Instructions: After reading the scenarios below, answer the questions at the end
ID: 3480572 • Letter: I
Question
Instructions: After reading the scenarios below, answer the questions at the end of each passage. Bring a hard copy (typed answers) of your responses to lecture (see Lecture Schedule).
All tissues of the body need oxygen, but if the brain is deprived of oxygen for about four minutes, brain cells begin dying which can lead to brain damage and ultimately death. The primary organs responsible for gas exchange are the lungs. In physiology, when we discuss gas exchange at the level of the lungs, we focus on the alveoli. There are several diseases and conditions of the respiratory system, they fall into two categories. The first grouping includes viruses (e.g., influenza), bacterial pneumonia, and enteroviruses. The second group includes chronic diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Lung cancer is often associated with smoking, but the disease can affect non-smokers as well. Common diagnostic tools used to assess respiratory function include chest x-rays, pulmonary function tests, and bronchoscopy.
Exercise 1. Explain the respiratory cycle in detail. Make sure to define key terms (e.g., inspiration, expiration) and that your explanation includes the big picture (i.e., lungs) and the molecular details (i.e., what is happening at the level of the alveoli). Include in your answer, the role of Boyle’s Law.
Exercise 2. Select one disease from each of the two groupings. Explain the disease and how it physiologically affects the respiratory system. What are common medical diagnoses for the diseases and treatments?
Explanation / Answer
Exercise 1
Respiratory cycle:
The process of inspiration and expiration from lung is called respiratory cycle. Inspiration is the process through which the air enters the lungs, during this process the lung expands. Conversely during expiration the lung deflates causing air to be expelled out. Many things happen during the episodes of exhalation and inhalation to aid this process. During expiration diaphragm relaxes and moves upwards creating a higher pressure in the chest cavity than atmosphere. Higher pressure in chest cavity thrusts the air out of the lung and alveoli while you exhale. During inspiration opposite happen, diaphragm contracts causing a drop in pressure inside chest cavity. Because of this low pressure inside lungs or alveoli, the air flow inwards causing them to expand.
The Boyle’s law:
The Boyle’s law explains the connection between the pressure and the volume of exchanged gas in lung. It states that the pressure and volume shares the inverse relationship which means that increase in one element will bring fall of other component. This is best exemplified by breathing process where relaxation of diaphragm cause decrease volume of thoracic cavity and increase pressure during exhalation, while during inspiration increase in volume of thoracic cavity drops the pressure in lung.
Exercise 2
Influenza
Influenza or flu is a respiratory disorder caused by virus infection. The influenza viruses belong to the family Orthomyxoviridae and are mainly from 4 major genera (influenza virus A B, C, and D). Influenza type A viruses has wide range of virulence across species while influenza B and C viruses are found only in humans. Several diagnostic tools are used for virus detection in humans and includes virus isolation, nucleic acid amplification test (NAAT), immuno-chromatography-based rapid diagnostic test (RDT), etc. Influenza can be treated by medications which either kill the virus or improve the symptoms providing time for immune system to recover from virus infection. The antiviral drugs used to treat influenza falls into two major categories, one that inhibits neuraminidase and another class of drugs which inhibit viral M2 protein.
Chronic obstructive pulmonary disease (COPD)
COPD is a disease in which the bronchial tubes which carries the air in and out of lung becomes inflammed and narrowed. They become fragile, clogged with mucus and tend to collapse while breathing. This drastically reduces the airflow through the bronchial tubes and irritates the tube. The irritation leads to coughing which in turn help in removal of mucus from lungs into the throat. COPD can be diagnosed by several means such as lung function test, x-ray, CT-scan etc. Medications like bronchodialators, steroid inhalers, phosphodiesterase 4 inhibitor etc and smoking cessation are commonly available treatments for COPD.