Interactive Physiology Respiratory System Anatomy Review Practice Test

Learning Objectives

By the finish of this section, yous will be able to:

• List the structures that make up the respiratory system
• Describe how the respiratory system processes oxygen and CO₂
• Compare and contrast the functions of upper respiratory tract with the lower respiratory tract

The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acrid-base balance. Portions of the respiratory organization are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as during childbirth or coughing (Effigy 22.2).

Effigy 22.2 Major Respiratory Structures The major respiratory structures span the nasal cavity to the diaphragm.

Functionally, the respiratory arrangement can be divided into a conducting zone and a respiratory zone. The conducting zone of the respiratory system includes the organs and structures not directly involved in gas exchange. The gas exchange occurs in the respiratory zone.

Conducting Zone

The major functions of the conducting zone are to provide a road for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air. Several structures within the conducting zone perform other functions as well. The epithelium of the nasal passages, for example, is essential to sensing odors, and the bronchial epithelium that lines the lungs can metabolize some airborne carcinogens.

The Nose and its Next Structures

The major entrance and exit for the respiratory system is through the nose. When discussing the olfactory organ, information technology is helpful to divide it into ii major sections: the external nose, and the nasal cavity or internal olfactory organ.

The external nose consists of the surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions (Figure 22.3). The root is the region of the nose located between the eyebrows. The bridge is the function of the nose that connects the root to the rest of the olfactory organ. The back nasi is the length of the nose. The apex is the tip of the nose. On either side of the apex, the nostrils are formed past the alae (singular = ala). An ala is a cartilaginous construction that forms the lateral side of each naris (plural = nares), or nostril opening. The philtrum is the concave surface that connects the apex of the nose to the upper lip.

Figure 22.3 Nose This illustration shows features of the external nose (top) and skeletal features of the nose (bottom).

Underneath the thin skin of the nose are its skeletal features (come across Figure 22.3, lower illustration). While the root and span of the nose consist of bone, the protruding portion of the olfactory organ is composed of cartilage. As a event, when looking at a skull, the nose is missing. The nasal os is one of a pair of bones that lies under the root and bridge of the nose. The nasal os articulates superiorly with the frontal bone and laterally with the maxillary bones. Septal cartilage is flexible hyaline cartilage connected to the nasal bone, forming the dorsum nasi. The alar cartilage consists of the apex of the nose; it surrounds the naris.

The nares open into the nasal cavity, which is separated into left and correct sections past the nasal septum (Figure 22.4). The nasal septum is formed anteriorly by a portion of the septal cartilage (the flexible portion you can bear on with your fingers) and posteriorly by the perpendicular plate of the ethmoid bone (a cranial bone located just posterior to the nasal basic) and the thin vomer basic (whose proper noun refers to its turn shape). Each lateral wall of the nasal crenel has three bony projections, chosen the superior, middle, and inferior nasal conchae. The inferior conchae are split bones, whereas the superior and middle conchae are portions of the ethmoid bone. Conchae serve to increment the surface surface area of the nasal cavity and to disrupt the flow of air as it enters the nose, causing air to bounciness forth the epithelium, where it is cleaned and warmed. The conchae and meatuses also conserve water and forestall dehydration of the nasal epithelium by trapping water during exhalation. The floor of the nasal crenel is composed of the palate. The hard palate at the inductive region of the nasal cavity is composed of bone. The soft palate at the posterior portion of the nasal crenel consists of muscle tissue. Air exits the nasal cavities via the internal nares and moves into the pharynx.

Figure 22.4 Upper Airway

Several bones that aid form the walls of the nasal cavity have air-containing spaces called the paranasal sinuses, which serve to warm and humidify incoming air. Sinuses are lined with a mucosa. Each paranasal sinus is named for its associated bone: frontal sinus, maxillary sinus, sphenoidal sinus, and ethmoidal sinus. The sinuses produce mucus and lighten the weight of the skull.

The nares and inductive portion of the nasal cavities are lined with mucous membranes, containing sebaceous glands and pilus follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity. An olfactory epithelium used to observe odors is plant deeper in the nasal cavity.

The conchae, meatuses, and paranasal sinuses are lined by respiratory epithelium composed of pseudostratified ciliated columnar epithelium (Figure 22.5). The epithelium contains goblet cells, one of the specialized, columnar epithelial cells that produce mucus to trap debris. The cilia of the respiratory epithelium help remove the mucus and droppings from the nasal cavity with a constant beating motion, sweeping materials towards the throat to exist swallowed. Interestingly, cold air slows the movement of the cilia, resulting in accumulation of fungus that may in plough lead to a runny olfactory organ during cold weather. This moist epithelium functions to warm and humidify incoming air. Capillaries located just beneath the nasal epithelium warm the air by convection. Serous and mucus-producing cells too secrete the lysozyme enzyme and proteins called defensins, which have antibacterial properties. Immune cells that patrol the connective tissue deep to the respiratory epithelium provide additional protection.

Figure 22.5 Pseudostratified Ciliated Columnar Epithelium Respiratory epithelium is pseudostratified ciliated columnar epithelium. Seromucous glands provide lubricating fungus. LM × 680. (Micrograph provided by the Regents of University of Michigan Medical Schoolhouse © 2012)

Throat

The throat is a tube formed by skeletal muscle and lined past mucous membrane that is continuous with that of the nasal cavities (see Figure 22.4). The pharynx is divided into three major regions: the nasopharynx, the oropharynx, and the laryngopharynx (Figure 22.6).

Figure 22.half-dozen Divisions of the Pharynx The throat is divided into three regions: the nasopharynx, the oropharynx, and the laryngopharynx.

The nasopharynx is flanked by the conchae of the nasal cavity, and it serves only as an airway. At the top of the nasopharynx are the pharyngeal tonsils. A pharyngeal tonsil, also called an adenoid, is an amass of lymphoid reticular tissue similar to a lymph node that lies at the superior portion of the nasopharynx. The function of the pharyngeal tonsil is not well understood, but it contains a rich supply of lymphocytes and is covered with ciliated epithelium that traps and destroys invading pathogens that enter during inhalation. The pharyngeal tonsils are large in children, but interestingly, tend to regress with age and may even disappear. The uvula is a small bulbous, teardrop-shaped structure located at the noon of the soft palate. Both the uvula and soft palate move like a pendulum during swallowing, swinging upward to close off the nasopharynx to forestall ingested materials from entering the nasal cavity. In addition, auditory (Eustachian) tubes that connect to each middle ear cavity open into the nasopharynx. This connection is why colds often pb to ear infections.

The oropharynx is a passageway for both air and food. The oropharynx is bordered superiorly by the nasopharynx and anteriorly by the oral cavity. The fauces is the opening at the connection between the oral crenel and the oropharynx. As the nasopharynx becomes the oropharynx, the epithelium changes from pseudostratified ciliated columnar epithelium to stratified squamous epithelium. The oropharynx contains two distinct sets of tonsils, the palatine and lingual tonsils. A palatine tonsil is ane of a pair of structures located laterally in the oropharynx in the area of the fauces. The lingual tonsil is located at the base of the tongue. Like to the pharyngeal tonsil, the palatine and lingual tonsils are composed of lymphoid tissue, and trap and destroy pathogens entering the torso through the oral or nasal cavities.

The laryngopharynx is inferior to the oropharynx and posterior to the larynx. Information technology continues the route for ingested material and air until its inferior end, where the digestive and respiratory systems diverge. The stratified squamous epithelium of the oropharynx is continuous with the laryngopharynx. Anteriorly, the laryngopharynx opens into the larynx, whereas posteriorly, information technology enters the esophagus.

Larynx

The larynx is a cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs (Figure 22.7). The construction of the larynx is formed by several pieces of cartilage. Three large cartilage pieces—the thyroid cartilage (anterior), epiglottis (superior), and cricoid cartilage (inferior)—form the major construction of the larynx. The thyroid cartilage is the largest piece of cartilage that makes upwardly the larynx. The thyroid cartilage consists of the laryngeal prominence, or "Adam's apple," which tends to exist more prominent in males. The thick cricoid cartilage forms a ring, with a wide posterior region and a thinner inductive region. Three smaller, paired cartilages—the arytenoids, corniculates, and cuneiforms—attach to the epiglottis and the vocal cords and muscle that help motion the vocal cords to produce speech.

Effigy 22.7 Larynx The larynx extends from the laryngopharynx and the hyoid os to the trachea.

The epiglottis, attached to the thyroid cartilage, is a very flexible piece of elastic cartilage that covers the opening of the trachea (see Figure 22.iv). When in the "closed" position, the unattached end of the epiglottis rests on the glottis. The glottis is composed of the vestibular folds, the true vocal cords, and the space between these folds (Figure 22.8). A vestibular fold, or faux vocal cord, is one of a pair of folded sections of mucous membrane. A true song cord is one of the white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the truthful vocal cords are free, allowing oscillation to produce sound. The size of the membranous folds of the true vocal cords differs betwixt individuals, producing voices with different pitch ranges. Folds in males tend to exist larger than those in females, which create a deeper vocalism. The act of swallowing causes the pharynx and larynx to lift upwards, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger expanse for nutrient to laissez passer through, while preventing food and beverages from inbound the trachea.

Figure 22.8 Song Cords The true vocal cords and vestibular folds of the larynx are viewed inferiorly from the laryngopharynx.

Continuous with the laryngopharynx, the superior portion of the larynx is lined with stratified squamous epithelium, transitioning into pseudostratified ciliated columnar epithelium that contains goblet cells. Similar to the nasal cavity and nasopharynx, this specialized epithelium produces mucus to trap debris and pathogens as they enter the trachea. The cilia beat the fungus upward towards the laryngopharynx, where it can exist swallowed down the esophagus.

Trachea

The trachea (windpipe) extends from the larynx toward the lungs (Figure 22.9a). The trachea is formed by 16 to 20 stacked, C-shaped pieces of hyaline cartilage that are continued past dense connective tissue. The trachealis musculus and elastic connective tissue together form the fibroelastic membrane, a flexible membrane that closes the posterior surface of the trachea, connecting the C-shaped cartilages. The fibroelastic membrane allows the trachea to stretch and expand slightly during inhalation and exhalation, whereas the rings of cartilage provide structural support and prevent the trachea from collapsing. In add-on, the trachealis muscle tin can be contracted to force air through the trachea during exhalation. The trachea is lined with pseudostratified ciliated columnar epithelium, which is continuous with the larynx. The esophagus borders the trachea posteriorly.

Figure 22.nine Trachea (a) The tracheal tube is formed by stacked, C-shaped pieces of hyaline cartilage. (b) The layer visible in this cross-section of tracheal wall tissue betwixt the hyaline cartilage and the lumen of the trachea is the mucosa, which is composed of pseudostratified ciliated columnar epithelium that contains goblet cells. LM × 1220. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

Bronchial Tree

The trachea branches into the right and left primary bronchi at the carina. These bronchi are also lined by pseudostratified ciliated columnar epithelium containing mucus-producing goblet cells (Figure 22.9b). The carina is a raised structure that contains specialized nervous tissue that induces trigger-happy coughing if a foreign trunk, such as nutrient, is nowadays. Rings of cartilage, like to those of the trachea, back up the structure of the bronchi and forestall their collapse. The primary bronchi enter the lungs at the hilum, a concave region where claret vessels, lymphatic vessels, and nerves also enter the lungs. The bronchi continue to branch into a bronchial tree. A bronchial tree (or respiratory tree) is the collective term used for these multiple-branched bronchi. The primary function of the bronchi, like other conducting zone structures, is to provide a passageway for air to move into and out of each lung. In addition, the mucous membrane traps debris and pathogens.

A bronchiole branches from the tertiary bronchi. Bronchioles, which are about one mm in diameter, farther branch until they become the tiny final bronchioles, which pb to the structures of gas exchange. In that location are more than than grand terminal bronchioles in each lung. The muscular walls of the bronchioles exercise not comprise cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube.

Respiratory Zone

In contrast to the conducting zone, the respiratory zone includes structures that are directly involved in gas exchange. The respiratory zone begins where the concluding bronchioles join a respiratory bronchiole, the smallest blazon of bronchiole (Figure 22.10), which then leads to an alveolar duct, opening into a cluster of alveoli.

Figure 22.10 Respiratory Zone Bronchioles lead to alveolar sacs in the respiratory zone, where gas exchange occurs.

Alveoli

An alveolar duct is a tube composed of smooth muscle and connective tissue, which opens into a cluster of alveoli. An air sac is one of the many small, grape-similar sacs that are attached to the alveolar ducts.

An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. An alveolus is approximately 200 μm in diameter with elastic walls that allow the alveolus to stretch during air intake, which profoundly increases the expanse available for gas exchange. Alveoli are continued to their neighbors by alveolar pores, which aid maintain equal air force per unit area throughout the alveoli and lung (Figure 22.11).

Figure 22.eleven Structures of the Respiratory Zone (a) The alveolus is responsible for gas exchange. (b) A micrograph shows the alveolar structures within lung tissue. LM × 178. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

The alveolar wall consists of 3 major prison cell types: type I alveolar cells, type II alveolar cells, and alveolar macrophages. A type I alveolar cell is a squamous epithelial jail cell of the alveoli, which constitute up to 97 percent of the alveolar surface area. These cells are nigh 25 nm thick and are highly permeable to gases. A type II alveolar jail cell is interspersed among the type I cells and secretes pulmonary surfactant, a substance composed of phospholipids and proteins that reduces the surface tension of the alveoli. Roaming around the alveolar wall is the alveolar macrophage, a phagocytic cell of the immune system that removes debris and pathogens that have reached the alveoli.

The uncomplicated squamous epithelium formed past type I alveolar cells is attached to a thin, elastic basement membrane. This epithelium is extremely thin and borders the endothelial membrane of capillaries. Taken together, the alveoli and capillary membranes form a respiratory membrane that is approximately 0.5 μm (micrometers) thick. The respiratory membrane allows gases to cantankerous by simple diffusion, allowing oxygen to exist picked up by the claret for transport and CO₂ to exist released into the air of the alveoli.

Diseases of the…

Respiratory System: Asthma Asthma is common condition that affects the lungs in both adults and children. Approximately 8.2 percent of adults (18.seven million) and 9.4 percent of children (7 million) in the United states endure from asthma. In add-on, asthma is the most frequent cause of hospitalization in children.

Asthma is a chronic illness characterized by inflammation and edema of the airway, and bronchospasms (that is, constriction of the bronchioles), which tin inhibit air from inbound the lungs. In addition, excessive mucus secretion tin occur, which further contributes to airway occlusion (Figure 22.12). Cells of the immune system, such as eosinophils and mononuclear cells, may also exist involved in infiltrating the walls of the bronchi and bronchioles.

Bronchospasms occur periodically and lead to an "asthma attack." An set on may exist triggered by environmental factors such as dust, pollen, pet hair, or dander, changes in the weather condition, mold, tobacco smoke, and respiratory infections, or by practice and stress.

Figure 22.12 Normal and Bronchial Asthma Tissues (a) Normal lung tissue does non have the characteristics of lung tissue during (b) an asthma attack, which include thickened mucosa, increased mucus-producing goblet cells, and eosinophil infiltrates.

Symptoms of an asthma attack involve coughing, shortness of breath, wheezing, and tightness of the chest. Symptoms of a severe asthma attack that requires immediate medical attention would include difficulty breathing that results in blue (cyanotic) lips or face, confusion, drowsiness, a rapid pulse, sweating, and astringent anxiety. The severity of the condition, frequency of attacks, and identified triggers influence the blazon of medication that an individual may crave. Longer-term treatments are used for those with more severe asthma. Short-term, fast-acting drugs that are used to treat an asthma assault are typically administered via an inhaler. For immature children or individuals who accept difficulty using an inhaler, asthma medications tin be administered via a nebulizer.

In many cases, the underlying cause of the status is unknown. However, recent research has demonstrated that certain viruses, such as human rhinovirus C (HRVC), and the bacteria Mycoplasma pneumoniae and Chlamydia pneumoniae that are contracted in infancy or early on babyhood, may contribute to the development of many cases of asthma.

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Source: https://openstax.org/books/anatomy-and-physiology/pages/22-1-organs-and-structures-of-the-respiratory-system

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