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Hugh's MD1 Respiratory > Normal Physiology > Flashcards

Normal Physiology Flashcards

1
Q

What percentage of O2 bound to Hb is used in one pass of the bodies systems

A

25%

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1
Q

An increase in [H+] causes what shift in the oxygen dissociation curve?

A

Right

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2
Q

How can low oxygenation of the blood be compensated for?

A

Greater amounts of Hb

Greater CO

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3
Q

How much CO2 does the body produce at BMR compared to while exercising?

A

At BMR: 200ml/min During exercise: >4000ml/min

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4
Q

What does PaO2 stand for?

A

Partial pressure of arterial O2

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4
Q

Why do small airways contribute low resistance?

A

Because there are a lot of them

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5
Q

What does central cyanosis reflect in the blood?

A

Arterial blood is not well oxygenated

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6
Q

How much O2 does the body use at BMR compared to while exercising?

A

At basal metabolic rate: 250ml/min During exercise: >4000ml/min

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7
Q

What is the function of carbonic anhydrase?

A

It catalyses the reaction of CO2 + H2O > H2CO3

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8
Q

An increase in PCO2 causes what shift in the oxygen dissociation curve?

A

Right

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9
Q

What are the main functions of the lungs?

A
  1. Oxygenate pulmonary arterial blood 2. Removed CO2 from pulmonary arterial blood 3. Maintain acid-base balance
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9
Q

What do central chemoreceptors respond to? Where are they located?

A

H+ Ventrolateral medullary surface

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10
Q

Why is diffusion of CO2 20x greater than O2 given that the driving pressure is greater for O2?

A

CO2 is more soluble

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11
Q

What does PiO2 stand for?

A

Partial pressure of inspired O2

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13
Q

What does PA02 stand for?

A

Partial pressure of alveolar O2

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14
Q

An elevated PaCO2 is generally due to a ventilation or diffusion problem? Why?

A

Ventilation, because CO2 diffusion is very fast.

14
Q

How many branches are there of the lung airways?

A

23

16
Q

What drives O2 to bind to Hb?

A

Its concentration dissolved in plasma (PaO2 or PvO2)

17
Q

Apart from central and peripheral chemoreceptors, what factors effect respiration?

A

Stretch receptors in the chest wall

Muscle and joint receptor

Cortical control

18
Q

What are the main muscles of expiration?

A

Internal intercostals

Abdominals

19
Q

What are implications of a right shift in the oxygen dissociation curve during exercise?

A

O2 is more easily unloaded

20
Q

An increase in temperature causes what shift in the oxygen dissociation curve?

A

Right

21
Q

What type is air flow is seen in the small and large airways?

A

Laminar and turbulent respectively

22
Q

Which way will the oxygen dissociation curve shift if Hb’s affinity for O2 is increased?

A

Left

23
Q

What is the vital capacity?

A

The difference between total lung capacity and residual volume

24
Q

T/F Carbon monoxide has a greater affinity for Hb than O2

A

True, 240x greater

25
Q

What is the normal PaO2, PaCO2 and pH of arterial blood?

A

O2 - 100mmHg

CO2 - 40 mmHg

pH - 7.4

26
Q

What percentage of CO2 is bound to Hb for transportation?

A

30%

26
Q

What do peripheral chemoreceptor respond to? Where are they located?

A

H+, CO2, O2 Carotid and aortic bodies

27
Q

What nerves are important in stimulating inspiration?

A

Phrenic (diaphragm)

Intercostal nerves (external intercostal muscle)

29
Q

What two factors contribute to the work of breathing?

A

Resistive - Overcoming airflow resistance

Elastic - Pushing against elastic lungs (imagine blowing up a balloon) and expanding the chest wall

30
Q

What percentage of CO2 is dissolved in plasma?

A

10%

32
Q

True or false, in healthy individuals undergoing exercise, there is not enough time for Hb to be completely oxygenated in alveolar capillaries.

A

False, the time required is 0.25s which is the time spent by blood in the capillaries during exercise.

34
Q

What is the difference between residual volume and functional residual volume?

A

Residual volume is what is left after maximal expiration (1,200ml) while function residual volume is what is left after normal expiration (2,200ml)

35
Q

What does a low V/Q match indicate?

A

Ventilation doesn’t match perfusion

36
Q

What are main muscles of inspiration?

A

Diaphragm

External intercostals

Sternocleidomastoids

37
Q

Why are more CO2 bound in the carboamino form in venous blood cf to arterial?

A

Because there is more reduced Hb (Hb without O2, H+ instead) with has a higher affinity for CO2 than HbO2

38
Q

What percentage of vital capacity is used at maximum exercise?

A

50%

39
Q

In what form is the majority of CO2 transported?

A

Bicarbonate: 60%

Hugh's MD1 Respiratory (15 decks)

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