Respiratory_system

The Respiratory System Overview

Introduction

  • Cooperation of Systems:

    • The cardiovascular and respiratory systems work together to supply oxygen (O2) and remove carbon dioxide (CO2).

    • The respiratory system is responsible for gas exchange, while the cardiovascular system transports these gases.

  • Importance:

    • Failure in either system disrupts homeostasis leading to rapid cell death from lack of oxygen and accumulation of waste products.

Respiration Process

  • Definition:

    • Respiration is the exchange of gases between the atmosphere, blood, and cells.

  • Basic Steps:

    1. Ventilation (Breathing)

    2. External (Pulmonary) Respiration

    3. Internal (Tissue) Respiration

Detailed Steps of Respiration

  • Pulmonary Ventilation:

    • Involves inspiration (inhaling) and expiration (exhaling).

  • External (Pulmonary) Respiration:

    • Gas exchange occurs between the lungs (alveoli) and blood.

  • Transport of Respiratory Gases:

    • O2 and CO2 are transported between tissues and lungs.

  • Internal (Tissue) Respiration:

    • Gas exchange between blood and tissue cells; RBCs deliver O2 and pick up CO2 as cells use O2 for metabolic processes.

Anatomy of the Respiratory System

Key Components

  • Parts:

    • Nose

    • Pharynx (throat)

    • Larynx (voice box)

    • Trachea (windpipe)

    • Bronchi (airways)

    • Lungs

  • Tract Division:

    • Upper Respiratory Tract: above vocal cords

    • Lower Respiratory Tract: below vocal cords

Conducting and Respiratory Portions

  • Conducting System:

    • Nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles conduct air into lungs.

  • Respiratory Portion:

    • Involves gas exchange areas: respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Pharynx Structure

  • Anatomy:

    • Nasopharynx

    • Oropharynx

    • Laryngopharynx

  • Physiology:

    • Common passageway for air & food, serves as a resonating chamber for speech.

Larynx Details

  • Function:

    • Connects pharynx with trachea.

  • Anatomical Features:

    • Contains thyroid cartilage (Adam’s apple), epiglottis (prevents food entry), and cricoid cartilage (connects larynx and trachea).

  • Voice Production:

    • Vocal folds (cords) produce sound; tension affects pitch.

  • Conditions:

    • Laryngitis (inflammation), associated with infection or irritants.

    • Cancer risk prevalent in smokers.

Trachea and Bronchial Tree

  • Structure:

    • Extends from the larynx to primary bronchi; composed of smooth muscle and C-shaped cartilage rings; lined with pseudostratified ciliated columnar epithelium.

  • Function:

    • Keeps airway open, cilia sweep debris towards throat.

Bronchi Structure

  • Division:

    • Trachea divides into right and left pulmonary bronchi, leading into secondary and tertiary bronchi and bronchioles.

  • Structure:

    • Bronchial walls contain cartilage rings, while bronchioles contain smooth muscle fibers.

Lungs Overview

  • Anatomy:

    • Paired organs within the thoracic cavity, covered by pleural membranes.

    • Parietal pleura (outer layer) and visceral pleura (inner layer); pleural cavity contains lubricating fluid.

  • Gross Anatomy:

    • Apex, base, separation by fissures; left lung has cardiac notch.

Functionality of Alveoli

  • Structure:

    • Alveolar ducts and sacs lead into alveoli; offer a large surface area (up to 2/3 of a tennis court).

  • Cell Types:

    • Type I cells (gas exchange), Type II cells (secretes surfactant), and macrophages removing debris.

  • Gas Exchange Mechanism:

    • Formed around alveoli by capillaries, with lungs controlling airway resistance.

Mechanics of Breathing (Pulmonary Ventilation)

  • Air Pressure Differences:

    • Air flows into the lungs when internal pressure is less than atmospheric pressure; flows out when greater.

  • Boyle’s Law and Ventilation:

    • States gas volume and pressure are inversely related; determines pressure changes during breathing.

Muscular Mechanics

  • Muscles for Inspiration:

    • Diaphragm and intercostal muscles expand thoracic cavity.

  • Muscles for Expiration:

    • Internal intercostals, abdominal muscles compress thoracic cavity to force air out.

Respiratory Efficiency and Compliance

  • Lung Compliance:

    • Affected by elasticity and surface tension; diseases may reduce compliance (e.g., tuberculosis, pulmonary edema).

Gas Transport Principles

Hemoglobin Function

  • Composition:

    • Consists of globin and heme, enabling high capacity for oxygen transport.

Oxygen Transport Mechanism

  • Distribution:

    • 98.5% of oxygen is bound to hemoglobin in red blood cells, while 1.5% is dissolved in plasma.

CO2 Transport Mechanisms

  • Forms of Transport:

    • Dissolved CO2 (7%), carbaminohemoglobin (23%), bicarbonate ions (70%); vital for maintaining pH balance.

Hypoxia and Its Types

  • Types of Hypoxia:

    • Hypoxic, anemic, stagnant, and histotoxic hypoxia represent various causes of oxygen deficiency.

Carbon Monoxide Poisoning

  • Cause:

    • CO binds to hemoglobin more tightly than O2, leading to toxicity; treated with pure oxygen administration.

Summary of Gas Exchange and Transport

  • Oxygen diffuses from hemoglobin to cells, while CO2 produced in tissues enters blood, facilitating gas exchange at capillary level.

Impact of Lifestyle on Respiratory Efficiency

Smoking Effects

  • Consequences:

    • Causes windedness, restricts air passage, promotes excess mucus, damages lung tissues leading to emphysema.

Aging Impacts on Respiratory System

  • Effects:

    • Changes in tissue rigidity, decreased vital capacity, reduced ciliary action, increased susceptibility to infections.

Respiratory Disorders

  • Common issues: asthma, chronic obstructive pulmonary disease (COPD), pneumonia, tuberculosis, influenza, and pulmonary edema.

Pneumothorax

  • Definition:

    • Air enters pleural space due to injuries, causing lung collapse on the affected side.