Exam 4 A&PIf you have other stuff to study for, just focus on the stuff in bold to get a passing grade, if you want to get a B or higher than I suggest reading this whole guide, things in bold come from class notes and slidesPart 1- The Respiratory SystemThe BasicsRespiration has three meanings:1. Ventilation of the lungs (breathing)2. The exchange of gases between air and blood and between blood and tissue fluid3. The use of oxygen in cellular metabolism (honestly not that important in this chapter)Basically, our respiratory system is an organ system that rhythmically takes in air and expels it from the body. By doing this, it supplies the body with oxygen and expels carbon dioxide.However, there is a broader range of functions commonly supposed1. Without the respiratory system we couldn’t talk, laugh, cry etc.2. It allows us to smell (helps us avoid danger and select food)3. By eliminating CO2 we can control our body’s pH. When CO2 reacts with our water (which is what our body is pretty much made of) it releases H+ ions which ultimately lowers the pH of the body…makes it acidic.4. Without the lungs, we could not synthesize angiotensin.5. The pressure gradients created by breathing promote the flow of lymph and venous blood between the thorax and the abdomen.6. Holding our breath helps us expel abdominal contents (urine, feces, and babies) via the Valsalva maneuver.The principal organs of the respiratory system are the nose, pharynx, larynx, trachea, bronchi, and lungs (duh).• The respiratory system is generally divided between 2 divisions and 2 tracts.• The conducting division consists of the passages that serve only for airflow. Essentially everything between the nostrils to the bronchioles.• The respiratory division consists of the alveoli and other gas exchange regions.• The upper respiratory tract (URT) is the airway from the nose to the larynx.• The lower respiratory tract (LRT) includes the regions from the trachea through the lungs.The NoseFunction and anatomy• (Ultimately, he will probably not be testing on much anatomy. However, understanding the anatomy of the lungs can help you understand the physiology a little better.)• Our nose warms, cleanses, and humidifies inhaled air like an air conditioner. It also detects odors and resonates our voice, ultimately amplifying it.• The nose extends from our anterior nares (nostrils) to a pair of posterior openings called the choanae (basically internal nostrils).• The nasal cavity is divided into right and left halves called nasal septum.• The beginning of the nasal cavity is called the vestibule and is lined with stiff guard hairs called vibrissae. They keep bugs and other crap from getting into your nose.The Pharynx• The pharynx is a muscular tunnel extending about 5 inches from the choanae to the larynx. The pharynx is divided into three regions.• The nasopharynx is the most superior portion of the pharynx.• The oropharynx is the space between the soft palate and the root of the tongue and extends inferiorly as far as the hyoid bone.• The laryngopharynx begins with the union of the nasopharynx and oropharynx at the level of the hyoid bone.The Larynx• The larynx (“voicebox”) is a cartilaginous chamber that primarily keeps food and drink out of the airway. The larynx also evolved the additional role of phonation in many animals.• The superior opening of the larynx is guarded by the epiglottis. When we swallow, laryngeal muscles pull the larynx upwards while the tongue pushes the epiglottis downwards. The two meet and form a barrier to keep us from choking on things.• The Trachea• The trachea (“windpipe”) is a rigid tube that lies anterior to the esophagus. It is supported by 16 to 20 hyaline cartilage rings. You can palpate some of these by rubbing just superior to your manubrium.Air flow through the trachea is controlled by a smooth muscle called the trachealis.• At its inferior end, the trachea forks into the right and left primary bronchi.• The inner lining of the trachea is covered in special cells called goblet cells. These cells produce a sticky mucus that traps foreign particles that might have made their way into the airway. Ciliated cells “push” this mucus up the trachea and to the pharynx where the foreign material is swallowed. This whole process is known as the mucociliary escalator. This is basically how phlegm is made. Gross.The Lungs By now you probably know what a lung looks like. • The inferior portion is called the base while the superior portion is called the apex. • The broad anterior wall of each lung is called the costal surface and the smaller medial wall is called the mediastinal surface. • The bronchus, blood vessels, lymphatic vessels, and nerves enter the interior of the lungs through a slit called the hilum. This entire region is collectively called the root of the lung.• The right lung is shorter than the left lung because liver is more prominent on the right side.• There is an indentation on the mediastinum of the left lung called the cardiac impression.• The right lung has three lobes and the left lobe only has two.The Bronchial Tree• The bronchial tree is the highly branched system of air tubes extending from the primary bronchus and terminating to roughly 65,000 terminal bronchioles.• Air reaching the bronchi is warm, cleansed of impurities, and saturated with water.• Like the trachea, the bronchi are supported by C shaped hyaline cartilage rings.• Upon entering the hilum, each primary bronchus branches into one secondary bronchus.• From each secondary bronchus divides a tertiary bronchi.• Bronchioles are continuations of the airway that lack supportive cartilage and are 1 mm or less in diameter.• The portion of the lung ventilated by a bronchiole is called the pulmonary lobule.• Bronchioles have ciliated cuboidal epithelium and a well-developed layer of smooth muscle in their walls. The bronchioles are NOT supported by cartilage and do not produce mucus. • From this point, each bronchiole stems into 50 to 80 terminal bronchioles.• Ultimately, these air passages undergo 23 orders of branching in the lungs.• (Check out the flow chart on slide 3 to see the branching order from largest to smallest.)• The presence of alveoli begins as terminal bronchioles feed into respiratory bronchioles.• Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs composed of
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