Chapter 23 Review

Billy's normal alveolar ventilation rate (AVR) during mild exercise is 6.0 L/min. While at the beach on a warm summer day, he goes snorkeling. The snorkel has a volume of 50 mL. assuming that the water is not too cold and that snorkeling is mild exercise for billy, what would his respiratory rate have to be for him to maintain an APR of 6.0 L/mn while snorkeling?

AVR=respiratory rate x (tidal volume - dead space). in this case, the dead air space is 200 mL; therefore, AVR = respiratory rate x (500-200). to maintain an AVR of 6.0- L/min, or or 6000 mL/min, respiratory rate must be 6000/(500-200), or 20 breaths per minute.

Mr. B has had chronic advanced emphysema for 15 years. While hospitalized with a respiratory infection, he goes into respiratory distress. Without thinking, his nurse immediately administers pure oxygen, which causes Mr. B to stop breathing. Why?

a person with chronic emphysema has constantly elevated blood levels of Pco2 due to an inability to eliminate CO2 efficiently because of physical damage to the lungs. over time, the brain ignores the stimulatory signals produced by the increased CO2 and begins to rely on information from peripheral chemoreceptors to set the pace of breathing. the peripheral chemoreceptors also accommodate to the elevated CO2 and respond primarily to the level of O2 in the blood, increasing breathing when O2 levels are high. when pure O2 was administered, chemoreceptors responded with fewer action potentials to the medulla oblongata, so Mr. B stopped breathing.

What is the significance of (a) Boyle's law, (b) Dalton's law, and (c) Henry's law to the process of respiration?

a. boyle's law describes the inverse relationship between ase pressure and volume. if volume increases, pressure falls. it is the basis for the direction of air movement in pulmonary ventilation. b. dalton's law states that each of the gases that make up a mixture of gases contributes to the total pressure in proportion to its relative abundance; that is, all the partial pressure added together equal the total pressure exerted by the gas mixture. this relationship is the basis for the calculation of the partial pressures of oxygen and carbon dioxide, and their exchange between blood and alveolar air. c. henry's law states that, at a given temperature, the amount of a particular gas that dissolves in a liquid is directly proportional to the partial pressure of the gas. henry's law underlies the diffusion of gases between capillaries, alveoli, and interstitial fluid.

What three integrated steps are involved in external respiration?

a. pulmonary ventilation b. gas diffusion across the respiratory membrane and between blood and interstitial fluids c. the transport of oxygen and carbon dioxide between alveolar and peripheral capillaries.

Gas exchange at the respiratory membrane is efficient because

a.the differences in partial pressure are substantial b.the gases are lipid soluble c.the total surface area is large

An increase in the partial pressure of carbon dioxide in arterial blood causes chemoreceptors to stimulate the respiratory centers, resulting in

an increased respiratory rate

What happens to the process of respiration when a person is sneezing or coughing?

both sneezing and coughing involve a temporary cessation of respiration, known as apnea.

By what three ways is carbon dioxide transported in the bloodstream?

carbon dioxide is transported in the blood as carbonic acid, bound to hemoglobin, and dissolved in the plasma.

Cary hyperventilates for several minutes before diving into a swimming pool. After he enters and begins swimming underwater, he blacks out and almost drowns. What caused this to happen?

cary's hyperventilation resulted in abnormally low Pco2. this reduced his urge to breathe, so he stayed underwater longer, unaware that his Po2 was dropping to the point of loss of consciousness.

The glottis closes partway through an exhalation. The abdominal and internal intercostal muscles then contract suddenly, creating pressure that blasts the air out of the respiratory passages. This describes a

cough

What important physiological differences exist between fetal hemoglobin and maternal hemoglobin?

fetal hemoglobin has a higher affinity for oxygen than does adult hemoglobin. thus, it binds more of the oxygen that is present, enabling it to "steal" oxygen from the maternal hemoglobin.

Surfactant

helps prevent the alveoli from collapsing

Which of the following does not occur in internal respiration?

hemoglobin binds move oxygen

Why do individuals who are anemic generally not exhibit an increase in respiratory rate or tidal volume, even though their blood is not carrying enough oxygen?

in anemia, the blood's ability to carry oxygen is decreased due to the lack of functional hemoglobin, red blood cells, or both. anemia does not interfere with the exchange of carbon dioxide within the alveoli, nor with the amount of oxygen that will dissolve in the plasma. because chemoreceptors respond to dissolved gases and pH, as long as the pH and the concentrations of dissolved carbon dioxide and oxygen are normal, ventilation patterns should not change significantly.

When the diaphragm and external intercostal muscles contract,

intrapleural pressure decreases

The hard palate separates the

nasal cavity and the oral cavity

How are pneumocytes type II involved with keeping the alveoli from collapsing?

pneumocytes type II produce surfactant, which reduces surface tension in the fluid costing the alveolar surface. without surfactant, the surface tension would be so high that the delicate alveolar would collapse.

How does pulmonary ventilation differ from alveolar ventilation, and what is the function of each type of ventilation?

pulmonary ventilation, the physical movement of air into and out of the respiratory tract, maintains adequate alveolar ventilation. alveolar ventilation, air movement into and out of the alveoli, prevents the buildup of carbon dioxide in the alveoli and ensures a continuous supply of oxygen that keeps pace with absorption by the bloodstream.

What are the differences between pulmonary volumes and respiratory capacities? How are pulao=mary volumes and respiratory capacities determined?

pulmonary volumes are determined experimentally and include resting tidal volume, expiratory reserve volume, residual volume, minimal volume, and inspiratory reserve volume. respiratory capacities include inspiratory capacity, functional residual capacity, vital capacity, and total lung capacity. the difference between the two measures is that respiratory capacities are the sums of various pulmonary volumes.

During the winter, brad sleeps in a dorm room that lacks any humidifier for the heated air. In the mornings he notices that his nose is "stuffy" similar to when he has a cold, but after showering and drinking some water, the stuffiness disappears until the next morning. What might be the cause of of Brad's nasal condition?

since the air Brad is breathing is dry, large amounts of moisture are leaving the mucus in his respiratory tract to humidify inhaled air. dying makes the mucus tacky and makes it difficult for the cilia to move, so mucus builds up, producing nasal congestion by morning. when brad showers and drinks fluids, body water is replaced, so the mucus loosens up and can be moved along as usual.

How would you justify the statement "The bronchioles are to the respiratory system what the arterioles are to the cardiovascular system"?

smooth muscle tissue in the walls of bronchioles allows changes in airway diameter, which provides control of the flow and distribution of air within the lungs, just as vasodilation and vasoconstriction of the arterioles control blood flow and blood distribution.

What is the functional difference between the dorsal respiratory group (DRG) and the ventral respiratory group (VRG) of the medulla oblongata?

the DRG is the inspiratory center that contains neurons that control lower motor neurons innervating the external intercostal muscles and the diaphragm. the DRG function sin every respiratory cycle, whether quiet or forced. the VRG functions only during forced respiration-active exhalation and maximal inhalation. the neurons involved with active exhalation are sometimes said to form an expiratory center.

For any partial pressure of oxygen, if the concentration of 2, 3-bisphosphoglycerate (BPG) increases,

the amount of oxygen released by hemoglobin will increase

Air moves into the lungs because

the gas pressure in the lungs is less than atmospheric pressure

Why is breathing through the nasal cavity more desirable than breathing through the mouth?

the nasal cavity cleanses, moistens, and warms inhaled air, whereas the mouth does not. drier air entering through the mouth can irritate the tracheas and cause throat soreness.

Doris has an obstruction of her right primary bronchus. As a result, how would you expect the oxygen-hemoglobin saturation curve for her lung to compare with that for her left?

the obstruction in doris's right lung would would prevent gas exchange. thus, blood moving through the right lung would not be oxygenated and would retain carbon dioxide, which would lead to a lower blood pH than that of blood leaving the left lung. the lower pH for blood in the fight lung would shift the oxygen-hemoglobin saturation curve to the left (he bohr effect) as compared with eh curve for the left lung.

Name the three regions of the pharynx. Where is each region located?

the regions of the pharynx are the superior nasopharynx, where the nasal cavity opens into the pharynx; the middle oropharynx, posterior to the oral cavity; and the inferior laryngopharynx, which is posterior to the hyoid bone and glottis.

List the cartilages of the larynx. What are the function of each?

the thyroid cartilage forms the anterior walls of the larynx; the cricoid cartilage protects the glottis and the entrance to the trachea; the epiglottis forms a lid over the glottis; the arytenoid cartilages and the corniculate cartilages are involved in the formation of sound; and the cuneiform cartilages are found in the folds of the larynx.

Distinguish the structures of the upper respiratory system from those of the lower respiratory system.

the upper respiratory system consists of the nose, nasal cavity, paranasal sinuses, and pharynx. the lower respiratory system consists of the larynx, trachea, bronchi, bronchioles, and alveoli of the lungs.