Cellular Respiration and Respiratory System Anatomy: AACN Critical Care Nursing Exam 2024, Exams of Nursing

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Cellular respiration cannot be directly measured but is estimated by the amount of - correct answer CO2 produced (V̇ CO2) and the amount of O2 consumed (V̇ O2). V̇ CO2 - correct answer CO2 produced in celluar respiration V̇ O2 - correct answer and the amount of O2 consumed in cellular respiration external respiration - correct answer The Exchange of O2 and CO2 at the alveolar-capillary level. It is the ratio of the CO2 produced to the O2 taken up per minute. V̇ CO2/min : V̇ O2/min Proper functioning of the respiratory circuit requires efficient interaction of the - correct answer 1. respiratory

2. circulatory
3. neuromuscular systems. In addition to its primary function of O2 and CO2 exchange, the lung also carries out metabolic and endocrine functions as a source of hormones and a site of hormone metabolism. In addition, the lung is a target of hormonal actions by other endocrine organs - correct answer (e.g., surfactant production and potentially activation of bradykinin). Anatomic divisions of Lungs: Right lung: Left Lung: - correct answer Right Lung: 3 lobes—upper, middle, lower

Left lung (two lobes—upper, lower). Lobes are divided into bronchopulmonary segments - correct answer 10 - RIGHT 9 - LEFT Bronchopulmonary segments are subdivided into - correct answer secondary lobules Secondary Lobules - correct answer Independent respiratory units of lung each bronchopulmonary segment is supplied independently by: a (tertiary) segmental bronchus a tertiary branch of pulmonary artery - carry low oxygen ("venous") blood to lungs for oxygenation a branch of bronchial artery What does a a tertiary branch of pulmonary artery do for secondary lobules? - correct answer - carries low oxygen ("venous") blood to lungs for oxygenation Smallest gross anatomic units of lung tissue; contain the primary functional units of the lung - correct answer Lobule: Lobule (the smallest gross anatomic units of lung tissue) consists of - correct answer 1. terminal bronchioles

2. alveolar ducts and sacs
3. pulmonary circulation Lymphatics surround the lobule keep the lung free of excess fluid and - correct answer carry macrophages to remove inhaled particles from distal areas of the lung.

Systemic source of circulation for the tracheobronchial tree and lung tissue down to the level of the terminal bronchiole. - correct answer Bronchial artery circulation Alveoli receive their blood supply directly from the - correct answer pulmonary circulation. Conducting airways: - correct answer Airways are a series of rapidly branching tubes of ever- diminishing diameter that eventually terminate in the alveoli. anatomic dead space. - correct answer The entire area from the nose to the terminal bronchioles where gas flows, but is not exchanged, is called Approx 150 mL but varies with patient size and position. Nose - correct answer a) Serves as a passageway for air movement into the lungs b) Preconditions air by the mucosal cells and turbinate bones

1. Warms air to within 2° to 3° F of the body's temperature; humidifies it to full saturation before it reaches the lower trachea
2. Filters by trapping particles larger than 6 μm in diameter Separation of food from air is controlled by - correct answer a) local nerve reflexes b) Opening of eustachian tube regulates middle ear pressure c) Lymphatic tissues control infection Larynx: a) Vocal cords: Speech function - correct answer Complex structure consisting of incomplete rings of cartilage and numerous muscles and ligaments
3. Contraction of muscles of the larynx causes the vocal cords to change shape.

2. Vibration of the vocal cords produces sound. Speech is a joint function of the vocal cords, lips, tongue, soft palate, and respiration with control by temporal and parietal lobes of the cerebral cortex.
3. Glottis: Opening between the vocal cords - correct answer b) Valve action by the epiglottis helps to prevent aspiration. c) Cough reflex: Cords close resulting in intrathoracic pressure increases to permit coughing or Valsalva maneuver. Cricoid cartilage - correct answer 1) Only complete cartilage ring
4. Narrowest part of the child's airway
5. Inner diameter sets the limit for the size of an endotracheal tube passed through the larynx Trachea: - correct answer Tubular structure consisting of 16 to 20 incomplete, or C-shaped, cartilaginous rings that stabilize the airway and prevent complete collapse with coughing Trachea - correct answer a) Begins the tracheobronchial tree b) Warms and humidifies air c) Mucosal cells trap foreign material d) Cilia propel mucus upward through the airway e) Cough reflex present especially at the point of tracheal bifurcation (carina) f) Smooth muscle innervated by the parasympathetic branch of the autonomic nervous system g) Carina—the point at which the trachea divides to form the mainstem bronchi Cough reflex present especially at - correct answer the point of tracheal bifurcation (carina) Right mainstem bronchus is and than the left - correct answer shorter and wider Terminal bronchioles - correct answer a) Smooth muscle walls (no cartilage); bronchospasm may narrow the lumen and increase airway resistance

b) Ciliated mucosal cells become flattened with progressive loss of cilia toward the alveoli c) Sensitive to CO2 levels: Increased levels induce bronchiolar dilation, decreased levels induce constriction In the terminal bronchioles, increased CO2 level - correct answer induce bronchiolar dilation In the terminal bronchioles, decreased CO2 levels - correct answer induce constriction a) Most important structures in gas exchange - correct answer Alveoli and alveolar bud Alveolar surface area is large and depends on body size. - correct answer Total surface area is about 75 to 80 m2 in a normal adult. Thickness of the respiratory membrane is about 0.6 μm. The large surface area distributes a large quantity of perfused blood into a very thin film to ensure near equalization of O2 and CO2. Alveolar cells - Type I: - correct answer 1) Squamous epithelium, adapted for gas exchange, sensitive to injury by inhaled agents, structured to prevent fluid transudation into the alveoli Alveolar cells - Type II: - correct answer Large secretory, highly active metabolically; origin of surfactant synthesis and type I cell genesis Alveolar macrophages: - correct answer Phagocytize foreign materials A Phospholipid monolayer at the alveolar air-liquid interface; able to vary surface tension with alveolar volume - correct answer Pulmonary surfactant

Pulmonary Surfactant Enables surface tension to decrease as - correct answer alveolar volume decreases during expiration, which prevents alveolar collapse Decreases the work of breathing, permits the alveoli to remain inflated at low distending pressures, reduces net forces causing tissue fluid accumulation - correct answer Pulmonary Surfactant Reduction in surfactant production makes - correct answer lung expansion more difficult; the greater the surface tension, the greater the pressure needed to overcome it Detoxifies inhaled gases and traps inhaled and deposited particles - correct answer Surfactant Alveolar-capillary membrane - correct answer 1. alveolar epithelium

2. interstitial space
3. capillary endothelium Gas exchange pathway: - correct answer Alveolar epithelium → alveolar basement membrane → interstitial space → capillary basement membrane → capillary endothelium → plasma → erythrocyte membrane → erythrocyte cytoplasm Alveolar ventilation (V̇ A): That part of total ventilation taking part in gas exchange and, therefore, the only part useful to the body - correct answer (a) Alveolar ventilation is one component of minute ventilation Minute ventilation (V̇ E): - correct answer Amount of air exhaled in 1 minute. Equal to exhaled tidal volume (VT) multiplied by respiratory rate (RR or f). - correct answer Minute Ventilation (VE) Normal resting minute ventilation in an adult is about - correct answer 6 L/min: VT - correct answer Exhaled Tidal Volume

VT * RR = VE - correct answer Exhaled Tidal Vol (VT) * Resp Rate (RR) = Minute Ventilation (VE) Tidal volume is easily measured at the bedside by hand-held devices or a mechanical ventilator. - correct answer spirometers (measure tidal vol) Exhaled minute ventilation is a routinely measured parameter for patients on ventilators. Minute ventilation is composed of both - correct answer 1. alveolar ventilation (V̇ A)

2. physiologic dead-space ventilation (V̇ D): alveolar ventilation - correct answer (V̇ A) physiologic dead-space ventilation - correct answer (V̇ D): VE = VA + VD - correct answer Minute Vnetilation = aveloar ventilation + physiologic dead-space ventilation manometer in respiratory therapy measures - correct answer pressure of expired air Physiologic dead-space ventilation is that volume of gas in the airways that does not participate in gas exchange. It is composed of both - correct answer 1. anatomic dead-space ventilation (V̇ Danat) and 2.. alveolar dead-space ventilation (V̇ DA). Ratio of dead space to tidal volume (VD/VT) measured to determine - correct answer how much of each breath does not contribute to gas exchange. Normal values for spontaneously breathing patients range from - correct answer 20% to 40% of VT. Alveolar ventilation is not measured directly; it is inversely related to arterial CO2 pressure (PaCO2) in a steady state by the following formula: - correct answer VA = VCO2 * 0.863 / PaCO

where 0.863 = correction factor for differences in measurement units and conversion to standard temperature [0° C] and pressure [760 torr], dry (STPD). (c) Since V̇ CO2 remains the same in a steady state, measurement of the patient's PaCO2 reveals the status of the alveolar ventilation. To assess ventilation, PaCO2 must be measured. - correct answer PaCO2 is the only adequate indicator of effective matching of alveolar ventilation to metabolic demand. If PaCO2 is low, alveolar ventilation is high; - correct answer hyperventilation is present If PaCO2 is within normal limits, - correct answer alveolar ventilation is adequate If PaCO2 is high, alveolar ventilation is low and - correct answer hypoventilation is present often leads to ventilator dependency. - correct answer Injury at or above C3 to C5 level