Chapter 18 Gas Exchange and transport

Question 1

normal alveolar and arterial PO2

Answer 1

about 100 mm Hg

Question 2

normal alveolar and arterial PCO2`

Answer 2

about 40 mm Hg

Question 3

normal venous PO2

Answer 3

about 40 mm Hg

Question 4

normal venous PCO2

Answer 4

about 46 mm Hg

Question 5

body sensors monitor blood oxygen, CO2, and pH in an effort to avoid

Answer 5

hypoxia and hypercapnia

Question 6

what affects alveolar PO2

Answer 6

composition of inspired air

effectiveness of alveolar ventilation

Question 7

what affects gas exchange efficiency and arterial PO2

Answer 7

changes in alveolar surface area, in diffusion barrier thickness, and in fluid distance between the alveoli and pulmonary capillaries

Question 8

amount of gas that dissolves in a liquid is proportional

Answer 8

to the partial pressure of the gas

and solubility of the gas in liquid

Question 9

CO2 is how many more times soluble in aqueous solutions than oxygen

Answer 9

20 x

Question 10

oxygen transported

Answer 10

less than 2% dissolved in plasma

greater than 98% bound to hemoglobin

Question 11

PO2 of plasma determines

Answer 11

how much oxygen binds to hemoglobin

Question 12

oxygen-hemoglobin binding is influenced by

Answer 12

pH
PCO2
temperature
2,3- BPG (DPG)

Question 13

venous blood carries CO2

Answer 13

7% dissolved in plasma

23% as carbaminohemoglobin

70% as bicarbonate ion in plasma

Question 14

Carbonic anhydrase in RBC converts

Answer 14

CO2 to H+ and HCO3-

the H+ ten binds to Hb, and HCO3- enters the plasma using the chloride shift

Question 15

Respiratory control

Answer 15

resides in networks of neurons in the medulla and pons

influence by input from Central and peripheral sensory receptors and higher brain centers

Question 16

medullary dorsal respiratory group (DRG)

Answer 16

contains mostly inspiratory neurons that control somatic motor neurons to the diaphragm

Question 17

ventral respiratory group (VRG)

Answer 17

includes the pre-botzinger complex with its pacemakers as well as neurons for inspiration and active expiration

Question 18

peripheral chemoreceptors

Answer 18

in carotid and aortic bodies

monitor PO2, PCO2, and pH

PO2 below 60 mm Hg triggers an increase in ventilation

Question 19

the primary stimulus for ventilation changes

Answer 19

CO2 is the primary

chemoreceptors in the medulla and carotid bodies respond to changes in PCO2

Question 20

protective reflexes

Answer 20

are monitored by peripheral receptors

they prevent injury to the lungs from inhaled irritants