Section IX: Homeostasis

Question 1

Chapter 51 Fetal and Neonatal Oxygen Transport

The vascular channel that allows fetal blood to pass from the pulmonary artery to the aorta is known as the:

a. Foramen ovale
b. Ductus arteriosus
c. Ductus venosus
d. Fetal cotyledon
e. Allantois

Answer 1

B

Question 2

Which of the following is the correct sequence of events that follow birth?
a. Closure of foramen ovale, first breath, rupture of umbilical vessels
b. Decrease in right atrial pressure, first breath, closure of the ductus arteriosus
c. First breath, closure of the ductus arteriosus, decrease in pulmonary arterial pressure
d. First breath, decrease in pulmonary arterial pressure, closure of the foramen ovale
e. Closure of the foramen ovale, closure of the ductus arteriosus, first breath

Answer 2

D

Question 3

Which of the following fetal blood structures contains blood with the highest PO2?

a. Aorta
b. Ductus arteriosus
c. Pulmonary artery
d. Left ventricle
e. Umbilical artery

Answer 3

D

Question 4

Which of the following statements about the fetal circulation is true?

a. Right atrial pressure is higher than left atrial pressure
b. Pulmonary vascular resistance is high
c. The placenta receives about 45% of the combined output of both ventricles
d. The output of the right ventricle is greater than that of the left ventricle
e. All the above

Answer 4

E

Question 5

Which of the following does not correctly describe the lung in utero?

a. Type II cells, which produce surfactant, are present within the first few days of gestation in sheep.
b. Chloride-rich fluid is secreted into the airways and flows into the amniotic cavity.
c. Components of surfactant can be detected in the amniotic fluid when the lung approaches maturity.
d. All the major branches of the tracheobronchial tree are present at birth, but alveoli continue to multiply after birth
in some species.
e. Breathing movements occur in utero, but the volume of fluid moved in and out of the lungs is small.

Answer 5

A

Question 6

Fetal O2 transport is assisted by:

a. Fetal hemoglobin, which has a lower O2 capacity than adult hemoglobin.
b. Fetal hemoglobin, which has a lower P50 than adult hemoglobin.
c. A cardiac output that is less per kilogram of body weight than in the adult.
d. A cardiac output that preferentially delivers the blood with the highest PO2 to the placenta.
e. A fetal lung, which is an efficient gas exchanger.

Answer 6

B

Question 7

Which of the following domestic mammals has a diffuse, epitheliochorial placenta in which fetal and maternal blood
flow is countercurrent in the microcotyledons?

a. Dog
b. Cow
c. Horse
d. Rabbit
e. Sheep

Answer 7

C

Question 8

Chapter 52 Acid-Base Homeostasis

Elevated PaCO2, low pH, and no base excess or deficit are characteristic of:

a. Acute respiratory acidosis
b. Acute respiratory alkalosis
c. Metabolic acidosis
d. Metabolic alkalosis
e. None of the above

Answer 8

A

Question 9

Elevated PaCO2, alkaline pH, and base excess are characteristic of:

a. Chronic respiratory acidosis
b. Chronic respiratory alkalosis
c. Metabolic acidosis
d. Metabolic alkalosis
e. None of the above

Answer 9

D

Question 10

Low PaCO2, acidic pH, and base deficit are characteristic of:

a. Chronic respiratory acidosis
b. Acute respiratory alkalosis
c. Metabolic acidosis
d. Metabolic alkalosis
e. None of the above

Answer 10

C

Question 11

The most likely acid-base disturbance to be found in a dog at the top of Mount McKinley (Denali) in Alaska (height, 20,320
ft [6353 m]) is:

a. Respiratory acidosis
b. Respiratory alkalosis
c. Metabolic acidosis
d. Metabolic alkalosis
e. None of the above

Answer 11

B

Question 12

The distal tubule of the kidney affects acid-base balance by:

a. Altering the pKa of the HCO3−/H2CO3 buffer
b. Concentrating CO2 in the renal tubular cell
c. Generating new HCO3−
d. Using ammonia to buffer H+
e. Both c and d

Answer 12

E

Question 13

Which of the following buffers will be most effective in blood (pH = 7.4)?

a. HX/X−, pKa = 4.2, plentiful
b. HY/Y−, pKa = 7.2, scarce
c. HZ/Z−, pKa = 9.6, scarce
d. HW/W−, pKa = 7.6, plentiful
e. HA/A−, pKa = 10.2, plentiful

Answer 13

D

Question 14

Chapter 53 Thermoregulation

Sweating is an effective cooling mechanism because:

a. Sweat secretion produces heat, which is carried to the skin surface in the sweat.
b. Conversion of sweat into water vapor requires heat, which is supplied to the skin by blood flow.
c. Sweat dripping from the body carries away large amounts of heat.
d. The ions in sweat carry large amounts of heat from the body.

Answer 14

B

Question 15

In the cold, animals both conserve and produce heat. Which of the following is a method of heat conservation?

a. Shivering
b. Brown fat metabolism
c. Increased thyroxine secretion
d. Countercurrent heat exchange in the limbs
e. All the above

Answer 15

D

Question 16

Which of the following methods of heat loss can occur in an animal (body temperature = 38° C) standing in a room (temperature = 40° C) with relative humidity of zero? The walls of the room have a temperature of 30° C.

a. Convection and evaporation
b. Convection and radiation
c. Evaporation and radiation
d. Radiation alone
e. Convection, evaporation, and radiation

Answer 16

C

Question 17

Which of the following describes thermoregulation?

a. Temperature receptors in both the brain and the skin can initiate thermoregulatory responses.
b. The brain temperature receptors have a greater influence on thermoregulation than do skin receptors
c. The core temperature at which shivering begins is higher if
the skin is cold than if it is warm.
d. Skin cooling can initiate shivering even if core temperature is normal.
e. All the above.

Answer 17

E

Question 18

Which of the following correctly describes fever?

a. It results when the set point for body temperature decreases.
b. It is accompanied by sweating to lose heat as body temperature rises.
c. It is accompanied by shivering to gain heat as body temperature decreases when pyrogens are metabolized.
d. It can be initiated by pyrogens from bacteria or leukocytes.
e. All the above

Answer 18

D