BI 233 - Respiratory Quizzes

Which of the following would cause the greatest increase in pulmonary ventilation rate and depth? a. A 10% increase in pulmonary arterial PCO2 b. A 10% increase in systemic arterial PCO2 c. A 10% decrease in pulmonary arterial PO2 d. A 10% decrease in systemic arterial PO2

A 10% increase in systemic arterial PCO2

Which statement is most likely TRUE about hemoglobin's affinity for oxygen? a. Affinity is highest in the systemic venous blood b. Affinity is lowest in the systemic arterial blood c. Affinity is lowest in the pulmonary arterial blood d. Affinity is highest in the pulmonary arterial blood

Affinity is lowest in the pulmonary arterial blood

What would happen to airflow into an alveolus when the bronchiole serving that alveolus constricts? a. Airflow would increase into the alveolus b. Airflow would decrease into the alveolus

Airflow would decrease into the alveolus

Hemoglobins' affinity for oxygen is how much oxygen is actually currently held by the hemoglobin. So, if hemoglobin has high oxygen saturation, hemoglobin's affininty for oxygen is high. What do you think happens to hemoglobin's affinity for oxygen as it moves through the systemic capillaries? a. As the RBC moves through the systemic capillary, hemoglobin's affinity for oxygen decreases. b. As the RBC moves through the systemic capillary, hemoglobin's affinity for oxygen increases. c. As hemoglobin moves through the systemic capillary, hemoglobin's affinity for oxygen stays the same.

As the RBC moves through the systemic capillary, hemoglobin's affinity for oxygen decreases. Correct! Hemoglobin is a protein molecule that behaves differently in different situations. When oxygen level changes, hemoglobin's affinity for oxygen changes. When oxygen is very abundant in the environment (high pO2), hemoglobin binds oxygen very tightly due to the way the molecule is shaped. When environmental oxygen is very low (low pO2), hemoglobin is shaped differently and does not bind oxygen as readily. In the case of the body, when hemoglobin travels through the pulmonary capillary it moves into a very high oxygen environment, causing it to have a high oxygen affinity. When the hemoglobin moves through the systemic capillary, it becomes exposed to a lower oxygen environment and then decreases its affinity for oxygen. This loss of affinity from a high state (bound with lots of oxygen) to a low state (less oxygen bound) causes oxygen to be released to the tissues.

Why can the pulmonary capillary blood achieve the same PO2 as alveolar air? a. Because there is an overabundance of oxygen in the alveoli compared to the pulmonary arteries b. Because the alveoli contain more total gas pressure than the blood

Because there is an overabundance of oxygen in the alveoli compared to the pulmonary arteries

Why do the lungs expand during inspiration? a. Because the diaphragm attaches directly onto the lungs and pulls the lungs down b. Because they are "pulled" open by the pleura c. Because positive intrapleural pressure "pulls" them open d. Because the intercostal muscles attach directly onto the lungs and pull the lungs outward

Because they are "pulled" open by the pleura Right! Increasingly negative intrapleural pressure generated by the expansion of the rib cage and inferior thoracic cavity during inhalation (inspiration) pulls the lungs open. Surface tension between the visceral and parietal pleura create a suction. If the parietal pleura (attached to inside thoracic cavity) move away from the lung, they generate a greater suck on the visceral pleura. The visceral pleura are attached to outside of the lung, and thus, when the visceral pleura moves, so does the lung. No muscles directly insert onto the lungs.

Why is it acceptable to make CO2 in RBCs found in pulmonary capillary blood? a. Because you can convert that CO2 back in to H+ & HCO3- b. Because you can release CO2 into the alveoli and remove it from the body

Because you can release CO2 into the alveoli and remove it from the body

Suppose your blood has too low pH. How can your body correct this? a. By holding your breath (decreasing respiratory rate) b. By secreting bicarbonate ions into the filtrate c. By increasing depth and rate of pulmonary ventilation d. By reabsorbing H+ ions from the filtrate

By increasing depth and rate of pulmonary ventilation Right! The respiratory system can correct acidosis (too low pH of the blood) by increasing respiratory rate and depth to eliminate more CO2 from the body. Doing this causes more H+ ions not to be free but to combine with HCO3- to make H2CO3 which then makes more CO2 and H20 at the lung. The CO2 is then removed from the system leaving only water. All of the other options would cause more H+ to remain in the body thus making the blood more acidic.

Inside the RBC, what happens to carbonic anhydrase activity and bicarbonate production if H+ ion concentration rises? a. Carbonic anhydrase makes more HCO3- b. Carbonic anhydrase makes less HCO3-

Carbonic anhydrase makes less HCO3-

Which of the following will most readily trigger an increase in respiration rate and depth? a. Femoral venous hemoglobin saturation = 80% b. Carotid PCO2 = 47 mmHg c. Pulmonary venous PCO2 = 40 mmHg d. Aortic PO2 = 90 mmHg e. Jugular PO2 = 40 mmHg

Carotid PCO2 = 47 mmHg Right! Femoral venous hemoglobin saturation = 80% is normal, maybe even a little high for a systemic vein according to what we discussed in lecture. Carotid PCO2 = 47 mmHg is too high, this should be =40 mmHg. Very small increases in systemic arterial PCO2 trigger increases in respiration rate to remove CO2 from the body. Pulmonary venous PCO2 = 40 mmHg - this is normal for blood entering the pulmonary capillary for oxygen pickup. Aortic PO2 = 90 mmHg - this is a little low, but hemoglobin is still nearly 100% saturated and this will not alter respiration rate. Jugular PO2 = 40 mmHg - this is normal for blood leaving a tissue at rest.

What does hemoglobin release when it binds O2?

H+

What happens to hemoglobin's affinity for oxygen when levels of CO2 increase? a. Hemoglobin's affinity for oxygen decreases b. Hemoglobin's affinity for oxygen increases c. Hemoglobin's affinity for oxygen does not change

Hemoglobin's affinity for oxygen decreases Nice! When the level of CO2 increases (or conditions become acidic or temperature increases), hemoglobin's affinity for oxygen decreases. This means that hemoglobin holds on to oxygen less tightly, thus releasing it more readily to a hungry tissue. This is also a right shift in the oxygen-hemoglobin dissociation curse and is beneficial because it allows more oxygen delivery for the same level of PO2.It would seem that this lower affinity of hemoglobin for oxygen would be bad because it would limit how much O2 could bind in the lung. But remember that hemoglobin is fully saturated at low levels of PO2 naturally (as low at 70 mmHg) and the high level of CO2 is erased at the pulmonary capillary when CO2 diffuses into the alveoli and is removed from the blood. So, while the hemoglobin curve shifts right when the hemoglobin is in the systemic capillaries, it shifts to the left again when the hemoglobin is in the pulmonary capillaries.

What happens to hemoglobin's affinity for oxygen when blood becomes more acidic? Note: affinity is how readily hemoglobin pick up O2. When affinity is high, HBO2% will be high. a. Hemoglobin's affinity for oxygen decreases b. Hemoglobin's affinity for oxygen increases c. Hemoglobin's affinity for oxygen does not change

Hemoglobin's affinity for oxygen decreases Nice! When the level of CO2 increases (or conditions become acidic or temperature increases), hemoglobin's affinity for oxygen decreases. This means that hemoglobin holds on to oxygen less tightly, thus releasing it more readily to a hungry tissue. This is also a right shift in the oxygen-hemoglobin dissociation curse and is beneficial because it allows more oxygen delivery for the same level of PO2.It would seem that this lower affinity of hemoglobin for oxygen would be bad because it would limit how much O2 could bind in the lung. But remember that hemoglobin is fully saturated at low levels of PO2 naturally (as low at 70 mmHg) and the high level of CO2 or H+ is erased at the pulmonary capillary when CO2 diffuses into the alveoli and is removed from the blood. So, while the hemoglobin curve shifts right when the hemoglobin is in the systemic capillaries, it shifts to the left again when the hemoglobin is in the pulmonary capillaries

What happens to hemoglobin's affinity for oxygen when blood becomes more acidic? a. Hemoglobin's affinity for oxygen decreases b. Hemoglobin's affinity for oxygen increases c. Hemoglobin's affinity for oxygen stays the same

Hemoglobin's affinity for oxygen decreases Nice! When the level of CO2 increases (or conditions become acidic or temperature increases), hemoglobin's affinity for oxygen decreases. This means that hemoglobin holds on to oxygen less tightly, thus releasing it more readily to a hungry tissue. This is also a right shift in the oxygen-hemoglobin dissociation curse and is beneficial because it allows more oxygen delivery for the same level of PO2.It would seem that this lower affinity of hemoglobin for oxygen would be bad because it would limit how much O2 could bind in the lung. But remember that hemoglobin is fully saturated at low levels of PO2 naturally (as low at 70 mmHg) and the high level of CO2 or H+ is erased at the pulmonary capillary when CO2 diffuses into the alveoli and is removed from the blood. So, while the hemoglobin curve shifts right when the hemoglobin is in the systemic capillaries, it shifts to the left again when the hemoglobin is in the pulmonary capillaries.

Which of the following will INCREASE respiratory rate? a. High carotid PCO2 b. High carotid PO2 c. Low aortic PCO2 d. High jugular PCO2

High carotid PCO2 Yes! If there is too much CO2 in the systemic arterial blood, then there was not enough removal of CO2 by the lungs. The chemoreceptors in the carotid bodies & aorta detect this high systemic arterial PCO2 and relay the information to the respiratory centers of the brainstem. Also, central chemoreceptors located in the medulla oblongata receive CO2 from systemic arteries. If too much CO2 moves across into the blood brain barrier, H+ ions form. These ions cannot be buffered (due to low protein composition of the cerebrospinal fluid) and the central chemoreceptors are triggered. The brainstem centers (in pons and medulla oblongata) are then stimulated to increase respiratory rate to remove more CO2 from the body.We do not monitor the composition of the systemic venous blood (i.e. Jugular vein) because the blood in these vessels has not reached the lungs for adjustment. Not matter how high the systemic venous blood CO2 level becomes, If the lungs are performing adequately, then enough CO2 is removed and there is no cause to increase ventilation rate. Too low O2 can stimulate increased respiration rate, but only when O2 levels reach less than 60 mmHg PO2 in systemic arteries.

Which of the following accurately describes the site of external respiration? a. It is the trachea, bronchi and bronchioles. b. It is very thick and covered with a thin layer of mucous. c. It is composed of tissue cell membranes, a thin layer of connective tissue and the wall of a systemic capillary. d. It allows easy diffusion of gases between the alveoli and the body. e. It is pseudostratified ciliated columnar epithelium.

It allows easy diffusion of gases between the alveoli and the body. Right! The respiratory membrane is the site of external respiration. It is made of the pulmonary capillary wall, a thin amount of connective tissue and the wall of an alveolus. It is free of cilia although it does have a little bit of fluid lining it. The respiratory membrane is very thin to allow easy diffusion of gases - in pneumonia the respiratory membrane becomes thickened and it is difficult to load the blood with oxygen because gases cannot diffuse into the blood.

In the systemic capillaries, what happens to the H+ ion created by the conversion of CO2 (+H2O) to HCO3? a. It becomes attached to hemoglobin, releasing an O2 to the tissue b. It combines with HCO3- to make more CO2 at the systemic capillary c. It is exported to the plasma in exchange for a Cl-

It becomes attached to hemoglobin, releasing an O2 to the tissue

In the pulmonary capillary, what happens to the H+ ion when O2 binds with hemoglobin? a. It binds with HCO3- to make CO2 (& H2O) b. It is removed from the RBC into the plasma in exchange for Cl- c. It re-attaches to hemoglobin again to release O2 back to the alveoli

It binds with HCO3- to make CO2 (& H2O)

The respiratory membrane is found at the site of external respiration. What best describes the respiratory membrane? a. It exists between the walls of the alveoli and the walls of the pulmonary capillaries b. It lines the nasal cavity c. It lines the trachea d. It lines the intrapleural space

It exists between the walls of the alveoli and the walls of the pulmonary capillaries

Which of the following best describes the air in the alveoli? a. It has a PO2 of 40 mmHg b. It has a PO2 of ~100 mmHg c. It has a PCO2 of ~100 mmHg d. It has a PCO2 of 45 mmHg

It has a PO2 of ~100 mmHg

Which of the following occur when ATP production increases at the tissues? a. Less oxygen is offloaded to the tissues b. Fewer H+ ions are buffered by hemoglobin in systemic capillaries c. More CO2 is produced in the RBCs at the pulmonary capillary d. More CO2 is transported by albumin e. Less bicarbonate ions (HCO3-) are made in the systemic capillaries

More CO2 is produced in the RBCs at the pulmonary capillary Right! When the tissues begin making more ATP they also make more CO2 (by aerobic metabolism). That CO2 diffuses into the blood and causes more O2 to be offloaded because high CO2 decreases hemoglobin's affinity for O2 and thus more O2 is released to the tissues. More H+ ions are made and the hemoglobin can buffer them because they have given up more O2 and now can bind more H+ to form HHb. At the tissues, more HCO3- is made when CO2 production increases. The confusing part is that the HCO3- and HHb travel in the blood up to the lungs and in the pulmonary capillary, the H+ comes off of the HHb (as oxygen binds to Hb) and binds to the HCO3-. When this happens, CO2 and H2O are formed. SO, CO2 is made in RBC in pulmonary capillaries because that CO2 can then diffuse into the alveoli and be removed from the body. Albumin does not transport CO2.

Where would you find hemoglobin that is relatively O2 poor in a healthy resting person? a. Systemic arteries & pulmonary veins b. Systemic veins & pulmonary arteries

Systemic veins & pulmonary arteries

Where would you find hemoglobin that is 65-70%% saturated with O2 in a healthy resting person? a. Systemic veins & pulmonary arteries b. Systemic arteries & pulmonary veins

Systemic veins & pulmonary arteries Great! During rest, tissue PO2 is 40 mmHg. Blood that loads oxygen in the pulmonary capillaries becomes fully saturated with O2 (hemoglobin saturated to maximum, effectively 100%). When blood arrives at the resting tissues and equilibrates, the blood achieves a PO2 of 40 mmHg. At 40 mmHg, hemoglobin is only 65-70% saturated (as determined by the oxygen-hemoglobin dissociation curve). Therefore, systemic venous blood is 65-70% saturated with oxygen. O2 does not leave the blood except at capillaries and so as blood flows through the heart from the systemic veins to the pulmonary arteries, no further oxygen is lost. Accordingly, pulmonary arterial blood has a PO2 =40 mmHg and also contains hemoglobin that is 65-70% saturated with oxygen.

Where would you find hemoglobin that is about 65% saturated with O2 in a healthy resting person?

Systemic veins & pulmonary arteries Great! During rest, tissue PO2 is 40 mmHg. Blood that loads oxygen in the pulmonary capillaries becomes fully saturated with O2 (hemoglobin saturated to maximum, effectively 100%, though often in the high 90's). When blood arrives at the resting tissues and equilibrates, the blood achieves a PO2 of 40 mmHg. At 40 mmHg, hemoglobin is only 65% saturated (as determined by the oxygen-hemoglobin dissociation curve). Therefore, systemic venous blood is 65% saturated with oxygen. O2 does not leave the blood except at capillaries and so as blood flows through the heart from the systemic veins to the pulmonary arteries, no further oxygen is lost. Accordingly, pulmonary arterial blood has a PO2 =40 mmHg and also contains hemoglobin that is 65% saturated with oxygen.

What would happen if intrapleural pressure became 0 mmHg when thoracic volume increased? a. The lungs would not expand b. Intrapulmonary pressure would become more negative c. The lungs would operate normally because this is the condition during rest

The lungs would not expand Right! Negative intrapleural pressure creates a suction between the lung and chest wall (thoracic body wall). The parietal pleura line the inside of the chest wall; the visceral pleura are the outermost layer of the lung. Between the two layers is some fluid that creates surface tension and a sucking pressure (negative pressure). This negative pressure keeps the lungs sucked against the chest wall. Because the chest wall has a greater volume than the lungs and a volume that cannot drop below the limits of the bony ribs, the lungs are always somewhat inflated (open). When the chest wall expands during inhalation, the intrapleural pressure becomes more negative (goes from -4 mmHg to -8 mmHg) thus pulling the lungs outward further (inflating the lung). If this pressure were to become 0 mmHg (meaning equal to atmospheric pressure), there would be no suck between the pleura and the lung would collapse due to its own elastic forces.

Which net direction does the CO2 equation move when the RBC is in the systemic capillary? a. To the right (to produce H+ & HCO3-) b. To the left (to produce CO2 & H2O)

To the left (to produce CO2 & H2O)

In normal, healthy individuals, the diaphragm moves superiorly during exhalation.

True

Think about the equation: HHb + O2 --> HbO2 + H+ when answering: The lower hemoglobin's affinity for oxygen, the more hemoglobin can prevent blood acidosis.

True Right!! Affinity here refers to hemoglobin's greediness for oxygen. When affinity is high, hemoglobin binds oxygen tightly and does not release it. When affinity is low, hemoglobin releases oxygen readily. High levels of CO2, H+ ions (low pH) and high temperature cause shape changes in hemoglobin molecules that decrease hemoglobin's affinity for oxygen. When hemoglobin releases an oxygen molecule, it provides a binding site on the hemoglobin for an H+. Free H+ cause pH to decline - creating acidosis - but H+ bound to a protein cannot affect pH (the binding protein buffers against pH changes). Hemoglobin does just this - it binds a H+ when oxygen affinity is low and acts to prevent acidosis of the body.

When would inspiratory air volume be lowest? (This is just the amount of air inhaled.) a. When intrapulmonary pressure = -1 mmHg b. When intrapulmonary pressure = -2 mmHg c. When intrapulmonary pressure = -5 mmHg d. When intrapulmonary pressure = -7 mmHg

When intrapulmonary pressure = -1 mmHg

In the pulmonary capillaries: a. oxygen combines with water to form bicarbonate ions and hydrogen ions b. the blood leaving the pulmonary capillaries is more acidic than the blood entering c. carbon dioxide must detach from hemoglobin to allow oxygen to bind d. hydrogen ions combine with bicarbonate ions to form carbon dioxide and water e. the lowest PO2 must be in red blood cell mitochondria

hydrogen ions combine with bicarbonate ions to form carbon dioxide and water Right! In the pulmonary capillaries oxygen loads into the blood and CO2 moves into the alveoli. CO2 is made in the systemic tissue mitochondria (there are no mitochondria in the RBCs) and transported away from tissue cells using the blood. Some CO2 dissolves in the plasma, some attaches to hemoglobin (NOT at the same binding site for oxygen) and the rest is converted to bicarbonate ions. The most conversion occurs inside RBCs where the enzyme carbonic anhydrase combines CO2 & water to create a hydrogen ion (H+) and bicarbonate ion (HCO3-). [Even though all the components of CO2 are found in bicarbonate ion, they are in the form of bicarbonate ion and not CO2.] The RBC then pushes bicarbonate out to the blood plasma and hemoglobin binds the H+. Some dissolved CO2 spontaneously combines with water to also make bicarbonate and H+ - acidifying the venous blood. The RBC then moves through the vascular tree up to the pulmonary capillaries. Once in the pulmonary capillaries, CO2 must move out of the blood into the alveoli for removal from the body. Bicarbonate ion cannot diffuse out of the blood into the alveolus, instead we need to "remake" CO2. To recreate CO2, bicarbonate ions combine with H+ and form CO2 and water in the RBC (also due to carbonic anhydrase). The CO2 then diffuses into the alveoli. The blood leaving the pulmonary capillary has less CO2 dissolved (because dissolved CO2 also moved into the alveoli) and therefore also has less free H+, making the pulmonary venous blood less acidic than the pulmonary arterial blood. O2 does not combine with water to make bicarbonate.