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Physiology 2nd Midterm > Respiratory 2 > Flashcards

Respiratory 2 Flashcards

1
Q

Characteristics of pulmonary circulation

A

Low resistance
High compliance
Low pressure (compared to systemic circulation)

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2
Q

What is the significance of the low perfusion pressure in the pulmonary circulation?

A

Low perfusion pressure = low filtration pressure = reducing the possibility of developing pulmonary edema and helps keep the alveoli dry

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3
Q

What is the normal cardiac output

A

5 L/min

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4
Q

Describe the distribution of pulmonary blood flow in supine position

A

MAP is the same all over the lungs = uniform perfusion pressure in lungs

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5
Q

Describe the distribution of pulmonary blood flow in standing position

A

Gravity changes the hydrostatic pressure and divides the lung into 3 zones:
- low flow (apex)
- moderate flow
- maximal flow (base)

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6
Q

Lowest blood flow is at the ______ of the lung

A

Apex

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7
Q

Highest blood flow is at the _______ of the lung

A

Base

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8
Q

How is pulmonary blood flow regulated

A
  1. Systemic arteries dilate (when tissue P02 is low)
  • to increase the blood flow and oxygen delivery to that hypoxic tissue
  1. Pulmonary arteries constrict (when alveolar PO2 is low)
  • to divert the blood to better ventilated regions
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9
Q

When would systemic arteries dilate to regulate pulmonary blood flow 

A

When tissue PO2 is low

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10
Q

When would Pulmonary arteries constrict to regulate pulmonary blood flow

A

When alveolar PO2 is low

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11
Q

What is the driving force for both O2 diffusion and CO2 diffusion ?

A

Partial pressure differences

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12
Q

Hypoxia at high altitudes :

Why is it so important to put on your own oxygen mask before assisting others in the case of depressurization at high altitudes?

A

To stay conscious

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13
Q

How to calculate partial pressure of inspired oxygen PIO2 ?

A

PIO2 (trachea) =
( barometric pressure - partial pressure of water) x fraction of inspired oxygen

So….
PIO2 = (PB - PH2O) x FIO2

Constants:
PB = 760 mmHg
PH2O = 47 mmHg
FIO2 = 0.21 (21% of air is made of O2)

NOTE: PB is also known as atmospheric pressure

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14
Q
A

PIO2 = (253 - 47) x 0.21 = 43 mmHg

LOW pressure cannot live without oxygen tank

(Normal level around 149-150)

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15
Q

What is the alveolar air equation for ?

A

Calculation of partial pressure of O2 in the alveoli

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16
Q

The alveolar partial pressure of oxygen is about

A

100 mmHg

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17
Q

Factors that control transfer of gases across the alveolar capillary membrane

A

Alveolar surface area (A)
Diffusion constant (D)
Partial pressure difference (P1-P2)
Thickness of membrane (T)

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18
Q

How to calculate gas diffusion Vgas

A
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19
Q

Gas diffusion across the respiratory membrane is directly proportional to

A
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20
Q

Gas diffusion across the respiratory membrane is inversely proportional to the ________________.

A

Thickness (T) of the membrane

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21
Q

Oxygen is carried in the blood in 2 forms

A
  1. Dissolved O2
  2. O2 bound to hemoglobin (oxyhemoglobin)
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22
Q

How is dissolved O2 measured

A

It is measured clinically in an arterial blood gas sample as PAO2

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23
Q

 Oxygen is carried in the blood in 2 forms : Which form carries the majority of oxygen

A
  1. Dissolved O2 (MINOR)
    - carries 3 mlO2/L of blood
  2. O2 bound to hemoglobin (MAJOR)
    - carries 196 mlO2/L of blood
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24
Q

What color is oxyhemoglobin

A

Red

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25
Q

What color is deoxyhemoglobin

A

Blue

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26
Q

Normal hemoglobin concentration

A

14-16 gm/dL

(Or 150 gm/L)

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27
Q

How to calculate O2 content ?

A

O2 content = dissolved O2 + O2 hemoglobin

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28
Q

What is cyanosis

A

Bluish color of skin occurs when blood concentration of deoxyhemoglobin is more than 6 - 8 gm/dL

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29
Q

Two types of cyanosis

A

Central cyanosis
Peripheral cyanosis

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30
Q

Central cyanosis indicates….

A

Ventilatory problem
Low O2 saturation
Low cardiac output

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31
Q

Peripheral cyanosis indicates⁣⁣⁣⁣⁣….

A

Poor circulation in the small peripheral vessels

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32
Q

Explain Hemoglobin – oxygen association/saturation curve

A
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33
Q

The hemoglobin- oxygen dissociation/saturation curve will shift to the RIGHT at which capillaries ??

A

Systemic capillaries

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34
Q

When the curve shifts to the RIGHT at systemic capillaries what does that mean

A

Decreased affinity of hemoglobin to O2 = release of O2 to the tissues

35
Q

The hemoglobin- oxygen dissociation/saturation curve will shift to the LEFT at which capillaries ??

A

Pulmonary capillaries

36
Q

When the curve shifts to the LEFT at pulmonary capillaries what does that mean

A

Increased affinity of hemoglobin to O2 = faster saturation of hemoglobin

37
Q

Factors that decrease hemoglobin affinity

A

(Hint: increase in everything BUT decrease in pH)

38
Q

Factors that increase hemoglobin affinity

A

(Hint: decrease in everything BUT increase in pH)

39
Q

Explain Bohr Effect

40
Q

Reduced affinity causes __________ shift and ________ O2 saturation

41
Q

Increased affinity causes __________ shift and ________ O2 saturation

42
Q

Carbon dioxide is transported in the blood in 3 forms ; what are they and give percentages

43
Q

Carbon dioxide is transported in the blood mainly as :

A

Bicarbonate ion (HCO3-)

80-90%

44
Q

How is CO2 chemically modified as bicarbonate ion?

A

At the alveoli : bicarbonate is converted to CO2 and H2O

At the tissue: CO2 and H2O are converted into HCO3-

45
Q

Which enzyme converts CO2 and H2O to H2CO3 and the other way around?

A

Carbon anhydrase

46
Q

Cellular gas exchange formula

A

Is the same as gas diffusion formula

47
Q

What is tissue uptake of O2 at rest

48
Q

Why does tissue oxygen uptake increase during exercise?

A

Due to higher internal respiration by the mitochondria to produce ATP for the active tissue

49
Q

What is hypoxia

A

A condition in which the tissue was deprived of adequate oxygen supply

50
Q

There are 4 types of hypoxia

A

Hypoxemic hypoxia
Anemic hypoxia
Stagnant hypoxia
Histotoxic hypoxia

51
Q

What is hypoxemic hypoxia

A

The oxygen pressure in the blood going to the tissues is too low to saturate the hemoglobin

52
Q

What causes hypoxemic hypoxia

A

Problems in ventilation, gas diffusion or high altitude

53
Q

Which type of hypoxia can occur due to high altitude

A

Hypoxemic hypoxia

54
Q

What is anemic hypoxia

A

The amount of functional hemoglobin is too low, and hence the capacity of the blood to carry oxygen is too low

55
Q

What is stagnant hypoxia

A

The flow of blood to the tissues is reduced or unevenly distributed

56
Q

What can cause stagnant hypoxia

A

Heart failure

57
Q

What is histotoxic hypoxia

A

The tissue cells are poisoned by cyanide or sodium azide (pesticides) and are therefore unable to utilize oxygen

58
Q

What 2 poisons can cause histotoxic hypoxia

A

Cyanide
Sodium azide (pesticides)

59
Q

The INVOLUNTARY control of breathing involves which components?

A
  • receptors
  • brain stem control of breathing
  • respiratory muscles
60
Q

What type of receptors are involved in involuntary control of breathing

A

Chemoreceptors for O2, CO2, and pH
Mechanoreceptors in the lungs and joints

61
Q

What part of the brain stem controls involuntary breathing

A

Medulla oblongata and pons

62
Q

The VOLUNTARY control of breathing involves what?

A

Commands from cerebral cortex DIRECTLY to the respiratory muscles

63
Q

Examples of voluntary breathing

A

Breath holding
Voluntary hyperventilation

64
Q

Central chemoreceptors are found in

A

Ventral surface of the Medulla oblongata

65
Q

Central chemoreceptors sense what?

A

Hydrogen H+

As it is sensitive to changes in pH of CSF , which indirectly reflects changes in PaCO2

So it responds INDIRECTLY to CO2

66
Q

Peripheral chemoreceptors are found in

A

Aortic body and carotid body

67
Q

Peripheral chemoreceptors sense

A

Low O2
High CO2
High H+

68
Q

Mechanoreceptors for breathing include

A

Stretch receptors
Irritant receptors

69
Q

Which tract is for voluntary control of breathing from the cerebral cortex directly to resp muscles?

A

Corticospinal tract

70
Q

Which tract is for involuntary control of breathing from respiratory centers to resp muscles?

A

Ventrolateral tract

71
Q

What are the medullary respiratory centers ?

A

Dorsal respiratory group DRG
Ventral respiratory group VRG
Pre-Botzinger complex

72
Q

Dorsal respiratory group DRG is responsible for

A

Primarily inspiratory

73
Q

Ventral respiratory group VRG is responsible for

A

Active in forced breathing (insp. + expir.)

74
Q

Pre-Botzinger complex is responsible for

A

Central pattern generator
Has pacemaker activity

75
Q

Pontine respiratory centers

A

Apneustic center
Pnumotaxic center

76
Q

Function of apneustic center

A

Excites medullary inspiratory center

It’s stimulation causes apneusis (Prolonged inspiration followed by brief expiration)

77
Q

Function of pneumotaxic Center

A

Inhibits inspiration and regulates respiratory rate

78
Q

When it comes to central chemoreceptors, what happens if PaCO2 is high

A

( high H+ in CSF and low pH)

Hyperventilation = PaCO2 decreases back to normal

79
Q

When it comes to central chemoreceptors, what happens if PaCO2 is low

A

( low H+ in CSF and high pH)

Hypoventilation = PaCO2 increases back to normal

80
Q

Peripheral chemoreceptors respond to changes in

A

Arterial PO2, PCO2, and pH

81
Q

Peripheral chemoreceptors send signals through sensory afferents via which nerves

A

Glossopharyngeal (CN IX)
Vagus (CN X)

82
Q

An increase in the breathing rate occurs due to

A

-Decreases in arterial PO2
-increases in arterial PCO2
-Decreases in arterial pH

83
Q

Effect of hypoventilation on PCO2 and PO2

A

increases PCO2
Decreases PO2

84
Q

Effect of hyperventilation on PCO2 and PO2

A

decreases PCO2
Increases PO2

Physiology 2nd Midterm (7 decks)

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