Chapter 21: Anatomy and Physiology - Respiratory System

Overview

• Introduction to the respiratory system, which aids in respiration (breathing).
• Key organ: Lungs (major organs) are part of a larger organ system made up of multiple organs.
• Organ classification:
  • Upper Respiratory Tract:
    • Nose (Nasal cavity)
    • Throat (Pharynx)
  • Lower Respiratory Tract:
    • Larynx
    • Trachea
    • Bronchi and Bronchioles

Upper Respiratory Tract Anatomy

Structures and Functions

• Nasal Cavity:
  • Openings (nostrils or external nares) for air intake.
  • Contains Nasal Conchae (superior, middle, inferior) for warming and humidifying air.
  • Nasal Epithelium: Contains chemoreceptors for sense of smell.
• Pharynx (throat):
  • Divided into three parts:
    • Nasopharynx (posterior to nasal cavity)
    • Oropharynx (posterior to oral cavity)
    • Laryngopharynx (posterior to larynx)

Lower Respiratory Tract Anatomy

Key Organs

• Larynx:
  • Contains vocal cords; referred to as the voice box.
  • Recognizable by Thyroid Cartilage (Adam's apple), larger in males.
  • Contains Epiglottis, which prevents food from entering the airway during swallowing.
• Trachea:
  • A long cartilaginous tube connecting larynx to bronchi.
• Bronchi Structure:
  • Primary bronchi (left and right), secondary bronchi, tertiary bronchi, and bronchioles (smaller branches).

Lungs and Gas Exchange

Lung Anatomy

• Lobes:
  • Right lung: 3 lobes (superior, middle, inferior)
  • Left lung: 2 lobes (superior, inferior) due to the position of the heart.
• Alveoli:
  • Microscopic air sacs where gas exchange occurs.
  • Surrounded by capillaries for oxygen and carbon dioxide exchange.

Gas Exchange Process

• External Respiration:
  • Oxygen intake from environment to alveoli.
  • Carbon dioxide expelled from blood into alveoli.
• Internal Respiration:
  • Oxygen delivered to tissues and cells.
  • Carbon dioxide transported back to the lungs.

Breathing Mechanism

Pulmonary Ventilation

• Inhalation and Exhalation processes:
  • Inhalation:
    • Requires muscle contractions (mainly diaphragm).
    • Decrease in chest pressure allows air to enter lungs.
  • Exhalation:
    • Passive process (muscles relax), increasing pressure in lungs expels air.

Boyle's Law

• Pressure and volume are inversely proportional, affecting airflow into and out of the lungs.

Lung Volumes and Capacities

Key Terms

• Tidal Volume: Volume of air during normal breathing (500 ml).
• Inspiratory Reserve Volume: Extra air inhaled beyond tidal volume.
• Expiratory Reserve Volume: Extra air expelled beyond tidal volume.
• Residual Volume: Air remaining in lungs after maximum expiration.
• Vital Capacity: Total air volume that can be moved (Tidal + Inspiratory + Expiratory).
• Total Lung Capacity: Total volume of air in lungs (includes residual volume).

Breathing Regulation

Control Centers

• Medulla Oblongata:
  • Contains inspiratory and expiratory areas to regulate breathing.
• Pons:
  • Contains pneumotaxic and apneustic areas to modify breath patterns.

Chemoreceptors

• Monitor oxygen and carbon dioxide levels, influencing respiration rates based on chemical concentration:
  • Central Chemoreceptors: Located in medulla, monitor CO2 and pH levels.
  • Peripheral Chemoreceptors: Found in carotid arteries and aortic arch, monitor O2/CO2 levels.

Factors Affecting Breathing

• Temperature: Affects the rate of chemical reactions.
• Pain: Sharp pain can cause apnea; visceral pain can slow breathing.
• Inflation Reflex: Prevents over-inflation of lungs during deep breathing.

Conditions Impacting Respiratory Health

Aging Effects

• Decreased lung elasticity; increased risk of pneumonia and respiratory infections.
• Reduced macrophage activity leading to increased infections.

Infections and Diseases

• Pulmonary Edema: Fluid buildup in alveoli, hindering gas exchange.
• Smoking Effects:
  • Involves harmful chemicals like carbon monoxide, which competes with oxygen for hemoglobin binding.
  • Paralyzes cilia, reducing the ability to clear mucus and pathogens.

Summary

• Importance of maintaining respiratory health for optimal gas exchange and cellular respiration.