E&T: Haemoglobin Flashcards

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1
Q

Haemoglobin

A

Large protein with quaternary structure, with 4 chains each containing a haem group with an iron ion.

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2
Q

Describe haemoglobins affinity for O2

A

High affinity - each molecule can carry 4 x oxygen

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3
Q

Describe the reaction between oxygen and haemoglobin in the lungs:

A

Haemoglobin + oxygen oxyhaemoglobin

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4
Q

Partial pressure of oxygen (pO2)

A

Measure of oxygen concentration

Greater concentration of dissolved oxygen = higher partial pressure

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5
Q

When does oxygen load onto haemoglobin?

A

Where there’s a high pO2

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6
Q

What happens when there is a high pO2?

A

Oxygen loads onto haemoglobin

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7
Q

What happens when there is a low pO2?

A

Oxyhaemoglobin unloads oxygen

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8
Q

What is the pO2 at the alveoli?

A

High - oxygen loads onto haemoglobin

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9
Q

What happens when cells respire?

A

Use up oxygen - lowers pO2

Allows red blood cells to deliver oxyhaemoglobin to respiring tissues

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10
Q

Where pO2 is high…

A

… haemoglobin has a high afinity for oxygen.

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11
Q

Where pO2 is low…

A

… haemoglobin has a low affinity for oxygen.

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12
Q

Why is the dissociation curve ‘S-shaped’?

A
  • When first O2 molecule combines, shape of Hb changes.
  • Makes it easier for more O2 molecules to join = steep curve in middle.
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13
Q

Affinity

A

Tendency to bind with oxygen

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14
Q

How does a higher partial pressure of CO2 affect haemoglobin?

A

Makes it give up oxygen more readily.

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15
Q

Explain the Bohr effect:

A
  • High concentration of CO2 causes oxyhaemoglobin curve to shift to the right
  • Affinity for oxygen decreases because acidic CO2 changes shape of haemoglobin
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16
Q

What does a higher pCO2 do to the dissociation curve?

A

Shifts to the right as rate of oxygen unloading increases.

17
Q

How does living in a low concentration of oxygen affect affinity?

A

Higher affinity - dissociation curve shifts left.

18
Q

How does being active and have a high oxygen demand affect haemoglobin?

A

Lowers affinity - dissociation curve to the right.