lecture 19: c02 transport in blood

Question 1

As O2 is used for cellular metabolism what is formed

• “

Answer 1

CO2 is formed

Question 2

explain diffsuion of CO2 from peripheral tissuee to caps to alveoli

Answer 2

• As O2 is used for cellular metabolism, CO2 is formed
• “ intracellular PCO2 ¢ pressure gradient between cells and
interstitial fluid ¢ CO2 diffusion from cells into interstitial fluid
• “ interstitial fluid PCO2 ¢ pressure gradient between
interstitial fluid and tissue capillaries ¢ diffusion of CO2 into
capillaries
• CO2 is then carried by blood to lungs
• PCO2 is higher in pulmonary capillaries than in alveoli
(pressure gradient) ¢ CO2 diffuses from capillaries into
alveoli where it gets expired

Question 3

as intracellular PCO2 increase during to 02 being used for cellular metabolism, what is the pressure relationship and what does that means

Answer 3

increase PCO2
=pressure gradient b/w cells and interstial f;uid
=co2 diffusion from cells to interstial fluid

Question 4

as intersitaul fluid PCO2 increases what is the pressure relationship bewween interstial fluid and capilarries and what does that mean

Answer 4

“ interstitial fluid PCO2 
 pressure gradient between
interstitial fluid and tissue capillaries
 diffusion of CO2 into
capillaries

Question 5

true or false: PCO2 is higher in pulm caps than in alveoli?

Answer 5

true

Question 6

since PCO2 is higher in pulm caps than in alveli, what is the movement of CO2

Answer 6

PCO2 is higher in pulmonary capillaries than in alveoli
(pressure gradient) ¢ CO2 diffuses from capillaries into
alveoli where it gets expired

Question 7

in each point of the gas transport chain, co2 moves diffuses in THE SAME direction or OPPOSITEdirection as o2

Answer 7

opposite

Question 8

besides the direction of diffusion between o2 and co2, what ist he main difference in terms of diffusion

Answer 8

c02 can diffuse 24x faster than 02

Question 9

what diffused faster : c02 or o2

Answer 9

co2

Question 10

pressure gradients required to cause CO2
diffusion are much LOWER or HIGHER than the gradients required for
O2 diffusion

Answer 10

lower

Question 11

are pressure gradients required to cause CO2

diffusion or o2 diffusion higher in 02 or co2

Answer 11

02

Question 12

explain how co2 can move from inside a tissue cell to the tissue intersticual fluid even if there is only a difference in partial pressures of 1 mmHG

Answer 12

c02 has a mu ch higher sollubility which means its easier to push co2 thru the membrane which means you need a much lower partial pressure/pressure gradient to move co2

Question 13

what is the affect of blood flow on c02 pressure in interstial fluid

Answer 13

if there is decrased blood flow
=decrease co2 transport away from tisse
=increased pCO2

Question 14

what is the affect of tissue metabolic rate on c02 pressure in interstial fluid

Answer 14

increased tisse metabolic rate
=more c02 production
-increased PCO2

Question 15

what are the 3 forms of co2 transport in the blood

Answer 15

dissolved in plasma
in the form of bicarbonate ion
bound with hb and plasma proteinsi in RBC

Question 16

true or false; co2 Dissolved in plasma Accounts for a MAJOR part of total CO2 transported by blood to lungs

Answer 16

false, only minor part of transport

Question 17

how is the main way carbon dioxide is transported

Answer 17

in the form of bicarbonate ion

Question 18

explain how co2 is transported in the form of bicarbonate ion

Answer 18

CO2 reacts with H2O (catalyzed by carbonic anhydrase) to form
H2CO3 (carbonic acid) _ H2CO3 then dissociates into HCO3
-(bicarbonate) and H+

Question 19

true or false: you can only have oxygen on the hemoglobin molcule

Answer 19

false, you can also have c02

Question 20

explain co2 transport by HB and plasma proteins

Answer 20

CO2 reacts with amine radicals of Hb molecules to form

carbaminohemoglobin (CO2Hgb)

Question 21

the partial pressure of co2 is dtermined by what

Answer 21

the amount of co2 dissolved in plasma

Question 22

combination of co2 and hb is loose and reversible or non revernsible

Answer 22

reversible

Question 23

what is the bond of co2 on hb determined by

Answer 23

Bond depends on PCO2, so CO2 is easily released into

alveoli since PACO2 is lower than in pulmonary capillaries

Question 24

is more co2 transpirted on Hb or plasma proteins and why

Answer 24

Small amount of CO2 also reacts with plasma proteins
● Much less significant form of transport than bound to Hb
because quantity of these proteins in blood is ¼ that of Hb

Question 25

what is the Quantity of CO2 that can be carried from tissues to lung via
carbamino combination with Hb and plasma proteins:

Answer 25

– ~30% of total quantity of CO2 transported @ 15 ml/100 ml blood

Question 26

what is the haldene affect

Answer 26

The Haldane effect describes the shift in the CO2 dissociation curve caused by oxygenation of Hb
=binding between hemo and c02 is affected by o2 pressure

Question 27

As blood passes through the lungs, PO2 increases and O2
binds with Hb ¢ Hb becomes a stronger acid

● The increased acidity due to O2 binding to Hb causes the
following two effects:
what are the.2 effeects

Answer 27

CO2 attached to Hb (carbaminohemoglobin) is displaced, and free
CO2 diffuses through pulmonary capillary membrane into alveoli

– Also promotes H+ dissociation from Hb = excess H+ binds with
the bicarbonate ion HCO3- to form carbonic acid H2CO3
= H2CO3 dissociates into H2O and CO2
= CO2 is released from blood into
alveoli and, finally, into air

Question 28

ADD SLIDES 14-17

Answer 28

SNDAJN

Question 29

what does RER reflect

Answer 29

– Reflects % aerobic vs. % anaerobic metabolism

– Also reflects % substrate utilization

Question 30

what is the RER equation

Answer 30

R=rate of c02 output/rate of o2 uptake

RER=VCO2/VO2

RER= (V-A)CO2 diff/(A-V)O2 difference

Question 31

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