respira

• What is the main entrance point for air to enter the respiratory system?

  The nose
• What is the function of the alveoli?

  Gas exchange
• What is the tube that connects the larynx to the bronchi?

  The trachea
• Nose


  Includes the nostrils, or nares. Leads to the nasal cavity, a large air-filled space behind the nose.
• Nasal Cavity


  Divided by the nasal septum. Contains the nasal conchae, or turbinates, curved bones that increase the surface area for warming and humidifying air. Lined by the nasal mucosa which secretes mucus to trap particles.
• Paranasal Sinuses


  Surrounding the nasal cavity. Include the frontal sinuses, ethmoid sinuses, sphenoid sinuses, and maxillary sinuses. Air-filled spaces that lighten the skull and produce mucus.
• Mouth


  Air can also enter through the mouth, or oral cavity, serving as a secondary entry point.
• Pharynx (Throat)


  A muscular tube serving as a passageway for food and air. Consists of the nasopharynx, oropharynx, and laryngopharynx.
• Larynx (Voice box)

  The larynx, or voice box, contains vocal cords crucial for speech. Includes the epiglottis, which prevents food from entering the trachea, the thyroid cartilage known as the Adam's apple, the cricoid cartilage, and the arytenoid cartilages, which anchor the vocal cords.
• Components of the Upper Respiratory Tract

  • Nose
  • Nasal Cavity
  • Paranasal Sinuses
  • Mouth
  • Pharynx (Throat)
  • Pharynx (Voice box)
• Nose


  Includes the nostrils, or nares. Leads to the nasal cavity, a large air-filled space behind the nose.
• Nasal Cavity


  Divided by the nasal septum. Contains the nasal conchae, or turbinates, curved bones that increase the surface area for warming and humidifying air. Lined by the nasal mucosa which secretes mucus to trap particles.
• Paranasal Sinuses


  Air-filled spaces surrounding the nasal cavity including the frontal, ethmoid, sphenoid, and maxillary sinuses. Lighten the skull and produce mucus.
• Mouth


  Serves as a secondary entry point for air
• Pharynx (Throat)


  Muscular tube serving as a passageway for food and air. Consists of the nasopharynx, oropharynx, and laryngopharynx.
• Pharynx (Voice box)


  Contains the larynx, or voice box, with vocal cords crucial for speech. Includes the epiglottis, thyroid cartilage, cricoid cartilage, and arytenoid cartilages.
• Trachea (Windpipe)


  Extends from the larynx to the bronchi, supported by C-shaped cartilaginous rings to maintain an open airway. Tracheal mucosa produces mucus and has cilia to trap and move particles.
• Bronchi


  The trachea divides into primary bronchi, which branch into secondary (lobar) and tertiary (segmental) bronchi.
• Bronchioles


  Smaller branches of the bronchi, with terminal bronchioles being the final branches of the conducting zone and respiratory bronchioles beginning the respiratory zone, leading to alveolar ducts.
• Alveolar Ducts


  Connect to alveolar sacs, which are clusters of alveoli. Alveoli are tiny air sacs where gas exchange occurs, consisting of alveolar type I cells, alveolar type II cells, and alveolar macrophages.
• Lungs


  The two organs of respiration. The right lung has three lobes, the left lung has two lobes. Each lobe contains smaller divisions called lobules. The lungs are surrounded by a double-layered membrane called the pleura.
• Supporting Structures


  The diaphragm is the main muscle of respiration, contracting during inhalation. The intercostal muscles, both external and internal, assist in breathing. Accessory muscles like the sternocleidomastoid, scalene, and pectoralis minor come into play during deep or labored breathing.
• Pulmonary Ventilation


  The flow of air into and out of the lungs, caused by alternating pressure differences created by contraction and relaxation of respiratory muscles. Influenced by alveolar surface tension, lung compliance, and airway resistance.
• Pressure Changes during Pulmonary Ventilation


  Air moves into the lungs when the air pressure inside the lungs is less than the air pressure in the atmosphere. Air moves out of the lungs when the air pressure inside the lungs is greater than the air pressure in the atmosphere.
• Inhalation


  1. Breathing in, caused by the lungs expanding to decrease the pressure inside below atmospheric pressure

  2. Diaphragm contracts to lower its dome, increasing the vertical diameter of the thoracic cavity

  3. External intercostals contract to elevate the ribs, increasing the anteroposterior and lateral diameters of the chest cavity

  4. Intrapleural pressure decreases, causing air to flow into the lungs

  5. Accessory muscles like sternocleidomastoid, scalene, and pectoralis minor may contract during deep/forced breathing to further increase thoracic cavity size
• Boyle's Law


  The pressure of a gas in a closed container is inversely proportional to the volume of the container
• Intrapleural Pressure


  The pressure within the pleural cavity, always negative (lower than atmospheric pressure). Allows the lungs to expand and recoil with changes in thoracic cavity size.
• Exhalation


  1. Breathing out, caused by the lungs recoiling due to elastic forces

  2. Inspiratory muscles relax, allowing the diaphragm to move superiorly and the ribs to be depressed, decreasing thoracic cavity size

  3. Alveolar pressure increases above atmospheric pressure, causing air to flow out

  4. Exhalation is normally a passive process, but can become active during forceful breathing
• Elastic recoil


  The natural tendency of the chest wall and lungs to spring back after they have been stretched
• Exhalation


  1. Inspiratory muscles relax

  2. Diaphragm relaxes and moves superiorly

  3. External intercostals relax and ribs are depressed

  4. Decreases lung volume

  5. Alveolar pressure increases

  6. Air flows from alveoli to atmosphere
• Active exhalation


  Occurs during forceful breathing, as when playing a wind instrument or during exercise
• Active exhalation


  1. Abdominal and internal intercostal muscles contract

  2. Increases pressure in abdominal region and thorax

  3. Abdominal muscles move inferior ribs downward and compress abdominal viscera, forcing diaphragm superiorly

  4. Internal intercostals pull ribs inferiorly
• Intrapleural pressure may briefly exceed atmospheric pressure during forceful exhalation, such as during a cough
• Surface tension


  Force exerted by the alveolar fluid, causing alveoli to assume the smallest possible diameter
• Surfactant


  Mixture of phospholipids and lipoproteins that reduces surface tension of alveolar fluid
• Respiratory distress syndrome


  Caused by deficiency of surfactant, leading to increased surface tension and alveolar collapse
• Compliance


  How much effort is required to stretch the lungs and chest wall
• High compliance


  • Lungs and chest wall expand easily
• Low compliance


  • Lungs and chest wall resist expansion
• Airway resistance


  Resistance to airflow through the airways, depends on pressure difference and airway diameter