6 Oxygen in the Blood Flashcards

1
Q

Does this diagram show the dissociation curve for haemoglobin or myoglobin?

A
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2
Q

What are the 2 haemoglobin ‘moods’?

A
  1. Tense - low affinty for oxygen - T state
    1. When partial pressure of O2= low

(as each O2 binds, molecule more relaxed)

  1. Relaxed- high affinity for oxygen - R state
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3
Q

Why is the haemoglobin dissociation curve sigmoid shaped?

A

Hb molecule ‘more stable’ with either 4 O2 bond or none.

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4
Q

What is the normal oxygen content of th blood?

A

8.8 mmol/L

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5
Q

If a patient is anaemic, what will be the oxygen content of their blood?

A

Lower than normal

(BUT pO2 will be normal)

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6
Q

What value should pO2 in tissues not fall below? Why is this?

A

3 kPa as pO2 must be high enough to drive diffusion of O2 into cells

(BUT- HIGHER CAPILLARY DENSITY: lower pO2 can fall as oxygen doesn’t have to diffuse so far)

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7
Q

Give an example of an organ in the body that is very metabolically active and has a high capillary density.

A

Heart

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8
Q

What is the Bohr shift?

A

Promotes release of O2 by Hb

pH and temperature affect affinity for haemoglobin

pH lower in metabolically active tissues- more O2 given up

temperature higher - more O2 given up

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9
Q

What effect does 2,3-Bisphosphoglycerate have on the Hb dissociation curve?

A

Increase in 2,3-BPG levels shifts curve to right

2,3-BPG levels increase in anaemia / at high altitude

More O2 given up at tissues

(2,3-BPG levels drop in stored blood)

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10
Q

What’s the difference between hypoxemia and hypoxia?

A

Hypoxemia= low pO2 in arterial blood

Hypoxia= low oxygen levels in body/tissues

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11
Q

What is cyanosis?

A

Bluish colouration due to unsaturated haemoglobin

Peripheral: poor local circulation

Central: Poorly saturated blood in systemic circulation

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12
Q

What is pulse oximetry used for?

A

Detect level of Hb saturation (not amount of Hb present)

Only detects pulsatile arterial blood

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13
Q

Which artery is an arterial blood gas sample usually taken from?

A

Radial artery

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14
Q

In a healthy patient, what would the concentration of oxygen be bound to haemoglobin?

A

8.8 mmol/L of oxygen bound to haemoglobin in a healthy patient

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