Respiratory System

• Two Major Functions:

  • respiration
  • air conditioning
• Respiration

  • obtain oxygen from the external environment and supply it to the cells and to remove from the body the carbon dioxide produced by cellular metabolism
• Air Conditioning

  • warming/cooling the inhaled air to bring it to the level of body temperature, humidifying the air, and also the removal of all the foreign particles present in it
• Other functions:

  • acid-base balance
  • phonation
  • pulmonary defense and metabolism
  • handling of bioactive materials
• Divided into conducting portion and respiratory portion
• Conducting Portion

  • responsible for transport of air
  • nose, pharynx, larynx, trachea, bronchi, and bronchioles
  • humidify, warm, and filter air
• Respiratory Portion

  • bronchioles, alveoli
  • involved in gas exchange
• Upper Respiratory Tract

  • nose
  • nasal cavity
  • sinuses
  • pharynx (nasopharynx, oropharynx, laryngopharynx)
  • throat
  • larynx
  • voice box
• Lower Respiratory Tract

  • trachea
  • windpipe
  • lungs
  • 3 right lobes, 2 left lobes
  • bronchi and bronchioles
  • alveoli
• Respiration

  • medical term to describe the exchange of gases between body cell and the environment
  • two main process
  • breathing
  • gas exchange
• Respiration: Breathing

  • mechanical process of moving air in (inhalation, inspired) and out (exhalation, expired) of the lungs
  • pulmonary ventilation supplies oxygen to the alveoli and excretes carbon dioxide
• Respiration: Gas exchange

  • External Respiration - between the alveolar air and the blood in the pulmonary capillaries (involved yung air galing sa environment)
  • Internal Respiration - between the bloodstream and body tissue
• Breathing muscles include:

  • diaphragm
  • intercostal muscles
  • abdominal muscles
  • muscles in the neck and collarbone area
• Gas Exchange

  • takes place in the millions of alveoli in the lungs and the capillaries that envelope them
  • inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli
• Defense Mechanisms of Respiratory System

  • average person who is moderately active during the daytime breathes about 20,000 liters (more than 5,000 gallons) of air every 24 hours
  • particles, such as dust and soot, mold, fungi, bacteria and viruses, deposit on airway and alveolar surfaces
  • goblet cells - secrete mucins = mucus
  • cilia
  • alveolar macrophages
• Effects of Ageing on the Respiratory System

  • respiratory performance declines with age
  • loss of elastic tissue in the lungs
  • small airways collapse and decrease lung volume
  • risk of respiratory infections
  • respiratory chemoreceptors reflexes become less efficient
  • age-related respiratory compromise is much more significant in smokers
• Disorders of the Upper Respiratory Tract

  • inflammation of the upper respiratory tract can be caused by inhaling irritants (cigarette smoke or air pollutants) but is commonly due to infection
  • viral infection - mild and self-limiting
  • bacterial infections - life-threatening if they spread to the lungs
• Disorders of the Lower Respiratory Tract: Common Cold

  • causative agent: rhinovirus (common virus), coronavirus, and respiratory syncytial virus
  • highly infectious but mild illness
  • characterized by runny nose (rhinorrhea), sneezing, sore throat and sometimes slight fever
  • treatment: OTC drugs
• Disorders of the Lower Respiratory Tract: Influenza

  • causative agent: influenza virus
  • more severe symptoms than common colds (high fever and muscle pain)
• Disorders of the Lower Respiratory Tract: COVID-19

  • causative agent: severe acute respiratory coronavirus 2 (SARS-CoV2), a new and highly contagious member of the coronavirus family
  • symptoms: persistent dry cough, headache and high fever, loss of sense of smell and taste
  • more severe symptoms: pneumonia, severe acute respiratory syndrome, renal failure and death
• Disorders of the Lower Respiratory Tract: Sinusitis

  • causative agent: spread of microbes from the nose and pharynx to the mucous membrane lining the paranasal sinuses
  • symptoms: facial pain and headache
• Disorders of the Lower Respiratory Tract: Tonsillitis

  • causative agents: viruses and Streptococcus pyogenes (scarlet fever)
  • symptoms: swelling of the palatine tonsils, palatine arches and wall of the pharynx
• Disorders of the Lower Respiratory Tract: Diptheria

  • Bacterial infection of the pharynx that may lead to the nasopharynx to trachea
  • a thick, fibrous membrane (pseudo membrane) forms over the area and may obstruct the airway
  • causative agent: Corynebacterium diptheriae
• Disorders of the Lower Respiratory Tract: Hay Fever

  • aka allergic rhinitis
  • hypersensitivity develops to foreign materials (antigen) like pollens, mites in pillow feathers and animal dander
  • symptoms: acute inflammation of nasal mucosa and conjuctiva
• Obstructive Lung Disorders

  • characterised by blockage of airflow through airways
  • obstruction may be acute or chronic
  • bronchitis
  • emphysema
  • asthma
  • bronchiectasis
• Obstructive Lung Disorders: Acute Bronchitis

  • secondary bacterial infections preceded by common cold or influenza
• Obstructive Lung Disorders: Chronic Bronchitis

  • individual has had a cough with sputum for 3 months and in 2 successive years
  • progressive inflammatory disease resulting from prolonged irritation of the bronchial epithelium
  • often a consequence of cigarette smoking and chronic exposure to airborne irritants
  • increased size and number of mucous glands
  • edema and other inflammatory changes
  • reduction in number and functions of ciliated cells
  • fibrosis of the airways
  • breathlessness
• Obstructive Lung Disorders: Pulmonary Emphysema

  • results of long-term inflammatory conditions or irritations of the airways
  • common condition for smokers/coal miners
  • due to alpha1-antitrypsin deficiency
  • types:
  • Pancinar emphysema
  • Centrilobular emphysema
• Obstructive Lung Disorders: Interstitial Emphysema

  • accumulation of air bubbles in the thoracic interstitial tissues
• Obstructive Lung Disorders: Panacinar emphysema

  • affects the alveoli and tiny bronchioles throughout the lungs
  • reversible
• Obstructive Lung Disorders: Centrilobular emphysema

  • irreversible dilation of the respiratory bronchioles supplying lung lobules and the distal alveoli
• Obstructive Lung Disorders: Emphysema

  • Abnormal Accumulation of air
  • Types:
  • Pulmonary emphysema
  • Interstitial emphysema
• Obstructive Lung Disorders: Asthma

  • common inflammatory disease of the airways with episodes of reversible hyperactivity of the airway smooth muscle
  • the mucus membrane and muscle layers of the bronchi and bronchioles are inflamed, edematous, and swollen
  • mucous glands are enlarge reducing airflow in the lower respiratory tract
  • non-specific factors that may precipitate asthma attacks include cold air, cigarette smoking, air pollutants, upper respiratory infections, emotional stress and strenuous activity
  • atopic asthma (allergic, childhood-onset, extrinsic)
  • adult onset (late onset)
• Obstructive Lung Disorders: Bronchiectasis

  • permanent abnormal dilation of bronchi and bronchioles
  • associated with chronic bacterial infection
  • bronchi become obstructive by mucus, pus and inflammatory exudate and the alveoli distal to the blockage collapse as trapped air is absorbed
• Restrictive Lung Disorders

  • characterized by increasing stiffness (low compliance) of lung tissue, making it harder to inflate and increasing the work of breathing
  • associated with progressive fibrosis cause by repeated and ongoing inflammation of the lungs
• Restrictive Lung Disorders: Pneumoconioses

  • group of lung diseases caused by prolonged exposure to inhaled dust, which triggers generalized inflammation and progressive fibrosis of the lung
  • coal workers pneumoconiosis
  • silicosis
  • asbestosis
• Lung Infections: Pneumonia

  • infection of the alveoli
  • occurs when the pulmonary defense mechanisms fail to prevent inhaled or blood-borne microbe reaching and colonizing the lungs
  • reduced respiratory tract defenses
  • damaged respiratory muscles
  • painful coughing
  • impaired ciliary action
  • depressed pulmonary macrophage activity
  • may lead to hospitalization
  • causative organisms: Streptococcus pneumoniae, Staphylococcus aureus and Haemophilus influenzae, Legionella pneumophila, Klebsiella pneumoniae and Pseudnomonas aeruginosa
  • Types: Community-Acquired Pneumonia and Hospital-Acquired Pneumonia
• Lung Infections: Tuberculosis

  • cause by Mycobacterium tuberculosis
  • contagious disease that can infect anyone exposed
  • types:
  • Pulmonary TB
  • Non-pulmonary TB
  • affects other parts of the body