Chapter 39 Learning Curve

Hemoglobin is found as an iron-containing ('heme') compound that reversibly binds oxygen in a variety of invertebrate and vertebrate animals, as well as many leguminous plants. Which of the following were likely selection pressures that favored the evolution of hemoglobin?

1.Hemoglobins likely evolved very early in the tree of life among multicellular organisms sharing a common ancestral hemoglobin structure. The hemoglobins found in invertebrate and vertebrate animals have been subsequently modified over the course of evolution to provide varying properties for reversibly binding oxygen. 2.Hemoglobin increases the amount of oxygen that can be transported by an animal's circulatory system by binding oxygen and removing it from the plasma solution. 3.Hemoglobins show quite variable oxygen-dissociation curves that enable some hemoglobins to bind increasing amounts of oxygen molecules at lower pO2, whereas other hemoglobins bind increasing amounts of oxygen molecules at higher pO2. 4.Hemoglobin was formed as the result of a genetic mutation that allowed the globular protein to form chemical bonds with iron. Iron in turn can exist in an oxidized or reduced state, favoring the reversible binding of oxygen.

Imagine a planet that has a similar atmospheric pressure to Earth (760 mmHg), but different concentrations of gases in its atmosphere. On this hypothetical planet, oxygen makes up 10% of the atmosphere, carbon dioxide makes up 15%, and nitrogen makes up the remaining 75%. Based on this information, what is the partial pressure of oxygen on this new planet?

76 mmHg

Which of the following would NOT be considered a step in gas transport and/or gas exchange?

All of these choices are a step in gas transport and/or gas exchange.

Which of the following INCREASES the amount of oxygen that a fish can extract from the surrounding seawater?

All of these choices are correct.

You may have heard of "polar bears," or people who choose to swim in the ocean during the winter months (often for charity). What happens to arterioles in the feet of a "polar bear" when he or she first steps into ice-cold water?

Arterioles will likely constrict to prevent the "polar bear" from losing heat from his or her feet

Birds are able to extract more oxygen than mammals from an equal volume of air. Which of the following statements reflects why birds are able to do so?

Birds don't have air mixing in their lungs; air flows in a unidirectional manner across the lung surface for increased diffusion.

Which of the following statements is TRUE regarding CO2 in the mammalian bloodstream?

CO2 is mainly transported through the mammalian bloodstream in the form of bicarbonate ions or carbonic acid.

In mammals, bulk flow only refers to the movement of oxygen (either into or out of the lungs and within the bloodstream). Bulk flow never refers to the movement of carbon dioxide.

False

Which of the following statements is TRUE regarding respiration in mammals?

Gas exchange occurs in the alveoli. Respiration depends on contractions of the diaphragm. Respiration depends on changes in air pressure in the chest cavity.

A man visits a doctor, and discovers that, due to tumors, he needs to have both of his carotid bodies removed. How will their removal affect his body?

His body will not be able to sense the oxygen concentration of brain-bound blood.

Which of the following occurs during exhalation?

None of the answer options is correct.

If the partial pressure of oxygen (pO2) in a man's blood plasma decreased below that in his red blood cells, what would be the result?

Oxygen would diffuse out of his red blood cells, and less oxygen would be transported throughout his body.

Which of the following statements is FALSE?

Oxygenated and deoxygenated blood are mixed in the circulatory system of fishes

Which of the following statements is TRUE regarding respiration in birds?

Respiration depends on the movement of air through air sacs. Oxygen enters the bloodstream via crosscurrent exchange.

Imagine that a young girl suffers a horseback-riding injury, and one of her ribs punctures her diaphragm. How will this injury affect the girl's breathing?

The injury will make it more difficult to increase negative air pressure in her chest cavity, making inhalation more difficult.

Which of the following statements is FALSE?

The walls of the right ventricle are thicker than the walls of the left ventricle.

Which of the following statements is FALSE?

There is a complete separation of pulmonary and systemic circulation in amphibians and most reptiles

What function do collagen and elastin have in arteries?

They provide elastic rebound of the arterial wall to help smooth out blood flow.

Which of the following blood vessels play an important role in controlling blood flow to different regions of the body through the contraction and relaxation of smooth muscles in their walls?

arterioles

Cells in which of the following regions of the heart produce action potentials, thus orchestrating a "regular" heartbeat?

atrioventricular node

Which of the following types of blood vessels would have the greatest resistance to flow?

capillaries

In which of the following animals does blood flow directly from respiratory organs to tissues without first returning to the heart?

fish

In the heart of a reptile or amphibian, where would you expect to find oxygenated blood?

mixed with deoxygenated blood in a common ventricle in the left atrium

BP = CO × PR expresses the relationship between blood pressure (BP),cardiac output (CO), and peripheral resistance (PR), which is the resistance to flow offered by systemic blood vessels. All of the following changes would result in an increase in blood pressure EXCEPT:

parasympathetic input to the pacemaker.

What is the function of surfactant in the mammalian respiratory system?

reduction of surface tension in the fluid covering the alveoli

Blood entering the heart from the body passes through the heart chambers and lungs in the following order:

right atrium, right ventricle, lungs, left atrium, left ventricle

Which of the following organisms would be able to extract the GREATEST percentage of oxygen from their respiratory medium?

salmon

Which of the following will NOT pass through the phospholipid bilayer of a membrane?

sodium ions

As fluid moves through a vessel, which factors determine the flow resistance? (Select all that apply.)

the length of the vessel the radius of the vessel the viscosity of the fluid

Which of the following describes the CORRECT path of air through a bird's respiratory system?

trachea, posterior air sacs, lungs, anterior air sacs, trachea