Gas Exchange

1
Gas Exchange

• Lizzie Cymanski

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Functions

• Acquisition of oxygen
• Distribution of gases
• Removal of carbon dioxide

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Importance

• Oxygen is needed for cellular respiration
• The body needs to get rid of carbon dioxide, the
  product of cellular respiration

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Cellular Respiration vs. Respiration

• Cellular Respiration -- the use of oxygen and
  production of carbon dioxide at a cellular level
• also called internal respiration
• Respiration -- the uptake of oxygen from the
  environment and the disposal of carbon dioxide at
  the body system level
• also called external respiration

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• Respiratory system needs
• large respiratory surface (lungs, gills)
• a method for ventilating respiratory surface
• a pump and circulatory system to distribute gases

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Bacteria

• In bacteria and other very small organisms, cells
  are in always in contact with the environment
• Gas exchange happens easily

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Respiratory Surfaces

• The first respiratory surface was skin
• doesnt work for larger animals
• Most amphibians still use skin for 100 of their
  gas exchange
• Fish, reptiles, humans get some respiratory gases
  from skin

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Evolution

• As animals grew larger, their bodys surface area
  wasnt large enough for gas exchange through skin
• Aquatic animals developed gills, terrestrial
  animals developed lungs

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Lungs

• Humans have two lungs -- the left divided into
  two lobes, the right, three
• Two zones -- the conducting zone and the
  respiratory zone
• Protected by the rib cage

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Conducting Zone

• Trachea -- connects the pharynx to the lungs,
  allows the passage of air
• Trachea divides into two bronchi which divides
  into bronchioles which divides into terminal
  bronchioles
• No gas exchange with blood
• Warms, cleans and humidifies air
• Reinforced with cartilage to keep airways open

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Respiratory Zone

• alveolar ducts -- the tiny ends of the airways
• alveoli -- form at the end of alveolar ducts,
  sac-like structures, site of gas exchange
• www.youtube.comhttp//www.youtube.com/watch?vAw9O
  JLTlClQfeaturefvst

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Pleural Cavity

• Lungs covered in visceral pleural membrane
• Lungs lined in parietal pleural membrane
• The pleural cavity is the space between the two
  membranes
• The cavity is filled with water to hold the two
  membranes together

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Interesting Facts

• The lungs
• contain 1500 miles of airways
• 300 to 500 million alveoli
• total surface area of 70 sq. miles -- about the
  size of one side of a tennis court
• If all the capillaries were unwound, they would
  be 620 miles long

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Circulatory System

• The circulatory delivers the oxygen to cells all
  over the body and then carries away carbon
  dioxide
• Most oxygen is bound to molecules of hemoglobin
  inside red blood cells

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Hemoglobin

• A protein made of four polypeptide bonds and four
  organic compounds called heme groups
• At the center of each heme group is an atom of
  iron
• The iron molecule can bond to a molecule of
  oxygen
• Each hemoglobin can carry four oxygens

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(De)Oxyhemoglobin

• Oxyhemoglobin hemoglobin that is full of
  oxygen, a bright red color
• Deoxyhemoglobin hemoglobin that has released
  its oxygen, a dark red that appears blue under
  tissue

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History of Hemoglobin

• Hemoglobin is an ancient protein
• Not only used in vertebrates but also in
  annelids, mollusks, echinoderms, flatworms, and
  even some protists
• Other invertebrates use hemocyanin which has a
  base of copper instead of iron

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Emphysema

• One of the main forms of Chronic Obstructive
  Pulmonary Disease (COPD)
• The destruction of the lungs over a long period
  of time
• Most common cause is smoking, also caused by
  exposure to pollution
• Cannot be cured but can be treated

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Emphysema Symptoms

• Cough with mucus
• Shortness of breath
• Fatigue
• Wheezing
• Frequent respiratory infections

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Tuberculosis

• Caused by the bacteria Mycobacterium tuberculosis
• Very contagious
• Can be cured but takes very long time
• If not treated properly, spreads to other organs

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TB Symptoms

• Cough
• Coughing up blood
• Excessive Sweating
• Fatigue
• Fever
• Weight loss

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Cystic Fibrosis

• Inherited disease
• Causes thick, sticky mucus to build up in lungs
  and digestive tract
• May also affect sweat glands and male
  reproductive system
• Most commonly affects Caucasians
• Only live to mid-30s

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Cystic Fibrosis Symptoms

• Salty-tasting skin
• Frequent lung infections
• Wheezing and shortness of breath
• Delayed growth
• Problems with bowel movement

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• http//cwx.prenhall.com/bookbind/pubbooks/martini1
  0/chapter24/custom2/deluxe-content.html
• http//www.ncbi.nlm.nih.gov/pubmedhealth/
• http//www.google.com/images
• http//health.howstuffworks.com/human-body/systems
  /respiratory/lung.htm
• http//icb.oxfordjournals.org/content/28/2/739.abs
  tract