respiratory system jewett
DESCRIPTION
Brief Respiratory System presentation for IB Biology SL. Figures from Campbell & Reece, 8th edition.TRANSCRIPT
Respiratory System (Gas Exchange)
IB Biology SL Core Topic 6.2
Jeff JewettAmerican College of Sofia
February 2010
Ventilation
• “movement of the respiratory medium over the respiratory surface” (CR p917)
• Moving air into (inspiration) and out of (expiration) the lungs
• In mammals, this is done by “negative pressure”, pulling the air in
• Lung expanding/contracting http://www.youtube.com/watch?v=oKH7CtsEgHw
• Diaphragm motion animation http://www.youtube.com/watch?v=hp-
gCvW8PRY&feature=PlayList&p=C0655CEFFEB5B4DE&index=5
• Inspiration/Expiration– http://faculty.stcc.edu/AandP/AP/AP2pages/Units21to23/respiration/inspirat.htm
Intracostal Muscles
• Surround the ribs• External – contract to expand the rib cage,
pulling in air (INSPIRATION)• Internal – contract for forced expulsion of
air (talking, playing a wind instrument, hard breathing, etc)
• Inhalation is active (always the diaphragm, sometimes the external intercostals and others)
• Exhalation is usually passive (diaphragm relaxing, rib elastic fibers returning to normal)– Abdominal muscles also help with forced exhalation
Negative Pressure Breathing
Pulling air in (not pushing)
MORE Volume = less pressureless Volume = more pressure
Gas flows from HIGH low pressure
Gas Exchange
• This is DIFFERENT than cellular respiration!
• Uptake of O2 from environment and discharge of CO2 to environment
• Respiration animation http://www.youtube.com/watch?
v=HiT621PrrO0&feature=PlayList&p=CEE41F232E0E67CF&index=3&playnext=2&playnext_from=PL
Label the parts of the mammalian respiratory system!
• Trachea and bronchi are surrounded by rings of cartilage to prevent collapse
• Bronchioles have smooth muscle fibers, allowing expansion/contraction
Gas Exchange
• Gas exchange occurs across plasma membrane must keep surface MOIST
• Movement of gases by diffusion • Rate of diffusion is proportional to:
– Surface area– Distance2
– Respiratory surfaces tend to be LARGE and thin
Structure of Alveoli
• Tiny air sacs (~0.2 mm in diameter) surrounded by dense network of capillaries
• Groups of alveoli attached to end of bronchiole• Alveoli walls only one layer of epithelium cells
thick, the cells have little cytoplasm (keep thin!)• < 1 μm between alveolus and erythrocyte• hundreds of millions of alveoli = HUGE surface
area (~80 m2)• Surfaces kept wet