Biology 20 – Unit D



Biology 20 – Unit D

Respiration

General Outcome 1: Students will explain how the human digestive and respiratory systems exchange energy and matter with the environment.

Launch Lab – Modeling Your Lungs

Procedure

1. Examine the model of human lungs shown in the diagram. With a partner or in a small group, share your ideas about how this model could work to cause the balloons to inflate.

2. If possible, obtain materials to build this model, or a similar model of human lungs, to test your ideas.

Analysis

1. Describe what happens to the balloons as the volume of air inside the container changes.

2. Would the model work (that is, would the balloons inflate) if the system were not airtight? Justify your answer.

3. Sketch a flowchart to show how air moves in and out of the balloons. Begin with the rubber membrane expanding.

A. Structures and their Functions

a. Nasal Cavity – the air conditioner of the respiratory system.

• Control of temperature – air is warmed or cooled by a rich supply of blood vessels as it passes through this area.

• Humidifier – supplies moisture from the tear glands (lacrimal glands).

• Filter – Hairs in the cavity with the aid of mucous trap large particles of debris.

• Sniffer – contains olfactory cells responsible for the sense of smell.

b. Pharynx

• Passage that extends from the nasal cavity to the larynx and esophagus. This is lined with mucous membrane for further cleansing.

c. Epiglottis

• A flap of cartilage that lies behind the tongue and in front of the larynx and closes of the glottis. The prevents food and drink from entering the trachea and passing into the bronchi. (1)

d. Glottis

• Allows the passage of air to the lower respiratory tract. Opening from the pharynx to the trachea. (2)

e. Larynx - commonly known as the Adam’s apple.

• Structure composed of cartilage, located between the pharynx and the trachea.

• This contains the voice box, and vocal cords. As air passes by the cords it causes them to vibrate, thereby producing sound.

f. Trachea – windpipe

• Dimensions – 2-3cm in diameter, 10-12cm long.

• The inner layer of the trachea is lined with a ciliated mucous membrane.

• The middle layer is strengthened with cartilage.

• The outer layer is made up of 10-20 C-shaped rings of cartilage. The C-rings protect the trachea while allowing food to pass through the esophagus as the open part of the C borders the esophagus inside your neck.

• The inner portion of the trachea also contains ciliated cells that move mucous into the mouth to be coughed out or swallowed. These ciliated cells move back and forth about 12 times a second.

g. Bronchi (singular – Bronchus)

• These are the major tubes that branch from the trachea – one primary bronchus goes to each lung. Each bronchus is further divided into secondary bronchi.

• Air flow is rapid in the bronchi, as the air is at the correct temperature and humidity.

• They contain cartilage to prevent them from collapsing, as these are major air routes.

• Their primary and only function is to conduct the air towards the lungs.

h. Bronchioles

• Similar branches that lead from the bronchi and spread out inside the lungs.

• These are not composed of cartilage – instead they are made of muscle.

• During spasms (sudden rapid muscular contractions), they can block the flow of air. (Asthma attacks)

• The bronchioles are needed to slow down the rate of air movement.

i. Alveolar Sacs – functional unit of the lungs.

• The alveoli look like clusters of grapes. There are about 300-600 million alveoli in the lungs, which increase the surface area of the lungs by 300 times.

• Each alveoli contains cilia that help to keep the inside of the lungs clean by sweeping particles out of the lungs.

• There is a capillary net which consists of about 1600km (the distance traveled between Grande Prairie and Calgary and back again), of capillaries passing over and surrounding the alveolar membrane. This web of blood and lymphatic vessels is necessary for gas and fluid exchange.

• Gases that move from the lungs into the blood must dissolve in water before they are able to diffuse across, therefore, the alveoli must be kept moist in order for the gases to diffuse.

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j. Thoracic Cavity

• This structure is made of bone and muscle. This is responsible for protecting the lungs.

k. Lungs

• The lungs are composed of alveolar sacs. They are a mass of spongy material.

• The collection of microscopic sacs form into lobes of the lung tissue. The right lung has three lobes and is larger than the left lung, as the left side also houses the heart.

• The lungs are protected from dust and microbes by cilia and special white blood cells called monocytes that hide in the lung tissue for years waiting for invaders.

• The lungs by themselves are not muscular, but flabby and unable to inflate or stand up on their own. They have a shiny smooth membrane covering them called the visceral pleura. A second membrane called the parietal pleura covers the chest cavity. There is a fluid between the chest membrane and lung membrane (visceral pleura and parietal pleura) which is responsible for the attachment of the lungs to the inside chest wall.

l. Diaphragm

• The diaphragm is a dome-muscle in the abdominal and thoracic cavity which influences the pressure inside the chest. This muscle plays a pivotal role in breathing.

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B. Mechanics of Breathing

• Breathing is involuntary, however it can be controlled to a certain extent.

• Inhaling and exhaling occur because of the differences between atmospheric pressure and pleural pressure (pressure in the chest).

• Movement is always from an area of high pressure to an area of low pressure. Muscles in the chest (intercostal muscles, diaphragm) contract and relax to cause pressure changes in the chest.

Exhalation/Expiration – air moves OUT!

• For air to go out of the lungs, the pressure must be higher on the inside of the lungs or in the alveoli than on the outside. Air moves from an area of high pressure to low pressure.

• This pressure is created by quickly changing the volume of the thoracic cavity or the chest. If the volume is decreased, the air pressure increases inside the chest and air rushes out.

• It is the same when you get hit hard in the stomach or chest – the internal volume of the chest is quickly reduced, thereby increasing the pressure very quickly and forcing the air out. This is called having the breath knocked out of you!

• However, most of the time this is a passive process as the muscles relax, the rib cage slowly drops.

Muscles of Exhalation:

1. External Intercostal

• Chest muscles relax which causes the rib cage to move down and air to move out of the lungs.

• These muscles are found between the ribs on the outside of the chest cavity.

2. Diaphragm

• A muscle between the abdominal and thoracic cavities. When relaxed, the muscle is in a dome-shaped position and moves upward in the abdominal cavity, causing air to rush out of the lungs due to the increased pressure in the chest.

3. Internal Intercostal

• Can contract to increase pressure on the chest and force exhalation with a little more power. These muscles are therefore used mainly for forced breathing.

• These muscles are found between the ribs on the inside of the chest cavity.

4. Abdominal Muscles

• The abdominal muscles can also contract, pushing against the diaphragm, which will cause the air to move out of the lungs.

• These muscles are also important in forced breathing.

Inhalation/Inspiration – air moves IN!

• Just before inhalation, the air pressure is the same in the alveoli as the atmospheric pressure. In order for air to move into the lungs, the pressure must be lower on the inside than the outside.

• Since we have no control over the atmospheric pressure, we have to manipulate the pressure inside the chest cavity. We actively decrease the pressure inside the chest by increasing the volume inside the chest. If the volume increases, the air pressure inside the chest will decrease.

• This is an active process as it requires the contraction of muscles to increase the area of the thoracic cavity. Your chest muscles pull your rib cage up and out.

Muscles of Inhalation

1. External Intercostal

• These muscles contract which cause the rib cage to move up and out. This causes air to be sucked into the lungs.

2. Diaphragm

• The diaphragm contracts (straightening it out from the relaxed natural dome-shaped position), which increases the area inside the chest cavity, thereby decreasing the pressure. This causes air to rush into the lungs – area of high pressure (atmosphere) to an area of low pressure (thoracic cavity).

[pic]

The Mechanics of Breathing

The diaphragm and the rib muscles (internal and external intercostals) control the air pressure inside the lungs that causes air to move in and out of the lungs.

1. Create a flow chart to illustrate the processes of:

a) Inhalation:

b) Exhalation:

2. Lung collapse:

a) What is the medical term for lungs “collapsing”?

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b) What causes this condition?

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c) Why would physicians insert a tube into the chest to “re-inflate” the lung?

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C. Rate of Breathing

• We calculate the number of breaths per minute the rate of breathing. This rate is controlled by the amount of CO2 in your blood – not O2. If the CO2 is high, your breathing rate will speed up in order to get rid of the CO2. At the same time, much needed O2 is picked up. More on this later!!

• The normal breathing rate is between 12-20 breaths per minute depending on the body size. Women tend to breath more rapidly than men, at about 16-20 breaths per minute. Children breathe twice as fast as adults because the lungs of children have less surface area for gases to exchange, and babies breath 40-60 times per minute.

D. Breathing Volumes

The volume of air that moves in and out of your lungs is measured with a spirometer.

• Total Lung Capacity (TLC)– the total volume of air that normal lungs can hold. This depends on body size, sex and fitness level. ~5800mL

• Tidal Volume (TV) – the volume of air that moves through your lungs while at rest. ~500mL

• Inspiratory Reserve Volume (IRV) – maximum amount of air that can be inhaled. ~3000mL

• Inspiratory Capacity – the maximum amount of air taken in, including the volume of a normal breath.

• Expiratory Reserve Volume (ERV) – the amount of forced air exhaled after exhaling a normal breath – forced. ~1100mL

• Vital Lung Capacity (VC) – the volume of air that can move into and out of the lungs with maximum effort in a single breath. ~4600mL

• Residual Air Volume (RV) – the air in the lungs that is needed for the lungs to remain inflated and attached against the chest wall. ~1200mL

Interpreting a Spirograph

A spirograph represents the amount of air that moves into and out of the lungs with each breath.

1. Define each of the following terms:

|Term |Definition |

|tidal volume | |

|inspiratory reserve volume | |

|expiratory reserve volume | |

|vital capacity | |

|residual volume | |

Study the spirograph below and answer the following questions:

[pic]

2. What is the typical tidal volume for humans? (in mL) _______________

3. What is the typical expiratory reserve volume for humans? (in mL) _______________

4. What is the typical vital capacity for humans? (in mL) _______________

Measuring Respiratory Volumes

Prediction

Predict what percentage of your vital capacity is represented by your tidal volume.

Safety Precautions

Do not inhale or exhale to the point of faintness.

Materials

• materials for recording data

• spirometer with disposable mouthpieces

• nose plug (optional)

Procedure

1. Set the spirometer gauge to zero, and insert a clean mouthpiece. If you are using a nose plug, put it on.

2. Begin by taking a few relaxed breaths. Then inhale normally, put the mouthpiece into your mouth, and exhale normally into the spirometer. Record the value in the following table as your tidal volume.

Measured and Calculated Respiratory Volumes

|tidal volume | |

|expiratory reserve volume | |

|inspiratory capacity | |

|inspiratory reserve volume | |

|calculated vital capacity | |

|recorded vital capacity | |

3. Reset the spirometer. Inhale and exhale normally. At the end of the normal exhalation, put the spirometer mouthpiece into your mouth and exhale as much as you can. Make sure you do this all in one breath. Record the value as your expiratory reserve volume.

4. Reset the spirometer. Inhale as deeply as you can, and then exhale normally into the spirometer. Do not force the exhalation. Record the value as your inspiratory capacity.

5. Calculate your inspiratory reserve volume by subtracting your tidal volume from your inspiratory capacity. Record your inspiratory reserve volume.

6. Calculate your vital capacity by adding your inspiratory reserve volume, expiratory reserve volume, and tidal volume. Record the value as your calculated vital capacity.

7. Reset the spirometer. Inhale as deeply as you can, and then exhale deeply into the spirometer, forcing out as much air as you can. Do this all in one breath. Record the value as your recorded vital capacity.

Analysis

1. Compare your calculated vital capacity with your recorded vital capacity. Explain any difference.

2. Compare your inspiratory reserve volume with your expiratory reserve volume. Explain any difference.

Conclusions

3. Can you use the spirometer to measure your total lung capacity? Explain

4. How might an athlete use information about his or her vital capacity? Predict how respiratory volumes relate to athletic performance.

Extension

5. Compare your respiratory volumes with those of other students by creating a class data table. How much variation do you see? Are there patterns in this variation, such as differences between males and females, or differences based on height? What factors could contribute to differences in respiratory volumes? Design an experiment to test the effects of two of these factors.

E. Regulation of Breathing

Breathing is regulated or controlled by the medulla oblongata. There are several factors that influence breathing rate:

1. Chemicals in the Blood

• Chemoreceptors monitor the level of CO2 and O2 in the blood.

• The pH of arterial blood tends to be between 7.35 and 7.45, which is a very narrow range. A condition called respiratory acidosis occurs when the blood pH drops, and respiratory alkanosis when the blood pH rises.

a) CO2 Receptors:

• CO2 dissolves in the blood to form an acid. The level of acid is monitored by receptors in the medulla oblongata. These are the most sensitive receptors and are the main regulators of breathing rate.

• If CO2 levels increase, the medulla oblongata sends a signal to the muscles of the diaphragm and ribs to increase the breathing rate. Once CO2 levels return to normal, the chemoreceptors become inactive and breathing rates return to normal.

b) O2 Receptors

• O2 receptors are located in the carotid artery and aorta. They are responsible for detecting levels of O2. This is only a backup and these receptors are only stimulated when O2 levels drop and CO2 levels remain constant. This situation will only happen in extreme situations such as carbon monoxide poisoning and high altitudes.

• Receptors send a signal to the medulla oblongata which stimulates the muscles in the chest and cause an increase in breathing rate.

2. Stretching of Lung Tissue

• There are stretch receptors located in the pleura, bronchioles and alveoli which are stimulated when pressure builds up inside the lungs causing the tissue to stretch.

• Nerve impulses are sent to the medulla oblongata which in turn sends a message to decrease breathing rates.

3. Emotional State

• Fear and pain cause an increase in breathing rate due to the increased need for O2.

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F. Gas Exchange

Label all the major parts on the diagram below. Provide colored arrows to show the direction of gas flow.

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Dalton’s Law of Partial Pressure

• Each gas in a mixture exerts its own pressure independently of all other gases in the mixer.

• Molecules always move from areas of high pressure and concentration to areas of low pressure and concentration.

Path of Oxygen

• Diffuses into the blood.

• Combines with hemoglobin to form oxyhemoglobin.

• Diffuses into the tissues.

• Dissolves in plasma.

Path of Carbon Dioxide

• Diffuses out of the blood.

• Combines with hemoglobin to form carbaminohemoglobin.

• Diffuses out of the tissues.

• Dissolves in the plasma (20% more soluble than oxygen)

• Forms carbonic acid when combined with water in the plasma.

Partial Pressure of Oxygen

• High outside of the body (in atmosphere).

• Medium in the alveoli.

• Low in the blood.

• Very low in the tissues.

• Therefore, oxygen diffuses IN!

Partial Pressure of Carbon Dioxide

• Very high in the tissues.

• High in the blood.

• Medium in the alveoli.

• Low outside of the body (in atmosphere).

• Therefore, carbon dioxide diffuses OUT!

How does this actually happen?

Composition of Atmospheric Air

Gas exchange occurs because gases exert partial pressures.

a. The air we breathe in has an overall partial pressure of 760mmHg.

b. The air is made up of several gases such as nitrogen, oxygen, carbon dioxide and others.

c. Each of these gases has a different concentration in the air. Together they account for only a part of the total pressure exerted by a single gas out of a mixture of gases.

d. A gas with a higher concentration exerts a higher partial pressure; for example oxygen makes up about 21% of the air and therefore has a partial pressure of about 158mmHg out of the total 760mmHg.

Composition of Inhaled Air

Inhaled air enters the respiratory tract with a partial pressure that is the same as the atmosphere. Freshly inhaled air has the following characteristics:

1. Atmospheric pressure = 760mmHg.

2. Oxygen makes up ~21% of the air, which is 160/760mmHg.

3. Carbon dioxide makes up 0.04% of the air, which is 0.3/760mmHg.

4. Nitrogen makes up about 78% of the air, which is 593/760mmHg.

5. The remaining portion of the air is made up of a variety of other gases.

Composition of Alveolar Air

Changes occur in these gas concentrations as you breathe, therefore there is a change in the partial pressure of the various gases as well.

1. Inhaled air mixes with the air that remains in the alveoli, called residual air volume.

2. The gas in the alveoli is always losing oxygen to the capillaries and picking up carbon dioxide. Therefore, the concentration of oxygen is lower than the concentration of carbon dioxide. Partial oxygen pressure will decrease, where as partial carbon dioxide levels will increase as compared to the inhaled air.

3. This mixture of inhaled air and residual air is called the alveolar gas, and has the following characteristics:

a) Oxygen makes up 14.5% of this air, which is about 110/760mmHg.

b) Carbon dioxide makes up 5.5% of this air, which is about 40/760mmHg.

c) Nitrogen makes up about 80% of this air, which is about 608/760mmHg.

Composition of Exhaled Air

Exhaled air is a mixture of alveolar gas and atmospheric air that remains in the trachea. This air will be higher in oxygen and lower in carbon dioxide than the alveolar air. The mixed air will however, be lower in oxygen and higher in carbon dioxide when it is compared to the atmospheric air. Exhaled air has the following characteristics:

a) Oxygen makes up about 16% of this air, which is about 122/760mmHg.

b) Carbon dioxide makes up about 5% of this air, which is about 38/760mmHg.

c) Nitrogen makes up about 80% of this air, which is about 608/760mmHg.

Partial Pressure in the Blood

There is a partial pressure of gases in the blood as well. Blood from the body entering the capillaries of the lungs has a pressure as follows:

1. Pressure of oxygen = 40mmHg.

2. Pressure of carbon dioxide = 45mmHg.

Blood leaving the lungs, after passing by the alveoli, will have an increased concentration of oxygen and decreased concentration of carbon dioxide. Therefore, the partial pressure of oxygen is about 95mmHg and carbon dioxide is about 45mmHg.

Partial Pressure in the Tissues

There is also partial pressure of gases in the cellular tissue of the body that will vary depending on exercise and the type of tissue. The pressures are as follows:

1. Pressure of oxygen = 25mmHg.

2. Pressure of carbon dioxide = 46mmHg.

Describe the response of each of the labeled structures to exercise.

[pic]

Respiratory System Disorders

Use pages 303-304 to fill in the following chart.

|Disorder |Cause |Effect on Respiratory Tract |Effect on breathing rate, |

| | | |inhalation, exhalation |

|Bronchitis | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

|Bronchial Asthma | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

|Emphysema | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

|Lung Cancer | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

[pic]

Other Disorders

1. The Bends

The blood and tissues of divers absorb extra amounts of gases because of the increased pressures under water. This is not a problem unless the individual comes to the surface too quickly. The gases will bubble in the tissue much like a can of pop will bubble when it is opened. This will cause dizziness, nausea, muscle and joint pains and in extreme cases, death.

2. Smoker’s Cough

Smoking causes the consistency of the mucous, which protects the respiratory system to change so that it is less effective. The monocytes, which protect you from infection and tumors are destroyed. The cilia, which are used to move the mucous away from the lungs and to filter the air are paralyzed. Eventually, the ciliated cells die out. As a result, the lungs fill up with mucous secretions and the smoker must cough to get the mucous out of the lungs. Statistics show that a smoker who smokes a pack a day will take seven years off his or her life. Lung cancer is also directly related to smoking.

3. Tuberculosis

Tuberculosis is a communicable disease of humans and animals caused by bacteria. It can manifest itself in the lungs, bones, urinary tract, brain and other parts of the body, however 90% of TB is pulmonary. It can cause mental illness and has a high infant mortality rate. Symptoms include fatigue, abnormal sound in the lungs, afternoon fevers and coughed up blood. It can be treated by collapsing the lung in order to rest it, or surgically removing the infected areas.

4. Pneumonia

Pneumonia is an acute or chronic disease, which causes inflammation of the lungs. Viruses, mold, bacteria or chemicals can cause it. This disease sometimes results in death, especially among elderly patients. Chest pains and fever are symptoms.

Match the respiratory disorder with the correct description. Terms may be used more than once.

Answer Choices

|A. Tonsillitis |D. Lung Cancer |G. Emphysema |

|B. Pneumonia |E. Laryngitis |H. Asthma |

|C. Bronchitis |F. Pleurisy |I. Cystic Fibrosis |

1. These are classified as upper respiratory tract infections. _____ , _____

2. Patients with this disorder usually have symptoms of sore throat and hoarseness. _____

3. To prevent this infection, children often have had surgery to remove the possibly offending structure—it is no longer a common procedure. _____

4. Treatments for this disorder include inhalers to spray healthy versions of the abnormal gene into the lungs. _____

5. Young patients with this disorder often have to use a nebulizer to administer their medicine as they are unable to use an inhaler properly. _____

6. This is a genetic condition that causes the lungs to become coated with very thick and sticky mucous. _____

7. What three disorders are caused primarily by cigarette smoking? _____, _____ and _____

8 This disorder is characterized by the uncontrollable and invasive growth of abnormal cells in the lungs. _____

9. This disorder is characterized by the swelling and irritation of the membranes that surround the lungs. _____

10. Almost all cases of this disorder are caused by smoking and those who develop it often need to use low-flow oxygen tanks. _____

11. People with AIDS suffer from a rare bacterial form of this disorder. _____

12. This disorder is an obstructive disorder that causes the walls of the alveoli to break down and lose their elasticity. _____

13. This is a disease that has two main types: lobular and bronchial, and it is typically caused by bacteria and viruses. _____

14. This disorder has carcinomas form caused by various carcinogens. _____

15. Patients with this disorder have constant inflammation in their airways and are extremely sensitive to triggers such as smoke and dust. _____

Thought Lab – Smoking and the Respiratory System

Procedure

Working alone or in small groups, plan a public-awareness product such as a poster, pamphlet, or multimedia presentation. Decide what audience your public-awareness product will address. Use your knowledge of the path of inhaled smoke through the respiratory system in your project. Make sure your research answers the following questions.

• By law, which chemicals in tobacco smoke must be listed on tobacco products? In what concentrations are they present, and what are their effects? (For example, ammonia is a chemical found in cigarette smoke in concentrations ranging from 50 to 130 μg/cigarette. Ammonia is a fatal poison in large-enough amounts in the body.)

• What other chemicals are found in tobacco smoke? List at least five, and give their concentrations and effects.

• How can tobacco chemicals appear in other body organs such as the bladder, heart, and reproductive organs?

• What are examples of long-term and short-term effects of smoking?

• In what ways is tobacco smoke particularly harmful for women who are pregnant?

• What technologies are available to assist people who choose to quit smoking?

Analysis

1. List three harmful effects of smoking on the respiratory system and three harmful effects on other body systems.

Spirograph and Respiratory Disorders

Use the following chart to answer the questions below.

|Patient |Tidal Volume (mL) |Vital capacity (mL) |Respiratory rate of patients at |

| | | |rest (breaths/min) |

|1 (normal) |500 |5 000 |18 |

|2 |500 |4 000 |20 |

|3 |400 |3 000 |38 |

|4 |550 |5 000 |17 |

|5 |550 |6 000 |17 |

1. Distinguish between tidal volume and vital capacity.

_____________________________________________________________________

____________________________________________________________________

____________________________________________________________________

_____________________________________________________________________

2. Which patient is likely a long distance runner? How do you know?

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

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3. Which patient is likely suffering from emphysema? How do you know?

_____________________________________________________________________

_____________________________________________________________________

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Thought Lab – You Diagnose It!

Your team has collected the following information about two people who recently visited your clinic complaining of having trouble breathing:

Person A: Male, age 15, is a non-smoker. He is complaining of wheezing and trouble breathing. He started having episodes in which he had difficulty breathing last summer, but the problem seemed to go away in the winter.

Person B: Female, age 35, smokes 10 to 15 cigarettes per day. She has started having trouble exhaling and gets tired very easily. She is also coughing a lot and bringing up mucus when she coughs.

Procedure

1. Review the symptoms for these two people.

2. Working together, make a list all of the possible respiratory disorders that could be causing their symptoms.

Analysis

1. Create a table that lists the symptoms of the most common respiratory disorders. Is it clear, from your table, which respiratory disorders the people are suffering from? Is there more that one possible disorder, given the symptoms? Explain your answer.

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