• We need to get oxygen to each and every cell in the body!
• We need to get carbon dioxide carried away from the cells and away from the body!
• Why do we need to transport these gases?
• What is oxygen used for?
• Why is carbon dioxide produced?
• Why is it a ‘waste’ material?
• Remember that oxygen is needed for ‘cellular respiration’. In the cell’s mitochondria, glucose is broken down to provide our energy needs.
• carbon dioxide is the waste gas produced.
What goes on in the head region???
What are the advantages of sending the air through the nasal
passages?
• The air is filtered!
• The air is moistened!
• The air is warmed!
• We get a chance to smell (olfaction)
• Can you describe some structural features of these passageways that allow them to be very effective?
• How often do we breathe?
• What affects our breathing rate?
• Where is the control centre?
• What parameters are monitored in the body to set the rate of breathing?
• Control centre is in brainstem
• The structure is called the medulla oblongata
• The brain continuously monitors blood levels for Co2, O2 and pH and adjusts breathing accordingly
Mechanics of breathing
• control centre is in brainstem• inspiratory signal triggers diaphragm and rib
muscles to contract• diaphragm flattens and ribs lift up and out• this increases volume of chest (thoracic) cavity• as a result the pressure in chest cavity drops• as a result air rushes in (inhalation)• in restful breathing exhalation is passive (recoil
of muscles).
Lung volumes/capacities
• Tidal volume
• Inspiratory reserve volume
• Expiratory reserve volume
• -----------------------------------------
• The above add up to the vital capacity
Summary points
• know the anatomy!• nasal passages: air is warmed, filtered and
humidified (olfaction as well)• role of epiglottis• role of larynx/voice box• adaptations of trachea and bronchiole passages:
cartilage rings, mucous, cilia, smooth muscle• adaptations of alveoli: thin, great surface area,
rich blood supply,
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