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Understanding the Respiratory System: Gas Exchange, Function, and Disorders

The respiratory system is vital for gas exchange, allowing oxygen (O2) uptake and carbon dioxide (CO2) expulsion. It consists of the upper and lower tracts, including the trachea, bronchi, and lungs. Alveoli, the tiny air sacs, maximize surface area for efficient gas transfer, requiring moist membranes for optimal diffusion. Breathing mechanics involve pressure changes within the thoracic cavity, regulated by the medulla. Disorders such as asthma and COPD threaten respiratory function. Understanding its structure and function is crucial for maintaining health and diagnosing ailments.

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Understanding the Respiratory System: Gas Exchange, Function, and Disorders

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  1. alveoli Gas Exchange Respiratory Systems elephantseals gills

  2. food O2 ATP CO2 Why do we need a respiratory system? • Need O2 in • for aerobic cellular respiration • make ATP • Need CO2 out • waste product fromKrebs cycle

  3. Gas exchange • O2 & CO2 exchange between environment & cells • need moist membrane • need high surface area

  4. Optimizing gas exchange • Why high surface area? • maximizing rate of gas exchange • CO2 & O2 move across cell membrane by diffusion • rate of diffusion proportional to surface area • Why moist membranes? • moisture maintains cell membrane structure • gases diffuse only dissolved in water

  5. Thoracic Cavity • 3Divisions: - Right and left pleural division - Mediastinum • Parietal pleura lines the entire thoracic cavity and each lung is encased in a separate pleural sac (visceral pleura) • Pleurisy • Thoracic capacity expands and contracts in combination with diaphragm contracting (increase) and relaxing (decrease) to allow for inspiration and expiration

  6. Respiratory System • 3 Divisions: • Upper respiratory tract nose, pharynx (nasopharynx, oropharynx, laryngopharynx), and larynx 2. Lower Respiratory tract trachea, bronchial tree, lungs 3. Accessory Structures oral cavity, ribcage, respiratory muscles

  7. Lungs Exchange tissue:spongy texture, honeycombed with moist epithelium

  8. Alveoli • Gas exchange across thin epithelium of millions of alveoli • total surface area in humans ~100 m2

  9. Negative pressure breathing • Breathing due to changing pressures in lungs • air flows from higher pressure to lower pressure • pulling air instead of pushing it

  10. Mechanics of breathing • Air enters nostrils • filtered by hairs, warmed & humidified • sampled for odors • Pharynx  glottis  larynx (vocal cords)  trachea (windpipe)  bronchi  bronchioles  air sacs (alveoli) • Epithelial lining covered by cilia & thin film of mucus • mucus traps dust, pollen, particulates • beating cilia move mucus upward to pharynx, where it is swallowed

  11. Pulmonary Volumes • Measured with a spirometer • TV (tidal volume) • ERV (expiratory reserve volume) • RV (residual volume) • IRV (inspirational volume) • Vital Capacity = IRV + TV + ERV

  12. Autonomic breathing control • Medulla sets rhythm & pons moderates it • coordinate respiratory, cardiovascular systems & metabolic demands • Nerve sensors in walls of aorta & carotid arteries in neck detect O2 & CO2 in blood

  13. Medulla monitors blood • Monitors CO2 level of blood • measures pH of blood & cerebrospinal fluid bathing brain • CO2 + H2O  H2CO3 (carbonic acid) • if pH decreases then increase depth & rate of breathing & excess CO2 is eliminated in exhaled air

  14. Hemoglobin • Why use a carrier molecule? • O2 not soluble enough in H2O for animal needs • blood alone could not provide enough O2 to animal cells • hemoglobin in vertebrates = iron (reddish) that absorbs oxygen heme group cooperativity

  15. Respiratory Disorders Inflammation, Infection, and Anatomical URI: • Rhinitis • Pharyngitis • Laryngitis

  16. Respiratory Disorders • Deviated Septum • Epistaxis LRI: • Acute Bronchitis • Tuberculosis • Lung Cancer

  17. Respiratory Function Disorders • General group of disorders that cause decreased lung volumes and capacities Obstructive Pulmonary disorders • Chronic Obstructive Pulmonary Disease (COPD) • Emphysema • Asthma

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