Answer:
Explanation:
During the process of inhalation, the diaphragm is pulled down and the lungs expand. High-pressure air from the environment is inhaled. The air passes the trachea and enters the lungs. It starts n the bronchi, enters the bronchioles and finally the alveoli. Bronchi are the main passageway into the lungs. There are two bronchi, right and left - leading into each lung.
Inhaled air passes through the mouth and nose, trachea, right and left mainstem bronchi, secondary and tertiary bronchi and reaches the alveoli- gas exchange region.
The rea gas exchange is carried out in the respiratory bronchioles, the alveolar ducts and alveoli. The gas exchanging surface is 70m². Alveoli posses a rich capillary network for gas exchange.
After passing through the nose and the mouth, the inhaled oxygen enters the larynx. The larynx is a passageway that air passes through before it gets to the trachea. It stops food and other things from making its way to the lower respiratory system. The larynx is also known as the voice box, this is where vocal sounds are produced.
After the oxygen is used up and turned into carbon dioxide we exhale. We exhale the exact amount of carbon dioxide as we inhaled oxygen. When this happens the carbon dioxide follows the same path out that the oxygen did in, just in the opposite order.
PaCO₂ is the partial pressure exerted by dissolved CO₂ in arterial blood (35-45 mmHg).
PaO₂ is the partial pressure exerted by dissolved O₂ in arterial blood (80-100 mmHg).
O₂ crosses the alveolar-capillary membrane, then dissolve in plasma. Thus, it binds to haemoglobin (98%), while 2% remains dissolved in plasma. O₂ bound to haemoglobin then comes off haemoglobin, dissolves in plasma and diffuses to the tissues.
Pulse oximetry (SpO₂) is the measurement of O₂ bound to haemoglobin.
At the tissue level, CO2 is a by-product of cellular metabolism. It diffuses from the tissue to the blood.
