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Chapter 42

Circulation and Gas Exchange

Gas exchange in the aquatic salamander known as the axolotl is correctly described as simple diffusion of oxygen into the salamander from the water.
Circulatory systems compensate for the slow rate at which diffusion occurs over large distances.
The fluid that moves around in the circulatory system of a typical arthropod is the interstitial fluid.
The circulatory system of bony fishes, rays, and sharks is similar to the portal systems of mammals, where two capillary beds occur sequentially, without passage of blood through a pumping chamber.
The only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart are the fishes
Which of the following develops the greatest pressure on the blood in the mammalian aorta? systole of the left ventricle
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. To travel from the artery in the arm to the left ventricle, this red blood cell must pass through 2 capillary beds
Which of the following is the correct sequence of blood flow in reptiles and mammals? vena cava → right atrium → right ventricle → pulmonary circuit
The semilunar valves of the mammalian heart prevent backflow of blood in the aorta and pulmonary arteries.
Heart rate will increase in the presence of increased epinephrine.
An increased concentration of nitric oxide within a vascular bed is associated with vasodialation
Small swollen areas in the neck, groin, and axillary region are associated with increased activity of the immune system.
Among the following choices, which organism likely has the highest systolic pressure? giraffe
The velocity of blood flow is the lowest in capillaries because the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system.
What will be the long-term effect of blocking the lymphatic vessels associated with a capillary bed? the accumulation of more fluid in the interstitial areas
The diagnosis of hypertension in adults is based on the blood pressure being greater than 140 mm Hg systolic and/or >90 diastolic.
Vasoconstriction of blood vessels delivering blood to the gut is a likely response when an individual is stressed and secreting stress hormones.
In a healthy human, the typical life span of a red blood cell is 4 months
The hormone that stimulates the production of red blood cells, and the organ where this hormone is synthesized, are erythropoietin and kidney, respectively.
Dissolved proteins in human plasma include which of the following? I. fibrinogen II. hemoglobin III. immunoglobulin I and III only
Cyanide poisons mitochondria by blocking the final step in the electron transport chain. Human red blood cells placed in an isotonic solution containing cyanide are likely to be unaffected.
The production of red blood cells is stimulated by erythropoietin.
The meshwork that forms the fabric of a blood clot is fibrin
The epiglottis of a human covers the glottis when he or she is swallowing
In mammals, most gas exchange between the atmosphere and the pulmonary blood occurs in the alveoli.
Countercurrent exchange is evident in the flow of water across the gills of a fish and that of blood within those gills.
Countercurrent exchange in the fish gill helps to maximize diffusion
Air-breathing insects carry out gas exchange across the finest branches of the trachea and cell membranes
Some human infants, especially those born prematurely, suffer serious respiratory failure because of lung collapse due to inadequate production of surfactant.
Air rushes into the lungs of humans during inhalation because the rib muscles and diaphragm contract, increasing the lung volume.
Breathing is usually regulated by CO2 and O2 concentration and pH-level sensors
Carbon dioxide levels in the blood and cerebrospinal fluid affect its pH. This enables the organism to sense a disturbance in gas levels as the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing.
Most carbon dioxide is carried from the body tissues to the lungs _____. as bicarbonate ions (HCO3 -)
By picking up hydrogen ions, hemoglobin prevents the blood from becoming too _____. acidic
True or false? The lungs of humans form from the embryonic foregut. True
True or false? The pressure inside the human chest cavity is always positive, so the lungs stay relatively inflated even upon exhalation False
True or false? The driving force for the unloading of oxygen from hemoglobin into tissues is the difference in PCO2 levels between the blood and body tissues. False
To become bound to hemoglobin for transport in a mammal, atmospheric molecules of oxygen must cross 5 membranes
An "internal reservoir" of oxygen in rested muscle is found in oxygen molecules bound to myoglobin
Most of the carbon dioxide produced by humans is converted to bicarbonate ions by an enzyme in red blood cells.
A portal system is vessel or vessels connecting two capillary beds.
Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have closed circulatory system
Sponges, cnidarians, and flatworms lack a specialized gas exchange surface because nearly all of their cells are in direct contact with the external environment.
Pulse is a direct measure of heart rate
Created by: 1482847251



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