pe2pt Flashcards
Which respiratory structure regulates lung ventilation by constricting and dilating?
Pores of Kohn (Pores of Kohn are small passageways that permit collateral airflow between adjacent alveoli. Bronchi contain a layer of smooth muscle that contracts or relaxes to create the activities of bronchoconstriction and bronchodilation.) Diaphragm (The diaphragm regulates ventilation by contracting during inhalation and relaxing during exhalation. Bronchi contain a layer of smooth muscle that contracts or relaxes to create the activities of bronchoconstriction and bronchodilation.) Bronchus (Bronchi contain a layer of smooth muscle that contracts or relaxes to create the activities of bronchoconstriction and bronchodilation.) Alveolus (Since alveoli do not contain muscle tissue, they cannot constrict or dilate. Bronchi contain a layer of smooth muscle that contracts or relaxes to create the activities of bronchoconstriction and bronchodilation.)
CORRECT Bronchus (Bronchi contain a layer of smooth muscle that contracts or relaxes to create the activities of bronchoconstriction and bronchodilation.)
Air is expelled from the alveoli during exhalation due to the effects of:
surfactant. (Surfactant reduces surface tension and has no effect on exhalation.) elastin. (Elastin fibers on the outside of the alveoli are stretched during inhalation and recoil during exhalation to passively expel air from the alveoli.) collagen. (Collagen does not have elastic recoil and is generally not a predominant fiber in the lung parenchyma.) smooth muscle. (Respiratory smooth muscle is found only in the conducting airways.)
Points Received: 1 of 1
CORRECT elastin. (Elastin fibers on the outside of the alveoli are stretched during inhalation and recoil during exhalation to passively expel air from the alveoli.)
Compliance refers to lung:
distensibility. (Compliance is the measure of lung (or chest wall) distensibility, defined as volume change per unit of pressure change.)
elasticity. (Elasticity is the lung’s ability to recoil during exhalation and return to the normal resting state.)
capacity. (Lung capacity is the volume of air the lung can contain. Lung capacity can be affected by alterations in lung compliance.)
perfusion. (Lung perfusion is the movement of blood into and out of the pulmonary capillary beds.)
distensibility. (Compliance is the measure of lung (or chest wall) distensibility, defined as volume change per unit of pressure change.)
Tidal volume is a measure of:
the amount of air left in the lungs after exhalation. (Residual volume is the amount of air left in the lungs after exhalation.)
the volume of air inhaled (or exhaled) during passive respiration. (Tidal volume, approximately 500 ml, is the amount of air exchanged between the atmosphere and the lungs during normal, quiet respirations.)
the maximum amount of air that can be expired from the lung. (Vital capacity is the maximum amount of air that can be expired from the lung.)
total lung capacity. (Total lung capacity is the sum of tidal volume, residual volume, expiratory reserve volume, and inspiratory reserve volume.)
CORRECT the volume of air inhaled (or exhaled) during passive respiration. (Tidal volume, approximately 500 ml, is the amount of air exchanged between the atmosphere and the lungs during normal, quiet respirations.)
Surfactant coats the inner surface of the alveoli and:
increases the work of breathing. (Surfactant decreases the work of breathing.)
improves lung elasticity. (Elastin fibers on the outside of the alveoli are responsible for lung elasticity (recoil).)
contains antibodies. (Surfactant does not contain antibodies.)
prevents alveolar collapse during expiration. (Surfactant reduces alveolar surface tension and makes it easier for the lung to inflate (due to increased compliance) at low lung volumes. The primary function of surfactant, however, is to prevent expiratory alveolar collapse.)
Points Received: 1 of 1
CORRECT prevents alveolar collapse during expiration. (Surfactant reduces alveolar surface tension and makes it easier for the lung to inflate (due to increased compliance) at low lung volumes. The primary function of surfactant, however, is to prevent expiratory alveolar collapse.)
Diffusion of respiratory gases takes place at the membrane between the:type I and type II alveolar cells. (Type I cells are a component of the alveolocapillary membrane, but type II cells produce surfactant.)
alveolar ducts and lymphatic capillaries. (The walls of the alveolar ducts are thin enough to diffuse respiratory gases, but they are not the main diffusion sites. Lymphatic capillaries remove excess tissue fluid to prevent edema accumulation.)
type I alveolar cells and pulmonary capillaries. (The alveolocapillary membrane where gas diffusion takes place is comprised of type I alveolar cells and the pulmonary capillaries.)
type II alveolar cells and pulmonary venules. (Type II alveolar cells produce surfactant, and venule walls are too thick to allow gas diffusion.)
CORRECT type I alveolar cells and pulmonary capillaries. (The alveolocapillary membrane where gas diffusion takes place is comprised of type I alveolar cells and the pulmonary capillaries.)
Covering the lungs is a serous membrane called the:
Student Answer: visceral peritoneum. (The visceral peritoneum is the serous membrane covering the abdominal organs.)
parietal peritoneum. (The parietal peritoneum is the serous membrane lining the inside of the abdominal cavity.)
visceral pleura. (The visceral pleura is the serous membrane covering the lung tissue.)
parietal pleura. (The parietal pleura is the serous membrane lining the inside of the thoracic cavity.)
visceral pleura. (The visceral pleura is the serous membrane covering the lung tissue.)
Trace a molecule of oxygen from the atmosphere to the lungs. Which answer has the respiratory structures that the oxygen passes through in the correct order?
Student Answer: Pharynx, esophagus, bronchioles, bronchi, alveolar sacs (Although oxygen will pass through the pharynx before reaching the conducting airways of the respiratory system, air should not enter the esophagus. In addition, the remaining respiratory structures are not in the correct order.)
Larynx, trachea, bronchi, bronchioles, alveolar ducts, alveoli (These respiratory structures are in the correct order.)
Trachea, bronchi, alveolar ducts, pleural cavity (The first three respiratory structures are in the correct order, but under normal conditions air should not enter the pleural cavity. Also note that some of the main conducting airways are missing from this answer.)
Bronchi, trachea, alveolar ducts, bronchioles, alveoli (All of these structures belong to the respiratory system; however, they are not in the correct order.)
Points Received: 1 of 1
CORRECT Larynx, trachea, bronchi, bronchioles, alveolar ducts, alveoli (These respiratory structures are in the correct order.)
Which of the following mechanisms causes air to move into the lung during passive inspiration?
Student Answer: Lifting of the ribcage by the accessory muscles of inspiration (Lifting of the ribcage by the accessory muscles of inspiration occurs with strenuous exercise or when the work of breathing is increased because of disease.)
Muscular contraction of the diaphragm (Contraction of the diaphragm is the primary driving force for inhalation during passive breathing.)
Dilation of the primary bronchi (Bronchodilation will decrease airway resistance and increase airflow into the lung, but it does not draw air into the lung.)
An increase in intrapleural pressure (Air is drawn into the lung by a decrease in intrapleural pressure caused by contraction of the diaphragm.)
CORRECT Muscular contraction of the diaphragm (Contraction of the diaphragm is the primary driving force for inhalation during passive breathing.)
Bronchodilation occurs with:
an increase in sympathetic activity. (Sympathetic stimulation will result in bronchial smooth muscle relaxation due to the effects of catecholamines on the beta 2-adrenergic receptors in the bronchi.) the release of inflammatory mediators such as histamine. (Release of most inflammatory mediators results in bronchoconstriction.) stimulation by the vagus nerve. (Stimulation of parasympathetic activity through the vagus nerve results in mild bronchoconstriction.) stimulation of irritant receptors in the conducting airways. (Stimulation of irritant receptors causes bronchoconstriction.)
Points Received: 1 of 1
Student Answer: CORRECT an increase in sympathetic activity. (Sympathetic stimulation will result in bronchial smooth muscle relaxation due to the effects of catecholamines on the beta 2-adrenergic receptors in the bronchi.)
According to Laplace’s law, the pressure required to inflate an alveolus is directly related to the:
Student Answer: amount of surfactant. (The pressure required to inflate an alveolus is inversely related to the amount of surfactant present in the alveoli.)
amount of surface tension. (An increase in surface tension will increase the pressure required to inflate an alveolus.)
minute volume. (The pressure required to inflate an alveolus is not related to minute volume.)
alveolar radius. (The pressure required to inflate an alveolus is inversely related to the alveolar radius.)
Points Received: 0 of 1
CORRECT amount of surface tension. (An increase in surface tension will increase the pressure required to inflate an alveolus.)
The fraction of the oxygen content transported that contributes to the partial pressure of oxygen in the arterial blood (PaO2) is:
Student Answer: dissolved in the plasma. (1.5% of total oxygen content is dissolved in the blood. This small amount of dissolved gas determines the partial pressure of oxygen.)
dissolved in the plasma. (98.5% of oxygen is bound to hemoglobin. This fraction of total oxygen content determines oxygen saturation of the blood.)
in the form of carbonic acid. (Carbon dioxide is primarily transported as carbonic acid.)
attached to plasma proteins. (Respiratory gases are not transported in the blood bound to plasma proteins.)
Student Answer: CORRECT dissolved in the plasma. (1.5% of total oxygen content is dissolved in the blood. This small amount of dissolved gas determines the partial pressure of oxygen.)
The region between the lungs that contains the heart, trachea, and primary bronchi is called the:
pleural cavity. (The pleural cavity is a potential space between the visceral and parietal pleura.) thoracic inlet. (The thoracic inlet designates the top of the thoracic cavity and is defined by a horizontal plane at the level of the first ribs.) mediastinum. (Between the lungs is the mediastium, a subregion of the thoracic cavity.) hilus. (The hilus is the point at which the bronchi and pulmonary vessels enter the lungs.)
CORRECT mediastinum. (Between the lungs is the mediastium, a subregion of the thoracic cavity.)
Lining the conducting airways is a specialized respiratory epithelium characterized by:
Student Answer: squamous epithelial cells for gas diffusion. (Gas diffusion takes place in the alveoli, not the conducting airways.)
keratinized epithelial cells. (Keratinized epithelial cells are found only in the epidermal layer of the skin.)
cells that secrete enzymes to digest foreign particulates. (The respiratory epithelial cells do not secrete digestive enzymes.)
mucous cells and cilia. (The lining of the conducting airways is a pseudostratified columnar epithelium lined with mucus for trapping particles and cilia for moving trapped debris out of the system.)
CORRECT mucous cells and cilia. (The lining of the conducting airways is a pseudostratified columnar epithelium lined with mucus for trapping particles and cilia for moving trapped debris out of the system.)
Alveolar hypoxia results in:
pulmonary artery and arteriole vasoconstriction. ( A decrease in alveolar oxygen content results in hypoxic vasoconstriction to shunt blood to segments of the lung that are adequately ventilated.) bronchoconstriction. (Alveolar hypoxia results in bronchodilation.) suppression of inflammatory mediators. (Alveolar hypoxia frequently results in an inflammatory response to cellular injury with the release of inflammatory mediators.) widespread vasodilation. (Cellular hypoxia results in vasodilation everywhere in the body except for the lungs.)
Student Answer: CORRECT pulmonary artery and arteriole vasoconstriction. ( A decrease in alveolar oxygen content results in hypoxic vasoconstriction to shunt blood to segments of the lung that are adequately ventilated.)
