Respiratory System Overview Quiz

Respiratory System

• The respiratory system is divided into the upper and lower respiratory tracts.

• The upper respiratory tract includes the nose, pharynx, nasal cavity, and paranasal sinuses.

• The lower respiratory tract includes the larynx, trachea, bronchi, bronchioles, and alveoli.

• The respiratory system can be divided into a conducting zone and a respiratory zone.

• The conducting zone transports air but does not participate in gas exchange.

• The conducting zone includes the nasal cavity, nasopharynx, oropharynx, laryngopharynx, larynx, trachea, bronchi, and bronchioles (except respiratory bronchioles).

• These structures are responsible for transporting, filtering, humidifying, and warming air.

• The respiratory zone is where gas exchange of O2 and CO2 occurs.

• Sites of gas exchange are called alveoli (singular: alveolus).

• All respiratory zone structures contain alveoli and include respiratory bronchioles, alveolar ducts, and alveolar sacs.

•  The nasal cavity has divider between nasal cavity called nasal septum.

• The nasal cavity floor is the hard palate; it separates the nasal cavity from the mouth cavity.

• The nasal cavity has ridges called conchae that increase the surface area and cause air to churn.

• Paranasal sinuses open into nasal cavity and are lined with mucous membranes.

• Nasolacrimal ducts connect the eyes to the nasal cavity.

• There is olfactory receptor at superior part of nasal cavity

• The cavity is lined with stratified squamous epithelium with coarse hairs to trap dust or large particles.

• Near the pharynx, cavity lining is pseudostratified columnar associated with goblet cells.

• The pharynx, shared by digestive and respiratory systems, is divided into three sections:

  • Nasopharynx (pseudostratified columnar) - superior portion; enclosed by uvula during swallowing.
  • Oropharynx (stratified squamous) - continuous with the oral cavity.
  • Laryngopharynx - from the tip of the epiglottis to the esophagus.

• The larynx, also known as the voice box, is composed of 9 cartilages, including three large ones (thyroid, cricoid, and epiglottis) and paired cartilages (cuneiform, corniculate, and arytenoid).

• The arytenoid cartilages change the position and tension of the vocal cords.

• Vocal cords are the primary source of voice production.

• They consist of two pairs of ligaments at the thyroid cartilage and extend posteriorly to the arytenoid cartilage.

• Superior ligament - vestibular fold (false vocal cord)

• Inferior ligament - true vocal cord

• Two pairs of ligament, extended posteriorly to arytenoid cartilage.

• Voice production involves air passing through the vocal cords, causing them to vibrate.

• The larynx muscles control the position and tension of the vocal folds.

• During swallowing, the larynx is elevated, and the epiglottis covers the glottis.

• The trachea, located inferior to the cricoid cartilage, extends to the mediastinum and divides into left and right primary bronchi at the 5th thoracic vertebra.

•  The trachea is lined with pseudostratified epithelium associated with goblet cells, secreting mucus due to abundant seromucous glands.

• The trachea has 16-20 C-shaped hyaline cartilage rings that prevent its collapse and provide space for the esophagus to expand during swallowing.

• The trachea posterior wall has no cartilage; it has smooth muscle and connective tissue to help with cough.

• The last tracheal cartilage is enlarged and forms a sensitive projection called the carina.

• The carina mucous membrane is more sensitive than the larynx and trachea.

• The carina is responsible for triggering the cough reflex.

•  The right primary bronchus is wider, shorter, and more vertical than the left. This configuration makes the right bronchus more prone to obstruction by foreign objects.

• The trachea divides into two main bronchi

• Air reaching the bronchi has been filtered, warmed, and humidified.

• The bronchi are lined with pseudostratified columnar epithelium supported by C-shaped cartilage.

• Each main bronchus divides into lobar bronchi (secondary bronchi).

• The right main bronchus has three lobar bronchi; the left has two.

• Lobar bronchi divide into segmental bronchi (tertiary bronchi).

• The bronchioles are the final branches of the bronchi.

• They lack cartilage and have smooth muscle that regulates airflow.

• Terminal bronchioles are the last bronchioles without alveoli.

• Respiratory bronchioles have alveoli and lead into alveolar ducts and alveolar sacs. 

• Cartilage in walls decreases, smooth muscle increase with branching

• Relaxation and contraction of smooth muscle control the diameter of air passageways

• The lungs have lobes: the right has three lobes; the left has two.

• Lung lobes are separated by fissures.

• The medial surface of the left lung has a concavity called the cardiac notch.

• Alveolar ducts contain many openings into alveoli (air sacs).

• Alveolar ducts and alveoli are where gas exchange takes place.

• The respiratory membrane is formed by 6 layers:

  • Thin layer of fluid
  • Alveolar epithelium (simple squamous)
  • Basement membrane (alveolar)
  • Interstitial space
  • Basement membrane (capillary)
  • Capillary endothelium (simple squamous)

• Alveolar cells (type I pneumocytes) line the alveolar surface.

• Septal cells (type II pneumocytes) secrete surfactant, a lipid-rich substance that reduces surface tension in the alveoli and prevents collapse.

• Alveolar macrophages (dust cells) engulf foreign particles.

• The pleura are serous membranes covering the lungs, including visceral pleura (attached to lungs) and parietal pleura (attached to thoracic wall).

• Pleural fluid lubricates the space between the pleura, facilitating lung movement.

• Atmospheric pressure, intrapleural pressure (pressure in the pleural cavity), and intrapulmonary pressure (pressure in the alveoli) are related to breathing.

•  Intrapleural pressure is lower than intrapulmonary pressure which maintains the lungs inflated.

• Changes in pressure differences during inhalation and exhalation drive airflow.

• Pulmonary ventilation is the physical movement of air into and out of the lungs, driven by pressure changes.

•  Exhalation occurs when diaphragm and ribcage relax decreasing the thoracic volume and increasing lung pressures.

• Inspiration occurs when diaphragm and ribcage contract increasing the thoracic volume and decreasing lung pressure.

• Breathing is controlled by the respiratory centers in the medulla and pons, which are affected by factors such as blood CO2 concentration (chemoreceptors), blood O2 concentration, pH, pain and other receptors in the body.

•  The efficiency of the respiratory system decreases with age.

•  Conditions such as emphysema, chronic bronchitis, and other obstructive diseases can hinder airflow and gas exchange.

• External respiration is the movement of O2 from the lungs to the blood and CO2 from the blood to the lungs.

• Gas transport refers to the mechanisms by which O2 and CO2 are moved through the blood.

• Oxygen is transported mainly by hemoglobin in red blood cells.

• 70% of carbon dioxide is carried as carbonic acid, 23% is bound to hemoglobin (carbaminohemoglobin) , 7% is dissolved in plasma.

• Respiration involves pulmonary ventilation, external respiration, gas transport, and internal respiration.

• The respiratory system is composed of various structures and processes, all working together to facilitate gas exchange, crucial for maintaining cellular life.