Respiratory System - Module 2 Lecture 1 - PDF

Module 2 lecture 1 Monday, 19 August 2024 10:14 pm Respiratory system Basic function - Gas exchange - homeostasis of CO2, O2 - Acid-base exchange - blood pH Respiratory physiology is heavily related to its anatomy Respiratory system definition: " the organs and tissues involved in gas...

Module 2 lecture 1 Monday, 19 August 2024 10:14 pm Respiratory system Basic function - Gas exchange - homeostasis of CO2, O2 - Acid-base exchange - blood pH Respiratory physiology is heavily related to its anatomy Respiratory system definition: " the organs and tissues involved in gas exchange" Conducting and respiratory zones - Functionally, the respiratory system is divided into the conducting and respiratory zon nes, each with distinct roles Increase in surface area of the respiratory zone Respiratory zone - Pulmonary arteries branch to supply blood to the pulmonary capillaries, where gas exc lung alveoli - Gas exchange through "passive diffusion" - Oxygenated blood returns via pulmonary veins to the left atrium change occurs within the Cellular transition across zones Cells of the alveoli - There are three types of cells that line the alveoli: Ø Type 1 pneumocytes Ø Type 2 pneumocytes Ø Alveoli macrophages  - There are three types of cells that line the alveoli: Ø Type 1 pneumocytes Ø Type 2 pneumocytes Ø Alveoli macrophages Fick's law of diffusion: Ø Shorter distance = greater rate of diffusion Ø Greater surface area = great rate of diffusion The pleurae of the lungs - Each lung is encased in a thin, two-layered, fluid-filled membrane called the pleura. Inner visceral pleura, outer parietal pleura, and between pleural cavity filled with pleural fluid The pleurae of the lungs - Each lung is encased in a thin, two-layered, fluid-filled membrane called the pleura. Inner visceral pleura, outer parietal pleura, and between pleural cavity filled with pleural fluid How do we breathe? Breathing: pulmonary ventilation - Boyle's law - the absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies, if the temperature and amount of gas is unchanged (confined). Pulmonary ventilation - Pulmonary ventilation refers to the moving of air in and out of the lungs - A mechanical process that depends on volume changes in the thoracic cavity - Such changes in volume are driven by the contraction / relaxation cycling of intercostal muscles and the diaphragm  - Such changes in volume are driven by the contraction / relaxation cycling of intercostal muscles and the diaphragm Quick recap from respiratory anatomy And expiration Lung pressures - Key factors influencing negative intra-pleural pressure - Surface tension: Ø Pleural fluid provides surface tension between pleural layers - Elastic force by the lungs (inwards): Ø Elastic tissue in lunges recoils and pulls lungs inwards Ø Visceral pleura pulled inwards - Elastic force by the thoracic cage (outwards) Ø Thoracic wall tends to naturally pull away from lung Ø Parietal pleura pulled outwards Pressure gradients: quiet breathing - Note this is quiet breathing (eupnea) - Tidal volume is the amount of air that moves in or out of the lungs with each respiratory cycle. 400-500 ml. Modes of breathing: quiet vs/ forces breathing - Quiet breathing (normal breathing / eupnea) Ø Occurs at rest, without cognitive thought Ø Inspiration: diaphragm, external intercostal muscles Ø Expiration: relaxation of diaphragm and intercostal muscles Ø Diaphragmic vs costal breathing - Forced breathing (hypernea) Ø Requires extra ,muscle contractions in BOTH inspiration and expiration Forced breathing - Hypereupnea: fast-forced breathing Summary - Can you describe the relationship between pulmonary pressure and volume? - Can you explain the steps involved in quite inspiration?