Haemoglobin and Gas Transport Flashcards

1
Q

How many ml of O2 dissolve per litre of plasma

A

3ml

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2
Q

How much does Haemoglobin in RBC increase O2 carrying capacity

A

200ml/L

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3
Q

How is the bulk of CO2 transported

A

In various forms of solution in plasma

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4
Q

Define Arterial Partial Pressure

A

Refers to the O2 in solution and is determined by O2 solubility and the partial pressure of O2 in the gaseous phase driving it into solution

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5
Q

Values assigned to the partial pressure of a gas in solution are equal to the partial pressure in gaseous phase that is driving that gas into solution (T/F)

A

T

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6
Q

What is the solubility of O2 in water

A

0.03ml/L/mmHg (for every litre of plasma 1 moleucle of O2 dissolves in 0.03 ml of plasma)

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7
Q

What is the partial pressure of O2 in 3ml/L plasma

A

3/0.03 = 100 mmHG

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8
Q

O2 delivery to tissues =

A

Arterial O2 content X Cardiac Output

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9
Q

What would be the O2 delivery to tissues if the arterial blood content was 3ml/L and the cardiac output was 5L/min

A

15ml/min

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10
Q

What is the O2 demand for resting tissues

A

250ml/min

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11
Q

If you add Hb (150g/L, 1.34 ml O2 per g) how much does the O2 delivery to tissues increase by

A

200ml/L X 5L/min = 1000ml/min

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12
Q

What percentage of arterial O2 is extracted by peripheral tissues

A

25%

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13
Q

What maintains the partial pressure gradient that allows the movement of O2 out of the alveoli

A

Haemoglobin

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14
Q

How long does it take for saturation to be complete once in contact with the alveoli

A

0.25s (total contact time 0.75s)

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15
Q

More than 98% of oxygen is bound to Hb where is the rest

A

Dissolved in plasma

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16
Q

How many oxygen molecules can bind to Hb

A

4

17
Q

How much oxygen binds to each gram of Hb

A

1.34ml

18
Q

92% of Hb is in RBCs where is the remaining 8%

A

HbA2 (delta chain replaces beta chain)

19
Q

What can be used to detect and monitor diabetes

A

Glycosylated Hb (HbA1a, HbA1b, HbA1c)

20
Q

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

A

Partial pressure of oxygen in arterial blood

21
Q

The affinity of O2 changes in response to

A

changes in certain chemical factors such as PH, PCO2, Temp and DPG

22
Q

Exercise moves the curve to the

A

Right- PH decreases
Co2 increases
Temperature increases
Makes O2 more accessible as tissue oxygen demand increases

23
Q

Cold weather moves the curve to the left

A

Left- PH increases
CO2 decreases
Temperature decreases
Hb holds on more tightly to the oxygen- unloading more difficult but aid cillection of oxygen in pulmonary circulation

24
Q

What is DPG

A

Metabolite produced by RBCs under stress (Cardiac, respiratory disease, high altitude)- decreases affinity for oxygen

25
Q

Compared to normal Hb wish side would a curve for HbF and myoglobin shift

A

Left (wants to hold on to oxygen more tightly)

26
Q

CO binds to Hb to form

A

Carboxyhaemoglobin

27
Q

What is CO affinity for Hb

A

250 time greater than O2

28
Q

Symptoms of CO poisoning

A
Hypoxia
Anaemia
Nausea
Headaches
Cherry red skin
Mucous membranes
29
Q

What is Hypoxia

A

Inadequate supply of oxygen to tissues

30
Q

Hypoxaemic Hypoxia

A

Reduction in oxygen diffusion at lungs either due to decreased PO2 (atmosphere) or tissue pathology

31
Q

Anaemic Hypoxia

A

Reduction in oxygen carrying capacity due to anaemia

32
Q

Stagnant Hypoxia

A

Heart disease results in inefficient pumping of blood to lungs/around the body

33
Q

Histotoxic Hypoxia

A

Poisoning prevents cells utilising oxygen delivered to them e.g. CO and Cyanide

34
Q

Metabolic Hypoxia

A

Oxygen delivery to the tissues does not meet increased oxygen demands

35
Q

Describe CO2 transport (6)

A
  1. Diffuse from tissue into blood
  2. 7% remains in plasma and erythrocytes
  3. 23% combines in the erythrocytes with deoxyhaemoglobin to form carbamino compounds
  4. 70% combines in the eryhtorcytes with water to form carbonic acid, which dissociates to yield carbonate ions and H+
  5. Chloride shift: most bicarbonate moves out of erythrocytes into plasma in exchange for Cl- ions
  6. Excess H+ ions bind to deoxyhaemoglobin
  7. The reverse occurs in the pulmonary capillaries and CO2 moves down its concentration gradient from blood to alveoli
36
Q

Pathway of CO2 (4)

A

Peripheral Tissue
Systemic Capillary
Venous circulation
Pulmonary capillary

37
Q

Hypoventilation causes

A

CO2 retention and decrease in PH (Hugh H+) (Acidosis)

38
Q

Hyperventilation causes

A

Blowing off more CO2 increase in PH (low H+) Alkalosis