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Topic 2.1 S&F of the ventilatory system. List the principle structures of the ventilatory system. Nose, mouth, pharynx, larynx, trachea, bronchi, bronchiole, lungs, alveoli. Outline the function of the conducting airways. the conducting portion consisting of a series of air passages
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List the principle structures of the ventilatory system • Nose, mouth, pharynx, larynx, trachea, bronchi, bronchiole, lungs, alveoli
Outline the function of the conducting airways • the conducting portion consisting of a series of air passages • Functions include: • air transport • humidification and temperature regulation (conditioning the air) • filtration and removal of particles • antibacterial and immunologic defense • the sense of smell (via specialised olfactory epithelium) • the production of sound (voice)
DEFINE: • Pulmonary ventilation – the inflow and outflow of air between the atmosphere and the lungs (aka breathing) • Total lung capacity (TLC) – volume of air in the lungs after a maximum inhalation • Vital capicity (VC) – maximum volume of air that can be exhaled following a maximum inhalation • Tidal volume (TV) – volume of air breathed in and out in any single normal breath
DEFINE: • Expiratory reserve volume (ERV) – volume of air in excess of tidal volume that can exhaled forcibly • Inspiratory reserve volume (IRV) – maximal inspired air over and above tidal volume • Residual volume (RV) – volume of air still contained in the lungs after maximum exhalation
Explain the mechanics of ventilation in the human lungs • www.youtube.com/watch?v=SWJHSTAWTCk
cont’d – Role of Boyle’s Law • Formulated by Robert Boyle (1662) states that at a fixed temperature, the volume of gas is inversely proportional to the pressure exerted by the gas. • In other words, when a gas is pumped into an enclosed space, it will shrink to fit into that space, but the pressure that the gas puts on the container will increase. • Boyle's Law can be written out mathematically: P x V = constant
Describe the nervous and chemical control of ventilation during exercise • Respiratory centers in the brain monitor blood composition. • During exercise CO2 levels increase. Why? • CO2 is produced by all active cells in the body • It is a result of cell converting nutrients (glucose) in to energy (ATP). CO2 is a byproduct of the process called aerobic cellular respiration
Cont’d • CO2 is detected by chemoreceptors in the respiratory center of the brain (brainstem)
CO2 = lower pH • How? Carbinic anhydrase • CO2 + H20 H2CO3 HCO3- + H+ • Free H+ = more acidity • The lower pH is what the chemoreceptors primarily monitor in the brain’s respiartory center
Cont’d • Neural control also includes lung stretch receptors • Try it!
Outline the role of hemoglobin in oxygen transport • Almost 99% of oxygen (O2) in your blood is transported by a large, complex protein that is located in your erythrocytes (red blood cells) called hemoglobin.
Cont’d • When hemoglobin Hb4 bonds with oxygen, the resulting molecule is called oxyhemoglobin Hb4O8
Explain the process of gaseous exchange at the alveloi • What are alveoli? • the primary gas exchange units of the lung
Cont’d • Alveoli are 1-cell layer thin and numerous (approx 1 million/lung) • The alveolar capillaries (the blood vessels tha surround the alveoli) are 1 cell layer thin • Both structures allow for easy diffusion (movement of a substance from a high concentration to a low concentration)
