Chapter 10 Lecture Outline See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright 2016 McGraw-Hill Education. Permission required for reproduction or display. 1
Respiratory System 2
Points to ponder What are the parts and functions of the upper and lower respiratory system? What is the mechanism for expiration and inspiration? How is breathing controlled by the nervous system and through chemicals? Where and how is exchange of gases accomplished? What are some common respiratory infections and disorders? What do you know about tobacco and health? 3
10.1 The Respiratory System Overview of the respiratory system Upper Respiratory Tract Nasal cavity filters, warms, and moistens air Pharynx passage way where pathway for air and food cross Glottis space between the vocal chords; opening to larynx Larynx (voice box) ; produces sound Trachea (wind pipe) ; passage of air to bronchi Bronchus passage of air to lungs Lower Respiratory Tract Bronchioles passage of air to alveoli Lung contains alveoli (air sacs); carries out gas exchange Diaphragm skeletal muscle; functions in ventilation Figure 10.1 The human respiratory tract. 4
10.1 The Respiratory System What is the pathway that air follows? nose pharynx larynx trachea bronchus bronchioles alveoli 5
10.2 The Upper Respiratory Tract What constitutes the upper respiratory tract? Nose sinus Pharynx Larynx nasal cavity hard palate nares uvula mouth tongue tonsils epiglottis glottis sinus tonsil nasopharynx Pharynx oropharynx laryngopharynx larynx esophagus trachea Figure 10.2 The upper respiratory tract. 6
10.2 The Upper Respiratory Tract The nose The nose opens at the nostrils/nares and leads into the nasal cavities. Hairs and mucus in the nose filter the air. The nasal cavity has a lot of capillaries that warm and moisten the air. Specialized cells act as odor receptors. Tear glands drain into the nasal cavities that can lead to a runny nose. 7
10.2 The Upper Respiratory Tract The pharynx The pharynx is a funnel-shaped cavity commonly called the throat. It has three portions based on location: nasopharynx, oropharynx, and laryngopharynx. Tonsils provide a lymphatic defense during breathing at the junction of the oral cavity and pharynx. 8
10.2 The Upper Respiratory Tract The larynx The larynx is a triangular, cartilaginous structure that passes air between the pharynx and trachea. It is called the voice box and houses vocal cords. There are two mucosal folds that make up the vocal cords with an opening in the middle called the glottis. 9
10.2 The Upper Respiratory Tract The larynx base of tongue epiglottis vocal cords glottis (left): CNRI Phototake Figure 10.4 The vocal cords. 10
10.3 The Lower Respiratory Tract What constitutes the lower respiratory tract? Trachea Bronchial tree Upper Respiratory Tract Nasal cavity filters, warms, and moistens air Pharynx passage way where pathway for air and food cross Glottis space between the vocal chords; opening to larynx Larynx (voice box) ; produces sound Trachea (wind pipe) ; passage of air to bronchi Bronchus passage of air to lungs Lungs Lower Respiratory Tract Bronchioles passage of air to alveoli Lung contains alveoli (air sacs); carries out gas exchange Diaphragm skeletal muscle; functions in ventilation Figure 10.1 The human respiratory tract. 11
10.3 The Lower Respiratory Tract The trachea The trachea is a tube, often called the windpipe, that connects the larynx with the primary bronchi. It is made of connective tissue, smooth muscle, and cartilaginous rings. The trachea is lined with cilia and mucus that help to keep the lungs clean. 12
10.3 The Lower Respiratory Tract The trachea cilia goblet cell epithelial cell particle movement mucus air tracheal lumen Figure 10.5 The cells lining the trachea. (bottom half): ED Reschke 13
10.3 The Lower Respiratory Tract The bronchial tree The bronchial tree starts with two main bronchi that lead from the trachea into the lungs. The bronchi continue to branch until they are small bronchioles about 1 mm in diameter with thinner walls. Bronchioles eventually lead to elongated sacs called alveoli. 14
10.3 The Lower Respiratory Tract The lungs The secondary bronchi, bronchioles, and alveoli make up the lungs. The right lung has three lobes while the left lung has two lobes. Each lobe is divided into lobules. Each lung is enclosed by membranes called pleura. 15
10.3 The Lower Respiratory Tract The alveoli There are 300 million alveoli in the lungs that greatly increase surface area. Alveoli are enveloped by blood capillaries. The alveoli and capillaries are one layer of epithelium to allow exchange of gases. Alveoli are lined with surfactant that act as a film to keep alveoli open. 16
10.3 The Lower Respiratory Tract The alveoli pulmonary vein blood flow pulmonary artery blood flow Pulmonary arteriole contains much CO 2, little O 2. bronchiole Pulmonary venule contains much O 2, little CO 2 lobule capillary network Figure 10.6 Pulmonary circulation to and from the lungs. alveoli 17
10.4 Mechanism of Breathing Two phases of breathing/ventilation 1. Inspiration an active process of inhalation that brings air into the lungs 2. Expiration a typically passive process of exhalation that expels air from the lungs 18
10.4 Mechanism of Breathing Boyle s Law Ventilation is governed by Boyle s Law. At a constant temperature the pressure of a given quantity of gas is inversely proportional to its volume. Figure 10.7 The relationship between air pressure and volume. 19
10.4 Mechanism of Breathing Inspiration The diaphragm and intercostal muscles contract. The diaphragm flattens and the rib cage moves upward and outward. Volume of the thoracic cavity and lungs increase. The air pressure within the lungs decreases. Air flows into the lungs. 20
10.4 Mechanism of Breathing Inspiration trachea Rib cage moves up and out. External intercostal muscles pull the ribs outward. lungs Diaphragm contracts and moves down. air in lung rib cage When Pressure in lungs decreases, air comes rushing in. a. Inspiration Figure 10.8a The thoracic cavity during inspiration. 21
10.4 Mechanism of Breathing Expiration The diaphragm and intercostal muscles relax. The diaphragm moves upward and becomes dome-shaped. The rib cage moves downward and inward. Volume of the thoracic cavity and lungs decreases. The air pressure within the lungs increases. Air flows out of the lungs. 22
10.4 Mechanism of Breathing Expiration Rib cage moves down and in. Internal intercostal muscles pull the ribs inward during forced expiration. Diaphragm relaxes and moves up. air out When pressure in lungs increases, air is pushed out. b. Expiration Figure 10.8b The thoracic cavity during expiration. 23
10.4 Mechanism of Breathing Different volumes of air during breathing Tidal volume the small amount of air that usually moves in and out with each breath Vital capacity the maximum volume of air that can be moved in plus the maximum amount that can be moved out during one breath Inspiratory and expiratory reserve volume the increased volume of air moving in or out of the body Residual volume the air remaining in the lungs after exhalation 24
10.4 Mechanism of Breathing Average Lung Volume (ml) Visualizing the vital capacity 5,800 4,800 maximum inspiration maximum expiration inspiratory reserve volume 3,600 2,900 2,400 tidal volume vital capacity total Lung capacity 1,200 expiratory reserve volume residual volume residual volume 0 Veronique Burger/Science Source Figure 10.9 Measuring the vital capacity of the lungs. 25
10.5 Control of Ventilation How is breathing controlled by the nervous system? Nervous control Respiratory control center in the brain (medulla oblongata) sends out nerve impulses to contract muscle for inspiration. Sudden infant death syndrome (SIDS) is thought to occur when this center stops sending out nerve signals. 26
10.5 Control of Ventilation How is breathing controlled by the nervous system? brain Respiratory center: region of the brain that automatically regulates breathing Intercostal nerves stimulate the intercostal muscles to contract. External intercostal muscles help expand the thoracic cavity by contracting. Phrenic nerve stimulates the diaphragm to contract. Diaphragm helps expand the thoracic cavity by flattening when it contracts. Figure 10.10 The control of breathing by the respiratory center. 27
10.5 Control of Ventilation How is breathing chemically Chemical control controlled? Two sets of chemoreceptors sense the drop in ph: one set is in the brain and the other in the circulatory system. Both are sensitive to carbon dioxide levels that change blood ph due to metabolism. 28
10.6 Gas Exchanges in the Body Exchange of gases in the body Oxygen and carbon dioxide are exchanged. The exchange of gases is dependent on diffusion. Partial pressure is the amount of pressure each gas exerts (P CO2 or P O 2 ). Oxygen and carbon dioxide will diffuse from the area of higher to the area of lower partial pressure. 29
10.6 Gas Exchanges in the Body External respiration Exchange of gases between the lung alveoli and the blood capillaries. P CO2 is higher in the lung capillaries than the air, thus CO 2 diffuses out of the plasma into the lungs. The partial pressure pattern for O 2 is just the opposite, so O 2 diffuses the red blood cells in the lungs. 30
10.6 Gas Exchanges in the Body External respiration Carbon dioxide transport: carbonic H + + HCO 3 - H 2 CO 3 anhydrase H 2 O + CO 2 Oxygen transport: Hb + O 2 HbO 2 31
10.6 Gas Exchanges in the Body The movement of oxygen and carbon dioxide in the body alveolus plasma HCO 3 pulmonary capillary CO 2 pulmonary capillary Hb H + CO 2 H + + HCO 3 H 2 CO 3 H 2 O Hb CO 2 RBC External respiration O 2 alveolus RBC O 2 Hb O 2 plasma CO 2 exits blood a. CO 2 O 2 lung O2 enters blood pulmonary artery pulmonary vein heart systemic vein tissue cells systemic artery Figure 10.11 Movement of gases during external and internal respiration. b. Hb H + CO 2 enters blood H + + HCO 3 H 2 CO 3 H 2 O Hb CO 2 HCO 3 RBC plasma tissue fluid systemic capillary CO 2 tissue cell CO 2 O 2 Internal respiration systemic capillary tissue cell tissue fluid plasma RBC Hb O 2 exits blood 32
10.6 Gas Exchanges in the Body Internal respiration The exchange of gases between the blood in the capillaries outside of the lungs and the tissue fluid. P O2 is higher in the capillaries than the tissue fluid, thus O 2 diffuses out of the blood into the tissues. 33
10.6 Gas Exchanges in the Body Internal respiration Oxyhemoglobin gives up oxygen: HbO 2 Hb + O 2 Most CO 2 is carried as a bicarbonate ion: CO 2 + H 2 O carbonic anhydrase H 2 CO 3 H + + HCO 3-34
10.7 Respiration and Health Upper respiratory tract infections Sinusitis blockage of sinuses Otitis media infection of the middle ear Tonsillitis inflammation of the tonsils Laryngitis infection of the larynx that leads to loss of voice 35
10.7 Respiration and Health Lower respiratory tract disorders Pneumonia infection of the lungs with thick, fluid build up Tuberculosis bacterial infection that leads to tubercles (collections of encapsulated bacteria) Pulmonary fibrosis lungs lose elasticity because fibrous connective tissue builds up in the lungs, usually because of inhaled particles 36
10.7 Respiration and Health Lower respiratory tract disorders Emphysema chronic, incurable disorder in which alveoli are damaged, and thus the surface area for gas exchange is reduced Asthma bronchial tree becomes irritated causing breathlessness, wheezing, and coughing Lung cancer uncontrolled cell division in the lungs that is often caused by smoking and can lead to death 37
10.7 Respiration and Health Some Diseases and Disorders of the Respiratory System mucus Pneumonia Alveoli fill with pus and fluid, making gas exchange difficult. Bronchitis Airways are inflamed due to infection (a cute) or due to an irritant (chronic). Coughing brings up mucus and pus. asbestos body tubercle Pulmonary Fibrosis Fibrous connective tissue builds up in lungs, reducing their elasticity. Pulmonary Tuberculosis Tubercles encapsulate bacteria, and elasticity of lungs is reduced. Figure 10.12 Some diseases and disorders of the respiratory system. Emphysema Alveoli burst and fuse into enlarged air spaces. Surface area for gas exchange is reduced. Asthma Airways are inflamed due to irritation, and bronchioles constrict due to muscle spasms. 38
10.7 Respiration and Health Things you should know about tobacco and health All forms of tobacco can cause damage. Smoking increases a person s chance of lung, mouth, larynx, esophagus, bladder, kidney, pancreatic, stomach, and cervix cancers. Smoking also increases the chance of chronic bronchitis, emphysema, heart disease, stillbirths, and harm to an unborn child. Passive smoke can increase a nonsmoker s chance of pneumonia, bronchitis, and lung cancer. 39