6 The Respiratory System 1.pptx

Dr. Elita Partosoedarso – The Respiratory System

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Overview of the Respiratory System

• Key Divisions:

  • Anatomical

  • Functional: including lungs, blood and nerve supply, pleura, bronchial tree, respiratory membrane, and alveoli.

General Functions of the Respiratory System

1. Gas Exchange:

   • O2 intake and CO2 elimination.

2. Regulation of Blood pH:

   • Through CO2 elimination.

3. Additional Functions:

   • Air filtration.

   • Olfactory functions (smell).

   • Speech production.

   • Straining (e.g., childbirth, coughing).

   • Excretion of water and heat.

• Chemical Reaction:

  • CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+.

Anatomy of the Respiratory System

• Upper Respiratory Tract:

  • Location: outside the thorax (Nose → Pharynx → Larynx).

• Lower Respiratory Tract:

  • Location: within the thorax (Trachea → Bronchi → Alveoli).

• Accessory Structures:

  • Oral cavity.

  • Rib cage.

  • Respiratory muscles (e.g., diaphragm).

Functional Divisions

• Conducting Zone:

  • Purpose:

    • Route for incoming/outgoing air.

    • Remove debris/pathogens.

    • Warm and humidify air.

  • Includes:

    • Upper respiratory tract.

    • Parts of the lower tract not involved in gas exchange.

    • Accessory structures.

• Respiratory Zone:

  • Purpose:

    • Site of gas exchange.

  • Includes:

    • Terminal bronchioles.

    • Alveolar duct.

    • Alveoli.

    • Pulmonary capillaries.

Functions of the Nose

• Key Functions:

  • Passageway for air.

  • Chemical examination for irritants (olfaction).

  • Mucus production to trap allergens and debris.

  • Rich blood supply for warming and moistening air.

• Components:

  1. External Nose: Surface structures and skeletal appearance.

  2. Internal Nose (Nasal Cavity):

     • Divided by the septum; lined with three conchae and meatuses.

     • Connects to pharynx, nasolacrimal ducts, and paranasal sinuses.

  3. Meatuses and Conchae:

     • Lined with mucous membranes to increase surface area.

     • Disrupt airflow to aid cleaning and warming.

     • Conserve water during exhalation.

Paranasal Sinuses

• Structure:

  • Four pairs of air-filled spaces open to the nasal cavity, lined with respiratory mucosa.

• Function:

  • Lighten the skull.

  • Moisten and warm incoming air.

  • Produce mucus swept into the nose.

  • Affect speech resonance.

Respiratory Epithelium

• Contains olfactory epithelium with nerve cells.

• Type: Pseudostratified ciliated columnar epithelium.

• Features:

  1. Goblet Cells: Produce mucus (>125 ml/day) for air purification.

  2. Cilia: Help clear debris via the ciliary escalator.

  3. Lysozyme Enzyme: Removes pathogens.

  4. Defensins: Antibacterial properties.

  5. Rich Blood Supply: Warms incoming air.

Pharynx Anatomy

• Overall Function: Pathway for both respiratory and digestive tracts.

• Regions of the Pharynx:

  1. Nasopharynx: Air passage; contains tonsils, pseudostratified columnar epithelium.

  2. Oropharynx: Passage for air and food/drink; stratified squamous epithelium.

  3. Laryngopharynx: Passage for air and food/drink; stratified squamous epithelium.

Larynx (Voice Box)

• Structure: Cartilaginous link between pharynx and trachea.

• Functions:

  • Regulates air volume into lungs.

  • Involved in respiration, vocalization, swallowing.

• Regions:

  1. Epiglottis: Covers trachea during swallowing.

  2. Glottis: Vocal cords, source of sound.

  3. Subglottis: Connects trachea, affects speech.

Trachea (Windpipe)

• Function: Passageway for air.

• Type of Epithelium: Pseudostratified ciliated columnar with goblet cells.

• Anatomy:

  • Supported by C-shaped hyaline cartilage rings to prevent collapse; elastic membranes allow stretching.

Lungs Anatomy

• Function: Distributing air to alveoli and facilitating gas exchange.

• Location: Thoracic cavity, bordered by diaphragm.

• Key Features:

  • Enclosed by pleurae, with a cardiac notch on the left lung for the heart.

  • Right lung has 3 lobes; left lung has 2 lobes.

  • Each lobe contains bronchopulmonary segments and pulmonary lobules.

Blood and Nerve Supply of the Lungs

• Blood Supply:

  • Delivers deoxygenated blood from right ventricle via pulmonary artery.

  • Oxygen uptake and CO2 elimination at pulmonary capillaries.

  • Oxygenated blood carried to left atrium by pulmonary vein.

• Nervous Innervation:

  • Parasympathetic system triggers bronchoconstriction.

  • Sympathetic system triggers bronchodilation.

  • Reflex actions (coughing, O2/CO2 regulation) managed by autonomic nervous system.

Pleura of the Lungs

• Components:

  1. Visceral Pleura: Inner layer on lungs.

  2. Parietal Pleura: Outermost layer lining thoracic cavity.

  3. Pleural Cavity: Space between two layers.

  4. Pleural Fluid: Lubricates pleura surfaces to reduce friction; maintains lung position against the thoracic wall.

Bronchial Tree

• Function: Passageway for air to lungs.

• Epithelium Type: Starts with pseudostratified ciliated columnar, transitioning to non-ciliated cuboidal in smaller bronchi.

• Branching Structure: 23 levels from trachea to alveoli.

  • Increased smooth muscle in smaller bronchi for adjusting airflow (bronchoconstriction/bronchodilation).

Respiratory Membrane and Alveoli

1. Respiratory Membrane: Alveoli and capillary membranes facilitate gas diffusion.

2. Alveolar Structure:

   • Ducts, individual alveoli (300 million), and clusters form the gas exchange area.

   • Type I and Type II alveolar cells play roles in gas exchange and maintaining surface tension, respectively.

   • Alveolar macrophages protect against pathogens.

Surfactant and Surface Tension

• Produced by: Type II alveolar cells.

• Composition: Detergent-like, containing phospholipids.

• Function: Reduces tension in alveoli, prevents collapse, and increases lung compliance.

Pulmonary Gas Exchange (External Respiration)

• Structural Features: Thin barrier for gas exchange, large surface area for optimization, proper blood distribution in lung capillaries.

• Influencing Factors: Alveolar ventilation, respiratory minute volume, pressure gradient.

Ventilation and Perfusion: V/Q Ratio

• Overview: Importance of matching ventilation (airflow) with perfusion (blood flow) for efficient gas exchange.

• Definitions:

  • Ventilation (V): Movement of air; regulated by airway diameter.

  • Perfusion (Q): Blood flow; affected by blood vessel diameter.

• V/Q Ratio: Critical for ensuring effective CO2 removal and O2 saturation in the blood.