Chapter 49: Gas exchange

Question 1

respiratory gases

Answer 1

animals must exchange oxygen and carbon dioxide

Question 2

partial pressures

Answer 2

concentrations of different gasses in a mixture

Question 3

adaptation that maximize respiratory gas exchange

Answer 3

1. increase SA
2. maximize the partial pressure difference driving diffusion
3. minimize the diffusion path length
4. minimize the diffusion that takes place in an aqueous medium

Question 4

external gill

Answer 4

highly branched and folded extensions of the body surface that provide a large surface area for gas exchange

Question 5

lungs

Answer 5

internal cavities for respiratory gas exchange with air

Question 6

dead space

Answer 6

the air remaining in lungs and airways after exhalation

Question 7

tidal

Answer 7

air flows in and exhaled gases flow out by the same route, causing dead space

Question 8

tidal volume

Answer 8

the amount of air that moves in and out per breath when at rest

Question 9

larynx

Answer 9

houses the vocal cords

Question 10

during inhalation

Answer 10

diaphragm contracts
thoracic cavity expands
intrapleural pressure becomes more negative
lungs expand 
air rushes in

Question 11

during exhalation

Answer 11

diaphragm relaxes
thoracic cavity contracts
intrapleural pressure becomes less negative
lungs contract
gases in lung are expelled

Question 12

surfactant

Answer 12

substance that reduces the surface tension of a liquid

Question 13

thoracic cavity

Answer 13

closed compartment bounded at the bottom by the diaphragm

lungs suspended in thoracic cavity

Question 14

pleural membrane

Answer 14

continuous sheet of tissue surrounding the lungs

Question 15

intercostal muscles

Answer 15

muscles between the ribs

Question 16

hemoglobin

Answer 16

a protein consisting of four polypeptide subunits, each of which surrounds a heme group

Question 17

myoglobin

Answer 17

oxygen binding molecule
located in muscle cells
one polypeptide chain with an iron-containing ring structure
higher affinity for oxygen than hemoglobin

Question 18

Bohr effect

Answer 18

influence of pH on the function of hemoglobin

decreased pH decreases affinity hemoglobin affinity for oxygen

Question 19

fetal hemoglobin affinity for oxygen

Answer 19

higher than mothers, so it can “steal” oxygen from mom in the placenta

Question 20

most important feedback stimulus for breathing?

Answer 20

level of carbon dioxide in the blood

Question 21

Chemoreceptors on the surface of medulla are sensitive to what?

Answer 21

partial pressure of CO2 and the pH or the cerebrospinal fluid

Question 22

Chemoreceptors on the carotid bodies are sensitive to what?

Answer 22

oxygen in the blood