Recording-2025-03-26T18:19:14.179Z

Bronchioles

• Last section of the conductive part of the respiratory system.

• Transition to the respiratory part that focuses on gas exchange.

Respiratory Bronchioles to Alveoli

• Respiratory bronchioles serve as the pathway to alveolar ducts which further lead to alveolar sacs.

• Alveolar sacs are likened to grape clusters, with each grape representing an alveolus (singular).

• Air supply to alveolar sacs comes through the alveolar duct.

Structure of Airways

• Trachea and larger airways have cartilage rings; smaller airways have flatter plates.

• Identification of branches such as the pulmonary artery (deoxygenated blood) and pulmonary vein (oxygenated blood).

Lymphatic System

• Lymphatic vessels present in the lungs assist in draining interstitial fluid.

Alveolar Structure

• Alveolar sacs are bordered by pulmonary venules (small veins) that carry oxygenated blood.

• Significance of terminal bronchioles transitioning to respiratory bronchioles.

Pulmonary Circulation vs. Bronchial Circulation

• Pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation.

• Bronchial arteries provide oxygenated blood to lung tissue, part of the systemic circulation.

Cell Types in Alveoli

• Pneumocyte Type I: Majority of cells, involved in gas exchange.

• Pneumocyte Type II: Less common, produce surfactant crucial for lung function.

Surfactant Function

• Reduces surface tension, preventing alveoli from collapsing.

• Essential for maintaining alveolar patency, especially when lungs recoil during breathing.

Hypoxic Response

• Body diverts blood flow to well-oxygenated areas of the lungs.

• Inadequate blood flow to non-ventilated areas leads to vasoconstriction, enhancing efficiency in gas exchange.

Patency

• Patency refers to keeping airways and alveoli open for effective airflow and gas exchange.

• Smooth muscle and surfactant are crucial for maintaining patency in alveoli.

Breathing Mechanics

• Diaphragm: Main muscle for inspiration; its contraction increases thoracic cavity volume, lowering pressure (Boyle's Law).

• Intrapleural Pressure: Always negative, assists in lung expansion by keeping lungs coupled to thoracic wall.

• Atmospheric and Alveolar Pressures: Atmospheric pressure (760 mmHg), alveolar pressure fluctuates to facilitate airflow.

Phases of Breathing Cycle

• Inspiration: Diaphragm contracts, lung volume increases, pressure drops below atmospheric pressure allowing air intake.

• Expiration: Foundationally passive; diaphragm and muscles relax, leading to increased alveolar pressure, allowing air out.

• Forced Breathing: Additional muscles involved during vigorous activity, altering pressures and airflow rates.

Lung Compliance and Resistance

• Compliance: Ability to expand lung tissue; conditions like pulmonary fibrosis affect this.

• Airway Resistance: Conditions like asthma or COPD inhibit airflow during exhalation, complicating breathing efforts.

Peptidal Surfactant

• Biochemical composition includes phospholipids; essential for preventing costly collapse of alveoli and ensuring effective gas exchange.

• Begins production around week 25 in fetal development; crucial for premature infants’ viability.

Diseases of the Respiratory System

• Pathologies like cystic fibrosis, tuberculosis, and emphysema can compromise lung function.

• Conditions lead to severe complications like COPD, affecting airflow dynamics through obstruction or compliance issues.

Intensive Rehabilitation Techniques

• Patients with respiratory distress or chronic illnesses may require therapies such as percussion and drainage techniques to clear mucus and maintain lung function.

• Use of devices or methods to facilitate effective breathing mechanisms and support lung health.