Study Notes: Respiratory System Overview

Introduction to the Respiratory System

• The respiratory system serves the critical function of providing oxygen (O2) to cells and removing carbon dioxide (CO2) waste from the body.

• It consists of:

  • Upper respiratory tract

  • Lower respiratory tract

• The two lungs are located in the thoracic cavity.

• Gas exchange is driven by partial pressures and the diffusion of dissolved gases.

• Respiratory functions are affected by age and various diseases.

Key Processes in Breathing

• When breathing occurs, four major processes take place:

  • Ventilation: Moving air into and out of the trachea, bronchi, and lungs.

  • Diffusion: The exchange of oxygen acquired during ventilation with carbon dioxide across alveolar–capillary membranes.

  • Perfusion: The supply of oxygenated blood to the lungs and various organ systems through blood vessels.

  • Respiration: The cellular process where oxygen is used aerobic to generate energy.

Importance for Healthcare Providers

• Recognizing issues relating to altered ventilation and diffusion is crucial for healthcare providers.

Module 1: Pulmonary Structure and Function

• The pulmonary system is responsible for both ventilation and diffusion, with its primary purpose being gas exchange between the environment and the blood.

Components of the Pulmonary System

• Comprises:

  • Lungs

  • Airways

  • Chest wall

  • Pulmonary circulation

• The structural path is divided into:

  • Upper Airways:

  • Nose

  • Mouth

  • Nasopharynx

  • Oropharynx

  • Laryngeal pharynx (connects upper and lower airways)

  • Lower Airways:

  • Trachea

  • Bronchi

  • Bronchioles

Anatomical Structure and Function

• The branching anatomy of the pulmonary system maximizes surface area, facilitating optimal gas diffusion across the alveoli.

Pulmonary Defense Mechanisms

• Given its exposure to the external environment, the pulmonary system has developed several defense mechanisms:

  • Protective Structures:

  • Hairs and turbinates (shell-shaped structures) in the nose trap foreign particles.

  • Cilia in the upper and lower airways serve a similar purpose.

  • Mucosal Lining:

  • Warms and humidifies inhaled air.

  • Irritant Receptors:

  • Located throughout the nose and airways, triggering cough or sneeze responses to expel harmful agents.

  • Immune Protections:

  • Immune coating in respiratory mucosa and macrophages within alveoli ingest and eliminate foreign materials through phagocytosis.

Consideration on Defense Mechanisms

• Question: How do defense mechanisms change in individuals who habitually breathe through the mouth?

Muscular and Membranous Structure of Lungs

• Intercostal muscles and ribs safeguard the lungs against injury.

• Muscles in the chest cavity and the diaphragm execute the muscular work for breathing.

• The lungs and chest cavity are lined with:

  • Parietal pleura (outer layer)

  • Visceral pleura (inner layer)

• Between these pleura layers is the pleural space, lubricated with fluid to minimize friction between layers during breathing.

Pulmonary Circulation

• Responsible for:

  • Delivering oxygen and nutrients to lung tissues.

  • Filtering clots, air, or foreign materials from circulation.

• Capillaries near alveoli allow for gas exchange of oxygen and carbon dioxide.

Ventilation Process

• Ventilation entails both acquiring oxygen (inspiration) and expelling carbon dioxide (expiration) from the blood.

• Oxygen transport through the lungs is the sole means of acquiring oxygen necessary for cellular metabolism.

Importance of Oxygen and Carbon Dioxide in Cellular Functioning

• Oxygen is crucial for efficient energy expenditure and proper cellular function.

• The release of carbon dioxide is vital for maintaining a stable pH range essential for cell functionality.

Regulation of Ventilation

• The rate and volume of ventilation are managed by:

  • Respiratory Control Centers: Located in the brainstem; respond to chemical signals in the body to regulate breathing.

  • Lung Receptors: Sensory receptors in the lungs that monitor breathing state and lung functionality.

  • Chemoreceptors: Detect changes in blood composition (e.g., CO2 and O2 levels) that influence respiration rates.

Respiratory Control Centers

• Comprises neurons in the pons and medulla which send neural impulses to various muscles, inducing contraction or relaxation.

  • Muscles involved include:

  • Diaphragm

  • Intercostal muscles

  • Sternocleidomastoid muscles

Autonomic Nervous System (ANS) Influence

• The ANS influences the lungs by innervating smooth muscles in the airways to:

  • Promote contraction (parasympathetic division) or dilation (sympathetic division).

  • Regulate diameter of airways, subsequently affecting airflow to and from the lungs.

Role of Lung Receptors

• Lung receptors are categorized based on their specific functionalities, e.g., receptors in the conducting airways that identify and react to irritants.