Respiratory © 2018 Pearson Education, Inc..

Organs of the Respiratory System
Nose Pharynx Larynx Trachea Bronchi Lungs—alveoli © 2018 Pearson Education, Inc.

Left main (primary) bronchus Right main (primary) bronchus
Figure 13.1 The major respiratory organs shown in relation to surrounding structures. Nasal cavity Oral cavity Pharynx Nostril Larynx Trachea Left main (primary) bronchus Right main (primary) bronchus Left lung Right lung Diaphragm

Functional Anatomy of the Respiratory System
Gas exchanges between the blood and external environment occur only in the alveoli of the lungs Upper respiratory tract includes passageways from the nose to larynx Lower respiratory tract includes passageways from trachea to alveoli Passageways to the lungs purify, humidify, and warm the incoming air © 2018 Pearson Education, Inc.

The Nose The only externally visible part of the respiratory system
Nostrils (nares) are the route through which air enters the nose Nasal cavity is the interior of the nose Nasal septum divides the nasal cavity © 2018 Pearson Education, Inc.

Cribriform plate of ethmoid bone
Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section. Cribriform plate of ethmoid bone Sphenoidal sinus Frontal sinus Posterior nasal aperture Nasal cavity • Nasal conchae (superior, middle, and inferior) Nasopharynx • Pharyngeal tonsil • Nasal meatuses (superior, middle, and inferior) • Opening of pharyngotympanic tube • Nasal vestibule • Nostril • Uvula Hard palate Oropharynx • Palatine tonsil Soft palate Tongue • Lingual tonsil Laryngopharynx Hyoid bone Larynx Esophagus • Epiglottis • Thyroid cartilage Trachea • Vocal fold • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract

The Nose Olfactory receptors are located in the mucosa on the superior surface The rest of the cavity is lined with respiratory mucosa, which Moistens air Traps incoming foreign particles Enzymes in the mucus destroy bacteria chemically © 2018 Pearson Education, Inc.

The Nose Conchae are projections from the lateral walls
Increase surface area Increase air turbulence within the nasal cavity Increased trapping of inhaled particles The palate separates the nasal cavity from the oral cavity Hard palate is anterior and supported by bone Soft palate is posterior and unsupported © 2018 Pearson Education, Inc.

The Nose Paranasal sinuses
Cavities within the frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity Sinuses: Lighten the skull Act as resonance chambers for speech Produce mucus © 2018 Pearson Education, Inc.

The Pharynx Commonly called the throat
Muscular passageway from nasal cavity to larynx Continuous with the posterior nasal aperture Three regions of the pharynx Nasopharynx—superior region behind nasal cavity Oropharynx—middle region behind mouth Laryngopharynx—inferior region attached to larynx © 2018 Pearson Education, Inc.

The Pharynx Oropharynx and laryngopharynx serve as common passageway for air and food Epiglottis routes food into the posterior tube, the esophagus Pharyngotympanic tubes open into the nasopharynx Drain the middle ear © 2018 Pearson Education, Inc.

(a) Regions of the pharynx
Figure 13.2a Basic anatomy of the upper respiratory tract, sagittal section. Pharynx • Nasopharynx • Oropharynx • Laryngopharynx (a) Regions of the pharynx

The Pharynx Tonsils are clusters of lymphatic tissue that play a role in protecting the body from infection Pharyngeal tonsil (adenoid), a single tonsil, is located in the nasopharynx Palatine tonsils (2) are located in the oropharynx at the end of the soft palate Lingual tonsils (2) are found at the base of the tongue © 2018 Pearson Education, Inc.

The Larynx Commonly called the voice box Functions
Routes air and food into proper channels Plays a role in speech Located inferior to the pharynx Made of eight rigid hyaline cartilages Thyroid cartilage (Adam’s apple) is the largest © 2018 Pearson Education, Inc.

The Larynx Epiglottis Spoon-shaped flap of elastic cartilage
Protects the superior opening of the larynx Routes food to the posteriorly situated esophagus and routes air toward the trachea During swallowing, the epiglottis rises and forms a lid over the opening of the larynx © 2018 Pearson Education, Inc.

The Larynx Vocal folds (true vocal cords)
Vibrate with expelled air Allow us to speak The glottis includes the vocal cords and the opening between the vocal cords © 2018 Pearson Education, Inc.

The Trachea Commonly called the windpipe
4-inch-long tube that connects to the larynx Walls are reinforced with C-shaped rings of hyaline cartilage, which keep the trachea patent (open) Lined with ciliated mucosa Cilia beat continuously in the opposite direction of incoming air Expel mucus loaded with dust and other debris away from lungs © 2018 Pearson Education, Inc.

gland in submucosa Seromucous Esophagus Posterior Mucosa Submucosa
Figure 13.3a Anatomy of the trachea and esophagus. Posterior Mucosa Esophagus Submucosa Trachealis muscle Seromucous gland in submucosa Lumen of trachea Hyaline cartilage Adventitia (a) Anterior

Figure 13.3b Anatomy of the trachea and esophagus.

The Main Bronchi Formed by division of the trachea
Each bronchus enters the lung at the hilum (medial depression) Right bronchus is wider, shorter, and straighter than left Bronchi subdivide into smaller and smaller branches © 2018 Pearson Education, Inc.

Left main (primary) bronchus Right main (primary) bronchus
Figure 13.1 The major respiratory organs shown in relation to surrounding structures. Nasal cavity Oral cavity Pharynx Nostril Larynx Trachea Left main (primary) bronchus Right main (primary) bronchus Left lung Right lung Diaphragm

The Lungs Occupy the entire thoracic cavity except for the central mediastinum Apex of each lung is near the clavicle (superior portion) Base rests on the diaphragm Each lung is divided into lobes by fissures Left lung—two lobes Right lung—three lobes © 2018 Pearson Education, Inc.

The Lungs Serosa covers the outer surface of the lungs
Pulmonary (visceral) pleura covers the lung surface Parietal pleura lines the walls of the thoracic cavity Pleural fluid fills the area between layers Allows the lungs to glide over the thorax Decreases friction during breathing Pleural space (between the layers) is more of a potential space © 2018 Pearson Education, Inc.

(in pericardial cavity of mediastinum)
Figure 13.4a Anatomical relationships of organs in the thoracic cavity. Intercostal muscle Rib Parietal pleura Lung Trachea Pleural cavity Visceral pleura Thymus Apex of lung Left superior lobe Right superior lobe Oblique fissure Horizontal fissure Right middle lobe Left inferior lobe Oblique fissure Right inferior lobe Heart (in pericardial cavity of mediastinum) Diaphragm Base of lung (a) Anterior view. The lungs flank mediastinal structures laterally.

Right lung Esophagus Posterior (in posterior mediastinum) Vertebra
Figure 13.4b Anatomical relationships of organs in the thoracic cavity. Esophagus (in posterior mediastinum) Posterior Vertebra Root of lung at hilum Right lung Left main bronchus Left pulmonary artery Parietal pleura Left pulmonary vein Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Heart (in mediastinum) Anterior mediastinum Sternum Anterior (b) Transverse section through the thorax, viewed from above

The Lungs The bronchial tree
Main bronchi subdivide into smaller and smaller branches Bronchial (respiratory) tree is the network of branching passageways All but the smallest passageways have reinforcing cartilage in the walls Conduits to and from the respiratory zone Bronchioles (smallest conducting passageways) © 2018 Pearson Education, Inc.

Respiratory Zone Structures and the Respiratory Membrane
Terminal bronchioles lead into respiratory zone structures and terminate in alveoli Respiratory zone includes the: Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli (air sacs)—the only site of gas exchange Conducting zone structures include all other passageways © 2018 Pearson Education, Inc.

bronchioles, alveolar ducts, and alveoli
Figure 13.5a Respiratory zone structures. Alveolar duct Alveoli Respiratory bronchioles Alveolar duct Terminal bronchiole Alveolar sac (a) Diagrammatic view of respiratory bronchioles, alveolar ducts, and alveoli

(b) Light micrograph of human lung tissue, showing
Figure 13.5b Respiratory zone structures. Alveolar duct Alveolar pores Alveolus (b) Light micrograph of human lung tissue, showing the ﬁnal divisions of the respiratory tree (120×)

Respiratory membrane (air-blood barrier) On one side of the membrane is air, and on the other side is blood flowing past Formed by alveolar and capillary walls Gas crosses the respiratory membrane by diffusion Oxygen enters the blood Carbon dioxide enters the alveoli © 2018 Pearson Education, Inc.

Alveolar macrophages (“dust cells”) Add protection by picking up bacteria, carbon particles, and other debris Surfactant (a lipid molecule) Coats gas-exposed alveolar surfaces Secreted by cuboidal surfactant-secreting cells © 2018 Pearson Education, Inc.

Capillary endothelium Alveoli (gas-ﬁlled air spaces)
Figure 13.6 Functional anatomy of the respiratory membrane (air-blood barrier). Red blood cell Endothelial cell nucleus Capillary Alveolar pores O2 Capillary CO2 Macrophage Alveolus Nucleus of squamous epithelial cell Respiratory membrane Alveolar epithelium Fused basement membranes Capillary endothelium Alveoli (gas-ﬁlled air spaces) Red blood cell in capillary Surfactant- secreting cell Squamous epithelial cell of alveolar wall

Respiratory Physiology
Functions of the respiratory system Supply the body with oxygen Dispose of carbon dioxide Respiration includes four distinct events (discussed next) Pulmonary ventilation External respiration Respiratory gas transport Internal respiration © 2018 Pearson Education, Inc.

Four events of respiration Pulmonary ventilation—moving air into and out of the lungs (commonly called breathing) External respiration—gas exchange between pulmonary blood and alveoli Oxygen is loaded into the blood Carbon dioxide is unloaded from the blood © 2018 Pearson Education, Inc.

Four events of respiration (continued) Respiratory gas transport—transport of oxygen and carbon dioxide via the bloodstream Internal respiration—gas exchange between blood and tissue cells in systemic capillaries © 2018 Pearson Education, Inc.

Mechanics of Breathing
Pulmonary ventilation Mechanical process that depends on volume changes in the thoracic cavity Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure © 2018 Pearson Education, Inc.

Inspiration (inhalation) Diaphragm and external intercostal muscles contract Intrapulmonary volume increases Gas pressure decreases Air flows into the lungs until intrapulmonary pressure equals atmospheric pressure © 2018 Pearson Education, Inc.

intercostals contract)
Figure 13.7a Rib cage and diaphragm positions during breathing. Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs are elevated as external intercostals contract External intercostal muscles Full inspiration (External intercostals contract) Diaphragm moves inferiorly during contraction (a) Inspiration: Air (gases) ﬂows into the lungs

to atmospheric pressure
Figure 13.8a Changes in (a) intrapulmonary pressure and (b) air flow during inspiration and expiration. Inspiration Expiration to atmospheric pressure Pressure relative +2 Intrapulmonary pressure +1 –1 –2 (a)

Expiration (exhalation) Largely a passive process that depends on natural lung elasticity Intrapulmonary volume decreases Gas pressure increases Gases passively flow out to equalize the pressure Forced expiration can occur mostly by contraction of internal intercostal muscles to depress the rib cage © 2018 Pearson Education, Inc.

Intrapleural pressure The pressure within the pleural space) is always negative Major factor preventing lung collapse If intrapleural pressure equals atmospheric pressure, the lungs recoil and collapse © 2018 Pearson Education, Inc.

Changes in anterior-posterior and superior-inferior dimensions
Figure 13.7b Rib cage and diaphragm positions during breathing. Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs are depressed as external intercostals relax Expiration (External intercostals relax) External intercostal muscles Diaphragm moves superiorly as it relaxes (b) Expiration: Air (gases) ﬂows out of the lungs

to atmospheric pressure
Figure 13.8 Changes in (a) intrapulmonary pressure and (b) air flow during inspiration and expiration. to atmospheric pressure Pressure relative Inspiration Expiration +2 Intrapulmonary pressure +1 –1 –2 (a) Volume of breath Volume (L) 0.5 –0.5 (b)

Respiratory Volumes and Capacities
Factors affecting respiratory capacity Size Sex Age Physical condition Tidal volume (TV) Normal quiet breathing 500 ml of air is moved in/out of lungs with each breath © 2018 Pearson Education, Inc.

Inspiratory reserve volume (IRV) Amount of air that can be taken in forcibly over the tidal volume Usually around 3,100 ml Expiratory reserve volume (ERV) Amount of air that can be forcibly exhaled after a tidal expiration Approximately 1,200 ml © 2018 Pearson Education, Inc.

Residual volume Air remaining in lung after expiration Cannot be voluntarily exhaled Allows gas exchange to go on continuously, even between breaths, and helps keep alveoli open (inflated) About 1,200 ml © 2018 Pearson Education, Inc.

Vital capacity The total amount of exchangeable air Vital capacity = TV + IRV + ERV 4,800 ml in men; 3,100 ml in women Dead space volume Air that remains in conducting zone and never reaches alveoli About 150 ml © 2018 Pearson Education, Inc.

Expiratory reserve volume
Figure 13.9 Graph of the various respiratory volumes in a healthy young adult male. 6,000 5,000 Inspiratory reserve volume 3,100 ml Milliliters (ml) 4,000 Vital capacity 4,800 ml 3,000 Total lung capacity 6,000 ml Tidal volume 500 ml Expiratory reserve volume 1,200 ml 2,000 1,000 Residual volume 1,200 ml

Nonrespiratory Air Movements
Can be caused by reflexes or voluntary actions Examples Cough and sneeze—clears lungs of debris Crying—emotionally induced mechanism Laughing—similar to crying Hiccup—sudden inspirations Yawn—very deep inspiration © 2018 Pearson Education, Inc.

Table 13.1 Nonrespiratory Air (Gas) Movements

Respiratory Sounds Sounds are monitored with a stethoscope
Two recognizable sounds can be heard with a stethoscope: Bronchial sounds—produced by air rushing through large passageways such as the trachea and bronchi Vesicular breathing sounds—soft sounds of air filling alveoli © 2018 Pearson Education, Inc.

External Respiration, Gas Transport, and Internal Respiration
Gas exchanges occur as a result of diffusion External respiration is an exchange of gases occurring between the alveoli and pulmonary blood (pulmonary gas exchange) Internal respiration is an exchange of gases occurring between the blood and tissue cells (systemic capillary gas exchange) Movement of the gas is toward the area of lower concentration © 2018 Pearson Education, Inc.

Blood leaving tissues and entering lungs:
Figure Gas exchanges in external and internal respiration. Inspired air: Alveoli of lungs: CO2 O2 O2 CO2 O2 CO2 External respiration Pulmonary arteries Alveolar capillaries Pulmonary veins Blood leaving tissues and entering lungs: Blood leaving lungs and entering tissue capillaries: Heart O2 CO2 O2 CO2 Tissue capillaries Systemic veins Systemic arteries Internal respiration CO2 O2 Tissue cells: O2 CO2

External Respiration Oxygen is loaded into the blood
Oxygen diffuses from the oxygen-rich air of the alveoli to the oxygen-poor blood of the pulmonary capillaries Carbon dioxide is unloaded out of the blood Carbon dioxide diffuses from the blood of the pulmonary capillaries to the alveoli © 2018 Pearson Education, Inc.

(a) External respiration in the lungs (pulmonary gas exchange)
Figure 13.11a The loading and unloading of oxygen (O2) and carbon dioxide (CO2) in the body. (a) External respiration in the lungs (pulmonary gas exchange) Oxygen is loaded into the blood, and carbon dioxide is unloaded. Alveoli (air sacs) O2 CO2 Loading of O2 Unloading of CO2 Hb  O HbO2 HCO3  H H2CO CO2  H2O (Oxyhemoglobin is formed) Bicar- bonate ion Carbonic acid Water Plasma Red blood cell Pulmonary capillary

Gas Transport in the Blood
Oxygen transport in the blood Most oxygen travels attached to hemoglobin and forms oxyhemoglobin (HbO2) A small dissolved amount is carried in the plasma © 2018 Pearson Education, Inc.

Carbon dioxide transport in the blood Most carbon dioxide is transported in the plasma as bicarbonate ion (HCO3–) A small amount is carried inside red blood cells on hemoglobin, but at different binding sites from those of oxygen © 2018 Pearson Education, Inc.

For carbon dioxide to diffuse out of blood into the alveoli, it must be released from its bicarbonate form: Bicarbonate ions enter RBC Combine with hydrogen ions Form carbonic acid (H2CO3) Carbonic acid splits to form water + CO2 Carbon dioxide diffuses from blood into alveoli © 2018 Pearson Education, Inc.

Internal Respiration Exchange of gases between blood and tissue cells
An opposite reaction from what occurs in the lungs Carbon dioxide diffuses out of tissue cells to blood (called loading) Oxygen diffuses from blood into tissue (called unloading) © 2018 Pearson Education, Inc.

Oxygen is unloaded and carbon dioxide is loaded into the blood.
Figure 13.11b The loading and unloading of oxygen (O2) and carbon dioxide (CO2) in the body. (b) Internal respiration in the body tissues (systemic capillary gas exchange) Oxygen is unloaded and carbon dioxide is loaded into the blood. Tissue cells CO2 O2 Loading of CO2 Unloading of O2 CO2  H2O H2CO H  HCO3 Water Carbonic acid Bicar- bonate ion HbO Hb  O2 Plasma Systemic capillary Red blood cell

Control of Respiration
Neural regulation: setting the basic rhythm Activity of respiratory muscles is transmitted to and from the brain by phrenic and intercostal nerves Neural centers that control rate and depth are located in the medulla and pons Medulla—sets basic rhythm of breathing and contains a pacemaker (self-exciting inspiratory center) called the ventral respiratory group (VRG) Pons—smoothes out respiratory rate © 2018 Pearson Education, Inc.

Breathing control centers: Pons centers Medulla centers
Figure Neural control of respiration. Breathing control centers: Pons centers Medulla centers Afferent impulses to medulla Efferent nerve impulses from medulla trigger contraction of inspiratory muscles: Phrenic nerves Intercostal nerves Breathing control centers stimulated by: CO2 and H increase in tissue. Nerve impulse from O2 sensor indicating O2 decrease Intercostal muscles Diaphragm O2 sensor in aortic body of aortic arch

Non-neural factors influencing respiratory rate and depth Physical factors Increased body temperature Exercise Talking Coughing Volition (conscious control) Emotional factors such as fear, anger, and excitement © 2018 Pearson Education, Inc.

Non-neural factors influencing respiratory rate and depth (continued) Chemical factors: CO2 levels The body’s need to rid itself of CO2 is the most important stimulus for breathing Increased levels of carbon dioxide (and thus, a decreased or acidic pH) in the blood increase the rate and depth of breathing Changes in carbon dioxide act directly on the medulla oblongata © 2018 Pearson Education, Inc.

Non-neural factors influencing respiratory rate and depth (continued) Chemical factors: oxygen levels Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and common carotid artery Information is sent to the medulla Oxygen is the stimulus for those whose systems have become accustomed to high levels of carbon dioxide as a result of disease © 2018 Pearson Education, Inc.

Non-neural factors influencing respiratory rate and depth (continued) Chemical factors (continued) Hyperventilation Rising levels of CO2 in the blood (acidosis) result in faster, deeper breathing Exhale more CO2 to elevate blood pH May result in apnea and dizziness and lead to alkalosis © 2018 Pearson Education, Inc.

Non-neural factors influencing respiratory rate and depth (continued) Chemical factors (continued) Hypoventilation Results when blood becomes alkaline (alkalosis) Extremely slow or shallow breathing Allows CO2 to accumulate in the blood © 2018 Pearson Education, Inc.

Respiratory Disorders
Chronic obstructive pulmonary disease (COPD) Exemplified by chronic bronchitis and emphysema Shared features of these diseases Patients almost always have a history of smoking Labored breathing (dyspnea) becomes progressively worse Coughing and frequent pulmonary infections are common Most COPD patients are hypoxic, retain carbon dioxide and have respiratory acidosis, and ultimately develop respiratory failure © 2018 Pearson Education, Inc.

Chronic bronchitis Mucosa of the lower respiratory passages becomes severely inflamed Excessive mucus production impairs ventilation and gas exchange Patients become cyanotic and are sometimes called “blue bloaters” as a result of chronic hypoxia and carbon dioxide retention © 2018 Pearson Education, Inc.

Emphysema Alveoli walls are destroyed; remaining alveoli enlarge Chronic inflammation promotes lung fibrosis, and lungs lose elasticity Patients use a large amount of energy to exhale; some air remains in the lungs Sufferers are often called “pink puffers” because oxygen exchange is efficient Overinflation of the lungs leads to a permanently expanded barrel chest Cyanosis appears late in the disease © 2018 Pearson Education, Inc.

Continual bronchial irritation and inﬂammation
Homeostatic Imbalance The pathogenesis of COPD. Tobacco smoke Air pollution Continual bronchial irritation and inﬂammation Breakdown of elastin in connective tissue of lungs Chronic bronchitis Excessive mucus produced Chronic productive cough Emphysema Destruction of alveolar walls Loss of lung elasticity Airway obstruction or air trapping Dyspnea Frequent infections Respiratory failure

Lung cancer Leading cause of cancer death for men and women Nearly 90 percent of cases result from smoking Aggressive cancer that metastasizes rapidly Three common types Adenocarcinoma Squamous cell carcinoma Small cell carcinoma © 2018 Pearson Education, Inc.

Developmental Aspects of the Respiratory System
Lungs do not fully inflate until 2 weeks after birth This change from nonfunctional to functional respiration depends on surfactant Surfactant lowers surface tension so the alveoli do not collapse Surfactant is formed late in pregnancy, around 28 to 30 weeks © 2018 Pearson Education, Inc.

Respiratory rate changes throughout life Newborns: 40 to 80 respirations per minute Infants: 30 respirations per minute Age 5: 25 respirations per minute Adults: 12 to 18 respirations per minute Rate often increases again in old age © 2018 Pearson Education, Inc.

Aging effects Elasticity of lungs decreases Vital capacity decreases Blood oxygen levels decrease Stimulating effects of carbon dioxide decrease Elderly are often hypoxic and exhibit sleep apnea More risks of respiratory tract infection © 2018 Pearson Education, Inc.

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