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Flashcards in Physiology Review Deck (120):
1

Where in the brain is CO2 O2 and pH of arterial blood sensed?

Respiratory centers in the medulla

2

How is the metabolic demand of the body sensed by the peripheral chemoreceptors?

CO2, O2 and pH

3

Peripheral chemoreceptors send information along which nerve to the medulla for integration?

CN IX and X

4

What do the central chemoreceptors detect? Where does this send signals to?

pCO2

5

What is the respiratory center in the brain called? What does this do?

Central pattern generator

Generates spontaneous rhythmic discharge to keep the diaphragm functioning at a reasonable rate based on metabolic demands

6

What nerves does the central pattern generator send efferent signals to, to affect the respiratory muscles?

7
9
10
11
12

7

Where in the breathing control mechanism can the higher CNS exerts effects? Along what tracts does it send signals?

At the level of the spinal cord (bypasses the central pattern generator)

corticospinal tract

8

Along which tract does the ANS send signals to the diaphragm?

White matter of the spinal cord

9

The diaphragm sends afferent signals to the brain via which nerve?

CN X

10

What are the smallest airways that do not have alveoli?

Terminal bronchioles

11

Where does the majority of the resistance to airflow come from? Why?

The bronchus and the bronchioles

This is where smooth muscle is

12

What are the three major histological areas that comprise the conducting airways?

Inner mucosal surface
Smooth muscle layer
Outer connective tissue layer (cartilage)

13

Where is the airways is cartilage found?

Main bronchi

14

What type of epithelium covers the bronchial wall?

Ciliated pseudostratified epithelium

15

What are the main components of the bronchial wall?

Epithelium
Smooth muscle cells
Mucus glands
CT
Cartilage

16

What are the main components of the smaller bronchial walls?

Simple cuboidal epithelium
No cartilage

17

Is there cartilage in the bronchioles?

No

18

What are the four major obstructive lung diseases?

-Inflammation (bronchitis)
-Increased secretion (Asthma)
-Constriction of the smooth muscles
-Physical blockade (tumors)

19

What is the equation for the resistance to airflow?

R = {8nl / pi(r)^4 | n = viscosity of inspired air, l = length of airway, r = radius of the airway}

20

What happens with M3 activation in the lungs?

SM constriction

21

What happens with Beta 2 activation in the lungs?

SM relaxation

22

What is the most influential factor that controls resistance to airflow?

radius of the bronchiole

23

What are the three conditions that result in obstruction from the airway wall?

Asthma
Acute and chronic bronchitis

24

What is the pulmonary disorder that results in obstruction of the airway d/t a loss of lung parenchyma?

COPD

25

What are the pulmonary disorders that result in obstruction of the airway due to an obstruction in the airway lumen? (5)

bronchiectasis
Bronchiolitis
CF
Epiglottitis
Croup

26

Where does respiration take place?

At the respiratory unit

27

What comprises the respiratory unit?

Respiratory bronchiole
Alveolar ducts
Atria
Alveoli

28

What describes the capillary flow around the alveoli?

"sheet of flow"

29

What comprises the respiratory membrane?

The cell membrane between type I alveolar cells and the capillary bed

30

True or false: Like the tight junctions between endothelial cells, the junctions between endothelial cells are tight, not allowing much to pass through them

False--Unlike the tight junctions
between adjacent epithelial cells, which constitute a tight seal, the junctions between endothelial cells are leaky, allowing water and solutes to move back and forth between plasma and the interstitial space, the region between epithelial and endothelial basement membranes.

31

What are the components of the respiratory membrane?

-Surfactant
-Alveolar epithelium
-Epithelial BM
-Interstitial space
-Capillary basement membrane
-Capillary endothelial membrane

32

What is contained within the interstitial space in the respiratory membrane

Elastin and collagen (fibroblasts)
SM
Lymphatics
Capillaries

33

What is Goodpasture syndrome?

Autoimmune attack against type IV collagen in the kidneys and lungs, resulting in failure

34

What are the two major ways that pulmonary edema can result?

Damage to the respiratory membrane, or increased hydrostatic pressure in the capillaries

35

What happens with an increased deposition of collagen in the respiratory interstitial space?

harder to expand

36

What is the equation that relates to diffusion of gas across the respiratory membrane?

(dP)(A)(S) / d (MW)^0.5

A = surface area
S = solubility of gas
d = distance between two sides of the membrane

37

What are the factors that you can change clinically to alter the diffusion of gas across the respiratory membrane?

dP

38

What happens to dP in restrictive lung diseases?

Decreases

39

What are the factors that can affect d in the diffusion equation?

Pneumonia
Pulmonary edema

40

Which is more soluble in blood: CO2 or O2? What is the significance of this?

CO2

Needs a smaller partial pressure to enter the blood than oxygen does

41

What are the two major factors mentioned in class that can alter the surface area of the respiratory membrane?

Atelectasis
Tumor

42

What allows for the smooth movement between the visceral and parietal pleura?

1 mL of fluid

43

Which has stomata, the visceral or parietal pleura? What is the function of these?

parietal pleura
Serve as exit points for the pleural liquid, protein, and cells from the pleural space, to the lymphatics

44

What happens to the pleural capillaries in the visceral pleura during CHF? What does this cause?

Increased hydrostatic pressure
Causes a pleural effusion

45

What is the blood supply to the visceral pleura?

Bronchial circulation with venous return via the sub visceral pleural cavities

46

What is the blood supply to the parietal pleura?

branches of the intercostal arteries, with venous return via the bronchial veins

47

True or false: normally, there is a steady and balanced influx and efflux of fluid into the parietal space

True

48

What is the only significant barrier to solute and water exchange in the pleural space?

Pleural interstitium

49

The contribution to pleural liquid and protein formation from the visceral pleura in humans is minimal. Why?

Because the distance between the microvessels and the mesothelium is
relatively large and because of the lower filtration pressure in the visceral pleural
microcirculation as bronchial venules empty into the pulmonary veins with their lower
pressure.

50

What are the three main mechanisms by which there is a buildup of fluid in the pleural space?

Increased effusion
Decreased clearance
Combination

51

Decreased oncotic pressure within the parietal capillaries will lead to pleural effusion. What can cause this? (3)

Hepatic failure
Kwashiorkor
Renal disease

52

What is the cause of atelectasis induce pleural effusion?

Collapse of the visceral pleura d/t decreased oxygenation leads to collapse

53

What is the most important cause of pleural effusions in CHF?

Increased pulmonary venous pressure causes fluid to move across the visceral mesothelium

54

What is the effect of inflammation of the pulmonary and pleural microvessels?

Pleural effusion d/t increased movement of fluid

55

How could a diaphragmatic defect result in a pleural effusion?

Fluid movement from the peritoneal to the pleural cavity

56

What are the two major mechanisms by which there is a decreased clearance of lymphatic drainage?

Systemic venous HTN
Blockage

57

What is the definition of lung compliance?

the extent to which the lungs will expand for each unit increase in transpulmonary pressure

58

What happens to lung volume as transpulmonary pressure increases?

increases

59

What accounts for the steep and sudden upward slope of the lung pressure to volume curve?

Max stretching is occurring

60

How is lung compliance represented on a pressure-volume curve?

Slope between two points, with steeper slopes reflecting more compliance

61

What is the relation between compliance and elasticity?

Inverse

62

What are the factors that determine compliance of lung tissue?

Elastic forces of lung tissue (elastin and collagen)
Elastic surface forces of surface tension

63

What are the four main categories of restrictive lung disease?

1. Lung parenchyma disorders
2. Pleural space disorders
3. Neuromuscular/chest wall disorders
4. Infection or inflammation of the lungs

64

What are the two main lung parenchyma disorders?

Fibrotic interstitial lung disease
Atelectatic disorders

65

What is fibrotic interstitial lung disease?

Diffuse interstitial lung disease or sarcoidosis

66

What are the atelectatic disorders?

ARDS, IRDS

67

What are the two major pleural space disorders?

Pneumothorax
Pleural effusion

68

What are the neuromuscular disorders?

Polio
ALS
Guillain-barre

69

What are the major chest wall deformities?

Scoliosis
Ankylosing spondylitis
Flail chest

70

What is the effect of adding collagen to the lung in terms of compliance? Why?

Decreases compliance
This is due to more pressure needed to pull on inelastic collagen to get the same drop in pressure in the alveoli

71

Why will pneumonia decrease the compliance of the lung?

Increased fluid between the two pleural surfaces (pressure changes has to transmit through more liquid/space

72

What is the largest vascular bed in the body?

Pulmonary circulation

73

What allows the pulmonary vasculature to be compliant enough to accommodate all of the cardiac output?

Large numbers
Thin wall
Lower muscularity

74

How does the pulmonary vasculature change in response to increases/decreases in CO?

Changes compliance
Change number of arteries open (recruitment and distention)

75

What is the blood supply to the lungs?

Bronchial arteries

76

What percent of CO does the bronchial circulation receive? What happens in diseases like CF?

1-2%
CF increases the amount of blood received, causing hemoptysis

77

Where does the blood in the bronchial circulation go after circulating through the alveoli?

1/3 goes straight back to the RA, other 2/3 goes to the LA via the pulmonary vein

78

Why is there a small decrease in blood pO2 in the pulmonary vein as it returns to the heart?

Dumping of the bronchial circulation (physiological shunt)

79

What is the general MOA of hypoxic pulmonary vasoconstriction?

If a pulmonary capillary gets less oxygen supply (less than 70 mmHg), it will constriction so blood goes to better aerated areas

80

Do pulmonary veins constrict with hypoxia?

No

81

What are the 5 major clinical scenarios in which there is an abnormal HPV response?

-Airway obstruction
-Failure of ventilation
-Acute lung damage
-High altitude
-COPD

82

What is the normal, average value of V/Q?

0.8

83

What is the "dead space" in the lungs?

Ventilation of those lung regions that are not perfused

84

What is the common pathological state that leads to dead space formation?

pulmonary embolism

85

What are shunts?

a portion of the cardiac output or blood flow that is diverted or
rerouted.

86

What are the two components of the physiologic shunt?

Bronchial blood flow
Coronary circulation that drains directly into the LV through the thebesian veins

87

What are the thebesian veins?

Veins from the coronary circulation that drain into the LV

88

What are the causes of right to left shunts?

VSDs or ASDs

89

Why is it that hypoxia always occurs with a right to left shunt?

Because a significant fraction of the cardiac output is not delivered to the lungs for oxygenation.

90

What is the defining characteristic of a right to left shunt /a way to test for one?

It cannot be
corrected by having the person breathe a high O2 gas (e.g., 100% O2) because the shunted blood never goes to the lungs to be oxygenated.

91

What are the two fairly common causes of left to right shunts?

PDA
Trauma

92

V/Q = 0 means what?

Shunt

93

V/Q = infinite means what?

Dead space

94

What is the tidal volume (Vt)? What determines this?

the volume of air entering or leaving the nose or mouth per breath.

VT is determined by the activity of the respiratory control centers in the brain as they affect the
respiratory muscles and by the mechanics of the lung and the chest wall.

95

What is residual volume? What determines this?

RV is the volume of gas left in the lungs after a maximal forced expiration.

RV is determined by the force generated by the muscles of expiration and the inward elastic
recoil of the lungs as they oppose the outward elastic recoil of the chest wall.

96

What happens to residual volume with COPD? Why?

Increases dramatically d/t increased trapping of air in the alveoli

97

What is the importance of residual volume?

Prevents the lungs from collapsing with total expiration

98

What is the expiratory reserve volume?

the volume of gas that is expelled from the lungs during a maximal forced expiration

99

What is the inspiratory reserve volume? What determines this?

the volume of gas that is inhaled into the lungs during a maximal forced inspiration
starting at the end of a normal tidal inspiration.

IRV is determined by the strength of contraction of the inspiratory muscles

100

What is the functional residual capacity? How does this relate to the elastic recoil in the lungs?

the volume of gas remaining in the lungs at the end of a normal tidal expiration.


Represents the balance point between
the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall.

101

What is the inspiratory capacity?

the volume of air that is inhaled into the lungs during a maximal inspiratory effort that
begins at the end of a normal tidal expiration (the FRC)

102

VT + IRV = ?

IC

103

What is the total lung capacity? What determines this?

TLC is the volume of air in the lungs after a maximal inspiratory effort.

TLC is determined by the strength of contraction of the inspiratory muscles and the inward
elastic recoil of the lungs and the chest wall.

104

RV + VT + IRV + ERV = ?

TLC

105

What is the vital capacity?

VC is the volume of air expelled from the lungs during a maximal forced expiration starting after
a maximal forced inspiration

106

TLC - RV = ?

VC

107

What lung volumes cannot be measured with a spirometer?

RV
FRC
TLC

108

What is the forced vital capacity (FVC)?

is the total volume of air that can
be forcibly expired after a maximal inspiration.

109

What is FEV(1)?

FEV in the first second of exhalation

110

What is the FEV1/FVC? What is the normal value of this? What does this represent?

he fraction of total FVC that can be expelled
in the first second. Normal value is 0.8. This ratio
reflects the resistance to airflow.

111

What is he forced expiratory flow (FEF(25-75%))?

is the flow rate at 25 – 75% of the exhaled vital capacity

112

What is the peak inspiratory flow (PIF)?

point of maximal flow during inspiration

113

Draw out the flow/volume curve.

Draw

114

What is represented by the area under the curve in the peak flow curve prior to the PEV? After>

Before PEF = large airways
After PEF = Small airways

115

What happens to the flow-volume curve with obstructive lung diseases?

PEF occurs sooner, is not as high, and drops faster

116

What happens to the flow-volume curve with an upper airway obstruction?

Flat peak at a much lower flow, as well as lower PIF. Volumes about the same.

117

What happens to the flow-volume curve with a restrictive lung disease?

Lower peaks, much lower volumes

118

What is the normal FEV1/FVC?

0.8

119

What is the FEV1/FVC in obstructive lung diseases?

Less than 0.7

120

What is the FEV1/FVC in restrictive lung diseases?

Increases