Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings LOWER

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Organs of the Lower Respiratory System 1.Main Bronchi or Bronchus 2.Secondary Bronchioli or Bronchioles 3.Lung  alveoli

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Bronchial (Respiratory) Tree Divisions  Formed by division of the trachea 1. Primary bronchi  Secondary bronchi  Tertiary bronchi 2. Bronchioles  Terminal bronchioles

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Bronchial (Respiratory) Tree Divisions Figure 13.5a

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings 3. Lungs  Occupy most of the thoracic cavity (Heart occupies central portion of mediastinum within the pericardium)  Apex of lungs is near the clavicle (superior portion)  Base rests on the diaphragm (inferior portion)  Each lung is divided into lobes by fissures  Left lung—two lobes  Right lung—three lobes

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Coverings of the Lungs  Serosa covers the outer surface of the lungs  Visceral pleura covers the lung surface  Parietal pleura lines the walls of the thoracic cavity  Pleural fluid fills the area between layers of pleura to allow gliding  These two pleural layers resist being pulled apart and therefore attach the lungs to the wall of the thoracic cavity

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Gas Exchange Site of gas exchange = alveoli only Oxygen in the alveoli diffuse into the pulmonary capillaries to be sent to the cells of the body Carbon dioxide diffuses from the capillaries to the alveoli in order to be expelled from the body

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Four Events of Respiration 1. Pulmonary ventilation—moving air in and out of the lungs (commonly called breathing) 2. External respiration—gas exchange between pulmonary blood and alveoli (the environment) 3. Respiratory gas transport— oxygen and carbon dioxide move through out the body via the bloodstream 4. Internal respiration—gas exchange between blood and tissue cells (within the body)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings 1.Pulmonary Ventilation Mechanics of Breathing  Completely mechanical (controlled by physical processes)  Depends on volume changes in the thoracic cavity  Volume changes lead to pressure changes  Which lead to the flow of gases (in or out) to equalize pressure  Two phases  Inspiration = inhalation  flow of air into lungs  Expiration = exhalation  air leaving lungs

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Diaphragm relaxed The Diaphram will pull down when it contracts What happens to the volume and pressure of the thoracic cavity?

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Inspiration (Inhale)  Diaphragm contract  The size of the thoracic cavity increases  Increase in intrapulmonary volume  Decrease in gas pressure  External air is pulled into the lungs due to

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Expiration (exhale)  Mainly passive  As muscles relax, air is pushed out of the lungs  Decrease in volume  Increase in gas pressure

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Animation  science.co.uk/flash/Breathing.swf science.co.uk/flash/Breathing.swf

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Respiratory Sounds  Sounds are monitored with a stethoscope  Two recognizable sounds can be heard with a stethoscope  Bronchial sounds—produced by air rushing through trachea and bronchi  Vesicular breathing sounds—soft sounds of air filling alveoli

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings 2. External Respiration  Oxygen loaded into the blood  The alveoli always have more oxygen than the blood  Oxygen moves by diffusion towards the area of lower concentration  Pulmonary capillary blood gains oxygen

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Respiration  Carbon dioxide unloaded out of the blood  Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli  Pulmonary capillary blood gives up carbon dioxide to be exhaled  Blood leaving the lungs is oxygen-rich and carbon dioxide-poor

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Respiration Figure 13.11a

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings 3. Gas Transport in the Blood  Oxygen transport in the blood  Most oxygen attached to hemoglobin to form oxyhemoglobin (HbO 2 )

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Gas Transport in the Blood  Carbon dioxide transport in the blood  Most is transported in the plasma as bicarbonate ion (HCO 3 – )  A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings 4. Internal Respiration  Exchange of gases between blood and body cells  An opposite reaction to what occurs in the lungs  Carbon dioxide diffuses out of tissue to blood (called loading)  Oxygen diffuses from blood into tissue (called unloading)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Respiration, Gas Transport, and Internal Respiration Summary Figure 13.10

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings FYI if interested: not test material Nonrespiratory Air (Gas) Movements Table 13.1