BIO respiratory system

• Respiratory system

  • Facilitates the exchange of gases between the air and the blood and between the blood and the body’s cells
  • Helps in smelling things and creating sound
• Five key functions of the respiratory system

  • Aids in breathing (pulmonary ventilation)
  • Facilitates gas exchange between air and blood, blood and body's cells
  • Helps in smelling things
  • Creates sound
  • External respiration (oxygen exchanged for carbon dioxide waste)
• Pulmonary ventilation

  1. Air is inhaled through nasal and oral cavities, moves through pharynx, larynx, trachea into lungs, then exhaled back through the same pathway

  2. Changes in volume and air pressure in lungs trigger pulmonary ventilation
• External respiration

  Oxygen is exchanged for carbon dioxide waste through alveoli
• Internal respiration

  Red blood cells carry oxygen absorbed from lungs around the body, release oxygen to body tissues, carbon dioxide diffuses from tissues into red blood cells and plasma
• Upper respiratory system structures

  • Nose and nasal cavity
  • Pharynx
  • Larynx
• Upper respiratory system structures

  Allow breathing and speaking, warm and clean the air we inhale
• Mucous membranes lining upper respiratory structures trap foreign particles before air travels to the lungs
• The nasal cavities are chambers of the internal nose with nostrils creating openings to the outside world
• Air is inhaled through the nostrils, warmed as it moves into the nasal cavities, humidified, warmed, and cleaned before entering the lungs
• Epithelial cilia and mucous membrane in the nasal cavities trap unwanted particles
• Paranasal sinuses are four paired, air-filled cavities found inside bones of the skull, named for the skull bones that contain them
• Air passage through the respiratory system

  1. Filtered, warmed air passes out of the back of the nasal cavities into the nasopharynx

  2. Air enters the sinuses from the nasal cavities, mucus formed by the mucosae drains into the nasal cavities

  3. During respiration, the pharynx conducts air between the larynx and trachea and the nasal and oral cavities

  4. The laryngopharynx connects to the larynx and the esophagus, and air passes freely between the laryngopharynx and the larynx
• Paranasal sinuses

  • Frontal
  • Ethmoidal
  • Sphenoidal
  • Maxillary
• Mucosae in paranasal sinuses

  They help to warm and humidify the air we inhale
• Pharynx regions

  • Nasopharynx serves only as a passageway for air
  • Oropharynx contains the palatine tonsils and both air and ingested food pass through it
  • Laryngopharynx connects to the larynx and the esophagus
• Larynx

  Connects the lower part of the pharynx to the trachea, keeps air passages open during breathing and digestion, and is the key organ for producing sound
• The larynx is comprised of nine cartilages
• The epiglottis closes like a trap door as we swallow, steering food down the esophagus and away from the windpipe
• Vocal folds in the larynx

  • Have elastic ligaments at their core and vibrate when air passes between them, producing sound
• Phonation

  Creation of sound by structures in the upper respiratory tract, involving air passing through the larynx and movements of the arytenoid cartilages and vocal cords
• Greater tension in the vocal cords creates more rapid vibrations and higher-pitched sounds, while lesser tension causes slower vibration and a lower pitch
• The hyoid bone is the only bone in the body that doesn't touch another bone
• Hyoid bone in the respiratory system

  Attached to the tongue and helps in swallowing at the start of digestion, serves as attachment points for neck muscles that raise and lower the larynx during speech and swallowing
• Olfaction

  Begins with olfactory fibers in the nasal cavities, where chemicals in the air bind to receptors on the cilia, sending signals to the brain through the olfactory bulbs and cranial nerve 1 to the olfactory area of the cerebral cortex
• The respiratory system, in close conjunction with the circulatory system, is responsible
• Neurons take the signal from the nasal cavities

  Through openings in the ethmoid bone, then to the olfactory bulbs, then along cranial nerve 1 to the olfactory area of the cerebral cortex
• The respiratory system

  In close conjunction with the circulatory system, is responsible for supplying all body cells with essential oxygen and removing potentially harmful carbon dioxide from the body
• The mouth and nose channel air from outside the body through a system of tubes of diminishing size that eventually reach the two lungs situated on either side of the heart within the chest cavity
• Healthy lungs

  • Approximately cone-shaped, pinkish in color, occupy most of the chest cavity
• Trachea

  • Reinforced by roughly 20 rings of cartilage, lined with a mucous membrane
• Bronchial cast

  • A cast made of the bronchial tree by filling a lung's airways with resin that hardens
• Alveoli

  • The lungs' microscopic air sacs, elastic, thin-walled structures arranged in clumps at the ends of respiratory bronchioles
• White blood cells known as macrophages are always present on the inner surfaces of alveoli, where they ingest and destroy airborne irritants such as bacteria, chemicals, and dust
• Oxygen passes from the air in the alveoli into the blood by diffusion through the alveolar and capillary walls
• Carbon dioxide diffuses from blood into the alveoli
• There are more than 300 million alveoli in both lungs, providing a huge surface area for gas exchange – about 40 times greater than the body's outer surface
• Alveoli are only 0.2mm (1/125 in) across when fully inflated
• Alveoli should collapse inwards like deflated balloons due to powerful surface tension in their fluid lining, prevented by a natural substance with detergent-like properties called surfactant
• Surfactant is produced by alveolar cells and consists mainly of fatty substances, such as cholesterol and phospholipids, and proteins. It plays a role in keeping alveoli inflated and disabling bacteria to prevent lung infections