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Systems 1 > Blood Supply, Gas Exchange, Ventilation and Perfusion > Flashcards

Blood Supply, Gas Exchange, Ventilation and Perfusion Flashcards

1
Q

What are the partial pressures of deoxygenated blood?

A

PO2: 40mmHg
PCO2: 46mmHg

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2
Q

Rate of diffusion is directly proportional to what?

A

Partial pressure gradient
Gas solubility
Surface area

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3
Q

Rate of diffusion is inversely proportional to what?

A

Membrane thickness

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4
Q

Why is the rate of CO2 diffusion so high despite the low pressure gdt?

A

CO2 much more soluble in water than O2

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5
Q

How does pulmonary oedema decrease the rate of diffusion?

A

Increased diffusion distance due to fluid in the interstitial space

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6
Q

What is ventilation?

A

Air getting to alveoli

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7
Q

What is perfusion?

A

Local blood flow

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8
Q

Where is the lung is blood flow best? Why?

A

The base

Because arterial pressure exceeds alveolar pressure

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9
Q

Roughly where in the lung does blood flow equal perfusion?

A

Rib 3

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10
Q

What are the local control measures to avoid shunt?

A

Bronchoconstriction to poorly perfused alveoli

Vasoconstriction to poorly ventilated alveoli

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11
Q

What is alveolar dead space?

A

Alveoli that are ventilated but not perfused

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12
Q

What is shunt?

A

Passage of blood through areas of the the lung that are poorly ventilated

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13
Q

What is Physiological Dead Space?

A

Alveolar and Anatomical dead space

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14
Q

Where is CO2 carried in the blood?

A

Solution in plasma

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15
Q

PaO2 is not the same as what?

A

Arterial O2 concentration

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16
Q

How much arterial O2 is extracted by peripheral tissues at rest?

A

25%

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17
Q

How much O2 in the blood is bound to Hb?

A

98%

18
Q

How long is blood in contact with the alveoli?

A

0.75s

19
Q

Why do fetal Hb (HbF) and myoglobin have a higher affinity for O2 than HbA?

A

To extract O2 from maternal blood?

20
Q

What is anaemia?

A

Condition where the O2 carrying capacity of blood is compromised

21
Q

What affect does decreasing blood pH have on affinity?

A

(acidosis)

Reduced affinity

22
Q

What effect does increased temperature have on affinity?

A

Reduced affinity

23
Q

What effect does increased PCO2 have on affinity?

A

Reduced affinity

24
Q

What effect does having no 2, 3DPG have on affinity?

A

Huge increase in affinity

25
Q

What effect does added 2, 3-DPG have on affinity?

A

Decreased affinity

26
Q

In which situations does 2, 3-DPG increase?

A

Inadequate Oxygen supply

27
Q

What pressure of CO causes progressive carboxyhaemoglobin formation?

A

0.4mmHg

28
Q

What are the symptoms of CO poisoning?

A

Hypoxia
Anaemia
Nausea/headaches
Cherry red skin/mucous membranes

29
Q

What are the effects of CO poisoning?

A

Potential brain damage

Death

30
Q

What is Hypoxaemic Hypoxia?

A

Reduction in O2 diffusion at the lungs

31
Q

What is Anaemia Hypoxia?

A

Reduction in O2 carrying capacity of blood due to anaemia

32
Q

What is stagnant Hypoxia?

A

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

33
Q

What is Histotoxic Hypoxia?

A

Poisoning preventing cells using Oxygen delivered to them

34
Q

What is metabolic hypoxia?

A

Oxygen delivery to tissues is inadequate compared to demand by cells

35
Q

What does Hypoventilation cause?

A

CO2 retention

Respiratory acidosis

36
Q

What does Hyperventilation cause?

A

CO2 reduction

Respiratory Alkalosis

37
Q

What happens to CO2 when combined in erythrocytes with deoxyhaemoglobin?

A

Carbamino compounds are formed

38
Q

What happens to the majority of CO2 (70%) when it binds with water?

A

Combines to form carbonic acid

Carbonic acid dissociated into bicarbonate and H+ ions

39
Q

What happens to the bicarbonate?

A

Moves out the erythrocyte into the plasma in exchange for Cl- ions (chloride shift)

40
Q

What happens to the excess H+ in carbonic acid dissociation?

A

Binds to deoxyhaemoglobin

Systems 1 (25 decks)

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