A&P: CH.22 [Respiratory System]

• pulmonary ventilation: breathing (inspiration and expiration)
• external respiration: O2 diffuses from lings to blood and CO2 diffuses from blood to lungs
• transport of respiratory gases: O2 transported from lungs to tissue cells and CO2 transported from tissue to lungs
• internal respiration: O2 diffuses from blood to tissue and CO2 diffuses from tissue to blood
• nose provides

  1. airway for respiration
  2. moistens and warms air
  3. filters and cleans inspired air
  4. resonation chamber for speech
  5. houses olfactory receptors
• respiratory zone: actual site of gas exchange (respiratory bronchioles, alveolar ducts, alveoli)
• conducting zone: respiratory passageways from nose to respiratory bronchioles
• type 2 alveolar cells secrete surfactant
• surfactant is secreted by type II pneumocytes and lowers surface tension of fluid lining the alveoli
• left lung is smaller than right lung
• intrapleural pressure is always negative as it is always lower than the Patm so the lungs don't collapse
• intrapulmonary pressure is the pressure in the alveoli, always equalizes with atmospheric pressure
• transpulmonary pressure is difference between intrapulmonary pressure and intrapleural pressure; pressure that keeps air space of lung open to prevent from collapse
• pulmonary ventilation, consists of inspiration and expiration, is a mechanical process that depends on volume changes in thoracic cavity
• *volume changes lead to pressure changes, and pressure changes lead to flow of gases to equalize pressure*
• during inspiration the external intercostal muscles contract and the ribcage moves up and out while diaphragm moves downward and contracts
• during expiration the external intercostals relax and the ribs and sternum are depressed while the diaphragm moves upward
• tidal volume: normal breathing, 500ml of air
• inspiratory volume: the volume of air that can be inspired in one breath forcibly beyond tidal volume
• expiratory reserve volume: additional amount of air that can be exhaled forcefully
• residual volume: minimum volume of gas remaining in lungs at end of forced exhalation which keeps alveoli open and prevents lung collapse
• inspiratory capacity= TV+IRV
• vital capacity = TV + IRV + ERV
• total lung capacity (TLC) = RV + ERV + TV + IRV
• functional residual capacity (FRC): sum of RV and ERV; volume of air left in lungs when pressure is equalized between atmosphere and alveoli
• dead space is the portion of the respiratory system where gases are not involved in exchange with blood
• alveoli contain less O2 and more CO2 and water vapor
• rhinitis: inflammation of the mucous membrane of the nose
• sinusitis: inflammation of the sinuses, usually caused by a bacterial infection
• where food enters, epithelium becomes stratified squamous epithelium
• respiratory zone: site of gas exchange, starting from respiratory bronchioles to alveoli
• conducting zone structures cleanse and humidify incoming air so lungs are not irritated and can work efficiently
• larynx: air passage way to lower respiratory tract and produces the voice
• atelectasis: collapse of the lung tissue, leading to a decrease in lung volume
• pneumothorax: air in pleural space, usually due to ruptured lung
• Ppul<Patm: air rushes into lungs along pressure gradient; inspiration ends when they are equalized
• thoracic and intrapulmonary volume decreases which compresses alveoli and Ppul rises forcing gas to flow out of lungs; intercostal muscles also help depress ribcage and decrease thoracic volume
• nonrespiratory movements: processes other than breathing that move air out lungs like coughing, sneezing etc.
• gas flow is equal to change in pressure over resistance; if gas flow decreases resistance is increased and vice versa
• amount of gas in and out of alveoli is difference in pressure