Ch 13. Gas Transfer in Air (Lungs and Other)

Question 1

2 things a gas-transfer system is influenced by

Answer 1

properties of the respiratory medium

requirements of the animal

Question 2

why is there such a big difference between lungs and gills

Answer 2

density and viscosity of water is 1000x that of air

water contains 1/13th as much O2 as air

Question 3

major difference btw lungs and gills

Answer 3

lungs: bidirectional movement of air into and out of the lungs
gills: unidirectional movement of water over the gills

Question 4

design objectives of gills

Answer 4

minimize diffusion distance

thin layer of water over the respiratory surface

Question 5

what does subdivision of the lung improve

Answer 5

increase in respiratory surface area per unit volume

Question 6

alveoli

Answer 6

many interconnected sacs that allow gas transfer to blood

Question 7

air ducts leading to respiratory portion of the lung are lined with _____

Answer 7

cilia

mucus is secreted by epithelium of ducts and moved by cilia to keep lungs clean

Question 8

type II cells

Answer 8

in lung epithelium

produce surfactants

Question 9

mixing of gases in ducts and alveoli occurs by what

Answer 9

diffusion

convection currents from breathing

Question 10

swan have really long necks…

Answer 10

high anatomic dead space so they have a larger tidal volume to maintain gas partial pressures

Question 11

amphibian Amphiuma

Answer 11

rises to the surface once an hour to breathe b/c it is preyed upon at the surface

tidal volume more than 50% of total lung capacity

large, slow oscillations in PO2

Question 12

O2 and CO2 levels in alveolar gas are determined by what 2 things

Answer 12

ventilation (breathing rate, tidal volume, anatomic dead space)

rate of gas transfer

Question 13

pulmonary circulation

Answer 13

deoxy blood from pulmonary artery enters the lung and gathers O2 and releases CO2

Question 14

in birds and mammals are blood pressures in the pulmonary circulation LOWER than those in systemic circulation?

Answer 14

yes

reduces filtration of blood into the lung

Question 15

why is there excessive lymph drainage from the lung

Answer 15

make sure fluid doesn’t collect so diffusion distance isn’t increased

Question 16

sheet flow

Answer 16

describes blood flow through pulmonary circulation

blood between two parallel surfaces of pulmonary capillaries

Question 17

if blood pressure increases, what happens to the sheet flow

Answer 17

the capillariy layers separate, leading to a thicker blood layer

Question 18

the lung apex is _______ than the base

Answer 18

higher

low flow to apex when vertical

more even flow distribution when horizontal

Question 19

if transmural pressure is negative

Answer 19

capillaries collapse and blood flow stops

Question 20

what does arterial blood pressure represent

Answer 20

blood flow

increases with distance from lung apex –> open capillaries and more flow at the base of the lung

Question 21

does reduced O2 levels/low pH cause vasoconstriction or vasodilation of pulmonary blood vessels

Answer 21

vasoconstriction

so blood will flow to better ventilated areas

Question 22

hypoxic pulmonary vasoconstriction via K channels

Answer 22

rapid onset due to inhibition of K channels, smooth muscle depol, and Ca release

Question 23

lung elasticity creates a pressure _______ atmospheric in the fluid-filled pleural space

Answer 23

below

Question 24

gas transfer in bird lungs

Answer 24

when breathing, volume changes in thoracic and abd air sacs, not the lungs

squeezing of air sacs moves air through parabronchi tubes

Question 25

valving in bird gas exchange

Answer 25

bidirectional flow through mesobronchus

unidirectional flow through parabronchi

Question 26

over 70% of the lung wall’s resistance to stretch is provided by

Answer 26

surface tension of fluid

Question 27

surfactants

Answer 27

lipoprotein complexes made by type II cells that give a low surface tension

Question 28

4 surfactant functions

Answer 28

low surface tension of alveoli so inflation is easier

prevent alveoli from sticking when deflated

so newborn babies can inflate lungs

reduce blood flow resistance

Question 29

3 things to do if a newborn doesn’t have surfactants (usually premature)

Answer 29

force air into lungs with positive pressure

surfactant replacement

pregnant women given cortisol injection –> stimulate type II cells in the fetus

Question 30

does increased lung ventilation cause increased heat and water loss?

Answer 30

yes

Question 31

cool, dry air entering the lungs is…

Answer 31

humidified with water vapor from nasal mucosa

heated from contact with blood

Question 32

nasal passage temperatures

Answer 32

cool at the tip and warmer toward the throat

high blood flow in a countercurrent system to maintain temp gradient

Question 33

why do animals exhale through the mouth

Answer 33

increase heat loss

at expense of water loss

Question 34

do gills use a unidirectional water flow system

Answer 34

yes

valves in the buccal cavity and opercular clefts maintain this

Question 35

why do water-breathing animals need a much higher ventilation rate

Answer 35

because the O2 content in water is much lower

uses more energy

Question 36

operculum

Answer 36

gill cover where water exits

Question 37

pathway for gill water flow

Answer 37

skeletal muscle pumps in the buccal and opercular cavities draw water into the mouth

passes over gills

exits through a cleft in the operculum

Question 38

is there a higher pressure in the buccal or opercular cavities

Answer 38

buccal

helps ensure unidirectional flow

Question 39

ram-ventilation

Answer 39

mouths are open while swimming to ventilate gills via forward motion

ex. tuna, remora

Question 40

blood flow through fish gills

Answer 40

sheet flow - pressure inc = thickness inc

concurrent, countercurrent, or a combination

Question 41

advantage of countercurrent blood and water flow

Answer 41

maintain a larger difference in PO2 so more gas is transferred

Question 42

is the flow rate of water across gills higher than blood?

Answer 42

yes, but O2 content of blood is higher in fish

Question 43

insect tracheal systems

Answer 43

air filled tubes - spiracles that are closed or open

Question 44

insect tracheal system flow

Answer 44

spiracles –> trachea –> tracheoles –> fluid in tips for O2 diffusion into flight muscles –> fluid dispersed

Question 45

diving insect O2 supply

Answer 45

air trapped in layers or body hair

from water

pO2 in air next to body is 100mmHg vs. pO2 of H2O is 150mmHg –> diffusion