Resptoiry system

• Respiratory system's primary function is to provide O2 to support the tissue and remove CO2
• the other functions of the respitory system is thermoregulation - metabolism of endogenous and exogenous substances - protection against inhaled dusts, toxic gases and infections agents - vocalization - olfaction
• Upper respiratory tract: inculdes the nose pharynx epiglotis and the larnyx
• Lower respiratory tract includes trachea bronchi and lungs
• Nose structure through which air enters and exits
• nostrils (nares): external openings of the respiratory tract that open into the nasal passages
• nasal trubinates: tiny cartilages in the nasal passages covered with vascular mucous membranes which secrete mucus that warms, moistens, and filters air
• nasal septum (sept/o): wall of cartilage that divides the nose into left and right nasal passages
• Sinus: air-filled or fluid-filled space with a bone
• the functions of the sinus is to provide mucus to make bone lighter to help produce sound to warm and humidify the air
• Pharynx: (throat) common passageway for both the digestive and respiratory systems
• the function of the pharynx is to allow the passage of food (and only food) into the esophagus and the passage of air (and only air) into the lungs)
• Epiglottis covers the larynx to prevent food from entering the trachea
• Trachea extends from the larynx to thorax composed of fibrous connective tissue and smooth muscle held open by cartilage rings (to keep the lumen open) lined with ciliated epithelium
• Bronchi branch from the trachea into each lung
• Bronchioles bronchi branch into smaller branches
• Lung Compliance refers to how easy a lung is to inflate
• Thoracic Cavity where the lungs are located
• Pleura thin membranous sac that encloses each lung
• Conducting Airways: nares, nasal cavity, larynx, pharynx trachea, bronchus and bronchioles no gas exchange occurs in these pathways
• bronchial circulation : a branch of systemic circulation that provides a nutritional blood supply to the airways and other structures within the lung
• Respiration : is the diffusion of gases (CO2 and O2 ) between the atmosphere and the cells of the body
• “External” respiration: occurs in the lungs exchange of O2 and CO
• “Internal” respiration: occurs everywhere in the body
• Ventilation: means intake of fresh air
• Inhalation/Inspiration drawing in of breath
• Exhalation/Expiration: releasing of breath
• Expiration physiolgy The forces of expiration are due to the elastic recoil of lung and muscle tissues and from the surface tension within the alveoli.
• In running animals, ventilation is synchronized with gait during inhaltion body is strecthed causing thorax to exapnd
• Ideally each region of the lung should receive equal amounts of ventilation but this never occurs
• Uneven distribution can be caused by: local decrease in lung compliance

  local airway obstructions

  recumbent large animals
• Collateral ventilation provides air to alveoli when their main parent bronchus is obstructed
• Control Mechanisms for ventialtion monitor:

  1) chemical composition of the blood

  2) the effort being exerted by the respiratory muscles

  3) presence of foreign materials in the respiratory tract
• slowly adapting stretch receptors

  associated with smooth muscle of trachea and bronchi - stimulated by deformation of the wall (lung inflation) - cause adjustments in rate and depth of breathing
• irritant receptors

  • in larynx, trachea, bronchi and intrapulmonary airways - stimulated by deformation that occurs with lung inflation, bronchoconstriction, and mechanical irritation of the airway - stimulation causes cough, bronchoconstriction, mucus secretion, rapid, shallow breathing , designed to clear irritant materials from respiratory system
• C fibers

  associated pulmonary interstitium close to pulmonary capillaries - monitor blood composition or degree of interstitium distention
• Chemoreceptors: monitor O2 , CO2 , and pH
• Pleural Fluid: fluid between the visceral and parietal pleura
• Diaphragm: respiratory muscle that separates the thoracic and abdominal cavity that is responsible for air movement into and out of the lungs
• Pulmonary Surfactant: prevents the lung from collapsing by reducing surface tension