Lesson 12: Topic 8 - O2 Transport

Question 1

what are the four steps of external respiration?

Answer 1

1. ventilation
2. O2 and CO2 exchange at the lungs
3. transport of the gases via blood
4. exchange at the tissues

Question 2

if we don’t have what, we cannot sustain life?

Answer 2

hemoglobin

Question 3

what are the two key methods of transport for oxygen in the blood?

Answer 3

1. physically dissolved (1.5%)
2. bound to hemoglobin (98.5%) - critical

Question 4

what is anemia?

Answer 4

they have a lower hemoglobin count so they have less oxygen being transported

Question 5

what is blood doping?

Answer 5

increasing the amount of hemoglobin that you have in order to transport O2

Question 6

what are the three key methods of transport in the blood for carbon dioxide?

Answer 6

1. physically dissolved (5-10%)
2. bound to hemoglobin (5-10%)
3. as bicarbonate (HCO3) (80-90%)

Question 7

haemoglobin combines with oxygen to form?

Answer 7

oxyhaemoglobin

Question 8

when does haemoglobin tend to combine with oxygen?

Answer 8

as oxygen diffuses from the alveoli into the pulmonary capillaries

Question 9

a small percentage of oxygen is dissolved in the _______.

Answer 9

plasma

Question 10

when we measure the partial pressure of O2, it is the O2 in the?

Answer 10

plasma

Question 11

when we measure the saturation of oxygen to hemoglobin, thats a percentage and?

Answer 11

the actual oxygen bound to hemoglobin

Question 12

in the setting of a high PO2, oxygen will?

Answer 12

bind to hemoglobin at the tissue level

Question 13

in the setting of a low PO2, oxygen will?

Answer 13

tend to jump off the hemoglobin (unbind) at the tissue level

Question 14

the dissociation of oxyhaemoglobin into haemoglobin and oxygen molecules occurs where?

Answer 14

at the tissue cells/levels

Question 15

at rest, how many ml of O2/min do we need in our blood for transport to our tissues for basal function?

Answer 15

250ml O2/min

Question 16

assuming the heart pumps 5L of blood/min and 3mL of oxygen is dissolved from every litre, how much ml O2/min is transported to our tissues without hemoglobin?

Answer 16

15ml/min (1-2%)

• we still need 235ml more that we can get from Hb

Question 17

what does one single hemoglobin consist of?

Answer 17

• 4 heme groups/molecule
• 4 O2 molecules can bind to one hemoglobin
• O2 binds to Fe 2+
• Hb lies in red blood cells (gives red colour)

Question 18

** hemoglobin binds how many ml of O2/g of Hb?

Answer 18

bind 1.34mils of O2 per gram of Hb

Question 19

hemoglobin concentrations in the blood is?

Answer 19

15g/100 ml of blood

Question 20

how many ml O2 / 100 ml blood? (Concentration of O2 in 100ml of blood

Answer 20

20.1 using the numbers from cards 18 and 19

Question 21

the answer from card 20 x heart pumps (5000ml blood/min) =

Answer 21

1005 ml O2/min at a resting state when we only needed 250ml

Question 22

what allows for way more oxygen to get into the bloodstream to be transported?

Answer 22

hemoglobin
- this is because partial pressures want an equilibrium, but an equilibrium of oxygen is not enough to sustain life in the bloodstream. so when oxygen binds to hemoglobin and becomes oxyhaemoglobin, it does not affect the partial pressure so it can diffuse without equilibrium until all the Hb are bound to an oxygen.

Question 23

what determines O2 carrying capacity?

Answer 23

1. total amount of hemoglobin
2. PO2 (alveolar and arterial)

Question 24

what in regards to hemoglobin depends on PO2?

Answer 24

• if all 4 O2 molecules are bound to Hb
• what percentage of Hb is saturated

Question 25

where is a PO2 of blood of 100mm Hb generally?

Answer 25

in the lungs

Question 26

where is a PO2 of blood of 40mm Hb generally?

Answer 26

right after gas exchange at the tissues

Question 27

where is the percent saturation of oxyhemoglobin (or oxygen to hemoglobin) high?

Answer 27

where the PO2 is high (generally at the level of the lungs)

Question 28

where is the percent saturation of oxyhemoglobin (or oxygen to hemoglobin) low?

Answer 28

where the PO2 is low (generally at the level of the tissue cells) - this is because at the tissue cells oxygen tends to dissociate from haemoglobin which is the opposite of saturation (PO2 is low after gas exchange to the tissues)

Question 29

at the tissue cells, oxygen tends to ______ from hemoglobin, the opposite of saturation.

Answer 29

dissociate

Question 30

at the tissue cells, oxygen tends to ______ from hemoglobin, the opposite of saturation.

Answer 30

dissociate

Question 31

what is happening as PO2 is dropping?

Answer 31

diffusion - so the oxygen hemoglobin will dissociate and O2 will diffuse into the cell

Question 32

there is a net diffusion of oxygen from the alveoli to the blood and occurs continuously until?

Answer 32

hemoglobin is as saturated as possible (97.5% at 100 mmHg)

Question 33

at the tissue cells, hemoglobin rapidly delivers oxygen into the?

Answer 33

blood plasma and on to the tissue cells

Question 34

an increase in carbon dioxide from the tissue cells into the systemic capillaries increases?

Answer 34

hemoglobin dissociation from oxygen (shifts the dissociation curve to the right)

Question 35

the shift of the curve to the right (more dissociation) is called?

Answer 35

the Bohr effect

Question 36

what can also produce the Bohr effect?

Answer 36

- higher temperatures - the production of 2.3-Bisphosphoglyceric acid (BPG) - these happen normally during exercise

Question 37

what is the main factor determining the percentage of hemoglobin saturation?

Answer 37

the partial pressure of oxygen (high PO2 is favouring oxygen binding)

Question 38

what are the two phases of an O2 dissociation curve?

Answer 38

- flat part - steep part

Question 39

the flat part of the O2 dissociation curve is generally where?

Answer 39

at the level of the lungs (pink part, essentially 50-100mmHg)

Question 40

the steep part of the O2 dissociation curve is generally where?

Answer 40

usually at the tissue cells (blue part, essentially 0-40mmHg)

Question 41

Hb affinity for O2 is ____ when % Hb saturation is low.

Answer 41

low - on the curve, it happens around the 40, x-axis

Question 42

as O2 binds to Hb, Hb affinity for O2?

Answer 42

increases - Hb changes shape O2, can bind to Fe2+(iron) in Hb

Question 43

high levels of oxygen favour?

Answer 43

binding

Question 44

Does oxyhemoglobin have pressure?

Answer 44

No. It does not count as a partial pressure of O2. If it did, partial pressure of O2 would be very high

Question 45

Where does hemoglobin lie?

Answer 45

red blood cells. Hb is what givens the red colour

Question 46

Lower levels of oxygen favour?

Answer 46

Unbinding

Question 47

Can we have a small drop in PO2 before we find a drop in our saturation?

Answer 47

Yes. However, as PO2 goes down, there tends to be a decreased affinity for O2 and its usually somewhere around 60-70mmHg of drop where it’s critically low and starts to favour unloading