Topic 2
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Principle structures of ventilatory system
Nose/Mouth, Pharynx and larynx, Trachea, Bronchi, Bronchioles, Lungs and Alveoli
Functions of the conducting airways
Low resistance pathway for airflow Warming and moistening air Defense against chemicals when inhaled
Nose/Mouth
Where air is inhaled into
Pharynx
Receives air from the nasal cavity
Larynx
Prevents food from entering the trachea during swallowing
Trachea
Carries air from the larynx to bronchi. Cartilage holds trachea open to maintain constant airflow.
Bronchi
Two large tubes which provide air to left and right lung.
Bronchioles
Further division of bronchi which provide air to the lungs
Lungs
Two air-filled structures found in the thorax which allow gas exchange between air and the bloodstream
Alveoli
Tiny air sacs which are the site of gas exchange between the air and the bloodstream
Total Lung capacity
The volume of air in the lungs after maximum inhalation
Vital Capacity
Maximum amount of volume of air exhaled after maximum inhalation
Tidal Volume
Volume of air breathed in and out per breath
Residual volume
The volume of air in the lungs after maximum exhalation
Expiratory reserve volume
Volume in air of excess of tidal volume that can be exhaled forcibly
Inspiratory reserve volume
Volume of air additionally inspired above tidal volume
Mechanics of inspiration
The pressure in the lungs decrease as the volume of air in the lungs increases The external muscles contract and intercostal relaxes The diaphragm contracts and flattens moves downwards The ribcage moves up and outward to get as much air in as possible.
Mechanics of expiration
The pressure in the lungs increase as the volume of air in the lungs decrease The internal intercostal muscles contract while the external one contracts The diaphragm relaxes and rises upwards and the abdominal muscles contract aswell. The ribcage moves upwards and inwards
What is Boyles law
A decrease in long volume leads to an increase in lung pressure.
Why are accessory muscles important
Muscles of the chest and shoulders can assist in compression but because its an actives process it requires energy from respiration.
The role of hemoglobin in oxygen transport
Most Oxygen in the blood is transported by haemoglobin within red blood cells.
Explain the process of gas exchange in the alveoli
Gas exchange occurs at the alveoli in the lungs and takes place by diffusion. The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries. Diffusion is the movement of gas from an area of high concentration to an area of low concentration. There is a high concentration of oxygen in the alveoli and a low concentration of oxygen in the blood, so oxygen diffuses from the alveoli into the blood. There is a high concentration of carbon dioxide in the blood and a low concentration in the alveoli, so carbon dioxide diffuses from the blood into the alveoli.
Why are alveoli well adapted to gas exchange
Increase the surface area for gas exchange Membrane is very thin allowing gases to have a short path for diffusion A rich blood supply as they have there own network of capillaries
Chemical control of Ventilation
Ventilation increases due to and increase in blood acidity levels due to increased CO2 in blood which leads to increased depth and rate of breathing