Which of the following statements is false?
|A)||Only arteries carry oxygenated blood.|
|B)||Both arteries and veins have a layer of smooth muscle.|
|C)||Both arteries and veins branch out into capillary beds.|
|D)||Precapillary sphincters regulate blood flow through capillaries.|
The lymphatic system is like the circulatory system in that they both
|A)||have nodes that filter out pathogens.|
|B)||have a network of arteries.|
|D)||are closed systems.|
A molecule of CO2 that is generated in the cardiac muscle of the left ventricle would not pass through which of the following structures before leaving the body?
In vertebrate hearts, atria contract from the top, while ventricles contract from the bottom. How is this accomplished?
|A)||The depolarization from the sinoatrial node proceeds across the atria from the top, while the depolarization from the atrioventricular node is carried to the bottom of the ventricles before it emanates over the ventricular tissue.|
|B)||The depolarization from the sinoatrial node is initiated from motor neurons coming down from our brain, while the depolarization from the atrioventricular node is initiated from motor neurons coming up from our spinal cord.|
|C)||Gravity carries the depolarization from the sinoatrial node down from the top of the heart, while contraction of the diaphragm forces the depolarization from the atrioventricular node to move from the bottom up.|
|D)||This statement is false; both contract from the bottom.|
Throughout evolution, natural selection has favored changes that optimize respiration mechanisms in animals. According to Fick's Law, which of the following changes would optimize the rate of diffusion, R?
|A)||decrease the surface area, A, over which diffusion takes place|
|B)||increase the distance, d, over which diffusion takes place|
|C)||increase the concentration difference, p, between the interior of the organism and the external environment|
|D)||increase the diffusion constant, D|
Which type of circulatory system regulation do some vertebrates employ to maintain body temperature in a cold environment?
|D)||nitric oxide production|
What is the stroke volume of a woman with a heart rate of 66 beats/minute and a cardiac output of 4.7 liters/minute?
If the total pressure of gas dissolved in blood plasma is 120 mm Hg, what is the partial pressure of nitrogen in the plasma? (Recall that air contains approximately 78% nitrogen.)
|A)||94 mm Hg|
|B)||42 mm Hg|
|C)||22 mm Hg|
|D)||78 mm Hg|
When you take a deep breath, your stomach moves out because:
|A)||swallowing air increases the volume of the thoracic cavity.|
|B)||your stomach shouldn't move out when you take a deep breath because you want the volume of your chest cavity to increase, not your abdominal cavity.|
|C)||contracting your abdominal muscles pushes your stomach out, generating negative pressure in your lungs.|
|D)||when your diaphragm contracts, it moves down, pressing your abdominal cavity out.|
If you hold your breath for a long time, body CO2 levels are likely to ____________, and the pH of body fluids is likely to _____________.