Chapter 42 - Circulation and Gas Exchange
At sea level, atmospheric pressure is 760 mm Hg. Oxygen gas is approximately 21% of the total gases in the atmosphere. What is the approximate partial pressure of oxygen?
160.0 mm Hg
57) At an atmospheric pressure of 870 mm Hg, what is the contribution of oxygen?
182 mm Hg
A patient has a blood pressure of 120/75, a pulse rate of 40 beats/min, a stroke volume of 70 mL/beat, and a respiratory rate of 25 breaths/min. This personʹs cardiac output per minute will be
2,800 mL.
The average resting stroke volume of the heart is 70 mL and it beats ~72 times per minute. This would result in which cardiac output?
5 L/minute
A person with a tidal volume of 450 mL, a vital capacity of 4,000 mL, and a residual volume of 1,000 mL would have a potential total lung capacity of
5,000 mL.
At the summit of a high mountain, the atmospheric pressure is 380 mm Hg. If the atmosphere is still composed of 21% oxygen, what is the partial pressure of oxygen at this altitude?
80 mm Hg
If the atrioventricular node could be surgically removed from the heart without disrupting signal transmission to the Purkinje fibers, what would be the effect?
Atria and ventricles would contract at about the same time.
Breathing is usually regulated by
CO2 and O2 concentration and pH-level sensors.
Dialysis patients, who will have blood withdrawn, dialyzed, then replaced, are always weighed when they enter the facility and then weighed carefully again before they leave. What is the most likely explanation for this requirement?
Even small changes in body weight may signify changes in blood volume and therefore blood pressure.
What would be the long-term effect if the lymphatic vessels associated with a capillary bed were to become blocked?
Fluid would accumulate in interstitial areas.
How does the hemocyanin of arthropods and molluscs differ from the hemoglobin of mammals?
Hemocyanin has protein coupled to copper rather than iron.
The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in
How is most of the carbon dioxide transported by the blood in humans?
What would be expected if the amount of interstitial fluid surrounding the capillary beds of the lungs were to increase significantly?
The amount of oxygen entering the circulation from the lungs would decrease.
A species has a normal resting systolic blood pressure of >260 mm Hg. What is the most probable hypothesis?
The animal has a very long distance between heart and brain.
Why is the respiratory system of a bird more efficient than the human respiratory system?
The bird respiratory system does not mix exhaled air with inhaled air.
Cyanide acts as a mitochondrial poison by blocking the final step in the electron transport chain. What will happen to human red blood cells if they are placed in an isotonic solution containing cyanide?
The cells will probably be unaffected.
Which of the following features do all gas exchange systems have in common?
The exchange surfaces are moist.
What is the reason that fluid is forced from the bloodstream to the surrounding tissues at the arteriole end of systemic capillaries?
The hydrostatic pressure of the blood is greater than the osmotic pressure of the blood.
An oil-water mixture is used as a spray against mosquitoes. How might this spray also affect gas exchange in other insects?
The oil might block the openings into the tracheal system.
Which of the following is correct for a blood pressure reading of 130/80?
The systolic pressure is 130 and The diastolic pressure is 80.
Why is the velocity of blood flow the lowest in capillaries?
The total surface area of the capillaries is larger than the total surface area of the arterioles.
Which of the following occurs with the exhalation of air from human lungs?
The volume of the thoracic cavity decreases.
Why is gas exchange more difficult for aquatic animals with gills than for terrestrial animals with lungs?
Water contains much less O2 than air per unit volume.
Organisms in which a circulating body fluid is distinct from the fluid that directly surrounds the bodyʹs cells are likely to have which of the following?
a closed circulatory system
In an animal species known for endurance running rather than fast sprinting, which of the following would you expect?
a much higher rate of oxygen consumption for its size
Diffusion rate is proportional to the square of the distance molecules/ions travel. Which of the following would therefore be preferable for a mid-size multicellular organism?
a system to circulate gases, nutrients, and wastes to and from cells
Where do air-breathing insects carry out gas exchange?
across the membranes of cells
Which of the following is a normal event in the process of blood clotting?
activation of prothrombin to thrombin
A blood vessel has the following characteristics: outer layer of connective tissue, a thick layer of smooth muscle with elastic fibers, no valves. It is which of the following?
an artery
Emphysema is a disease, frequently caused by smoking, that results in loss of the elastic elements of lung tissue. The effect will be more like which of the following?
an increase in airway resistance
Where are semilunar valves to be found in the mammalian heart?
at the places where the anterior and posterior venae cavae enter
Which of the following is used to diagnose hypertension in adults?
blood pressure of >140 mm Hg systolic and/or >90 diastolic
The blood level of which gas is most important in controlling human respiration rate?
carbon dioxide
Large proteins such as albumin remain in capillaries rather than diffusing out. Which of the following does this cause?
creation of an osmotic pressure difference across capillary walls
Countercurrent exchange in the fish gill helps to maximize which of the following?
diffusion
Which of these speed up heart rate?
epinephrine
Which of these stimulate the production of red blood cells?
erythropoietin
The meshwork that forms the fabric of a blood clot consists mostly of which protein?
fibrin
Human plasma proteins include which of the following?
fibrinogen and immunoglobulin
Which of the following are the only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart?
fishes
If, during protein starvation, the osmotic pressure on the venous side of capillary beds drops below the hydrostatic pressure, then
fluids will tend to accumulate in tissues.
To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n)
four-chambered heart.
In which animal does blood flow from the pulmocutaneous circulation to the heart before circulating through the rest of the body?
frog
A nonfunctional sinoatrial node would
have little significant effect on stroke volume.
Hydrogen ions produced in human red blood cells are prevented from significantly lowering pH by combining with
hemoglobin.
Some human infants, especially those born prematurely, suffer serious respiratory failure. This most probably relates to which of the following?
inadequate production of surfactant
Which of the following is predicted in someone who smokes and whose diet includes significant trans fats?
increased blood vessel inflammation
Which of the following is a function of plasma proteins in humans?
maintenance of blood osmotic pressure
Which of these are involved in the early stages of blood clotting?
platelets
A group of students was designing an experiment to test the effect of smoking on grass frogs. They hypothesized that to keep the frogs in a smoke-filled environment for defined periods would result in lung cancer in the animals. However, when they searched for previously published information to shore up their hypothesis, they discovered they were quite wrong in their original assessment. Even though they were never going to go ahead with their experiment (so as not to harm frogs needlessly) they knew that a more likely outcome would be which of the following?
skin cancer
Which of the following is/are a cause(s) of vasoconstriction?
stress or hormone concentration
Tidal volume in respiration is analogous to what measurement in cardiac physiology?
stroke volume
An anthropologist discovers fossilized animal remains that give strong evidence that the organism had a large, well-formed, most likely 4-chambered heart, with no connection between the right and left sides. Which of the following could most reasonably be hypothesized from this observation?
that the animal had a high energy requirement and was endothermic
Which of the following is an example of countercurrent exchange?
the flow of water across the gills of a fish and that of blood within those gills
Air rushes into the lungs of humans during inhalation because
the rib muscles and diaphragm contract, increasing the lung volume.
Which of the following is measured by an electrocardiogram?
the spread of impulses from the SA node
Which of the following lung volumes would be different in a person at rest compared with when the person exercises?
tidal volume
Which of the following is a characteristic of both hemoglobin and hemocyanin?
transports oxygen
A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a cell in the thumb. From this point in the artery, how many capillary beds must this red blood cell pass through before it returns to the left ventricle of the heart?
two
Which sequence of blood flow can be observed in either a reptile or a mammal?
vena cava → right atrium → ventricle → pulmonary circuit
Average blood pressure is lowest in which structure(s)?
venae cavae
Which of the following would be described as a portal system?
vessel or vessels connecting two capillary beds
Damage to the sinoatrial node in humans
would disrupt the rate and timing of cardiac muscle contractions.
