Flashcards in Kaplan Ch. 6 - The Respiratory System Deck (10):
Describe the path that air follows as from when it enters the body to when it experiences gas exchange.
Air flows in through the nasal cavity, where nasal hairs remove dirt and filter the air. Then the air passes into the pharynx, the larynx, the trachea, the bronchi, the bronchioles, and the alveoli where gas exchange occurs.
Both air and food travel in the pharynx, but only air is to travel into the larynx. How is food prevented from entering the larynx?
The top of the larynx is covered with a membrane (epiglottis) that closes off the entrance to the larynx when we swallow.
Where are the vocal chords?
In front of the larynx
What are the alveoli covered with?
A surfactant that lowers surface tension (inside the alveoli) and keeps the alveoli from collapsing in on themselves
What are the pleurae?
What order are they in?
What is their function as it pertains to breathing?
Membranes that surround the lungs.
The order, from medial —> lateral is lung, visceral pleura, intrapleural space, parietal pleura
The intrapelural space is filled with fluid that helps lubricate the membranes and also create a pressure differential compared to the inside of the lungs that drives breathing
Describe the process of inhalation and exhalation.
Diaphragm flattens and chest wall expands outwards, increasing volume in the intrapleural space which this decreases pressure here. The pressure in the lungs (1 atm) is now larger than the pressure in the intrapleural space so the lungs expand and as they expand they draw in air.
As diaphragm and intercostal muscles relax, the volume of the intrapleural space decreases which increases its pressure. The lungs (still at 1atm) are now at lower pressure than the pleural space so the lungs are compressed and air is pushed out.
What area of the brain controls breathing?
Medulla oblongata - contains neuron somas that control muscles that contract to perform ventilation. These neurons have chemoreceptors that are sensitive to partial pressure of carbon dioxide and oxygen.
Describe how gas exchange works in the alveoli.
The alveoli are surrounded by capillary beds. The heart pumps deoxygenated blood to the lungs from the right ventricle via the pulmonary artery where it flows into these capillaries around the alveoli. The partial pressure of CO2 is high in the blood and low in the alveoli so CO2 diffuses down its  gradient into the alveoli. The partial pressure of oxygen is higher in the alveoli than the blood so it also diffuses down its  gradient into the blood. The oxygenated blood then returns to the left atrium of the heart via the pulmonary vein where it is pumped to the body.
How do the lungs participate in thermoregulation?
The capillaries in the lungs can expand and this dissipate more thermal energy or they can contract and maintain thermal energy.