Ch. 22 Study Guide

[Ch. 22 Specific Question #9] Explain in words why contraction of the diaphragm and external intercostal muscles causes expansion of the lungs. Give both a 1-sentence explanation and a 4-sentence explanation; the latter should mention the pleural cavity.

1 sentence: These muscles expand the thoracic cavity, which allows the lungs to expand as well. 4 sentences: These muscles expand the thoracic cavity. The increased volume in the thoracic cavity increases the volume and decreases the pressure in the pleural cavity between the thorax wall and the lungs. The drop in pleural cavity pressure increases the pressure gradient across the walls of the lungs. This increased pressure gradient allows the lungs to expand a bit before their elastic recoil prevents further expansion.

[Ch. 22 CYU #20] List three ways CO2 is transported in blood.

About 70% of CO2 is transported as bicarbonate ion (HCO3-) in plasma. Just over 20% is transported bound to hemoglobin in the RBCs, and 7-10% is dissolved in plasma.

[Ch. 22 Specific Question #6] How does the enzyme carbonic anhydrase both allow CO2to influence pH and vice versa? Write the chemical equation as part of your answer.

Allow blood to get acidic: carbonic anhydrase can combine CO2 and H2O to form H2CO3, which can then dissociate into H+ and HCO3-, thus making the blood more acidic. Aid the buffering capacity of the blood: if lots of H+ are added to the blood, the carbonic anhydrase reaction can run in the reverse direction to get rid of some of those H+ and minimize the pH change. (Likewise, if lots of H+ were removed from the blood, the carbonic anhydrate reaction would run in the forward direction to restore some of the H+.)

[Ch. 22 CYU #21] What is the relationship between CO2 and pH in the blood? Explain.

As blood CO2 increases, blood pH decreases. This is because CO2 combines with water to form carbonic acid. (However, the change in pH in blood for a given increase in CO2 is minimized by other buffer systems.)

[Ch. 22 Specific Question #1] How do peripheral chemoreceptors differ from central chemoreceptors?

Peripheral chemoreceptors are located in the aorta and carotid artery, and sense O2 as well as CO2 and H+. Central chemoreceptors are located in the brainstem, especially the medulla, and only sense CO2 and H+.

[Ch. 22 CYU #6] What features of the alveoli and their respiratory membranes suit them to their function of exchanging gases by diffusion?

The many tiny alveoli together have a large surface area. This and the thinness of their respiratory membranes make them ideal for gas exchange.

[Ch. 22 CYU #23] Which brain step respiratory area is thought to generate the respiratory rhythm?

The ventral respiratory group of the medulla (VRG) is thought to be the rhythm-generating area

[Ch. 22 Specific Question #10] If given an appropriate graph of volume of air in lung vs. time, estimate or calculate FEV1/FVC ratio, FVC, residual volume, TLC, tidal volume, and/or minute ventilation (see slide)

There are multiple ways to do this. The key is to choose a respiratory rate (breaths per minute) and a tidal volume (milliliters of air per breath) that, when multiplied together, give you 4000 mL air/minute. \ For example, I can draw a curve to show a tidal volume of 400 mL and a respiratory rate of 10 breaths/minute. Minute ventilation = (tidal volume)*(respiratory rate) = (400 mL air/breath)*(10 breaths/min) = 4000 mL air/min.

[Ch. 22 PT #16] Which form of CO2 transport accounts for the greatest amount of CO2 transported in blood? (a) dissolved in plasma (b) as carbon monoxide in plasma (c) as bicarbonate ions in plasma (d) chemically bound to hemoglobin

c) as bicarbonate ions in plasma Blood transports CO2 from the tissue cells to the lungs in three forms: 1. Dissolved in plasma (7-10%). The smallest amount of CO2 is transported simply dissolved in plasma. 2. Chemically bound to hemoglobin (just over 20%). In this form, dissolved CO2 is bound and carried in the RBCs as carbaminohemoglobin. 3.As bicarbonate ion in plasma (about 70%). Most carbon dioxide molecules entering the plasma quickly enter RBCs, where most of the reactions that prepare carbon dioxide for transport as bicarbonate ions in plasma occur.

[Ch. 22 Specific Question #8] When infants are born prematurely, they may lack surfactant, a substance coating the lungs that reduces surface tension of the lungs. Is this an obstructive respiratory disease or a restrictive respiratory disorder?

restrictive

[Ch. 22 Clicker Question #4] The data below do NOT look appropriate for calculating/estimating (see clickers) (a) FEV1/FVC (b) Minute Ventilation (c) Respiration Rate (d) Tidal Volume

(a) FEV1/FVC

[Ch. 22 Clicker Question #2] The maximum volume of air that you can exhale from your lungs is called the (a) FVC (or VC) (b) RV (c) FEV1 (d) TV (e) TLC

(a) FVC (or VC)

[Ch. 22 RQ #17) (a) Define hyperventilation. (b) If you hyperventilate, do you retain or expel more carbon dioxide? (c) What effect does hyperventilation have on blood pH?

(a) Hyperventilation is rapid or deep breathing. (b) Hyperventilation causes and increases the release of carbon dioxide from the blood. (c) Hyperventilation increases blood pH, due to the increased loss of H+ associated with CO2 in the blood.

[Ch. 22 Specific Question #2] If arterial oxygen increases, arterial CO2 decreases, and arterial pH increases, your medulla will cause you to breathe (a) Less (b) More (c) It's hard to say, since these are conflicting signals (d) The same as before

(a) Less

[Ch. 22 Specific Question #4] A low FEV1/FVC is associated with patients with (a) Obstructive lung disease (b) Restrictive lung disease (c) Both obstructive lung disease and restrictive lung disease (d) Neither obstructive lung disease nor restrictive lung disease

(a) Obstructive lung disease

[Ch. 22 Clicker Question #6 Devin is born with a genetic mutation that causes his lung tissue to be unusually fragile. One day a bit of mild jostling on the soccer field causes his left lung to "rip" slightly (opening up a tiny hole in the lung). Is this a pneumothorax? (a) Yes -- air will leak from his lungs into the pleural cavity. (b) No -- he's fine! No harm, no foul. (c) No -- only holes in the chest wall cause pneumothorax. (d) No -- this will lead to overinflation of the lung, not collapse of the lung.

(a) Yes -- air will leak from his lungs into the pleural cavity.

[Ch. 22 Clicker Question #3] What is the primary problem with restrictive lung diseases? (a) The airways are narrowed and can't conduct air as quickly as they should. (b) The lungs are not as stretchy as they should be and don't inflate as fully as they should. (c) The medulla is less active than usual, restricting the respiratory drive. (d) The thorax volume is restricted, thus limiting lung inflation.

(b) The lungs are not as stretchy as they should be and don't inflate as fully as they should.

[Ch. 22 RQ #14] The bulk of CO2 is carried (a) chemically combined with the amino acids of hemoglobin as carbaminohemoglobin in the RBCS (b) as the ion HCO3- in the plasma after first entering the RBC (c) as carbonic acid in the plasma (d) chemically combined with the heme portion of Hb

(b) as the ion HCO3- in the plasma after first entering the RBC

[Ch. 22 RQ #8] Oxygen and CO2 are exchanges in the lungs and through all cell membranes by (a) active transport (b) diffusion (c) filtration (d) osmosis

(b) diffusion

[Ch. 22 Clicker Question #5] Which aspect of these data is completely unrealistic? (see clickers) (a)CO2 is too low. (b) RR is too high. (c) RV is too low. (d) TV is too low.

(c) RV is too low.

[Ch. 22 CQ #10] Which respiratory structure has the smallest diameter? (a) larynx (b) secondary bronchi (c) bronchiole (d) trachea (e) pharynx

(c) bronchiole The bronchioles are air passages under 1 millimeter in diameter.

[Ch. 22 RQ #9] Most oxygen carried in the blood is (a) in solution in the plasma (b) combined with plasma proteins (c) chemically combined with heme in RBCs (d) in solution in the RBCs

(c) chemically combined with heme in RBCs

[Ch. 22 Specific Question #5] Control of respiration mostly resides in this part of the brain: (a) frontal cortex (motor cortex) (b) hypothalamus (c) medulla oblongata (d) pons (e) spinal cord segments C3, C4, and C5

(c) medulla oblongata

[Ch. 22 RQ #4] The detergent-like substance that keeps alveoli from collapsing between breaths because it reduces the surface tension of the water film in the alveoli is called (a) lecithin (b) bile (c) surfactant (d) reluctant

(c) surfactant

[Ch. 22 PT #8] The __________ are the main site of gas exchange within the lungs. (a) hila (b) respiratory bronchioles (c) bronchi (d) alveoli

(d) alveoli Many people mistakenly equate alveoli, the site of gas exchange, with alveolar sacs, but they are two different structures. The alveolar sac is analogous to a bunch of grapes, and the alveoli are the individual grapes.

[Ch. 22 CQ #5] Most of the carbon dioxide transported by the blood is __________. (a) dissolved in plasma (b) bound to hemoglobin (c) bound to the same protein as oxygen (d) converted to bicarbonate ions and transported in plasma (e) carried by white blood cells

(d) converted to bicarbonate ions and transported in plasma Seventy percent of CO2 is converted to bicarbonate ions and transported in plasma.

[Ch. 22 CQ #23] The transpulmonary pressure is the difference between the __________ and the __________ pressure. (a) atmospheric; intrapleural (b) intrapleural; alveolar (c) atmospheric; intrapulmonary (d) intrapulmonary; intrapleural

(d) intrapulmonary; intrapleural

[Ch. 22 CQ #1] During inspiration, air moves into the lungs because __________. (a) contraction of the diaphragm decreases the volume of the pleural cavity (b) abdominal muscles contract (c)the volume of the lungs decreases with inspiration (d) the gas pressure in the lungs becomes lower than the outside pressure as the diaphragm contracts (e) contraction of the internal intercostal muscles decreases the thoracic cavity volume

(d) the gas pressure in the lungs becomes lower than the outside pressure as the diaphragm contracts Boyle's law states that volume changes lead to pressure changes.

[Ch. 22 CQ #16] Which of the following is NOT a function of the conducting zone of the respiratory tract? (a) transport of air (b) warming of air (c) cleansing of air (d) mucous secretion (e) gas exchange

(e) gas exchange The walls of the conducting zone are too thick to allow gas exchange.

[Ch. 22 Specific Question #7] If a patient had a severe mutation in the gene for carbonic anhydrase, what would be the effects (if any) on carbon dioxide transport and blood pH?

This mutation would impair the buffering function mentioned in the previous answer, so the pH of the blood would be less stable. Most CO2 in the blood is normally transported as bicarbonate (HCO3-), but converting CO2 to HCO3- would not be possible without a functional carbonic anhydrase.

[Ch. 22 Specific Question #3] Say in words what it means to have a low FEV1/FVC.

You can't exhale lots of air quickly, suggesting that the airflow is obstructed in some way.