the respiratory system
DESCRIPTION
The structure and function of th respiratory system, and the mechanics of breathing at rest and during exercise.TRANSCRIPT
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The Respiratory SystemThe Respiratory System
Structure, Function, Mechanics of Structure, Function, Mechanics of Breathing (External Respiration)Breathing (External Respiration)
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Questions you need to answer
• What is the function of the respiratory system?
• Describe the passage of air from the body into the blood.
• Explain the mechanics of breathing and how they change during exercise.
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Air Pathways and Partial PressuresAir Pathways and Partial Pressures
• Air passes into;• Lungs• Bronchus• Bronchi• Bronchioles• Alveoli
• at alveoli air passes through the one cell thick sacs into pulmonary capillaries
• O2 passes in and CO2 out.
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Mechanics of BreathingMechanics of Breathing
• Inspiration• external ribs contract - pull ribs up, sternum out• diaphragm contracts and flattens• decrease air pressure in thoracic cavity, lung
volume increases - air rushes to fill the lungs
• Expiration• passive relaxation of the respiratory muscles and
elastic recoil of lungs - air forced out of the lungs• forced expiration internal intercostal muscles and
abdominals contract to pull ribs down and pull diaphragm up
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Gaseous Exchange
Internal Respiration, Breathing Control, Respiratory Volumes and
measures
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Questions you need to answer
• Describe gaseous exchange at the alveoli and movement of oxygen due to partial pressure.
• Explain the effect of temperature, acidity, and carbon dioxide on oxygen dissociation.
• Explain how breathing rate and depth is controlled by the body.
• Know the definitions of breathing volumes and typical values at rest and exercise.
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Partial Pressure of gases (mmHg)
Oxygen (02) Carbon Dioxide (CO2)
160 Atmosphere 0.3
105 Alveoli 40
40 Tissues 45
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• O2 attracted into capillaries by partial pressure of gases and haemoglobin.
• 97% O2 carried in this way.
• Oxygen saturation of haemoglobin is affected by several factors as well as its own partial pressure
• body temperature
• partial pressure of CO2
• acidity ‘Bohr Effect’
• Only 23% CO2 carried by haemoglobin• 70% combines with water to form carbolic acid
which is buffered by hydrogen ions to form Bicarbonate.
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Breathing ControlBreathing Control
• Controlled by the respiratory centre in the medulla oblongata.
• The inspiratory centre controls rhythmic cycle of in/expiration during rest.
• The expiratory centre is inactive at rest but affects breathing during exercise
• 2 methods of control• Neural• Chemical
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VolumesVolumes• Tidal Volume
• air breathed in/out each breath
• Inspiratory Volume• max volume inspired
after tidal volume
• Expiratory Volume• max volume expired
after tidal volume
• Residual Volume• volume left in lungs
after max expiration (stops lungs collapsing)
MeasuresMeasures• Vital Capacity
• max air expired after inspiring as much as possible
• Total Lung Capacity• vital capacity +
residual volume
• Minute Ventilation• Tidal Volume x
frequency of breathing per minute