Respiratory Figs(8 pages)
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- Lecture number:
- Lecture Note
- University of Southern California
- Bisc 307l - General Physiology
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BISC 307L 2nd Edition Lecture 34 Current Lecture Functions of the Respiratory System 1. Gas Exchange -O2 and Co2 (respiratory gases) between blood and atmosphere 2. Regulation of Body pH -H+ + HCO3- D H2CO3 D CO2 + H2O -this is the way that the respiratory system regulates body pH because it can get rid of variable amounts of Co2 and push the reaction to the right, lowering H ion concentration. This is the second line of defense against changes in blood pH. Buffers in the blood and the kidneys have a powerful ability to secrete acid or not. The capacity of the respiratory system to regulate pH is slower to act than the buffers, but it has a greater capacity. So buffers are faster but limited capacity – respiratory system is slower but it has a much greater capacity. The slowest, but most powerful, are the kidneys ability to secrete or not secrete acid. 3. Protection from Inhaled Pathogens/Irritants -viruses, spores, other particles 4. Vocalization -air blowing over the vocal folds will cause them to vibrate in order for speech and communication to occur. Lungs and Thoracic Cavity The main body cavity is divided into an upper thoracic and lower abdominal cavity. In the thoracic, there are three cavities: a right and left pleural cavity, along with a pericardial cavity. The pleural cavity is the cavity in which the lung sits, and the whole cavity is lined with the pleural membranes, which covers the lungs and also covers the inside of the pleural cavity. So there are two layers, and between them, there is an intrapleural space. Most of the actual pleural space is a very small volume – a few mm on each side of the chest, because the lung occupies most of that cavity. In the intrapleural space, is a small volume of pleural fluid, which is slippery mucus. It is slippery because in breathing movements, the lung has to move relative to the wall, so the pleura will rub against each other, and the lubricating fluid prevents there from being any friction during those movements. The muscles involved in the inspiration/expiration – inspiratory muscles are the diaphragm, the external intercostal muscles (between the ribs), and the two sets of neck muscles which attach at the top of the rib cage – the scalenes and sternocleiomastoids. The expiratory muscles are the abdominal muscles and the internal intercostal muscles. Lung Lobules and Alveoli Figure on the right shows the microscopic anatomy of the lungs. The airways – the larynx through trachea through the bronchi are all rigid tubes of rough cartilage. When you get down to the bronchioles, you can see a terminal bronchiole, which aren’t reinforced by cartilage, have smooth muscle, and are collapsible. The smooth muscle around the bronchioles are capable of contraction causing bronchoconstriction or relaxing to cause bronchodilation. These airways lead to the alveoli, where gas exchange occurs. Bottom left – here is the inside of the alveoli. There are two types of epithelial ...
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