Systems Physiology SBEG103 Fall 2024 Lecture 9 Respiration PDF

Systems Physiology SBEG103 Fall 2024 Lecture 9 Respiration Prof Aliaa Rehan Youssef [email protected] What are our objectives for today? Explain Function of different parts of the respiratory system Describe Respiration as a mechatroni...

Systems Physiology SBEG103 Fall 2024 Lecture 9 Respiration Prof Aliaa Rehan Youssef [email protected] What are our objectives for today? Explain Function of different parts of the respiratory system Describe Respiration as a mechatronic system Identify How biomedical devices can assess and treat respiratory functions. What are the main parts of the respiratory system? What are the main parts of the respiratory system?  The respiratory tract External For the intake of air. nostrils Nasal which is lined with hair and mucus to filter the air chamber from dust and dirt. It is a passage behind the nasal chamber and serves Pharynx as the common passageway for both air and food. It houses the vocal chords, which are paramount in Larynx the generation of sound. It is a flap-like structure that covers the glottis and Epiglottis prevents the entry of food into the windpipe.  The respiratory tract Trachea It is a long tube passing through the mid-thoracic cavity. Bronchi The trachea divides into left and right bronchi. Each bronchus is further divided into finer channels known as Bronchioles bronchioles. The bronchioles terminate in balloon-like structures known as Alveoli the alveoli. Humans have a pair of lungs, which are sac-like structures and Lungs covered by a double-layered membrane known as pleura. What is the main function of the respiratory system?  Function of the Respiratory System Filters (first defence line against Nose pathogens), warms, and humidifies air Larynx (voice box) Air passageways, sound production Pharynx Air and food passageways, It functions by preventing the entry of food particles into the windpipe Trachea (the windpipe) & Air transport to lungs Bronchi Lungs Gas exchange  Repiratory system: a biomechatronic system Biological Components: The gas exchange organ where oxygen is absorbed Lungs: and carbon dioxide is expelled. Diaphragm and The primary actuators driving the mechanical Intercostal Muscles: process of breathing. Airways (Trachea, The conduits for air movement to and from the Bronchi, Bronchioles): lungs. The brainstem (medulla oblongata and pons) serves as the system's controller, regulating Neural Control: breathing rates and patterns based on sensory feedback.  Repiratory system: a biomechatronic system Mechanical Analogues:: The thoracic cavity acts as a dynamic chamber, similar to a piston-cylinder system, changing volume to create pressure gradients for air movement. Elastic recoil and compliance of lung tissue resemble mechanical springs that store and release energy. How could you assess Thoracic movement?  Repiratory system: a biomechatronic system Sensory and Feedback Systems: Chemoreceptors: Monitor oxygen, carbon dioxide, and pH levels, analogous to chemical sensors. Mechanoreceptors: Detect stretch and pressure changes in the lungs, like strain gauges or pressure sensors in a mechanical system.  Repiratory system: a biomechatronic system Control System: The central nervous system (CNS) functions like a microcontroller, integrating sensory data and modulating output signals to respiratory muscles to maintain homeostasis.  Neural Control Medulla Oblongata and Pons: These brainstem regions regulate the rhythmic breathing cycle by controlling respiratory muscle activity. Peripheral and Central Chemoreceptors: These receptors detect changes in CO₂, O₂, and pH levels in the blood and cerebrospinal fluid, adjusting breathing accordingly. Together, these centers coordinate automatic and rhythmic breathing, adapting to metabolic demands and environmental changes.  Breathing Mechanics Coordinated interaction of muscles, bones, and lung structures to facilitate the exchange of oxygen and carbon dioxide. It consists of two main phases: inhalation (inspiration) and exhalation (expiration).  Inhalation (Inspiration) This is the active phase of breathing, requiring muscle contraction to draw air into the lungs. Diaphragm Movement: The diaphragm, a dome-shaped muscle separating the thoracic and abdominal cavities, contracts and flattens. This increases the vertical dimension of the thoracic cavity. Intercostal Muscles: The external intercostal muscles contract, lifting the ribs and sternum outward and upward. This increases the thoracic cavity's lateral (side-to-side) and anteroposterior (front-to-back) dimensions. Pressure Changes: The expansion of the thoracic cavity decreases the intrapulmonary (alveolar) pressure below atmospheric pressure, creating a pressure gradient that allows air to flow into the lungs. Accessory Muscles (during deep or labored breathing): Additional skeletal neck muscles may help elevate the ribcage further  Exhalation (Expiration): This phase can be passive (during quiet breathing) or active (during forceful breathing). Passive During quiet breathing, expiration occurs due to the elastic recoil of the lungs and thoracic cage as the diaphragm and intercostal muscles relax. Expiration: This reduces the thoracic cavity's volume, increasing intrapulmonary pressure above atmospheric pressure, pushing air out. Active Expiration (during forced Abdominal muscles and rib cage muscles contract to forcefully reduce the thoracic cavity's volume, expelling air quickly. breathing):  Mechanical Components Influencing Breathing Compliance: Lung compliance refers to the ease with which the lungs expand. High compliance makes breathing easier, while low compliance (e.g., in fibrosis or restrictive lung diseases) makes it harder. Airway Resistance: Resistance in the airways affects airflow. Increased resistance (e.g., in asthma or COPD) makes it harder to breathe. Surface Tension: Surfactant, produced by alveolar cells, reduces surface tension in the alveoli, preventing their collapse during exhalation. Elasticity: The lungs' elastic fibers help them return to their resting state during exhalation.  Alveolar Structure and Surfactant Role Alveolar Structure: The alveoli are small, spherical air sacs in the lungs where gas exchange occurs. Their thin walls, made of a single layer of epithelial cells, maximize surface area for gas exchange. Surfactant Role: Pulmonary surfactant is a lipid-protein substance secreted by alveolar cells. It reduces surface tension within the alveoli, preventing collapse (atelectasis) during exhalation and aiding efficient gas exchange.  Diffusion of Gases (Partial Pressure Gradients, Fick’s Law) Partial Pressure Gradients: Oxygen and carbon dioxide move between alveoli and capillaries based on differences in their partial pressures. Oxygen diffuses from high partial pressure in alveoli to lower partial pressure in blood, while carbon dioxide moves in the opposite direction. Fick’s Law: Describes the rate of gas diffusion, which is proportional to the surface area and partial pressure difference and inversely proportional to membrane thickness.  Oxygen Transport in Blood (Hemoglobin, Dissociation Curve) Hemoglobin: A protein in red blood cells that binds oxygen. Each molecule can carry up to four oxygen molecules, allowing efficient oxygen transport to tissues. Dissociation Curve: The oxygen-hemoglobin dissociation curve shows the relationship between oxygen saturation and partial pressure. It reflects how hemoglobin’s affinity for oxygen changes under different conditions, such as pH and temperature.  Assessing Respiratory Function: Respiratory Volumes and Capacities Tidal Volume (TV): – Air per normal breath (about 500 mL). Vital Capacity (VC): – Maximum exhalable air after maximum inhalation (about 3,100 to 4,800 mL). Residual Volume (RV): – Air left in the lungs after forced exhalation (about 1,200 mL). Total Lung Capacity (TLC): – Total lung volume (about 5,800 mL).  Assessing Respiratory Function: Respiratory Volumes and Capacities Spirometers are essential for measuring airflow and diagnosing obstructive diseases, and they are widely used in clinical practice.  Assessing Respiratory Function: Respiratory Volumes and Capacities Pulse Oximetry: A non-invasive device that measures blood oxygen saturation (SpO₂) by analyzing light absorption through tissue. Blood Gas Analyzers: These devices measure arterial blood gases, including oxygen (PaO₂), carbon dioxide (PaCO₂), and pH, providing critical data for assessing respiratory function.  Assignment: Presentation Based on physiology, how can wearable sensors, mobile apps, or smart devices assess different body functions? Present a device or technology not previously studied in this course and propose at least one enhancement feature.  Guidelines 1. Presentation Team: 1. Form a team of 4–5 members. 2. Collaborate to divide responsibilities (e.g., research, design slides, presenting specific sections). 2. Content Requirements: 1. Introduction: Brief overview of how physiology governs the assessment of body functions using wearable technology. 2. Example of a New Device or Technology: Introduce and explain one wearable or smart device not covered in this course. 3. Proposed Enhancement: Describe one specific feature that could improve its function, usability, or impact. 4. Conclusion: Summarize the device's role in health monitoring and the value of the proposed enhancement. 3. Duration: 1. 5 minutes total presentation time. 2. All team members should participate within the allotted time.  Guidelines Presentation Format: 1. Venue: Online. 2. Scheduled during the week starting December 21 (exact date to be announced). Preparation Tips: 1. Research an innovative device or app beyond course content. 2. Keep slides concise with a balance of visuals and key points. 3. Ensure the proposed enhancement is innovative, feasible, and clearly linked to improving health outcomes. Evaluation (4 points): 1. Creativity in selecting and enhancing the device. 2. Relevance of the enhancement to physiological monitoring. 3. Clarity, teamwork, and engagement in the presentation.