answer multiple choice questions about physiology:  1. Analysis of simple acid-base balance:
        1. Normal: pH = 7.4; PCO2 = 40 mm Hg; [HCO3–] = 24 mEq/L.
        2. Respiratory alkalosis with renal compensation: pH < 7.4; PCO2 < 40 mm Hg; [HCO3–] < 24 mEq/L.
        3. Metabolic acidosis with respiratory compensation: pH > 7.4; PCO2 < 40 mm Hg; [HCO3–] < 24 mEq/L.
        4. Respiratory alkalosis with renal compensation: pH > 7.4; PCO2 < 40 mm Hg; [HCO3–] < 24 mEq/L.
        5. Metabolic acidosis with respiratory compensation: pH < 7.4; PCO2 < 40 mm Hg; [HCO3–] < 24 mEq/L.
        6. Normal: pH = 7.2; PCO2 = 24 mm Hg; [HCO3–] = 40 mEq/L.
        7. Metabolic alkalosis with respiratory compensation: pH < 7.4; PCO2 > 40 mm Hg; [HCO3–] > 24 mEq/L.
        8. Respiratory acidosis with renal compensation: pH > 7.4; PCO2 > 40 mm Hg; [HCO3–] > 24 mEq/L.
        9. Respiratory acidosis with renal compensation: pH < 7.4; PCO2 > 40 mm Hg; [HCO3–] > 24 mEq/L.
        10. Metabolic alkalosis with respiratory compensation: pH > 7.4; PCO2 > 40 mm Hg; [HCO3–] > 24 mEq/L.
    2. About the respiratory regulation of acid-base balance, it can be said that:
        1. If the rate of pulmonary ventilation is decreased, the PCO2 in the extracellular fluid decreases.
        2. If the rate of pulmonary ventilation is increased, the PCO2 in the plasma fluid increases.
        3. A decreased ventilation increases the H+ concentration in the extracellular fluid.
        4. If the rate of metabolic formation of CO2 increases, the PCO2 of the extracellular fluid is decreased.
        5. A decreased metabolic rate increases the PCO2.
        6. Normally, CO2 dissolved in the extracellular fluid corresponds to a PCO2 of 140 mm Hg.
        7. CO2 diffuses from the cells into the interstitial fluids and blood and the flowing blood transports it to the lungs, where it diffuses into the alveoli and then is transferred to the atmosphere by pulmonary ventilation
        8. An increase in ventilation reduces the H+ concentration in the extracellular fluid.
        9. CO2 is formed continually in the body by intracellular metabolic processes.
        10. The second line of defense against acid-base disturbances is control of extracellular fluid CO2 concentration by the lungs.
    3. About respiratory regulation of acid-base balance, it can be said that:
        1. Increasing alveolar ventilation decreases extracellular fluid H+ concentration.
        2. Increasing alveolar ventilation decreases extracellular fluid pH.
        3. If the rate of pulmonary ventilation is increased, CO2 is blown off from the lungs and the PCO2 in the atmospheric air decreases.
        4. Decreased ventilation increases CO2, thus increasing pH in the extracellular fluid.
        5. If the rate of pulmonary ventilation is increased, CO2 is blown off from the lungs and the PCO2 in the extracellular fluid decreases.
        6. Increasing alveolar ventilation raises extracellular fluid pH.
        7. Decreased ventilation increases CO2, thus also increasing H+ concentration in the extracellular fluid.
        8. If the higher the alveolar ventilation remains constant, the higher metabolic formation of CO2, the lower is the PCO2 in extracellular fluid.
        9. Increasing alveolar ventilation raises extracellular fluid H+ concentration.
        10. If the metabolic formation of CO2 remains constant, the higher the alveolar ventilation, the lower is the PCO2 in extracellular fluid.
    4. About respiratory regulation of acid-base balance, it can be said that:
        1. Increased H+ concentration stimulates alveolar ventilation.
        2. A rise in plasma pH above 7.4 causes a decrease in the ventilation rate.
        3. The change in ventilation rate per unit pH change is much greater at reduced levels of pH compared with increased levels of pH.
        4. The alveolar ventilation rate increases as the pH decreases from the normal value of 7.4.
        5. A rise in plasma pH above 7.4 causes an increase in the ventilation rate.
        6. The change in ventilation rate per unit pH change is much greater at increased levels of pH compared with reduced levels of pH.
        7. Increased pH increases alveolar ventilation.
        8. The respiratory compensation for an increase in pH is not nearly as effective as the response to a marked reduction in pH.
        9. The respiratory compensation for a marked reduction in pH is not nearly as effective as the response to an increase in H+ concentration.
        10. The alveolar ventilation rate increases as the HCO3- concentration increases.
    5. About respiratory regulation of acid-base balance, it can be said that:
        1. Whenever the H+ concentration increases, the respiratory system is stimulated, alveolar ventilation increases, the PCO2 in extracellular fluid decreases and the H+ concentration decreases back toward normal.
        2. If pH falls below normal, the respiratory center becomes depressed, alveolar ventilation decreases, and pH increases back toward normal.
        3. Impairment of lung function increases the ability of respiration to respond to metabolic acidosis.
        4. If the pH is suddenly decreased by adding acid to the extracellular fluid and pH falls from 7.4 to 7.0, the respiratory system can return the pH to a value of about 7.2 to 7.3.
        5. Impairment of lung function can cause respiratory alkalosis.
        6. Respiratory regulation of acid-base balance is a physiological type of buffer system because it acts rapidly and keeps the H+ concentration from changing too much until the slowly responding kidneys can eliminate the imbalance.
        7. Ordinarily, the respiratory mechanism for controlling H+ concentration is 100% effective.
        8. Severe emphysema causes a buildup of O2 in the extracellular fluid and a tendency toward respiratory alkalosis.
        9. Because increased H+ concentration stimulates respiration and because increased alveolar ventilation decreases the H+ concentration, the respiratory system acts as a typical negative feedback controller of H+ concentration.
        10. Respiratory control cannot return the H+ concentration all the way back to normal when a disturbance outside the respiratory system has altered pH.
    6. About the functions of respiration, we can say that:
        1. The pulmonary ventilation means diffusion of O2 and CO2 between the atmosphere and the lung alveoli.
        2. The pulmonary ventilation means the inflow and outflow of air between the atmosphere and the lung alveoli.
        3. One of the four major components of respiration is the pulmonary ventilation.
        4. The main functions of respiration are to provide CO2 to the tissues and remove O2.
        5. One of the four major components of respiration is diffusion of O2 and CO2 between the alveoli and the blood.
        6. One of the four major components of circulation is the pulmonary ventilation.
        7. The main functions of respiration are to provide O2 to the tissues and remove CO2.
        8. One of the four major components of respiration is transport of O2 and CO2 in the blood and body fluids to and from the body’s tissue cells.
        9. One of the four major components of respiration is transport of O2 and CO in the body.
        10. One of the four major components of respiration is diffusion of O2 and CO2 between the lungs and the heart.
    7. Mechanics of pulmonary ventilation:
        1. The upward movement of the diaphragm increases the anteroposterior diameter of the chest cavity.
        2. The lungs can be expanded and contracted.
        3. The upward movement of the diaphragm shortens the chest cavity.
        4. The lungs can be voluntarily contracted and relaxed.
        5. The downward movement of the diaphragm decreases the anteroposterior diameter of the chest cavity.
        6. The depression of the ribs decreases the anteroposterior diameter of the chest cavity.
        7. The depression of the ribs lengthens the chest cavity.
        8. The elevation of the ribs increases the anteroposterior diameter of the chest cavity.
        9. The downward movement of the diaphragm lengthens the chest cavity.
        10. The elevation of the ribs shortens the chest cavity.
    8. Muscle involved in breathing are characterized by:
        1. Normal quiet breathing is accomplished almost entirely by the movement of the diaphragm.
        2. During inspiration elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs and pulls the lower surfaces of the lungs downward.
        3. During expiration the diaphragm becomes flat.
        4. During heavy breathing extra force is achieved mainly by contraction of the diaphragm.
        5. During heavy breathing extra force is achieved mainly by contraction of the abdominal muscles.
        6. During expiration the elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs and expels the air.
        7. Normal quiet breathing is accomplished almost entirely by the movement of the abdominal muscles.
        8. During inspiration contraction of the diaphragm pulls the lower surfaces of the lungs downward.
        9. During expiration the contraction of the diaphragm expels the air.
        10. During expiration the diaphragm relaxes.
    9. Muscle involved in breathing are characterized by:
        1. All the muscles that depress the chest cage are classified as muscles of expiration.
        2. All the muscles that elevate the chest cage are classified as muscles of expiration.
        3. All the muscles that depress the chest cage are classified as muscles of inspiration.
        4. When the rib cage is elevated → the ribs project forward → the sternum moves downward.
        5. Raising the rib cage → ↑ the anteroposterior thickness of the chest about 20% greater during maximum inspiration than during expiration.
        6. Raising the rib cage → ↑ the vertical length of the chest about 20% greater during maximum inspiration than during expiration.
        7. Raising the rib cage expands the lungs.
        8. All the muscles that elevate the chest cage are classified as muscles of inspiration.
        9. When the rib cage is elevated → the ribs project forward → the sternum moves forward.
        10. Raising the rib cage contracts the lungs
    10. The muscles involved in lung expansion and contraction are characterized by:
        1. The scaleni muscles lift the last twelve ribs.
        2. The sternocleidomastoid muscles lift upward on the sternum.
        3. The most important muscles that raise the rib cage are the external intercostals.
        4. The anterior serrati muscles lift many of the limbs.
        5. The most important muscles that raise the rib cage are the internal intercostals.
        6. The sternocleidomastoid muscles lift upward on the jaw.
        7. The muscles that raise the rib cage are the external intercostals, sternocleidomastoid muscles, anterior serrati, scaleni.
        8. The muscles that raise the rib cage are the external intercostals, sternocleidomastoid muscles, diaphragm, scaleni.
        9. The scaleni muscles lift the first two ribs.
        10. The anterior serrati muscles lift many of the rib.
    11. The muscles involved in lung expansion and contraction are characterized by:
        1. Muscles that cause lung expansion include the abdominal recti muscles that lift upward on the sternum.
        2. Muscles that cause lung expansion include the internal intercostals that raise the rib cage.
        3. Muscles that cause lung expansion include the diaphragm that pulls the lower surfaces of the lungs downward.
        4. Muscles that cause lung expansion include the scaleni that lift the first two ribs.
        5. Normal quiet breathing is accomplished almost entirely by elevation and depression of the ribs.
        6. Muscles that cause lung expansion include the external intercostals that raise the rib cage.
        7. Muscles that cause lung expansion include the anterior serrati that lift many of the ribs.
        8. Muscles that cause lung expansion include the external oblique abdominal muscle that lift many of the ribs.
        9. Muscles that cause lung expansion include the sternocleidomastoid muscles that lift upward on the sternum.
        10. Muscles that cause lung expansion include the internal oblique abdominal musle that lift the first two ribs.
    12. Mechanics of pulmonary ventilation are characterized by:
        1. As external intercostals contract, they cause leverage on the ribs to raise them upward.
        2. As internal intercostals contract, they pull the upper ribs forward in relation to the lower ribs.
        3. The contraction of the diaphragm compresses the lungs.
        4. The internal intercostals angle between the ribs backward and upward.
        5. As external intercostals contract, they pull the upper ribs forward in relation to the lower ribs.
        6. The external intercostals during expiration are elongated forward and downward.
        7. During heavy breathing, the diaphragm simply relaxes, and the elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs and expels the air
        8. The internal intercostals during expiration are elongated forward and downward.
        9. The ribs during expiration are angled downward.
        10. During heavy breathing, the rapid expiration is achieved mainly by contraction of the diaphragm.
    13. Indicate the correct statement(s):
        1. Pleural fluid that lubricates movement of the lungs within the abdominal cavity.
        2. The lung is an elastic structure that expels all its air through the trachea whenever there is no force to keep it inflated
        3. The lungs are glued to the thoracic wall.
        4. The lungs are well lubricated and can slide freely in and out the thoracic cage.
        5. Continual suction of excess fluid into lymphatic channels maintains a slight suction between the lungs and the ribs.
        6. Between lungs and the walls of the chest cage, there are no attachments.
        7. The lung is an elastic structure that collapses like a balloon whenever there is no force to keep it inflated.
        8. The lung “floats” in the thoracic cavity, surrounded by a thin layer of pleural fluid.
        9. The lungs can be expanded and contracted by contraction and relaxation of their muscles.
        10. The lung is suspended at its hilum from the mediastinum.
    14. Changes in lung volume, alveolar pressure, pleural pressure, and transpulmonary pressure during normal breathing could be described by:
        1. The transpulmonary pressure is a measure of the elastic forces in the lungs that tend to collapse the lungs at each instant of respiration.
        2. During inspiration there is an increase negativity of the pleural pressure with 0.5 liter.
        3. During normal inspiration, alveolar pressure decreases to about −1 centimeters of mercury.
        4. Alveolar pressure is the air pressure inside the lung alveoli.
        5. During expiration, alveolar pressure decreases and forces the 0.5 liter of inspired air out of the lungs during the 2 to 3 seconds.
        6. Transpulmonary pressure the difference between alveolar and pleural pressures.
        7. During expiration, alveolar pressure rises to about 80 mmHg forces the inspired air out of the lungs.
        8. The recoil pressure is a measure of the elastic forces in the lungs that tend to collapse the lungs.
        9. The normal pleural pressure at the beginning of inspiration is about −0.5 liter of water.
        10. Pleural pressure is the pressure of the fluid in the thin space between the lung pleura and the chest wall pleura.
    15. Changes in lung volume, alveolar pressure, pleural pressure, and transpulmonary pressure during normal breathing could be described as:
        1. During inspiration: the negativity of the pleural pressure increases from (−5) to (−7.5).
        2. During expiration: alveolar pressure rises to about +1 centimeter of water.
        3. During inhalation: the transpulmonary pressure is decreasing.
        4. During normal breathing: the pressure in the alveoli is higher on the beginning of inspiration than at the beginning of expiration.
        5. During inspiration: the pleural pressure increases from (−5) to (−7.5).
        6. During inspiration: the lung volume increases with 5 liter.
        7. The normal pleural pressure at the beginning of inspiration is about −5 centimeters of water.
        8. The normal pleural pressure at the end of inspiration is about −5 centimeters of water.
        9. During inspiration: the lung volume increases with 0.5 liter.
        10. During expiration: the 0.5 liter of inspired air moves out of the lungs.