PHGY 214 Lecture Notes - Lecture 1: Respiratory Tract, Epiglottis, Chemiosmosis
3 May 2018
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4.2 The Respiratory System and Gas Exchange
• Oxygen is necessary for the last step in chemiosmotic synthesis.
• The primary job of the respiratory system is to deliver oxygen to the blood and expel
carbon dioxide
• The respiratory tract prepares the air by warming, moistening and cleaning it
• Ciliated ells filter the air y trapping foreign partiles. traps particulate matter
• Microtubules are found in cilia; a defect in microtubule production may result in
breathing problems
• The respiratory system is also important for thermoregulation: regulating the body
temperature within a normal range
• Panting increases respiration rate – enables more water to be brought up into the upper
respiratory tract that can evaporate
• Evaporation has a cooling effect on the body
• Nasal and tracheal capillary beds are involved in cardiovascular thermoregulation
Anatomy of the respiratory system
• Respiratory system allows gas exchange between external environment and blood
• Changes in the pressure differential between the chest cavity and external environment
governs the movement of oxygen and carbon dioxide through the respiratory system
• Air enters through the nose and then moves through the pharynx, larynx, trachea,
bronchi, bronchioles, and into the alveoli
• The alveoli are where carbon dioxide from the blood is exchanged for oxygen
• The nasal cavity is the space inside the nose
• There are many structures and substances in the nasal cavity that filter, moisten, and
warm incoming air
• Nasal hairs are at the front of the cavity; they trap large dust particles
• Mucus is secreted by goblet cells
• Mucus traps smaller dust particles that could bypass the nasal hairs; mucus also
moistens the air
• Capillaries within the nasal cavity also warm the air
• Cilia can move mucus and dust bodies toward the pharynx to be removed by spinning or
swallowing
• Essentially, the nasal cavity is vital in immunity within the respiratory system; the nasal
cavity prevents potentially harmful substances from entering the body
• The pharynx is also known as the throat. It functions as a passageway for food and air.
• The larynx contains the vocal chords. The larynx sits behind the epiglottis.
• The epiglottis is the cartilaginous structure that rises to block the opening of the
trachea during swallowing, preventing food from entering the airway
• If any non-gaseous material were to enter the larynx, it would trigger a coughing reflex
and be forced back out
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