Allows us to inhale oxygen
- Oxygen: gas needed by our cells
Exhale carbon dioxide
- Carbon dioxide: gaseous metabolic waste that needs to be eliminated

Gas Exchange:

External Respiration: air brought into lungs; oxygen and carbon dioxide exchange in bloodstream at capillaries surrounding alveoli
Internal Respiration: oxygen and carbon dioxide move between the bloodstream and the body’s cells

Upper Respiratory Tract

Paranasal sinuses
Nasal cavity
Nose
Pharynx

Lower Respiratory Tract

Larynx
Lungs
Trachea
Bronchi
Bronchioles
Alveoli

Nose

Air enters nose through opening called nostrils
Lines with small hairs that trap particles and prevent them from entering respiratory tract
Air passes into nasal cavity
Nasal septum divides nose into left and right halves
Here, air is warmed and moistened
- Mucus: clear, sticky secretion, coats lining of nasal cavity to filter out particles
- Paranasal sinuses: air-filled cavities in bones of face connected to nasal cavity
  - Included frontal, ethmoidal, maxillary, sphenoidal

Pharynx (throat)

Divided into three sections: nasopharynx, oropharynx, laryngopharynx

Tonsils (lymphatic tissue)

Aid in filtering bacteria
Three pairs:
- Pharyngel tonsils (adenoids); nasopharynx
- Palatine tonsils; oropharynx
- Lingual tonsils; base of posterior tongue

Larynx

Also known as voice box
Organ that produces sound
Located between pharynx and trachea
Made up of cartilages and elastic membranes
Air enters larynx through a slit-like opening called glottis
Flap of cartilage (epiglottis) protects glottis during swallowing to prevent food or liquids from entering respiratory tract
As air flows over vocal cords, they vibrate to produce sound

Trachea

Known as windpipe
Cartilaginous tube that conducts air from larynx to bronchial tree
Bronchial tree consists of air-passage tubes that lead from trachea to the lungs

Bronchi

Two major airways: left bronchus and right bronchus
Air passes through bronchi; subdivide into smaller branches called bronchioles
Flow of air terminates in bronchial tree in tiny air sacs called alveoli
Alveoli: structures where gas exchange of oxygen and carbon dioxide occurs

Lungs

Paired, spongy organs of breathing located in thoracic cavity
Enclosed in pleura → membrane composed of two layers called parietal pleura and visceral pleura
Right Lung
- Slightly larger than left
- Three lobes: superior lobe, middle lobe, lower lobe
Left Lungs
- Two lobes: superior lobe and inferior love
Each cone-shaped lung has an upper apex and lower base, which rests on diaphragm

Diaphragm

Sheet of muscle that separates thoracic cavity (houses the lungs) from lower abdominal cavity
Major muscle used in breathing
When diaphragm contracts, inhalation occurs
When diaphragm relaxes, exhalation occurs

Diseases

Airways need to remain patent (open) in order for proper air exchange to take place

Reflex to cough or sneeze when pathway becomes blocked; may produce sputum or hemoptysis

Abnormal breath sounds are indication of respiratory disease

Rales: also known as crackles; high-pitched popping sounds usually originating in smaller airways, fluid
Rhonchi: low-pitched sounds that come from larger airways
Wheezing or whistling sounds: may indicate excessive secretions or partially obstructed narrow airways, heard on exhalation
Stridor: high-pitched squaking sound that occurs when one breaths in; sign of respiratory obstruction in the upper airway, larynx, trachea, or epiglottis
Eupnea: normal breathing; should be regular and effortless

Abnormalities:

Tachypnea
Bradypnea
Apnea
Dyspnea
Orthopnea
Cheyne-Stokes
Kussmaul breathing

Infectious disorders

Infectious rhinitis: virus strain; common cold
Sinusitis: inflammation of any sinus mucous membrane
Croup: also called laryngotracheobronchitis
Epiglottitis: inflammation of epiglottis
Influenza (flu): acute infectious respiratory disease caused by influenza viruses
Pneumonia: inflammation of the lung parenchyma; bacteria or virus
Laryngitis: inflammatino of larynx mucous membrane
Pertussis: whooping cough
Tuberculosis (TB): infectious disease caused by mycobacterium tuberculosis

Obstructive lung disease

Impair flow through bronchial tree
Asthma: lung disease characterized by reversible inflammation and constriction
Cystic fibrosis (CF): genetic disorder in which lungs become clogged with excessive amounts of abnormally thick mucus
Chronic obstructure pulmonary disease (COPD): umbrella term that includes both emphysema and chronic bronchitis
Emphysema: alveoli enlarged and inefficient, leading to shortness of breath (SOB)
Chronic bronchitis: inflammation of mucous membrane of bronchi

Expansion disorders

Atelectasis: collapsed lungs
Pneumothorax: accumulation of air in pleural cavity

Diagnostic Tests, Treatments, and Surgical Procedures

Noninvasive procedures and tests
- Chest X-rays (CXRs)
- Lung scans
- Pulse oximetry
- Computed tomography scans (CT)
- Arterial blood gases
Invasive procedures
- Thoracentesis (pleural tap): insertion of needle into pleural cavity to withdraw fluid
- Bronchoscopy: examination of trachea and bronchial tree through a viewing instrument called bronchoscope
Conducted by respiratory therapist
- Pulmonary function tests (PFTs): to assess breathing
- Spirometer: instrument used for measuring air capacity of the lungs
Medications:
- Antihistamines: drugs used to treat acute allergic reactions
- Decongestants: used to treat congestion

Practice and Practitioners

Pulmonologist: physician who specializes in pulmonology, which is the study of the lungs and related structures

Otolaryngologists: and otorhinolaryngologists: diagnose and treat disorders of ears, nose, and throat

Respiratory therapists: allied healhcare professionals who specialize in airway management, mechanical ventilation (breathing), and blood acid-base balance

Note