Haemoglobin and Gas Transport Flashcards

1
Q

How much oxygen will dissolve in 1l of plasma?

A

3ml

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2
Q

What does the partial pressure tell us?

A
  • The amount of oxygen in solution- not bound to Haem.

- The force pushing the oxygen out of the alveoli and into the haemoglobin.

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3
Q

What is the partial pressure of oxygen in alveoli?

A

100mmHg

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4
Q

How much oxygen can we transport with Haemoglobin?

A

200ml/l

So with each CO = 200 x 5 = 1000ml per minute

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5
Q

How much oxygen do our cells need?

A

250ml of Oxygen per minute.

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6
Q

Define Co-operative binding

A

When one molecule of O2 is bound it increases the affinity of the Haemoglobin to other O2 molecules.

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7
Q

Does the Partial pressure change?

A

No

  • the high affinity of Haem pulls O2 out of solution
  • this maintains the partial pressure gradient
  • meaning o2 keeps entering the blood.
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8
Q

Name the main type of haemoglobin

A

Adult Haem= HbA

Makes up 92%

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9
Q

What are the other forms of Hb?

A

HbF = Foetal Haem= higher affinity than HbA
HbA2 (delta instead of beta)
Myoglobin- found in muscle cells.
HbA1 (a/b/c) - show the exposure to glucose

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10
Q

At 40mmHg what is the Haemoglobin saturation?

A

75%

Below 40mmHg = death zone.

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11
Q

Why is this important?

A

It means that even in places with a lower partial pressure of O2 the haemoglobin can still supply cells.

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12
Q

What effect does Anaemia have on Partial Pressure?

A

None- there is lower levels of Haemoglobin

But partial pressure only refers to the plasma.

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13
Q

What is the effect of lowering the affinity of Haemoglobin?

A
  • More O2 is offloaded to tissues

- The curve shifts to the right (need higher PaO2 to achieve same result)

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14
Q

What would lower the affinity of Hb?

A
  • High temperature
  • High PaCo2
  • Low pH
  • Higher 2,3-DPG
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15
Q

Why is Carbon Monoxide a problem?

A

It has an affinity which is 250x higher than O2

  • Symptoms- cherry red skin, hypoxia, anaemia, nausea.
  • treat with 100% O2
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16
Q

Name 5 types of Hypoxia

A

1) Hypoxic- not enough air (low ventilation)
2) Ischaemic (poor blood supply)
3) Anaemic (not enough oxygen carried in blood)
4) Histotoxic (poisoning- CO or cyanide)
5) Metabolic (exercise- demand exceeds supply)