Introduction

The respiratory system consists of the upper respiratory tract (the nasal cavity, pharynx, larynx, trachea, and bronchi) and the lower respiratory tract (the lungs). As you learn about the various diseases that affect the respiratory system, it is important for you to understand the structures that can be affected by disease. Complete this lab to become familiar with a healthy system and to identify diseases related to both the upper and lower respiratory tracts.

PART ONE: basic functions

Provide brief answers to the following questions to help you get acquainted with the basic functions of a healthy respiratory system. Refer to Ch. 21 in Microbiology: Principles and Explorations.

1. How do body reflexes like coughing and sneezing help prevent or fight infection? The upper respiratory tract contains a variety of normal microflora that help prevent infection by pathogens that may be inhaled. Mucus from the membranes that line the nasal cavity and pharynx traps microorganisms and most particles of debris, preventing them from passing beyond the pharynx. Mucus also contains lysozyme.

Coughing and sneezing mechanically agitate mucus, increasing exposure of microorganisms to mucus and helping to expel them. Coughing or sneezing is an automatic reflex that can rid the body of irritants. The body is expelling bacteria and other particles with a sudden, involuntary burst of air. Coughing is the body’s way to keep the throat and airways clear. Secretions and foreign substances are expelled by rush of air and can be projected a great distance.

2. What role do cilia play in maintaining a healthy respiratory system? They move the mucus moisture layer upward and out of the lungs, along with any dust it may have accumulated. It also prevents your lungs from getting clogged up with dust. The cilia and hairs which line the nasal cavities traps another foreign particles and the rich supply of blood surrounding the cavities warms the air before it enters the lungs.

3. Compare normal microflora of the upper respiratory tract with normal microflora of the lower respiratory tract.

Normal microflora of the upper respiratory tract:

The nares (nostrils) are always heavily colonized, predominantly with Staphylococcus epidermidis and corynebacteria with Staphylococcus aureus, this being the main carrier site of this important pathogen. The healthy sinuses, in contrast are sterile.

The pharynx (throat) is normally colonized by streptococci and various Gram-negative cocci. Sometimes pathogens such as Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Neisseria meningitidis colonize the pharynx.

Normal microflora of the lower respiratory tract

Free of microorganisms, mainly because of the efficient cleansing action of the ciliated epithelium which lines the tract. Any bacteria reaching the lower respiratory tract are swept upward by the action of the mucociliary blanket that lines the bronchi, to be removed subsequently by coughing, sneezing, swallowing, etc.

PART two: basic structures

Visit Chapter 21 of Microbiology: Principles and Explorations in WileyPlus to view an in-depth presentation of a healthy respiratory system by completing the following steps:

Select the Chapter 21 WileyPlus reading link located on your student Web page.
Locate the heading Chapter Review.
Select the Anatomy Overview: The Respiratory System link.
Complete this lab as you explore the Respiratory System multimedia piece.

Overview

Roll over each component of the Conducting and Respiratory portions of the
Respiratory System multimedia piece. Take note of how the preserved trachea and lung photograph on the left compares to the illustrated diagram on the right.

Upper Respiratory System (Conducting Portion: Nasal Cavity)

Roll over and click either the nasal cavity or pharynx components of the Conducting portion of the Respiratory System multimedia piece to navigate to the Nasal Cavity. Refer to Nasal Cavity component of the multimedia piece and Ch. 21, Figure 21.8 in Microbiology: Principles and Explorations to label the structures in the following diagram of a healthy upper respiratory system.

Lower Respiratory System (Respiratory Portion: Lungs)

Click the icon in the upper left corner of the Nasal Cavity diagram to return to the main menu in the Respiratory System multimedia piece. Click the lungs component of the Respiratory Portion to navigate to the Lung diagram. Refer to Lung diagram of the multimedia piece and Ch. 21, Figure 21.1 in Microbiology: Principles and Explorations to label the structures in the following diagrams of a healthy lower respiratory system. Please note: The first diagram that follows is found only in Ch. 21, Figure 21.1, and not in the Lung component of the multimedia piece.

PART three: investigate and apply

Visit the Centers for Disease Control and Prevention. Access the Public Diseases & Conditions A-Z Index at http://www.cdc.gov/DiseasesConditions/ Scroll down to the section titled Top Requested Diseases & Conditions. Review the list of diseases about that the general public is most frequently requesting information about. You will notice some familiar diseases from your assigned readings. Click on at least one microbe-related respiratory system disease and complete the following activity.

Read the information on the CDC site and provide a brief, 1-2 paragraph summary of the respiratory illness. Include in your description:

The respiratory illness
The microbe causing the illness
Which structures of the respiratory system are affected—Use one or more structures included in Part Two. Asthma is caused by irritation to the bronchial airways. This irritation causes inflammation and results in chest tightening and restriction

Who is at risk
How serious the disease is

Asthma is a disease that affects our lungs. It is a chronic, or long-term, disease that inflames and narrows the airways of the lungs. It causes repeated episodes of wheezing, breathlessness, chest tightness, and night time or early morning coughing. The microbe that causes the illness is chronic Mycoplasma pneumonia and Chlamydia pneumonia infections, and are associated with the onset and exacerbation of asthma. An asthma attack affects the respiratory system and causes airway inflammation, bronchial restriction and irregular airway obstruction. Airway inflammation is the body’s response to an irritant and is characterized by swelling, breathing passageway restriction and mucus secretion.

Bronchial restriction occurs when the muscles in your airways constrict and tighten around your primary bronchial tubes (the breathing tubes in your lungs). Mucus or fluid that is secreted by the reaction can obstruct your trachea and make it increasingly difficult to breathe effectively. Asthma affects people of all ages, but it most often starts during childhood. Young children who often wheeze and have respiratory infections and are at highest risk of developing asthma that continues beyond 6 years of age. Among children, more boys have asthma than girls.

But among adults, more women have the disease than men. Most, but not all, people who have asthma have allergies. Asthma can be a serious disease if not recognized and treated properly. It causes narrowing of the airways which leads to shortness of breath and wheezing. Uncontrolled Asthma can cause death. We should always take asthma seriously. It’s a chronic (long-lasting) condition that has no cure. Its symptoms can come on suddenly and get worse quickly.