BIO 241 1st Edition Lecture 14 Outline of Last Lecture I. RespirationII. Respiratory organsIII. Nose anatomyIV. Nose physiologyV. PharynxVI. LarynxVII. TracheaVIII. Bronchial treeIX. Anatomical changes in bronchial treeOutline of Current Lecture II. Lungs 1III. Lungs 2IV. Alveolar-capillary membraneV. Physiology of respirationVI. InspirationVII. ExpirationCurrent LectureII. Lungs are surrounded by pleura, which are membranes. There is a parietal layer (outer layer) and a visceral layer (inner). This forms a pleural cavity which contains pleural fluid (similar to theheart’s layers). This functions to reduce friction, create a pressure gradient, and compartmentalize the different lobes. The apex is the upper point of the lung and the base is the lower point. It has a hilus much like lymph nodes have a hilus that is the root of the lung. The right lung has 3 lobes (superior, middle, inferior) and 2 fissures (horizontal and oblique). Theleft lung has 2 lobes (superior and inferior) and 1 fissure (oblique). III. The lungs have bronchopulmonary segments (A subdivision of one lobe of a lung based on the connection to the segmental bronchus. For example, the right upper lobe has apical, anterior, and posterior segments). These become lobules (composed of alveolar ducts, alveolar sacs and alveoli). The alveolar wall cell types consist of simple squamous epithelial cell, macrophages (helps rid of dust), and septal cells (produces surfactant which reduces surface tension). IV. The alveolar-capillary membrane aka the respiratory membrane allows for gas exchange in the lungs. Its components are surfactant, type I alveolar epithelial cell, a fused basement membrane, and capillary endothelial cells. Its large surface area (around 70 m2) aids in gas exchange. That is about 25 x 30 ft which equals 750 ft2 with approximately 100 mL of blood. Both lungs are 1,500 ft2 with about 200 mL of blood which is about ¾ the size of a tennis court.V. The purpose of respiration is to supply tissues with oxygen and to rid tissues of wastes. Three processes are required for respiration that were mentioned in lecture 13: pulmonary ventilation, external respiration, and internal respiration. Some concepts relating to pulmonary ventilation (breathing) are inspiration (inhalation) vs expiration (exhalation), atmospheric and intrapulmonary pressure (when intrapulmonary pressure is greater than atmospheric pressure, air moves out of the alveoli; therefore, higher atmospheric pressure hardens respiration). These two pressures create a pressure gradient which causes inhalation and exhalation. VI. Inspiration is an active process meaning it requires expenditure of energy. It follows Boyle’s law (pressure and volume of a gas have an inverse relationship, when temperature is held constant). As intrapulmonary pressure increases, the volume of the lungs decreases. It occurs byinspiratory muscles. Phrenic nerves (C3-5) and thoracic nerves (T1-11) are the nerves within the lung. Here is the basic process of inspiration: thoracic volume increases → pleural volume increases → intrapleural pressure decreases → lung volume increases → intrapulmonic pressuredecreases → air flows into lungs.VII. Expiration is a passive process at rest because it has elastic recoil and surface tension. The process of expiration is thoracic volume decreases → pleural volume decreases → intrapleural pressure increases → lung volume decreases → intrapulmonic pressure increases → air flows out of lungs. Expiration is forced by the internal intercostals (11 pairs), rectus abdominis, abdominal obliques, and transversus abdominis which are
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