The Respiratory System PDF

CHAPTER 23 The Respiratory System The Respiratory System Two systems that cooperate to supply O2 and eliminate CO2 are the cardiovascular and the respiratory system. 1. The respiratory system provides for GAS EXCHANGE. 2. The cardiovascular system TRANSPORTS the respiratory gases. Failure...

CHAPTER 23 The Respiratory System The Respiratory System Two systems that cooperate to supply O2 and eliminate CO2 are the cardiovascular and the respiratory system. 1. The respiratory system provides for GAS EXCHANGE. 2. The cardiovascular system TRANSPORTS the respiratory gases. Failure of either system has the same effect on the body: Disruption of homeostasis and rapid death of cells from oxygen starvation and buildup of waste products.  Steps involved in Respiration Respiration supplies the body with O2 and removes CO2. 3 basic steps: 1. Pulmonary ventilation (breathing) inhalation and exhalation of air involves exchange of air between atmosphere and alveoli 2. External (pulmonary) respiration exchange of gases between alveoli and blood in the pulmonary capillaries. 3. Internal (tissue) respiration exchange of gases between blood in the systemic capillaries and *Cellular respiration – use of oxygen by cells to make ATP tissue cells.  Structures of the Respiratory System Structurally, - divided into 2 parts: Upper respiratory system - nose, pharynx, and associated structures Lower respiratory system - larynx, trachea, bronchi, and lungs Functionally, - divided into 2 zones: Conducting zone Interconnecting cavities and tubes outside and within the lungs. Function to moisten air and conduct it into the lungs. Respiratory zone – Consists of tubes and tissues within the lungs where gas exchange occurs. Internal Anatomy of the Nose The bony framework of the nose is formed by the frontal, nasal, and maxillary bones. The interior structures of the nose are specialized for warming moistening filtering incoming air receiving olfactory stimuli serving as large, hollow resonating chambers to modify speech sounds. Pharynx The pharynx (throat) is a muscular tube lined by a mucous membrane. The pharynx functions as: A passageway for air (respiration) and food digestion. Resonating chamber for speech sounds. Houses the tonsils - participate in immunological reactions against foreign invaders. Larynx The larynx (voice box) is a passageway that connects the pharynx and trachea. It contains: thyroid cartilage epiglottis - prevents food from entering the larynx. vocal folds - produce sound when they vibrate.  Trachea Trachea (windpipe) - anterior to the esophagus, extends from the larynx to the primary bronchi. Composed of smooth muscle and C-shaped rings of cartilage. cartilage rings keep the airway open Lined with pseudostratified ciliated columnar epithelium. The cilia sweep debris away from the lungs and back to the throat to be swallowed. Bronchi The trachea divides into the right and left pulmonary bronchi. Bronchial tree - trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles. Primary bronchi further divide to form smaller and smaller diameter branches. * The terminal bronchioles are the end of the conducting zone Bronchi Lungs Paired organs in the thoracic cavity. Enclosed and protected by the pleural membrane. The parietal pleura - outer layer, attached to the wall of the thoracic cavity. The visceral pleura - inner layer, covering the lungs. The pleural cavity contains a serous lubricating fluid secreted by the membranes. Extend from the diaphragm to just slightly superior to the clavicles and lie against the ribs anteriorly and posteriorly.  Lobes and Fissures of the Lungs Right lung - three lobes separated by two fissures. Left lung - two lobes separated by one fissure and a depression- cardiac notch. BASE – inferior portion, fits over the diaphragm APEX – superior portion Secondary bronchi give rise to branches called tertiary (segmental) bronchi, which supply lung tissue called bronchopulmonary segments. Each bronchopulmonary segment consists of many lobules, which contain lymphatics, arterioles, venules, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.  Alveoli Conducting zone ends at the terminal bronchioles - the respiratory zone begins. The respiratory zone terminates at the alveoli, the “air sacs” found within the lungs. Alveolus 2 types of alveolar cells: Type I alveolar (squamous pulmonary epithelial) cells Type II alveolar (septal) cells, and alveolar macrophages (dust cells). secrete alveolar fluid, keeps the alveolar cells moist, contains surfactant. Surfactant lowers surface tension of alveolar fluid, preventing the collapse of alveoli with each expiration. Gas exchange occurs across the alveolar-capillary membrane.  Respiratory Membrane The respiratory membrane is composed of: A layer of type I and II alveolar cells and alveolar macrophages that constitutes the alveolar wall. An epithelial basement membrane underlying the alveolar wall A capillary basement  1. Pulmonary ventilation Steps (breathing) involved in 2. External (pulmonary) respiration Respiration 3. Internal (tissue) respiration  In pulmonary ventilation, air Pulmonar flows between the atmosphere y and the alveoli of the lungs Ventilatio because of alternating n pressure differences created by contraction and relaxation of respiratory muscles. Ventilation occurs in 2 basic steps: Inhalatio Exhalati n on (inspirati (expirati on) on) Pulmonary Ventilation Inhalation (inspiration) is the process of bringing air into the lungs. Movement of air depends on pressure changes. Expanding the lungs involves contraction of the main inspiratory muscle - the diaphragm. Inhalation occurs when alveolar (intrapulmonic) pressure falls below atmospheric pressure. Contraction of the diaphragm and external intercostal muscles INCREASES the size of the thorax Thus, DECREASING the intrapleural pressure so that the lungs expand. Expansion of the lungs decreases alveolar pressure so that air moves along the pressure gradient from the atmosphere into the lungs. Pulmonary Ventilation Exhalation (expiration) is the movement of air out of the lungs. Exhalation occurs when alveolar pressure is higher than atmospheric pressure. Relaxation of the diaphragm and external intercostal muscles results in elastic recoil of the chest wall and lungs. Which INCREASES intrapleural pressure DECREASES lung volume INCREASES alveolar pressure so that air moves from the lungs to the atmosphere *Forced expiration employs contraction of the internal intercostals and abdominal muscles. Position of the Diaphragm During Inhalation and Exhalation  Muscles of Inhalation and Exhalatio n  Eupnea - normal variation in breathing rate and depth. Breathing Apnea - breath holding. Patterns and Dyspnea - painful or difficult breathing. Respirato ry Tachypnea - rapid breathing rate. Movemen Costal breathing - combinations of various ts patterns of intercostal and extracostal muscles, usually during need for increased ventilation, as with exercise. Diaphragmatic breathing is the usual mode of operation to move air by contracting and relaxing the diaphragm to change the lung volume. Exchange of O2 and CO2 External and Internal Respiration During external respiration, oxygen will diffuse from the alveoli into the pulmonary capillaries. *PULMONARY gas exchange. Converting deoxygenated blood from the right heart to oxygenated blood that returns to the left heart. CO2 moves in the opposite direction During internal respiration, oxygen will diffuse from the systemic capillaries into the tissues. *SYSTEMIC gas exchange. O2 leaves blood stream, oxygenated blood is converted to deoxygenated blood. CO2 moves in the opposite direction  Red blood cell Capillary Capillary O2 CO2 Alveolus Respiratory Alveolar epithelium membrane Fused basement membranes Capillary endothelium Alveoli (gas- Red blood Squamous filled air cell in epithelial cell spaces) capillary of alveolar wall Transport of O2 and CO2 in the Blood Oxygen In each 100 ml of oxygenated blood: 1.5% of the O2 is dissolved in the plasma 98.5% is carried with hemoglobin (Hb) inside RBCs as oxyhemoglobin. Carbon dioxide 7% of the CO2 is dissolved in the plasma 23% of the CO2 is carried by Hb inside RBC’s 70% of the CO2 is transported as bicarbonate ions (HCO3) Respiratory Volumes and Capacities Tidal volume (TV) normal breathing volume moves about 500 ml of air *Avg adult at rest – 12 rpm Respiratory Volumes and Capacities Inspiratory reserve volume (IRV) amount of air that can be taken in forcibly over tidal volume usually between 1900mL and 3100 mL Respiratory Volumes and Capacities Expiratory reserve volume (ERV) amount of air that can be forcibly exhaled over tidal volume approximately 1200 ml Respiratory Volumes and Capacities Residual volume air remaining in lung after expiration about 1200 ml Respiratory Volumes and Capacities Vital capacity (VC) the total amount of exchangeable air vital capacity = TV + IRV + ERV Dead space volume - air that remains in conducting zone and never reaches alveoli Control of Respiration Respiratory center is located in the brain stem. Medullary Respiratory Center Located in the medulla Generation of the rhythm of breathing Pontine Respiratory Group Located in the pons Modifies rhythm of breathing during exercise, sleeping, or speaking Control of Respiration Cortical influences Voluntary control our pattern of breathing Protection against water or irritating gases from entering the lungs Limited by build up of CO2 Chemoreceptor Central and peripheral chemoreceptors monitor levels of O2 and CO2 and provide input to the respiratory center. Hyperventilating allows inhalation of more O2 and exhalation of CO2 Exercise and The respiratory and cardiovascular systems adjust in response to both the intensity and the duration of exercise. Respiratory As cardiac output rises, the blood flow to the lungs, termed pulmonary perfusion, increases as System well.  Aging results in decreased: Aging Vital capacity and the Blood O2 level Alveolar macrophage Respirat activity Ciliary action of ory respiratory epithelia System Consequently, elderly people are more susceptible to pneumonia, bronchitis, emphysema, and other issues  Hypoxia - Oxygen deficiency at the tissue level Asthma Chronic Obstructive Pulmonary Diseas Disorders e : Lung cancer Homeost Pneumonia atic Tuberculosis Imbalanc es Common cold Pulmonary edema Severe Acute Respiratory Distress