Transport Of O₂ Flashcards Preview

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Flashcards in Transport Of O₂ Deck (11):
1

Haemoglobin

carries 4 oxygen molecules
protein
4 sub units
4 polypeptide chains
haem (non-protein) group in each = iron ion Fe²⁺
iron ion has high affinity (attraction to oxygen)

2

haemoglobin ___________ curve is _ shaped.
___ is plotted against ___

dissociation
S
pO₂
% saturation with O₂

3

use what key words when talking about haemoglobin and oxygen?

associates/dissociates with
binds with

4

how is the concentration of oxygen measured?

by relative pressure it contributes to mixture of gases
this is the partial pressure of oxygen or pO₂ also called oxygen tension
units kPa

5

What is the partial pressure of oxygen (pO₂)?

the relative pressure that it contributes to a mixture of gases

6

What is oxygen tension?

partial pressure of oxygen

7

What happens at low oxygen tension?

Haemoglobin doesn't readily associate with oxygen because the haem group is in the middle so oxygen molecules can't reach it. So there is a low saturation level of haemoglobin at low oxygen tensions.

8

What happens when oxygen tension rises?

The diffusion gradient into haemoglobin molecules increases.
When the first O₂ associates, a conformational change in haemoglobin occurs, then it easily allows more O₂ to bind. This causes the steepness of the curve as pO₂ rises.

9

What happens at high oxygen tension?

as approaches 100% saturation of haemoglobin, the curve levels off

10

_____ in lungs is _________, and ______ in ____ is _______ to _________

oxygen tension
high to produce close to 100% saturation
oxygen tension
tissues
low
cause oxygen to dissociate from oxyhaemoglobin

11

Fetal haemoglobin has a ___________ so the curve ___________.
This is because ______________.
In the placenta _______________.

higher affinity for oxygen

for haemoglobin dissociation, is to the left of the adult haemoglobin curve (is steeper so associates more easily to oxygen as low pO₂)

fetal haemoglobin must be able to associate with oxygen in an environment where oxygen tension is low enough to make adult haemoglobin dissociate with oxygen.

pO₂ is low, fetal H will absorb O₂ from surrounding tissues making pO₂ even lower, so O₂ diffuses from mother's blood fluid to placenta, reducing pO₂ in mother's blood. This makes maternal haemoglobin release more oxygen.