3.2.7- Transport Of Oxygen Flashcards
What does ‘dissociation’ mean?
Releasing the oxygen from the oxyhemoglobin.
What is feral haemoglobin?
The type of haemoglobin usually only found in the fetus.
Explain that ‘haemoglobin’ is.
A protein that is the red pigment used to transport oxygen in the blood and is found in erythrocytes.
When, haemoglobin takes up oxygen, what does it become?
Oxyhemoglobin.
Explain the structure of a haemoglobin molecule.
It is a protein with four subunits- each of which consist of a polypeptide chain and a harm group that contains a single iron (Fe2+) ion.
What is the function of the Fe2+ ion in the haem group of haemoglobin?
To attract and hold the oxygen.
Each haem group can hold ______ oxygen molecule.
One.
How many oxygen molecules can be held in one haemoglobin molecule?
Four- one on each of the four haem groups.
The haem group in haemoglobin had a High ________ for oxygen molecules.
Affinity.
Oxygen binds _________ to haemoglobin.
Reversibly.
Explain the sequence of events simply that describe the transport of oxygen in the body.
Oxygen passes from the alveoli, to blood plasma and diffuse into RBC’s. Oxygen molecules bind to haemoglobin reversibly to make oxyhemoglobin that travels to the bodies tissues. Here oxyhemoglobin dissociates to release oxygen to body tissues.
Explain how the formation of oxyhemoglobin helps to allow more oxygen to flow into the blood from the alveoli.
It helps to maintain the steep concentration gradient as it removes oxygen from the blood when they diffuse into erythrocytes so more oxygen can diffuse in.
What does the ability of haemoglobin to associate with and release oxygen depend on?
The concentration of oxygen in the surrounding tissues.
What is the concentration of oxygen in the surrounding tissues measures in?
By the relative pressure it contributes to a mixture of gases- the partial pressure of oxygen (pO2)- aka the oxygen tension. Measured in kPa (units of pressure).
Explain what the haemoglobin dissociation curve is.
The partial pressure of oxygen in kPa (x) plotted against percentage saturation with oxygen (y).
What shape if the haemoglobin dissociation curve?
An S Shaped Curve.
At low oxygen tension, the haemoglobin does not…
Readily associate with oxygen molecules.
Explain why haemoglobin doesn’t readily associate with oxygen molecules at low oxygen tension.
Because the haem groups that attract the oxygen are at the centre of the haemoglobin molecule, making it difficult for the oxygen molecule to reach the haem group and associate with it.
As the oxygen tension rises, what else does?
The diffusion gradient into the haemoglobin molecule.
Explain what happens to the haemoglobin molecule once one oxygen molecule enters it and associates with one of the haem groups.
It causes a slight shape change in the haemoglobin molecules shape- called a conformal change.
Explain what affect the conformal change of the haemoglobin molecule will have on it.
It will allow more oxygen molecules to enter the haemoglobin molecule and associate with other haem groups relatively easily- this accounts for the steepness of the haemoglobin dissociation curve as oxygen tension rises.
What happens as the percentage saturation with oxygen approaches 100% saturation?
The haemoglobin dissociation curve starts to level off.
Why is the oxygen tension in respiring tissues low?
To cause oxygen to readily dissociate from oxyhemoglobin.
Compare the affinity for oxygen of adult and fetal haemoglobin.
Fetal has a higher affinity for oxygen than adult does.
Compare the positioning of the s shaped curve of the haemoglobin dissociation curve of adult and fetal haemoglobin.
For fetal, it is slightly to the Left of that of adult haemoglobin.
Explain why the haemoglobin dissociation curve for fetal haemoglobin is slightly to the left of the one for adult haemoglobin.
The fetal haemoglobin has a higher affinity for oxygen , therefore fetal haemoglobin is able to associate with oxygen in an environment where the oxygen tension is low enough to make adult haemoglobin dissociate with oxygen.
In the placenta, oxygen tension is ________.
Low
Explain the sequence of events that take place in the placenta, relating to oxygen tension and haemoglobin and why these things happen.
Oxygen tension’s low in the placenta- f.haemoglobin absorbs oxygen from the surrounding blood fluid, further lowering oxygen tension- causing oxygen to diffuse from the mothers blood into the placenta, which reduces the mothers blood’s oxygen tension to make the maternal haemoglobin dissociate with more oxygen, releasing it into her blood.
Define what ‘affinity’ means.
A strong attraction.
