Physiology Chapter 18
How much oxygen can half gram of hemoglobin carry at 100% saturation?
0.67 milliliters
You have decided to ascend to the summit of Mount Everest, where the partial pressure of oxygen in the atmosphere has been estimated to be about 54 mmHg. Recall that when this air arrives in the alveoli, the partial pressure of oxygen drops even lower because of displacement by the partial pressure of carbon dioxide and water vapor. The arterial concentration of oxygen at the pulmonary capillaries is measured and found to be 25 mmHg. What is the percent saturation of hemoglobin at this partial pressure?
45%
Using the oxygen dissociation curve, determine the percent saturation of hemoglobin at a partial pressure of 50 mmHg?
85%
Approximately what percentage of the total blood oxygen is bound to hemoglobin instead of dissolved in plasma?
98%
In which form is most carbon dioxide transported in the blood?
As bicarbonate ion
Changes in the amount of __________ are the main stimulus driving changes in ventilation.
CO2
Which change would cause a shift to the left in the oxygen-hemoglobin binding curve?
Decreased temperature
Which characteristic makes hemoglobin's structure such a good match for its function as an oxygen carrier?
Each hemoglobin molecule can bind four oxygen molecules.
What is the main difference between fetal and adult hemoglobin?
Fetal hemoglobin has a higher affinity for oxygen.
Use the oxygen-dissociation curve below to answer the following question. How does affinity to hemoglobin in fetal blood compare to maternal blood and what does this mean regarding oxygen loading to hemoglobin?
Fetal hemoglobin has an increased affinity to oxygen, which means that it is more saturated than maternal hemoglobin at any given partial pressure of oxygen.
A patient with an opioid overdose has a decreased ventilation rate. Which of the following would you expect?
Increased carbon dioxide in the blood and decreased pH
Choose the combination of factors that would lead to the greatest oxygen unloading from hemoglobin.
Low pH, high temperature, high PCO2, high 2,3-BPG
What is the significance of the shape of the oxygen-hemoglobin dissociation curve?
Only significant changes in the partial pressure of oxygen will result in significant changes to hemoglobin saturation.
Emphysema causes a loss of walls between individual alveoli, resulting in fewer, but larger, alveoli. Which part of gas diffusion would be most affected by emphysema?
Surface area
What is the chloride shift?
The exchange of bicarbonate for Cl- ions in red blood cells, causing HCO3- to leave the cell
The relationship between hemoglobin and oxygen is dependent on the affinity between the two molecules, which describes the degree to which hemoglobin will bind oxygen. There are several factors that can change hemoglobin's affinity for oxygen, including the partial pressure of carbon dioxide, temperature, and plasma pH. Which of the following best describes the affinity between oxygen and hemoglobin?
The higher the affinity, the more likely it is that oxygen binds to hemoglobin.
The expiratory neurons control the ________ muscles, whereas the inspiratory neurons control the ________ muscles.
abdominal muscles and internal intercostals, diaphragm and external intercostals
From which structures do oxygen molecules move from the lungs to the blood?
alveoli
increased airway resistance
asthma
Most of the carbon dioxide in the blood is transported as
bicarbonate ions
The chloride shift occurs when
bicarbonate ions leave the red blood cells.
Most of the oxygen transported by the blood is
bound to hemoglobin.
About 23% of the carbon dioxide in blood is carried __________.
by hemoglobin, bound to amino groups
The most important chemical regulator of respiration is
carbon dioxide
Of the factors that influence diffusion of respiratory gases, the most variable and, therefore, important factor to consider is the
concentration gradient.
Protective reflexes of the lungs include
coughing and bronchoconstriction.
How does a rightward shift in the oxygen hemoglobin dissociation curve affect hemoglobin's affinity to oxygen?
decrease
Match the factor with its effect on the affinity of hemoglobin for oxygen. increased 2,3-DPG
decrease
Match the factor with its effect on the affinity of hemoglobin for oxygen. increased PCO2
decrease
Match the factor with its effect on the affinity of hemoglobin for oxygen. increased temperature
decrease
The process by which dissolved gases are exchanged between the blood and interstitial fluids is
diffusion
decreased surface area for gas exchange
emphysema
destruction of alveoli
emphysema
If the partial pressure of oxygen in both air and water is 100 mm Hg, then the concentration of the oxygen is the same in the air and water.
false
thickened alveolar membrane and decreased lung compliance
fibrotic lung disease
High carbon dioxide concentration in body fluids is called
hypercapnia
Central chemoreceptors that monitor cerebrospinal fluid will stimulate an increase in ventilation __________.
if either CO2 or H+ increases (resulting in decreased pH)
Match the factor with its effect on the affinity of hemoglobin for oxygen. increased pH
increase
A inhibitor of carbonic anhydrase would
increase blood pH.
Carbon dioxide is more soluble in water than oxygen. To get the same amount of oxygen to dissolve in plasma as carbon dioxide, you would have to
increase the partial pressure of oxygen.
An increase in the level of carbon dioxide in the blood will
increase the rate of breathing.
Which would make the oxygen-hemoglobin curve shift right?
increased H+ concentration
The Hering-Breuer reflex
limiting ventilation volumes.
Chemoreceptors that monitor O2,CO2, and pH are located in the __________.
medulla oblongata, carotid arteries, and aorta
What will happen to the amount of oxygen that dissolves in plasma with no hemoglobin present?
no change
Because this factor normally varies, the most important variable that influences the diffusion of respiratory gases is the __________.
pressure or concentration gradient
fluid accumulation in interstitial spaces
pulmonary edema
increased diffusion distance
pulmonary edema
Which of the following describes the shape of the oxygen-hemoglobin dissociation curve?
sigmoidal
What is the main mechanism by which gases move from the alveoli into the blood and cells and back?
simple diffusion
During inhalation,
the diaphragm and rib muscles contract.
