Lesson 12: Topic 8 - O2 Transport Flashcards
what are the four steps of external respiration?
- ventilation
- O2 and CO2 exchange at the lungs
- transport of the gases via blood
- exchange at the tissues
if we don’t have what, we cannot sustain life?
hemoglobin
what are the two key methods of transport for oxygen in the blood?
- physically dissolved (1.5%)
- bound to hemoglobin (98.5%) - critical
what is anemia?
they have a lower hemoglobin count so they have less oxygen being transported
what is blood doping?
increasing the amount of hemoglobin that you have in order to transport O2
what are the three key methods of transport in the blood for carbon dioxide?
- physically dissolved (5-10%)
- bound to hemoglobin (5-10%)
- as bicarbonate (HCO3) (80-90%)
haemoglobin combines with oxygen to form?
oxyhaemoglobin
when does haemoglobin tend to combine with oxygen?
as oxygen diffuses from the alveoli into the pulmonary capillaries
a small percentage of oxygen is dissolved in the _______.
plasma
when we measure the partial pressure of O2, it is the O2 in the?
plasma
when we measure the saturation of oxygen to hemoglobin, thats a percentage and?
the actual oxygen bound to hemoglobin
in the setting of a high PO2, oxygen will?
bind to hemoglobin at the tissue level
in the setting of a low PO2, oxygen will?
tend to jump off the hemoglobin (unbind) at the tissue level
the dissociation of oxyhaemoglobin into haemoglobin and oxygen molecules occurs where?
at the tissue cells/levels
at rest, how many ml of O2/min do we need in our blood for transport to our tissues for basal function?
250ml O2/min
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?
15ml/min (1-2%)
- we still need 235ml more that we can get from Hb
what does one single hemoglobin consist of?
- 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)
** hemoglobin binds how many ml of O2/g of Hb?
bind 1.34mils of O2 per gram of Hb
hemoglobin concentrations in the blood is?
15g/100 ml of blood
how many ml O2 / 100 ml blood? (Concentration of O2 in 100ml of blood
20.1 using the numbers from cards 18 and 19
the answer from card 20 x heart pumps (5000ml blood/min) =
1005 ml O2/min at a resting state when we only needed 250ml
what allows for way more oxygen to get into the bloodstream to be transported?
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.
what determines O2 carrying capacity?
- total amount of hemoglobin
- PO2 (alveolar and arterial)
what in regards to hemoglobin depends on PO2?
- if all 4 O2 molecules are bound to Hb
- what percentage of Hb is saturated
where is a PO2 of blood of 100mm Hb generally?
in the lungs
where is a PO2 of blood of 40mm Hb generally?
right after gas exchange at the tissues
where is the percent saturation of oxyhemoglobin (or oxygen to hemoglobin) high?
where the PO2 is high (generally at the level of the lungs)
where is the percent saturation of oxyhemoglobin (or oxygen to hemoglobin) low?
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)
at the tissue cells, oxygen tends to ______ from hemoglobin, the opposite of saturation.
dissociate
at the tissue cells, oxygen tends to ______ from hemoglobin, the opposite of saturation.
dissociate
what is happening as PO2 is dropping?
diffusion
- so the oxygen hemoglobin will dissociate and O2 will diffuse into the cell
there is a net diffusion of oxygen from the alveoli to the blood and occurs continuously until?
hemoglobin is as saturated as possible (97.5% at 100 mmHg)
at the tissue cells, hemoglobin rapidly delivers oxygen into the?
blood plasma and on to the tissue cells
an increase in carbon dioxide from the tissue cells into the systemic capillaries increases?
hemoglobin dissociation from oxygen (shifts the dissociation curve to the right)
the shift of the curve to the right (more dissociation) is called?
the Bohr effect
what can also produce the Bohr effect?
- higher temperatures
- the production of 2.3-Bisphosphoglyceric acid (BPG)
- these happen normally during exercise
what is the main factor determining the percentage of hemoglobin saturation?
the partial pressure of oxygen
(high PO2 is favouring oxygen binding)
what are the two phases of an O2 dissociation curve?
- flat part
- steep part
the flat part of the O2 dissociation curve is generally where?
at the level of the lungs (pink part, essentially 50-100mmHg)
the steep part of the O2 dissociation curve is generally where?
usually at the tissue cells (blue part, essentially 0-40mmHg)
Hb affinity for O2 is ____ when % Hb saturation is low.
low
- on the curve, it happens around the 40, x-axis
as O2 binds to Hb, Hb affinity for O2?
increases
- Hb changes shape O2, can bind to Fe2+(iron) in Hb
high levels of oxygen favour?
binding
Does oxyhemoglobin have pressure?
No. It does not count as a partial pressure of O2. If it did, partial pressure of O2 would be very high
Where does hemoglobin lie?
red blood cells. Hb is what givens the red colour
Lower levels of oxygen favour?
Unbinding
Can we have a small drop in PO2 before we find a drop in our saturation?
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
