Lecture 14 Unit 2

Question 1

What two forms can O2 be transported in?

Answer 1

• dissolved in the plasma (1.5% of total

- bound to the protein hemoglobin (98.5%)

Question 2

what does the extent to which O2 binds depend on?

Answer 2

the P(O2) in the plasma

Question 3

what does the oxy-hemoglobin dissociation curve tell us?

Answer 3

the relationship between the extend of oxygen binding to hemoglobin and the P(O2)

Question 4

What does the oxy-hemoglobin dissociation curve show us?

Answer 4

that the binding release from O2 from hemoglobin is critically dependent on the P(O2)

Question 5

What does lung P(O2) exceed?

Answer 5

the P(O2) in the blood that is entering the pulmonary capillaries

Question 6

What happens when lung P(O2) exceeds the P(O2) in the blood?

Answer 6

O2 diffuses into blood and binds to hemoglobin

Question 7

how does tissue P(O2) become low?

Answer 7

the release of O2 from hemoglobin

Question 8

What is the Bohr shift to the right caused by?

Answer 8

a reduction in blood pH, increases in blood PCO2 and increase in temperature

Question 9

What is the Bohr shift to the left caused by?

Answer 9

an increase in blood pH, decreases in blood PCO2 and decreases in temperature

Question 10

what is the importance of the Bohr shift?

Answer 10

the hemoglobins molecules will release more oxygen at any given PO2

Question 11

What happens with hemoglobin at tissue capillaries?

Answer 11

the hemoglobin in blood flowing though these vessels will release oxygen more readily

Question 12

How is CO2 transported?

Answer 12

it is released from active tissue cells then diffuses into the plasma and then into RBCs

Question 13

what two substances are formed in RBCs?

Answer 13

H2CO3 and carbaminohemoglobin

Question 14

how is 70% of total CO2 transported?

Answer 14

in plasma as bicarbonate ions

Question 15

how is 23% of the CO2 transported?

Answer 15

carbaminohemoglobin

Question 16

how is 7% of the CO2 transported?

Answer 16

it is dissolved in plasma

Question 17

what increases the rate of reaction of the formation of the bicarbonate ion?

Answer 17

carbonic anhydrase

Question 18

what GENERALLY happens in internal respiration and the chloride shift across RBCs

Answer 18

CO2 crosses the systemic capillary wall into the RBC and oxygen comes out. chloride goes into the RBC and the bicarbonate ion comes out

Question 19

what GENERALLY happens in external respiration and reverse chloride shift across RBCs?

Answer 19

O2 is inhaled and crosses the pulmonary capillary wall into the RBC. the bicarbonate ion goes into the RBC and chloride ion comes out. CO2 crosses the pulmonary capillary wall and is exhaled out

Question 20

what constitutes as a time dependent process?

Answer 20

oxygen loading at the pulmonary capillaries

Question 21

what does oxygen loading at the pulmonary capillary depend on?

Answer 21

the rate of gas diffusion and the rate of blood flow through the pulmonary capillaries or “transit time”

Question 22

how long does complete diffusion of oxygen take in a healthy lung in most alveolar capillary units?

Answer 22

0.25 seconds

Question 23

what is transit time at rest?

Answer 23

0.8 seconds

Question 24

what does transit time allow for?

Answer 24

plenty of time for oxygen diffusion