6: The Respiratory System

The lungs do not fill passively. a. What do they require to expand? (Hint: what type of muscle) b. The diaphragm is the most important of these muscles, a thin, muscular structure that divides the thoracic cavity from the abdominal cavity. The diaphragm is under (somatic/autonomic?) control, even though breathing itself is under (somatic/autonomic?) control

- require skeletal muscle to generate the negative pressure for expansion - somatic; autonomic

If H+ is an acid and HCO⁻3 is a base, then why doesn't increasing both of them maintain a constant pH?

because H+ is a strong acid, while HCO3- is a weak base

Why is no energy required for gas transfer in the lungs

because the gradient between the blood and air in the lungs is already present as the blood enters the lungs

DPQ #13 Premature infants with respiratory distress are often placed on ventilators. Often, the ventilators are set to provide positive end-expiratory pressure. Why might this setting be useful for a premature infant? 1. Premature infants lack surfactant. 2. Premature infants lack lysozyme. 3. Premature infants cannot thermoregulate. 4. Premature infants are unable to control pH.

A

DPQ #14 In emphysema, the alveolar walls are destroyed, decreasing the recoil of the lung tissue. Which of the following changes may be seen in a patient with emphysema? 1. Increased residual volume 2. Decreased total lung capacity 3. Increased blood concentration of oxygen 4. Decreased blood concentration of carbon dioxide

A

DPQ #9 Studies have indicated that premature babies are often deficient in lysozyme. What is a possible consequence of this deficiency? 1. Respiratory distress and alveolar collapse shortly after birth 2. Increased susceptibility to certain infections 3. Inability to humidify air as it passes through the nasal cavity 4. Slowing of the respiratory rate in response to acidemia

B

DPQ #12 A patient presents to the emergency room with an asthma attack. The patient has been hyperventilating for the past hour and has a blood pH of 7.52. The patient is given treatment and does not appear to respond, but a subsequent blood pH reading is 7.41. Why might this normal blood pH NOT be a reassuring sign? 1. The patient's kidneys may have compensated for the alkalemia. 2. The normal blood pH reading is likely inaccurate. 3. The patient may be descending into respiratory failure. 4. The patient's blood should ideally become acidemic for some time to compensate for the alkalemia.

C

DPQ #15 Allergic reactions occur due to an overactive immune response to a substance. Which cells within the respiratory tract play the largest role in the generation of allergic reactions? 1. Alveolar epithelial cells 2. Macrophages 3. Mast cells 4. Ciliated epithelial cells

C

DPQ #3 Total lung capacity is equal to the vital capacity plus the: 1. tidal volume. 2. expiratory reserve volume. 3. residual volume. 4. inspiratory reserve volume.

C

DPQ #1 All of the following facilitate gas exchange in the lungs EXCEPT: 1. thin alveolar walls. 2. multiple subdivisions of the respiratory tree. 3. differences in the partial pressures of O2and CO2 . 4. active transporters in alveolar cells.

D

DPQ #10 Some forms of pneumonia cause an excess of fluids such as mucus or pus to build up within an entire lobe of the lung. How will this affect the diffusion of gases within the affected area? 1. Carbon dioxide can diffuse out, but oxygen will not be able to enter the blood. 2. Oxygen can diffuse into the blood, but carbon dioxide cannot diffuse out. 3. No change in diffusion will occur. 4. No diffusion will occur in the affected area.

D

DPQ #7 Which of the following is a correct sequence of passageways through which air travels during inhalation? 1. Pharynx → trachea → bronchioles → bronchi → alveoli 2. Pharynx → trachea → larynx → bronchi → alveoli 3. Larynx → pharynx → trachea → bronchi → alveoli 4. Pharynx → larynx → trachea → bronchi → alveoli

D

Respiratory failure refers to inadequate ventilation to provide oxygen to the tissues. How would the pH change in respiratory failure?

In respiratory failure, ventilation slows, and less carbon dioxide is blown off. As this occurs, the buffer equation shifts to the right, and more hydrogen ions are generated. This results in a lower pH of the blood.

List the structures in the respiratory pathway, from where air enters the nares to the alveoli.

Nares → nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

What is the purpose of surfactant?

Surfactant reduces surface tension at the air-liquid interface in the alveoli. This prevents their collapse.

What is the mathematical relationship between vital capacity (VC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and tidal volume (TV)?

Vital capacity is the sum of the inspiratory reserve volume, expiratory reserve volume, and tidal volume: VC = IRV + ERV + TV

If blood levels of CO2 become too low, how does the brain alter the respiratory rate to maintain homeostasis?

When CO2 levels become too low, the brain can decrease the respiratory rate in order to raise CO2 levels.

The capillaries bring deoxygenated blood from the pulmonary _____, which originate from the right vesicle of the heart. The oxygenated blood returns to the left atrium of the heart via the pulmonary ____.

arteries; veins

What does Boyle's law state

at a constant temperature, the pressure and volume of gases are inversely related

During active tasks, we can speed exhalation by using the ___ intercostal muscles and abdominal muscles, which oppose the external intercostals and pull the rib cage down

internal

Ventilation is primarily regulated by a collection of neurons in the ____ ____ called the ventilation center. These neurons contain ______ that are primarily sensitive to carbon dioxide concentration.

medulla oblongata; chemoreceptors

During inhalation, the lungs will expand into the intrapleural space, and the pressure in the lungs will drop. Air will then be sucked in from a higher-pressure environment--the outside world. This mechanism is called? Why?

negative-pressure breathing; the driving force is the lower (relatively negative) pressure in the intrapleural space compared with the lungs

The left lung has a small indentation, making it slightly smaller than the right lung. It also contains only two lobes, while the right lung contains three. Why?

position of the heart in the thoracic cavity

Emphysema is a disease characterized by the destruction of the alveolar walls. This results in what?

reduced elastic recoil of the lungs, making the process of exhalation extremely difficult

How does the bicarbonate buffer system control pH when blood pH decreases

respiration rate increases to compensate by blowing off carbon dioxide; this causes a left shift in the buffer equation, reducing hydrogen ion concentration

What is surface tension

tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of liquid

Which muscle(s) are involved in inhalation? Exhalation?

- Inhalation uses the diaphragm and external intercostal muscles; in labored breathing, muscles of the neck and back may also be involved. - Passive exhalation uses the recoil of these same muscles; active exhalation also uses the internal intercostal muscles and abdominal muscles.

What does the mucociliary escalator do?

- the internal airways are lined with mucus, which traps particulate matter and larger invaders - underlying cilia then propel the mucus up the respiratory tract to the oral cavity, where it can be expelled or swallowed

The large surface area of interaction between the alveoli and capillaries allows the respiratory system to assist in thermoregulation through vasodilation and vasoconstriction of capillary beds. When does vasodilation/vasoconstriction happen?

- vasodilation - warm temp: more blood can pass through vessels, and a large amount of thermal energy can be dissipated - vasoconstriction - cold temp: less blood can pass, conserving thermal energy

What are some of the mechanisms used in the respiratory system to prevent infection?

- vibrissae in the nares - lysozyme in the mucous membranes - the mucociliary escalator - macrophages in the lungs - mucosal IgA antibodies - mast cells

What are the following structures: - visceral pleura - parietal pleura - intrapleural space

- visceral pleura - lies adjacent to the lung itself - parietal pleura - lines the chest wall - intrapleural space - between visceral and parietal pleura, contains thin layer of liquid, which lubricates the two pleural surfaces

Match the following terms to their definitions: 1. total lung capacity (TLC) 2. residual volume (RV) 3. vital capacity (VC) 4. tidal volume (TV) 5. expiratory reserve volume (ERV) 6. inspiratory reserve volume (IRV) a. the volume of additional air that can be forcibly exhaled after a normal exhalation b. the minimum volume of air in the lungs when one exhales completely c. the difference between the minimum and maximum volume of air in the lungs d. the volume of additional air that can be forcibly inhaled after a normal inhalation e. the volume of air inhaled or exhaled in a normal breath f. the maximum volume of air in the lungs when one inhales completely; usually 6 to 7 liters

1. TLC - F 2. RV - B 3. VC - C 4. TV - E 5. ERV - A 6. IRV - D

DPQ #11 Some people with anxiety disorders respond to stress by hyperventilating. It is recommended that these people breathe into a paper bag and then rebreathe this air. Why is this treatment appropriate? 1. Hyperventilation causes an increase in blood carbon dioxide, and breathing the air in the bag helps to readjust blood levels of carbon dioxide. 2. Hyperventilation causes a decrease in blood carbon dioxide, and breathing the air in the bag helps to readjust blood levels of carbon dioxide. 3. Hyperventilation causes an increase in blood oxygen, and breathing the air in the bag helps to readjust blood levels of oxygen. 4. Hyperventilation causes a decrease in blood oxygen, and breathing the air in the bag helps to readjust blood levels of oxygen.

B

DPQ #4 The intrapleural pressure is necessarily lower than the atmospheric pressure during: 1. inhalation, because the expansion of the chest cavity causes compression of the intrapleural space, decreasing its pressure. 2. inhalation, because the expansion of the chest cavity causes expansion of the intrapleural space, decreasing its pressure. 3. exhalation, because the compression of the chest cavity causes compression of the intrapleural space, decreasing its pressure. 4. exhalation, because the compression of the chest cavity causes expansion of the intrapleural space, decreasing its pressure.

B

DPQ #5 A patient presents to the emergency room with a stab wound to the left side of the chest. On a chest x-ray, blood is noted to be collecting in the chest cavity, causing collapse of both lobes of the left lung. The blood is most likely located between: 1. the parietal pleura and the chest wall. 2. the parietal pleura and the visceral pleura. 3. the visceral pleura and the lung. 4. the alveolar walls and the lung surface.

B

DPQ #8 Idiopathic pulmonary fibrosis (IPF) is a disease in which scar tissue forms in the alveolar walls, making the lung tissue significantly more stiff. Which of the following findings would likely be detected through spirometry in a patient with IPF? 1. Decreased total lung capacity 2. Decreased inspiratory reserve volume 3. Increased residual volume 1. I only 2. II only 3. I and II only 4. I, II, and III

B

DPQ #6 Each of the following statements regarding the anatomy of the respiratory system is true EXCEPT: 1. the epiglottis covers the glottis during swallowing to ensure that food does not enter the trachea. 2. the trachea and bronchi are lined by ciliated epithelial cells. 3. the pharynx contains two vocal cords, which are controlled by skeletal muscle and cartilage. 4. the nares are lined with vibrissae, which help filter out particulate matter from inhaled air.

C

DPQ #2 Which of the following associations correctly pairs a stage of respiration with the muscle actions occurring during that stage? 1. Inhalation—diaphragm relaxes 2. Inhalation—internal intercostal muscles contract 3. Exhalation—diaphragm contracts 4. Exhalation—external intercostal muscles relax

D

As the diaphragm flattens and the chest wall expands outward, the intrathoracic volume (increases/decreases?); the intrathoracic pressure (increases/decreases?)

increases; decreases

Inhalation is an active process. We use our diaphragm as well as the ___ intercostal muscles to expand the throracic cavity

intercostal