Anatomy and Pathophysiology of Respiratory System PDF

Anatomy and pathophysiology of respiratory system PROFESSOR D R YA S S E R O S M A N  Anatomy of the Respiratory System ❖ Upper Respiratory Tract: o Nose: The primary entry point for air, containing the nasal cavity which filters, warms, and humidifies inco...

Anatomy and pathophysiology of respiratory system PROFESSOR D R YA S S E R O S M A N  Anatomy of the Respiratory System ❖ Upper Respiratory Tract: o Nose: The primary entry point for air, containing the nasal cavity which filters, warms, and humidifies incoming air. o Pharynx: A muscular tube that serves as a pathway for both air and food. o Larynx: Contains the vocal cords and is responsible for sound production. It also acts as a passageway for air between the pharynx and trachea. ❖ Lower Respiratory Tract: o Trachea: A tube that connects the larynx to the bronchi, lined with cilia and mucus to trap and expel particles. o Bronchi and Bronchioles: The trachea divides into two main bronchi, which further branch into smaller bronchioles within the lungs. o Lungs: Composed of lobes (three on the right, two on the left), containing alveoli where gas exchange occurs. o Alveoli: Tiny air sacs surrounded by capillaries, facilitating the exchange of oxygen and carbon dioxide. ❖ Muscles of the Respiratory System Diaphragm: The primary muscle of respiration, located below the lungs. It contracts and flattens during inhalation, increasing thoracic cavity volume. Intercostal Muscles: Located between the ribs, these muscles assist with expanding and contracting the rib cage during breathing. Accessory Muscles: Includes the sternocleidomastoid and scalene muscles, which are used during deep or labored breathing. ❖ Nerve Supply Phrenic Nerve: Innervates the diaphragm, originating from the cervical spinal cord (C3-C5). Intercostal Nerves: Supply the intercostal muscles, originating from the thoracic spinal cord. Vagus Nerve: Provides parasympathetic innervation to the lungs, regulating bronchoconstriction and mucus secretion.  Physiology of Respiration 1. Mechanics of Breathing: o Inhalation: Diaphragm contracts and moves downward, intercostal muscles contract, expanding the chest cavity and reducing pressure, allowing air to flow into the lungs. o Exhalation: Diaphragm and intercostal muscles relax, decreasing chest cavity volume and increasing pressure, pushing air out of the lungs. 2. Gas Exchange: o External Respiration: Occurs in the alveoli where oxygen diffuses into the blood and carbon dioxide diffuses out. o Internal Respiration: Occurs at the cellular level where oxygen is delivered to tissues and carbon dioxide is collected for transport back to the lungs. 3. Control of Respiration: o Medulla Oblongata and Pons: Brainstem regions that regulate the rate and depth of breathing. o Chemoreceptors: Located in the medulla, aorta, and carotid arteries, these receptors detect changes in blood pH, carbon dioxide, and oxygen levels, adjusting breathing accordingly. Inhalation (Inspiration)  Diaphragm Contraction: The diaphragm, a dome-shaped muscle at the base of the lungs, contracts and moves downward. This increases the vertical dimension of the thoracic cavity.  Intercostal Muscle Contraction: The external intercostal muscles, located between the ribs, contract to lift the rib cage upward and outward. This increases the lateral and anteroposterior dimensions of the thoracic cavity. Thoracic Volume Increase: The combined actions of the diaphragm and intercostal muscles increase the overall volume of the thoracic cavity. Pressure Decrease: According to Boyle’s Law, increasing the volume of the thoracic cavity decreases the intrapulmonary pressure (pressure within the lungs) below atmospheric pressure. Airflow into Lungs: The pressure gradient created by the lower intrapulmonary pressure causes air to flow into the lungs until the pressures equalize. Exhalation (Expiration) Diaphragm Relaxation: The diaphragm relaxes and moves upward, returning to its dome shape. Intercostal Muscle Relaxation: The external intercostal muscles relax, allowing the rib cage to move downward and inward. Thoracic Volume Decrease: The relaxation of these muscles decreases the volume of the thoracic cavity. Pressure Increase: The decrease in thoracic volume increases the intrapulmonary pressure above atmospheric pressure. Airflow out of Lungs: The pressure gradient created by the higher intrapulmonary pressure causes air to flow out of the lungs until the pressures equalize.  Accessory Muscles  During deep or labored breathing, additional muscles are recruited: Inspiration: The sternocleidomastoid and scalene muscles help elevate the sternum and upper ribs. Expiration: The internal intercostal muscles and abdominal muscles (rectus abdominis, external oblique, internal oblique, and transversus abdominis) contract to forcefully decrease thoracic volume.  Lung Compliance and Elasticity Compliance: Refers to the ease with which the lungs can expand. High compliance means the lungs can expand easily, while low compliance indicates stiffness. Elasticity: Refers to the ability of the lungs to return to their original shape after being stretched. Elastic fibers in the lung tissue contribute to this property.  Surface Tension and Surfactant Surface Tension: The alveoli are lined with a thin layer of fluid, creating surface tension that can cause the alveoli to collapse. Surfactant: A substance produced by type II alveolar cells that reduces surface tension, preventing alveolar collapse and making it easier for the lungs to expand  Respiratory Volumes and Capacities Tidal Volume (TV): The amount of air inhaled or exhaled during normal breathing. Inspiratory Reserve Volume (IRV): The additional air that can be inhaled after a normal inhalation. Expiratory Reserve Volume (ERV): The additional air that can be exhaled after a normal exhalation. Residual Volume (RV): The air remaining in the lungs after a maximal exhalation. Vital Capacity (VC): The total amount of air that can be exhaled after a maximal inhalation (TV + IRV + ERV).  Pathology of respiratory system Congenital anomalies Traumatic Infection bacterial viral or fungal Tumors Others as ischemic changes you too embolism  The pathology can be acute or chronic and can also be classified is temporary that heals completely example common cold or permanent with damage that do not heal completely example chronic obstructive pulmonary disease Examples of respiratory system pathology Infections Upper Respiratory Tract Infections (URTIs): Common cold, sore throat, and flu are typical URTIs caused by viruses like rhinovirus and influenza. Lower Respiratory Tract Infections (LRTIs): Pneumonia, bronchitis, and bronchiolitis are common LRTIs. Pneumonia can be caused by bacteria (e.g., Streptococcus pneumoniae), viruses, or fungi Obstructive Airway Diseases Asthma: Characterized by chronic inflammation and hyperreactivity of the airways, leading to wheezing, shortness of breath, and coughing. Chronic Obstructive Pulmonary Disease (COPD): Includes chronic bronchitis and emphysema, often caused by smoking. Symptoms include persistent cough, mucus production, and difficulty breathing. Restrictive Lung Diseases Pulmonary Fibrosis: Scarring of lung tissue leading to stiffness and reduced lung capacity. Sarcoidosis: Inflammatory disease that can affect multiple organs, including the lungs, causing granulomas (small inflammatory nodules). Neoplasms Lung Cancer: Includes small cell lung cancer (SCLC) non-small cell lung cancer (NSCLC). Risk factors include smoking, exposure to radon gas, and asbestos. Miscellaneous Disorders Pulmonary Embolism: Blockage of a pulmonary artery by a blood clot, leading to chest pain and shortness of breath. Pulmonary Hypertension: Increased blood pressure in the pulmonary arteries, which can lead to heart failure. Thank you