Respiratory System Quiz

Organs of the Respiratory System

• Nose
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs (alveoli)

Functions of the Respiratory System

• Oversees gas exchanges between the blood and external environment
• Exchange of gases takes place within the alveoli
• Passageways to the lungs purify, warm, and humidify the incoming air

The Nose

• The only externally visible part of the respiratory system
• Air enters the nose through the external nares (nostrils)
• The interior of the nose consists of a nasal cavity divided by a nasal septum
• Olfactory receptors are located in the mucosa on the superior surface
• The rest of the cavity is lined with respiratory mucosa that moistens air and traps incoming foreign particles
• Lateral walls have projections called conchae, which increase surface area and air turbulence within the nasal cavity
• The nasal cavity is separated from the oral cavity by the palate (anterior hard palate and posterior soft palate)

Paranasal Sinuses

• Cavities within bones surrounding the nasal cavity (frontal, sphenoid, ethmoid, and maxillary bones)
• Functions: lighten the skull, act as resonance chambers for speech, and produce mucus that drains into the nasal cavity

Pharynx (Throat)

• Muscular passage from nasal cavity to larynx
• Three regions: nasopharynx, oropharynx, and laryngopharynx
• The oropharynx and laryngopharynx are common passageways for air and food
• Auditory tubes enter the nasopharynx
• Tonsils of the pharynx: pharyngeal tonsil (adenoids), palatine tonsils, and lingual tonsils

Larynx (Voice Box)

• Routes air and food into proper channels
• Plays a role in speech
• Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis)
• Vocal cords vibrate with expelled air to create sound (speech)
• Thyroid cartilage: largest hyaline cartilage, protrudes anteriorly (Adam's apple)
• Epiglottis: superior opening of the larynx, routes food to the larynx and air toward the trachea
• Glottis: opening between vocal cords

Trachea (Windpipe)

• Connects larynx with bronchi
• Lined with ciliated mucosa that beats continuously to expel mucus loaded with dust and other debris away from lungs
• Walls are reinforced with C-shaped hyaline cartilage

Primary Bronchi

• Formed by division of the trachea
• Enters the lung at the hilus (medial depression)
• Right bronchus is wider, shorter, and straighter than left
• Bronchi subdivide into smaller and smaller branches

Lungs

• Occupy most of the thoracic cavity
• Each lung is divided into lobes by fissures (left lung has two lobes, right lung has three lobes)
• Pulmonary (visceral) pleura covers the lung surface
• Parietal pleura lines the walls of the thoracic cavity
• Pleural fluid fills the area between layers of pleura to allow gliding

Respiratory Tree Divisions

• Primary bronchi
• Secondary bronchi
• Tertiary bronchi
• Bronchioles
• Terminal bronchioli

Respiratory Zone

• Structures: respiratory bronchioli, alveolar duct, and alveoli
• Site of gas exchange

Alveoli

• Structure: alveolar duct, alveolar sac, and alveolus
• Gas exchange takes place within the alveoli in the respiratory membrane
• Squamous epithelial lining alveolar walls
• Covered with pulmonary capillaries on external surfaces

Respiratory Membrane (Air-Blood Barrier)

• Site of gas exchange between the air and blood

Gas Exchange

• Gas crosses the respiratory membrane by diffusion
• Oxygen enters the blood, and carbon dioxide enters the alveoli
• Macrophages add protection
• Surfactant coats gas-exposed alveolar surfaces

Events of Respiration

• Pulmonary ventilation: moving air in and out of the lungs
• External respiration: gas exchange between pulmonary blood and alveoli
• Respiratory gas transport: transport of oxygen and carbon dioxide via the bloodstream
• Internal respiration: gas exchange between blood and tissue cells in systemic capillaries

Mechanics of Breathing (Pulmonary Ventilation)

• Mechanical process dependent on volume changes in the thoracic cavity
• Two phases: inspiration (flow of air into the lung) and expiration (air leaving the lung)
• Inspiration: diaphragm and intercostal muscles contract, increasing the size of the thoracic cavity and pulling in external air
• Expiration: passive process dependent on natural lung elasticity, with air being pushed out of the lungs as muscles relax
• Forced expiration: occurs mostly by contracting internal intercostal muscles to depress the rib cage