4.3.3 - Transporting carbon dioxide and oxygen Flashcards

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1
Q

Describe the structure of haemoglobin.

A

Made up of 4 polypeptide chains each with a haem group.
2 Alpha glucose chains. 2 Beta glucose chains.

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2
Q

What is haemoglobin known as when it’s oxygenated?

A

Oxyhaemoglobin

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3
Q

Role of haemoglobin.

A

Readily associates with oxygen in the lungs.
Readily dissociates with oxygen at respiring tissues.

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4
Q

Why is it easier for oxygen molecules to associate with haemoglobin after the first one is loaded?

A

The haemoglobin changes shape.

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5
Q

Why does it become more difficult for the 4th oxygen molecule to load?

A

Less chance - only one more oxygen molecule can load onto that haemoglobin molecule.

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6
Q

Where does the loading and unloading of oxygen occur?

A

Loading - The lungs
Unloading - Respiring tissues

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7
Q

What is the affinity of haemoglobin?

A

The chemical attraction of haemoglobin towards oxygen.

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8
Q

What does a high affinity of haemoglobin mean?

A

Takes up oxygen easily, releases less easily.

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9
Q

What is partial pressure?

A

The pressure exerted by a gas (the concentration)

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10
Q

In the graph showing the relationship between saturation of haemoglobin with oxygen and pp, why is the graph shallow at first?

A

The shape of haemoglobin makes it difficult for oxygen to load.

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11
Q

In the graph showing the relationship between saturation of haemoglobin with oxygen and pp, why does the graph get steeper in the middle?

A

The haemoglobin molecule changes shape after the first oxygen molecule binds making it easier for other oxygen molecules to bind.

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12
Q

In the graph showing the relationship between saturation of haemoglobin with oxygen and pp, why does the graph plateau?

A

Most binding sites are occupied so more unlikely for an oxygen molecule to find an empty binding site.

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13
Q

Describe how oxygen is transported, loaded and unloaded in the blood.

A

Haemoglobin carries oxygen
In red blood cells
Loading of O2 takes place in lungs
At a high PO2
Unloads at respiring tissues
At a low PO2
Unload at a higher C02 concentration.

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14
Q

What does a further left curve mean?

A

A greater affinity of haemoglobin for oxygen.

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15
Q

What happens to the affinity of haemoglobin for oxygen at high PCO2?

A

It is reduced, enables more oxygen to be unloaded at respiring tissues.

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16
Q

Which way will the graph shift if carbon dioxide concentration is increased?

A

Shift right.

17
Q

What is the Bohr effect?

A

The greater the concentration of carbon dioxide, the more readily haemoglobin unloads oxygen.

18
Q

Features of fetal haemoglobin.

A

Higher affinity for oxygen at the same PO2 as adult Hb.
Loads at a PO2 which adult Hb deloads.

19
Q

Features of myglobin

A

Higher affinity for O2 than fetal Hb
Stores O2 in muscle
Only unloads when oxygen concentration is very low.
Found in human muscles.

20
Q

Is the fetal Hb curve to the left or right of the adult Hb curve?

A

Left - greater affinity

21
Q

Is the myoglobin curve to the left or right of the adult Hb curve?

A

Left