Unit 14 The Respiratory System PDF

Unit 14: The Respiratory System Functions of the Respiratory System It takes in oxygen and removes carbon dioxide. Regulates blood pH by removing carbon dioxide. Warm and moisten inhaled air. Filters particles from inhaled air. Provides a sense of smell. Produce...

Unit 14: The Respiratory System Functions of the Respiratory System It takes in oxygen and removes carbon dioxide. Regulates blood pH by removing carbon dioxide. Warm and moisten inhaled air. Filters particles from inhaled air. Provides a sense of smell. Produces sound by moving air past vocal cords. Key Terms Ventilation: Movement of air into and out of the lungs. Inspiration (Inhalation): Breathing in. Expiration (Exhalation): Breathing out. Respiration: Gas exchange. Cellular Respiration: Use of oxygen by cells to make ATP. Functional Division of the Respiratory System Conducting Zone: Moves air into and out of lungs. o Components: Nose, Mouth, Pharynx, Larynx, Trachea, Bronchi, Bronchioles, Terminal Bronchioles. Respiratory Zone: Where gas exchange occurs. o Components: Alveolar Ducts, Alveoli. Anatomy of the Respiratory System Pharynx (Throat): Pathway for air and food. Eustachian Tube: Connects to the middle ear; equalizes air pressure. Epiglottis: Covers larynx to prevent food entry. Larynx (Voice Box): Contains vocal cords. Trachea (Windpipe): Supported by cartilage rings, lined with mucous membrane. Bronchi: Split from trachea, leading into lungs. Vocal Folds of the Larynx Inside the larynx, 2 vocal cords False Vocal Cords: Upper pair; no sound production. True Vocal Cords: Lower pair; involved in sound production. Glottis: Opening between true vocal cords. The Trachea Located anterior to the esophagus, surrounded by 16-20 incomplete rings of hyaline cartilage to keep airway open. Lined with mucous membrane and ciliated epithelium; contains goblet cells that produce mucus. Branches into left and right bronchi at T5. The Pleura Pleura: mucous membrance, surrounds the lungs Visceral Pleura: Covers lungs. Parietal Pleura: Covers inside of the thoracic cavity. Pleural Cavity: Small space between the 2 pleuras, filled with fluid to prevent friction during breathing. The Alveoli Sites of gas exchange, surrounded by capillaries and lymph vessels. Type I Alveolar Cells: Comprise most of the wall lining for gas exchange. Type II Alveolar Cells: Secrete surfactant (detergent-like substance) to maintain alveolar stability. o Surfactant creates surface tension which keeps the alveoli open, without it, they would collapse from the pull of the hydrogen bonds in the water molecules (within the alveoli) Pulmonary Ventilation and Pressure Changes It occurs due to pressure changes in the thoracic cavity. Muscles used for quiet (regular) breathing: o Inspiration: Diaphragm and external intercostals contract.  o Expiration: Diaphragm and intercostals relax. Intrapleural and alveolar pressures causes air to move in or out of the lungs o Decreased pressure – air moves in o Increased pressure – air moves out Ventilation is defined as the exchange of air between the atmosphere and alveoli. Boyle’s law says that at a constant temperature the pressure of a gas varies inversely with its volume Ventilation Compliance Compliance can be considered the inverse of stiffness. The greater the lung compliance, the easier it is to expand the lungs. two major determinants of lung compliance: o “stretchability” of the lung tissues, o surface tension at the air-water interfaces within the alveoli – surfactant Recoil is required for the lungs to push the air out of the lungs during exhalation. Lung Volumes and Capacities The volume of our lungs is directional proportional to the size of a person’s body This ratio is approximately 8 to 10 mL/kg of body weight 4 distinct lung (respiratory) volumes: Tidal Volume (TV): volume of air that enters or leaves the lungs during one respiratory cycle (~500 mL). Inspiratory Reserve Volume (IRV): Extra amount of air inhaled, in addition to tidal volume, during forced inspiration (~3 L). Expiratory Reserve Volume (ERV): Extra amount of air exhaled, beyond tidal volume, during maximal forced expiration (~1.2 L). Residual Volume (RV): Air left in lungs after maximal exhalation (~1.2 L). Respiratory capacities: combinations of 2 or more respiratory volumes: Inspiratory capacity (IC): is volume of air that can be inhaled after a normal, resting expiration; Vital Capacity (VC): Maximum air exhaled after maximum inhalation. Total Lung Capacity (TLC): Total volume of the lungs  Anatomical dead space: located in the bronchial tree and is not involved in gas exchange (i.e. the air that enters the respiratory tract but does not reach the alveoli and stays in this space ~150 mL) Alveolar Ventilation (AV) Alveolar Ventilation refers to the amount of air that reachesthe alveoli in one minute: o AV = (tidal volume – dead space) X respiration rate We also have alveolar dead space, if some alveoli have less blood flow at that time. Gas Exchange and Transport Dalton’s Law: Total pressure is the sum of partial pressures of each gas. Henry’s Law: Gas solubility in liquid is proportional to the pressure of the gas. o This means that the partial pressure of oxygen in air (21%) is proportional to the amount dissolved in blood. o If we breathe a higher concentration of oxygen, more will dissolve into the blood. o The reverse is also true; CO2 will diffuse out of the blood into a gas phase if the partial pressure is higher in the blood than the air. (Diffusion is moving molecules from higher FFto lower concentration.) Carbon Dioxide Transport In 3 ways: o 7-10% dissolved in plasma. o 25-30% bound to hemoglobin. o 60-65% converted to bicarbonate ions. Regulation of Breathing Primarily regulated by the medulla oblongata, signals the diaphragm and external intercostal muscles to contract o Medulla has pacemaker cells to control the rhythm of breathing Pons: affects the rate of breathing by inhibiting or stimulating the medulla oblongata COPD and Asthma chronic obstructive pulmonary disease (COPD): Includes emphysema and chronic bronchitis; cause severe difficulties not only in ventilation but also in oxygenation of the blood. o Emphysema: destruction and collapse of the smaller airways and loss of elastic ability to exhale o Chronic bronchitis: excessive mucus production in the bronchi and chronic inflammatory changes in the small airways. The cause of obstruction is an accumulation of mucus in the airways and thickening of the inflamed airways Asthma: a disease characterized by intermittent episodes in which airway smooth muscle contracts strongly, markedly increasing airway resistance. o The basic defect in asthma is chronic inflammation of the airways, caused by allergies, viral infections, and sensitivity to environmental factors. List and describe several protective mechanisms of the respiratory system. Summary of Key Points Functions include gas exchange, pH regulation, air filtration, sound production, and olfaction. Structures involved encompass nasal cavity, pharynx, larynx, trachea, bronchi, and alveoli.  Gas exchange dynamics are influenced by pressures, partial pressures, and chemical concentrations in blood.