respiration gas transport

Question 1

what enters and leaves blood in the pulmonary circuit?

Answer 1

• O2 enters
• CO2 leaves

Question 2

what enters and leaves blood in the systemic circuit?

Answer 2

• O2 leaves
• CO2 enters

Question 3

textbook values

Question 4

what process do gases use to move through the respiratory system?

Answer 4

diffusion

Question 5

what are the unique features of the respiratory and circulatory systems to facilitate gas diffusion?

Answer 5

• Large surface area for gas exchange.
• Large partial pressure gradients.
• Gases with advantageous diffusion properties.
• Specialised mechanisms for transporting O2 and CO2 between lungs and tissues.

Question 6

what are partial pressures?

Answer 6

the concentration of a gas within a mixture of gases

Question 7

partial pressure no. s

Question 8

what are the two forms in which O2 is carried in the blood?

Answer 8

• dissolved (smaller %)
• bound to haemoglobin (Hb)

Question 9

what is the amount of O2 dissolved in the blood proportional to?

Answer 9

its partial pressure

Question 10

where is haemoglobin found?

Answer 10

red blood cells

Question 11

how many haem groups are in haemoglobin?

Answer 11

4 (two alpha and two beta polypeptide chains)

Question 12

what does each haem group contain?

Answer 12

iron in the reduced ferrous form (Fe+++)

Question 13

where is the site of O2 binding on haemoglobin?

Answer 13

iron

Question 14

how much haemoglobin is on each rbc?

Answer 14

280 million per rbc

Question 15

how much haemoglobin is on each rbc?

Answer 15

280 million per rbc

Question 16

why is it necessary for binding and dissociation of O2 with Hb to be done in milliseconds?

Answer 16

RBCs are only in capillaries for 1 second

Question 17

what factors can affect oxygen haemoglobin binding?

Answer 17

pH and temperature

Question 18

is oxygen binding to haemoglobin reversible?

Answer 18

yes

Question 19

when is haemoglobin almost 100% saturated?

Answer 19

100mmHg PO2

Question 20

what partial pressure of oxygen begins to have an effect on Hb saturation?

Answer 20

<60mmHg PO2

Question 21

what happens to Hb binding below 60mmHg PO2?

Answer 21

large amount of O2 is released from Hb facilitating release into tissues

Question 22

how many O2 atoms can each haemoglobin molecule bind?

Answer 22

4

Question 23

what is total O2 capacity?

Answer 23

211mls O2/ 1litre of blood

Question 24

what is SaO2?

Answer 24

to the amount of O2 bound to Hb relative to maximal amount that can bind

Question 25

how many ml of oxygen can Hb transport compared to dissolved oxygen in the blood?

Answer 25

Hb can transport 208ml
Dissolved can only transport 3ml

Question 26

what can be used to measure O2 saturation in clinic?

Answer 26

pulse oximeters

Question 27

how does a pulse oximeter measure O2 saturation?

Answer 27

it measures the ratio of absorption of red and infrared light by oxyHb and deoxyHb

Question 28

what is the respiratory exchange ratio?

Answer 28

ratio of expired CO2 to O2 uptake
in normal conditions it is 0.8

Question 29

what are the three forms in which CO2 is carried in the blood?

Answer 29

• 7% dissolved
• 23% bound to haemoglobin
• converted to bicarbonate

Question 30

what % of CO2 transports in the blood through RBCs?

Answer 30

93%

Question 31

what enzyme converts CO2 into H2CO3?

Answer 31

carbonic anhydrase

Question 32

what can the conversion of CO2 to bicarbonate affect?

Answer 32

the pH of blood

Question 33

systemic/pulmonary transport of CO2

Question 34

what does the conversion of CO2 to bicarbonate act as?

Answer 34

a buffer

Question 35

what is the main way CO2 is carried around the body?

Answer 35

as bicarbonate