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Respiratory System > Haemoglobin and Gas Transport > Flashcards

Haemoglobin and Gas Transport Flashcards

1
Q

How much oxygen is dissolved per litre of plasma?

A

3ml

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2
Q

Haemoglobin in red blood cells increases the oxygen carrying capacity to what?

A

200 ml/L

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3
Q

Arterial pressure of oxygen is determined by what two factors?

A

Oxygen solubility

Partial pressure of oxygen that is driving oxygen into solution

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4
Q

Gases travel in solution in the plasma. If they traveled in the gaseous phase, it would lead to what?

A

Air embolism (fatal)

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5
Q

Oxygen delivery to the tissues can be calculated using what equation?

A

Oxygen delivery to tissues =
Arterial O2 Content (ml/L)
x Cardiac Output (L/min)

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6
Q

What is the O2 demand of normal, resting tissues?

A

250ml/min

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7
Q

What is normal cardiac output?

A

5L/min

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8
Q

What percentage of arterial oxygen is extracted by peripheral tissues at rest?

A

25%

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9
Q

What volume of oxygen binds to each gram of Haemoglobin?

A

1.34ml

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10
Q

What percentage of haemoglobin is in the form HbA?

A

92%

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11
Q

What is the difference between HbA and HbA2?

A

Alpha chains replace beta

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12
Q

Haemoglobin in the form HbF is formed when beta chains are replaced by what chains?

A

Gamma

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13
Q

What is the major determinant of the degree to which haemoglobin is saturated with oxygen?

A

Partial pressure of oxygen in arterial blood

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14
Q

Oxygen is moved out of the alveoli down a partial pressure gradient until what?

A

The haemoglobin becomes saturated with oxygen

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15
Q

Within how many seconds of contact with the alveoli is saturation complete?

A

0.25 seconds

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16
Q

What is the normal systemic arterial PO2?

A

100 mmHg

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17
Q

At normal venous PO2, what is the reserve capacity?

A

75%

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18
Q

Do Foetal Haemoglobin and Myoglobin have a higher or lower affinity for oxygen than HbA?

A

Higher

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19
Q

Where is myoglobin found?

A

Muscle (particularly concentrated in oxidative muscle)

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20
Q

What do the higher affinities of myoglobin and foetal haemoglobin (compared to HbA) allow them to do?

A

Extract more oxygen
Myoglobin from skeletal muscle
Foetal Haemoglobin from the maternal blood

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21
Q

How is Anaemia defined?

A

Any condition where the oxygen carrying capacity of the blood is compromised

22
Q

Is it possible for red blood cells to be fully saturated with oxygen in anaemia?

A

Yes

23
Q

Why is it possible for red blood cells to be fully saturated with oxygen in anaemia?

A

As PaO2 is normal - there is no problem with ventilation or diffusion so alveolar volume and diffusion should be normal (exception is iron deficiency anaemia)

24
Q

Why is there a low oxygen content in anaemia?

A

Due to a low haemoglobin content as red blood cells are missing/not being synthesised properly due to anaemia

25
Q

What factors would decrease the affinity of haemoglobin for oxygen?

A

Decreased pH
Increased PCO2
Increased temperature
Increased binding of DPG

26
Q

What cells synthesise DPG?

A

The erythrocytes

27
Q

Under what circumstances would the binding of DPG increase?

A

Inadequate oxygen supply

28
Q

What does DPG help to maintain?

A

Oxygen release in the tissues

29
Q

How is carbon monoxide formed?

A

From incomplete combustion of carbon fuel

30
Q

Carbon monoxide binds to haemoglobin to form what?

A

Carboxyhaemoglobin

31
Q

Carbon monoxide’s affinity for haemoglobin is how many times greater than that of oxygen?

A

250

32
Q

What is the typical, physical symptom of carbon monoxide poisoning?

A

Cherry red skin, mucous membranes and nail beds

33
Q

What affect would CO poisoning have on respiration rate?

A

No affect - respiration rate is unaffected due to normal arterial PCO2

34
Q

The treatment for CO poisoning is administering 100% oxygen, why is this treatment difficult?

A

Haemoglobin is already 98% saturated with oxygen, so providing pure oxygen can only increase this by 2%

35
Q

What are the 5 main types of Hypoxia?

A 
Hypoxic
Anaemic
Ischaemic
Histoxic
Metabolic
36
Q

What is the most common type of hypoxia?

A

Hypoxic hypoxia

37
Q

What is hypoxia?

A

A deficiency/inadequacy in the volume of oxygen reaching the tissues

38
Q

The reduction in O2 diffusion at the lungs in hypoxic hypoxia is due to what?

A

Decreased atmospheric PO2
or
tissue pathology

39
Q

Heart disease results in the inefficient pumping of blood to the lungs and around the body, what type of hypoxia does this cause?

A

Ischaemic

40
Q

What type of hypoxia may be found in an unfit person exercising?

A

Metabolic

41
Q

What is anaemic hypoxia?

A

A reduction in oxygen carrying capacity of blood due to anaemia

42
Q

What type of hypoxia is found when CO poisoning prevents cells from utilising oxygen delivered to them?

A

Histoxic

43
Q

When CO2 molecules diffuse from tissue to the blood, what percentage remains dissolved in plasma and erythrocytes?

A

7%

44
Q

70% of CO2 which remains in the plasma and erythrocytes after diffusion combines with water to form what?

A

Carbonic acid

45
Q

Carbonic acid dissociates to yield what?

A

Bicarbonate and H+ ions

46
Q

Normally, pH is stable because all CO2 produced is eliminated where?

A

In expired air

47
Q

CO2 retention leading to increased [H]+ will cause what?

A

Respiratory acidosis

48
Q

Blowing off more CO2 leading to decreased [H]+ will cause what?

A

Respiratory alkalosis

49
Q

Is respiratory alkalosis found in hypo or hyper-ventilation?

A

Hyperventilation

50
Q

Is respiratory acidosis found in hypo or hyper-ventilation?

A

Hypoventilation

Respiratory System (17 decks)

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