can be further divided into single circulatory systems and double circulatory systems

  
• Single circulatory system


  • Has a double chambered heart with an atrium and ventricle
  • Found in fish
  • Heart pumps deoxygenated blood to the gills where it gets oxygenated
  • Oxygenated blood is then supplied to the entire fish body, with deoxygenated blood returned to the heart

  
• Double circulatory systems


  • Found in birds and mammals
  • Have a four-chambered heart
  • Right atrium receives deoxygenated blood from the body and right ventricle sends it to the lungs to be oxygenated
  • Left atrium receives oxygenated blood from the lungs and left ventricle sends it to the rest of the body
  • Made up of two circuits - pulmonary and systemic circulatory systems

  
• Circulatory system


  Combined with the cardiovascular system, helps to fight off disease, helps the body maintain a normal body temperature, and provides the right chemical balance to provide the body's homeostasis
• Major components of the circulatory system

  • Heart
  • Arteries
  • Veins
  • Blood

  
• Heart


  • About the size of two adult hands held together, rests near the center of the chest, keeps the circulatory system working at all times through consistent pumping

  
• Arteries


  • Carry oxygen-rich blood away from the heart and where it needs to go
• Veins


  • Carry deoxygenated blood to the heart where it is directed to the lungs to receive oxygen
• Blood


  • Transport media of nearly everything within the body, transports hormones, nutrients, oxygen, antibodies, and other important things needed to keep the body healthy
• Types of circulation in the body

  • Pulmonary circulation
  • Systemic circulation
  • Coronary circulation

  
• Pulmonary circulation


  1. Right ventricle pumps blood into pulmonary artery

  2. Pulmonary artery carries deoxygenated blood to the lungs

  3. Blood is oxygenated and carbon-dioxide is removed

  4. Oxygenated blood travels back to the heart through pulmonary vein into left atrium

  
• Systemic circulation


  1. Blood travels out of the left ventricle through the aorta

  2. Aorta breaks into various arteries and then down to capillaries

  3. Capillaries deliver oxygenated blood and other nutrients to the cells of the body, including myocytes (muscle cells) and removes carbon-dioxide

  4. Blood continues to travel through the veins and back to the right atrium via the vena cava