Respiratory System

• The trachea, or windpipe, is a tube that connects the larynx to the bronchi.
• Lungs contain alveolar ducts, which lead to clusters of alveoli called acini.
• The purpose of the principal structures of the respiratory system include the nasal passages, pharynx, larynx, epiglottis, trachea, bronchi, bronchioles, alveoli, diaphragm, rib muscles, and pleural membranes.
• The mechanism of breathing in gas exchange involves the respiratory system taking in oxygen and releasing carbon dioxide to the environment.
• We need oxygen for cellular respiration, which requires oxygen (O2) to make ATP.
• Carbon dioxide is a by-product of cellular respiration and is not used by our cells, making it a waste product.
• The function of the respiratory system is to take in oxygen and release carbon dioxide to the environment.
• Two main requirements for respiration to take place are a large surface area for a maximal oxygen and carbon dioxide exchange rate and a moist environment to dissolve oxygen and carbon dioxide.
• Stages in respiration include breathing (inspiration and expiration), external respiration, internal respiration, and cellular respiration.
• The respiratory system consists of structures such as the nasal passages, pharynx, larynx, epiglottis, trachea, bronchi, bronchioles, alveoli, diaphragm, rib muscles, and pleural membranes.
• Alveoli are specialized for optimal diffusion with a moist membrane, a large surface area, thin walls for diffusion, and are immediately next to pulmonary capillaries, which are just large enough for a RBC to get through.
• The trachea is also lined with cilia and mucous-secreting cells which beat 20x per minute to move the trapped particles up to the pharynx.
• Alveoli are tiny clusters of air sacs and are the site of gas exchange where CO2 dissolved in blood is exchanged for O2.
• O2 rich blood travels to tissues where it diffuses into cells to be used in cellular respiration.
• The lungs are the primary organ of the respiratory system and are divided into lobes, with the right lung having three lobes and the left lung having only two to make room for the heart.
• Alveoli are terminal bronchioles (the last ones) that end at a group of alveolar ducts and sacs.
• O2 moves from the external environment through the airway into alveoli, diffuses into blood and dissolves into plasma to be carried by hemoglobin.
• Bronchioles are subdivisions of bronchi within each lung and do not contain cartilage.
• The larynx, or voice box, contains the vocal cords which contract and vibrate when you speak.
• The trachea, or windpipe, carries air to the lungs and is supported by rings of cartilage.
• The inner surface of the alveoli is covered with a single layer of lipid, which is surfactant, that reduces surface tension so they easily expand to twice their size with each breath.
• Just above the heart, the trachea branches into two bronchi which are supported by cartilaginous rings and lined with cilia and mucus-producing cells.
• The diaphragm is a dome-shaped layer of muscle that separates the lungs from the stomach and liver and works with rib muscles to move air in and out of the lungs.
• The pleural membrane is a thin, fluid-filled membrane that surrounds the lungs and allows the lungs to expand and contract with the movement of the chest.
• Smokers cilia are less effective due to the effects of cigarette smoke.
• Failure of the epiglottis causes choking.
• The purpose of principal structures of the respiratory system includes the nasal passages, pharynx, larynx, epiglottis, trachea, bronchi, bronchioles, alveoli, diaphragm, rib muscles, and pleural membranes.
• The mechanism of breathing involves gas exchange.
• Respiratory volumes and spirographs can be analyzed.
• The average male has a lung volume (total lung capacity) of 5.7 L, while the average female has a lung volume of 4.2 L, including the residual volume.
• Residual volume is the amount of air that remains in the lungs after maximum expiration, keeping the lungs partially inflated (about 1 L).
• During quiet breathing, lungs generally inflate from 2.2 L to 2.7 L, with about 500 mL inhaled during quiet breathing, known as tidal volume.
• The largest breath you can take is called vital capacity, which involves expanding the lungs to a greater extent than normal, recruiting the diaphragm, intercostals and neck muscles, and exhaling actively by recruiting the abdominal muscles.
• Vital capacity includes tidal volume, the extra you can inhale (inspiratory reserve volume), and the extra you can exhale (expiratory reserve volume).
• Only about 0.35 L of the 500 mL inhaled with every normal breath reaches the alveoli, with the rest filling the trachea, bronchi and bronchioles.
• Exercise performed over an extended period of time will strengthen the muscles involved in breathing, which will increase tidal volume and vital capacity.
• Illness can reduce vital capacity and tidal volume by affecting the number of alveoli that can successfully exchange oxygen, or by weakening the muscles in breathing.
• Respiratory volumes can be measured with a device known as a spirometer.
• A typical spirograph shows the tidal volume (TV), inspiratory reserve volume (RV), expiratory reserve volume (ERV), vital capacity (VC), residual volume (RV), total lung capacity (Vital capacity + Residual Volume), and the amount of air exchanged per minute (Lung volumes will be affected by height and gender).
• The thoracic cavity size determines the overall lung size.