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Chapter Summary:
In this section, we learned all about the respiratory system. The respiratory system includes the nasal and oral cavities, the trachea, lungs and the diaphragm. The respiratory system if responsible for bringing into our bodies the oxygen that we need to support life. The respiratory system also warms and humidifies the air that we bring in. Inside our lungs is where the gas exchange occurs that brings the fresh oxygen into our cells and releases the carbon dioxide waste products that are eliminated through exhalation.

Structure of the Respiratory System:
The respiratory system begins with the nasal and oral cavities. It continues on down to the larynx and the trachea. The trachea separates into the right and left primary bronchus. The bronchi then separate further into bronchioles which end in the alveoli sacs. The bronchioles and alveoli are contained within the lungs. The lungs each have separate lobes. The left lung has 2 lobes and the right lung has 3 lobes. Under the lungs is the diaphragm. The diaphragm is the muscle that is an integral part of the respiration process. The diaphragm separates the thoracic cavity from the abdominal cavity. The respiratory system contains the conducting zone and the respiratory zone. The conducting zone is the parts of the respiratory tract that air travels through before reaching the respiratory zone. The conducting zone consists of the trachea, primary bronchus, bronchial tree and terminal bronchioles. The respiratory zone contains the respiratory bronchioles and the alveolar sacs. The alveolar sacs are where the gas exhange occurs that gives our cells fresh oxygen and removes carbon dioxide waste products.





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The Respiratory System


Pulmonary Disorders:
Our respiratory system is a delicate system that is very susceptible to disease and illness. The respiratory system has direct access to the outside air that contains microorganisms and microscopic particles. Our respiratory system can fall victim to disorders that are considered to be either restrictive or obstructive. Restrictive pulmonary disorders reduce the amount of air that is in the vital capacity of the lungs. Air can be forcibly exhaled with no issues however. In obstructive disorders, the vital capacity of the lungs stays within normal range but air is extremely difficult to force out of the lungs due to an obstruction of air passages. Asthma and chronic obstructive pulmonary disease are examples of obstructive pulmonary disorders. Chronic obstructive pulmonary disease or COPD is a combination of chronic bronchitis, and emphysema. Bronchitis is an inflammation of the bronchioles that is characterized by a chronic cough with mucous production. The mucous that is produced makes exhalation difficult. Emphysema results in fewer alveoli that are larger than normal. The gas exchange that normally takes place in the lungs is reduced because of decreased surface area for gas exchange to occur. Smoking is the single most common cause of COPD and the most preventable risk factor. COPD is treatable but not curable. Below is a picture of the effects that COPD has on a person's respiratory system. Source


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The Effects of COPD


Below is an RSS feed from COPDBlog.com. The articles are all related to COPD and the complications that can arise from the disease.


    Hemoglobin:
    In order for oxygen to be carried from our lungs to our tissues, it must be bound chemically to the hemoglobin that is contained within our red blood cells. The oxygen that is carried by our red blood cells is bound to the iron molecules found within those red blood cells. The bonding of the oxygen and iron created a substance called oxyhemoglobin. The bonding of the iron with the oxygen is a reversible reaction. When the oxygen leaves the red blood cell and moves into the tissues, it leaves the iron behind and the hemoglobin becomes deoxyhemoglobin. When deoxyhemoglobin travels back to the lungs, its loading reaction occurs. The loading reaction is when the oxygen binds with the iron in the red blood cells and becomes oxyhemoglobin. When the oxyhemoglobin releases its oxygen into the systemic capillaries, this reaction is called the unloading reaction. The strength of the loading and unloading reactions are affected by the oxygen concentration of the air being brought into the lungs and the affinity of the hemoglobin for the oxygen. If the air being brought into the lungs has a high oxygen concentration, the loading reaction will be favored. If the air being brought into the lungs has a low oxygen concentration, the unloading reaction will be favored. The affinity of the hemoglobin for oxygen is a measure of the bond strength that the two have, if the bond is strong, it will favor the loading reaction but will lessen the unloading reaction because the bond is harder to break. If the bond is weak, it will favor the unloading reaction and the loading reaction will be lessened because the oxygen has an easy time breaking away from the hemoglobin. The affinity of the hemoglobin for oxygen can be affected by many different things. One thing that greatly affects the affinity of hemoglobin for oxygen is the body's pH level. If the pH goes up, the affinity is increased. If the pH drops, the affinity is decreased. Below is a graph that shows this concept of pH relation to oxygen saturation.

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    Application to Nursing:
    Respiratory physiology has numerous applications to the field of nursing. One thing that comes to mind immediately is with ventilated patients. Working in the critical care unit we often have patients that are intubated and being mechanically ventilated. The doctors will decided how the vents need to be set. The doctors decided how much the tidal volume should be and the rate at which the patient should breathe. The nurse must have an accurate knowledge of how much a tidal volume for a patient should be on average. If a doctor sets a tidal volume for a vented patient that doesn't seem correct, the nurse can step in a question it. For example, if a nurse had a 75 year old female who was 5'0" and 112 pounds who was on the vent and a doctor set a tidal volume of 2000 mL, the nurse needs to be understanding of what a normal tidal volume and lung capacity would be for this size of patient. A nurse that has this knowledge would know that 2000 mL is too high of a tidal volume for this type of patient and would know that 500 mL would be more appropriate. I know this example seems a little extreme, but it is truly amazing how many doctors that come in and write vent orders who are unfamiliar with ventilator settings. The nurses I work with question tidal volumes all the time. Having an understanding of respiratory physiology will also help a nurse be able to explain respiratory issues to patient's family members if they end up being mechanically ventilated. Families are usually scared to see their loved one on a vent and they usually have a lot of questions. To understand the patient's respiratory issues and needs for being vented will help as a nurse to be able to explain the condition to others in terms they can understand.

    Essential Question:


    "How is ventilation accomplished? Incorporate the role of Boyle's Law, as well as the action of muscles, volume change and pressure change in thoracic cavity during inhalation and exhalation."

    Ventilation is a seemingly simple but actually quite complicated process. Ventilation has two parts. Part one is inhalation or breathing in and part two is exhalation or breathing out. Our diaphragm plays an integral role in allowing us to breathe. When the diaphragm contracts, it pulls the thoracic cavity open in longitudinal manner. When the vertical expansion of the thoracic cavity occurs, the intercostal muscles, external and internal, also contract. The contraction of these muscles draws the ribs upward which expands the thoracic cavity in a lateral direction. The expansion of the thoracic cavity increases its volume. Boyle's law states the the "pressure of a given quantity of gas is inversely proportional to its volume." Because of Boyle's law, the pressure in the thoracic cavity decreases when its volume is increased. The decrease in pressure draws external air into the thoracic cavity. The drawing in of this air is known as inhalation. Exhalation works the same way, only in reverse. When the diaphragm and intercostal muscles relax, the volume of the thoracic cavity is decreased. Because the volume is inversely proportional to the pressure inside the thoracic cavity, the pressure is increased and any gas remaining in the thoracic cavity is forced out. The forcing out of the air from the thoracic cavity is known as exhalation. Exhalation is actually a passive process because the diaphragm and intercostal muscles are relaxing and are at rest. 



    The video below is an animation of inspiration and exhalation.





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