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PHGY 210 > respiration 2 > Flashcards

respiration 2 Flashcards

1
Q

what is determined by the HbO2 dissociation curve?

A

the amount of O2 carried by Hb for a given partial pressure of O2

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2
Q

how is the curve at high values of P02/alveolar PO2 levels?

A

the curve is flat

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3
Q

how is the curve at low values of P02/peripheral tissue levels of PO2?

A

the curve is steep

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4
Q

what happens to the amount of O2 bound to Hb at high values of PO2?

A

the amount stays relatively constant

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5
Q

what happens to HB02 when alveolar PO2 drops from 100 mmHg to 80 mm Hg?

A

Nothing really, pressure needs to drop by 60 mm Hg in order for drop of HbO2 to be significant

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6
Q

what does a small drop of PO2 in peripheral tissues cause?

A

unloads O2 from Hb into the tissues

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7
Q

when does HbO2 dissociate more readily?

A

under low PO2 values

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8
Q

what happens if their is a drop in PO2 in peripheral tissues from 40 mm Hg to 20 mm Hg?

A

results in a decrease in %HbO2 from about 75% to 35%

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9
Q

a drop in PO2 is more significant in tissues or in tissues? why?

A

tissues are significantly more affected by drop in PO2. because it where metabolic processes requiring O2 take place

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10
Q

when blood enters tissue capillaries, which PO2 is greater; plasma or Interstitial fluid?

A

Plasma > intersitital fluid

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11
Q

what does O2 diffuse into from the capillary membrane? what does this cause?

A

diffuses into the interstitial fluid, which causes lowering of Plasma PO2

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12
Q

what happens to erythrocytes when plasma PO2 decreases?

A

O2 diffuses out of the erythrocytes into the plasma

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13
Q

what does the lowering of erythrocyte PO2 cause?

A

the dissociation of HbO2 into Hb and O2

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14
Q

what happens to the O2 which diffused into the interstitial fluid?

A

it will move into the cell

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15
Q

through what process are large amount of O2 from HbO2 brought into the cell?

A

via passive diffusion

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16
Q

at the end of the tissue capillaries, under resting conditions, how saturated is the Hb?

A

b is still 75% saturated

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17
Q

how can cells obtain more oxygen as needed during exercise?

A

due to the presence of myoglobin

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18
Q

what is the function of myglobin?

A

act as an intracellular carrier which facilitates the diffusion of oxygen throughout the muscle cell

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19
Q

what determines the affinity of Hb for O2?

A

the quaternary strucutre

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20
Q

what can increase the affinity of heme for O2? what is the process known as?

A

binding of a first O2 will increase affinity of heme binding to a second O2. this is known as cooperative binding

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21
Q

where is myoglobin found in?

A

skeletal muscle

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22
Q

how many O2 can myoglobin bind? hemoglobin?

A

1 O2 for myoglobin versus 4 O2 for Hb

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23
Q

how can the O2-myoglobin curve be described as?

A

hyperbolic in shape

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24
Q

when does myoglobin release its single O2?

A

only released under very low PO2

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25
Q

on what does the total amount of O2 in the blood depend on?

A

it depends on the Hb concentration

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26
Q

in what cases may Hb concentrations be reduced?

A

anemia

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27
Q

what is the Bohr Effect?

A

is the shift of the HbO2 dissociation curve to the right when blood CO2 or temperature increases, or blood pH decreases (

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28
Q

what is the logic behind the bohr effect?

A

when we exercise, we increase our CO2 and acid production and generate heat. The curve shifting to the right means that for a given drop in PO2, an additional amount of O2 is released from Hb to the working tissues

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29
Q

do the effects taken into account for the bohr effect have a high effect on amount of O2 if above 80 mm Hg

A

NO

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30
Q

what is 2,3-DPG

A

end product of red blood cell metabolism

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31
Q

when are levels of 2,3-DPG generally increased?

A

in cases of chronic hypoxia

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32
Q

what has an extremly high affinity for 02 binding sites in Hb?

A

CO (carbon monoxide)

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33
Q

what happens if CO binds to Hb?

A

reduces the amount of O2 bound to Hb and will shift O2-Hb curve to the left

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34
Q

what happens if the O2-Hb curve is shifted to the left?

A

decreases the unloading of O2 to the tissue.

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35
Q

why is there little stimulation to incrrease ventilation in CO poisoning?

A

because PaO2 remains normal

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36
Q

how much O2 is used and how much CO2 is produced per minute?

A

300 mL o2 used

250 mL CO2 produced

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37
Q

in how many different forms can CO2 be found in blood?

A

3 different forms

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38
Q

what forms can CO2 be found in blood?

A
  • physically dissolved in the blood
  • combined with Hb to form HbCO2
  • as bicarbonate
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39
Q

what proportions of each form is CO2 found in the blood?

A

10% physically dissolved in the blood

  • 11% combined with Hb to form HbCO2
  • 79 %as bicarbonate
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40
Q

which law states that CO2 from tissues diffuses into the plasma where it is physically dissolved?

A

Henry’s Law

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41
Q

with what portion of Hb does CO2 bind? what portion does O2 bind?

A

CO2 will bind with the globin portion of Hb while O2 will bind with the heme portion

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42
Q

is there competition for binding of O2/CO2 to Hb?

A

no competition due different sites of interest

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43
Q

with what does CO2 bind to form bicarbonate?

A

bind with water

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44
Q

what enzyme aids the binding of CO2-H2O? when does this enzyme function?

A

carbonic anhydrase (CA) when CO2 diffuses into the erythrocytes

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45
Q

what happens if CO2 production is increased?

A

the production of HbCO2, HCO3-, and H+ increases

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46
Q

what happens if PCO2 is lowered?

A

HCO3- going to H2CO3 and further into CO2 and H2O and HbCO2 into Hb and CO2

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47
Q

when does PCO2 lower?

A

when venous blood flows through the lung capillaries

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48
Q

how is Hb in the tissue capillaries?

A

its free from O2

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49
Q

why is Hb free of O2 in tissue capillaries?

A

This occurs because reduced Hb is less acidic than HbO2. Hb acts as a buffer

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50
Q

what is reduced Hb?

A

HHb

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51
Q

what does the presence of reduced Hb aid in? what is this known as?

A

presence of reduced Hb in the tissue capillaries helps with the blood loading of CO2. this is known as the haldane effect

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52
Q

what is the haldane effect?

A

the fact that mixed venous blood can carry more CO2 than can arterial blood.

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53
Q

in what type of blood oxygenated or deoxygenated blood is there a greater [co2] being carried?

A

in deoxygenated blood

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54
Q

when does PCO2 lower?

A

when venous blood flows through the lung capillaries

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55
Q

what happens when PCO2 lowers?

A

HCO3- going to H2CO3 and further into CO2 and H2O, and HbCO2 generating Hb and CO2

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56
Q

how does the CO2 dissociation curve differ from the O2 dissociation curve?

A

no steep nor flat portion, mostly linear relationship between CO2 and PCO2

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57
Q

what happens if we hypoventilate and alveolar PCO2 increases?

A

then arterial, capillary, tissue and venous CO2 also rise

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58
Q

what happens to PCO2 if we double alveolar ventilation?

A

halves alveolat PCO2

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59
Q

what is the relationship between alveolar ventilation and CO2 removal?

A

propotional thus is one increases so does the other

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60
Q

when does respiratory failure occur?

A

when the respiratory system is unable to do its job properly

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61
Q

what may be some causes of respiratory failure?

A
  • failure of gas exchanging capacities of the lungs
  • failure of the neural control of ventilation
  • failure of the neuromuscular breathing apparatus
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62
Q

what does blood hypoxia refer to?

A

deficient blood oxygenation (low PaO2 and low % Hb saturation)

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63
Q

what happens in hypoxic conditions if PaO2 decreases below 60 mm Hg?

A

O2 content in arterial and venous blood becomes lower than the normal values at sea level

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64
Q

what are the 5 general causes of hypoxia?

A
  1. inhalation of low PO2
  2. hypoventilation
  3. ventilation/perfusion imbalance in the lungs
  4. shunts of blood across the lungs
  5. o2 diffusion impariment
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65
Q

when is it possible to inhale low PO2?

A

in high altitudes

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66
Q

what happens to PaO2 and PaCO2 during hypoventilation

A

PaO2 decreases and PaCO2 increases

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67
Q

when does hypoventilation occur?

A

diseases affecting the central nervous system, neuromuscular diseases, barbiturates, other drugs and narcotics

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68
Q

when does Ventilation/perfusion imbalance in the lungs occur?

A

when the amount of fresh gas reaching an alveolar region per breath is too little for the blood flow through the capillaries of that region

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69
Q

why can hypoventilation be caused by shunts of blood across the lungs?

A

venous blood bypasses the gas exchanging region of the lungs and returns to systemic circulation, deoxygenated

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70
Q

in what cases can O2 diffusion be impaired?

A

thickening of the alveolar-capillary membrane, or pulmonary edema

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71
Q

what controls gas exchanges in our bodies?

A

the CNS

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72
Q

what type of control (voluntary/involuntary) is breathing under?

A

voluntary and involuntary control

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73
Q

what part of breathing is voluntarily controlled

A

hyperventilation

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74
Q

when part of breathing is involuntarily controlled?

A

while sleeping

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75
Q

what part of the brain is responsible for voluntary control of breathing?

A

the cerebral hemispheres

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76
Q

can the cerebral hemisphere be effective even when automatic control no longer functions?

A

yes

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77
Q

what part of the brain is responsible for involuntary control of breathing?

A

brainstem

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78
Q

why does your breath start again even if you try to forcefully prevent it?

A

this occurs because the arterial PCO2 has reached about 50 mm Hg and arterial PO2 has reached about 70 mm Hg thats when volontary control gets over ridden

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79
Q

what is the breaking point of respiration?

A

its when the volontary control of breathing is over ridden

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80
Q

how does the overriding of the voluntary control by the automatic control depends on?

A

depends upon the information from the receptors sensitive to CO2 and O2 levels

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81
Q

what are the 3 basic elements involved in the respiratory control system

A
  • sensors
  • controllers
  • effectors
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82
Q

what is the function of sensors in respiratory control?

A

they gather information about lung volume and co2/o2 content

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83
Q

what types of sensors are used for in respiratory control

A

pulmonary receptors and chemoreceptors

84
Q

the information from the sensors is sent to what?

A

to the controllers

85
Q

where are the controllers of respiration found? via what?

A

in the pons and medulla via neural fibers

86
Q

what happens once information reaches the controllers of the pons and medulla?

A

the peripheral information and inputs from the higher structures of the central nervous system are integrated.

87
Q

as a result of of integration in the efforts of respiration what happens?

A

the neural impulses are generated and sent via spinal motoneurons to the effectors (respiratory muscles)

88
Q

what is the function of the effectors of respiration?

A

allows for ventilation to be adapted to the person’s metabolic needs

89
Q

what happens when demand for O2 and production of CO2 increases?

A

ventilation must therefore also increase

90
Q

briefly summerize the relationship between the 3 basic elements of repsiratory control

A

sensors from lungs and chemoreceptors send signal to the central controlers (medulla and pons) which signal an output sent to the effector (respiratory muscles) to control respiration

91
Q

what type of cell is contained in the medulla?

A

pacemaker cells

92
Q

into what types of cells groups are the pacemaker cells of the medulla grouped into?

A

ventral respiratory and and dorsal respiratory group

93
Q

what is contained in the ventral respiratory group of cells?

A

pre-botzinger complex

94
Q

what is generated by the ventral respiratory group of cells?

A

generate basic rhythm

95
Q

what do the ventral and dorsal respiratory cells connect to?

A

inspiratory motor neurones and connect to each other

96
Q

what cells are responsible for turning off inspiration and causing a smaller tidal volume?

A

cells of the upper pons

97
Q

what happens when inspiration is turned off yielding a smaller tidal volume?

A

increase in breathing frequency to maintain adequate alveolar ventilation

98
Q

what happens if the pneumotaxic centres are cut?

A

breathing to become deep and slow

99
Q

what are cells located in the lower pons known as?

A

apneustic center

100
Q

what are cells located in the upper pons known as?

A

pneumotacxic center

101
Q

what do the cells of the lower pons cause?

A

release of excitatory impulese to respiratory group of the medulla which promotes inspiration

102
Q

what happens if influence from upper pons and vagus nerve is removed?

A

apneuses

103
Q

in what cases are apneuses often seen in?

A

severe brain injuries

104
Q

what are apneuses

A

tonic inspiratory activity interrupted by short expirations

105
Q

what gets detected by chemoreceptors?

A

P02, PCO2, pH arterial blood

106
Q

what happens if chemorecptors sens a change in pH or pressures?

A

ventilation will change in attempt to return to normal

107
Q

where is info from the chemoreceptors carried to?

A

to the respiratory neurones

108
Q

in what cases will activity of respiratory neurons increase?

A

PaO2 is too low (less than 60 mm Hg) or PaCO2 is higher than 40 mm Hg

109
Q

in what cases will activity of respiratory neurones decrease?

A

PaO2 is higher than 100 mm Hg or PaCO2 is lower than 40 mm Hg

110
Q

what are the different types of chemoreceptors?

A

central and peripheral

111
Q

where are the central chemoreceptors located?

A

ventral surface of the medulla

112
Q

what is the function of the central chemoreceptors

A

gives rise to the main drive to breathe under normal conditions

113
Q

how can the sensitivity of central chemoreceptors be tested?

A

CO2 rebreathing test

114
Q

what does the stimulation of central chemoreceptors increase?

A

minute ventilation and resulting hyperventilation will reduce PCO2 in blood and in the CSF

115
Q

what causes the pH of the CSF to be reduced?

A

the presence of CO2

116
Q

what happens when the pH of CSF decreases?

A

stimulation of centralc hemoreceptors

117
Q

what are peripheral chemoreceptors sensitive to?

A

sensitive to changes in PO2, increases of PCO2 or decreased pH

118
Q

where are peripheral chemoreceptors located?

A

in the carotid bodies and in aortic bodies

119
Q

what makes up the carotid and aortic bodies

A

blood vessels, structual supporting tissue and numerous nerve endings

120
Q

where do the afferent fibers of peripheral chemoreceptors project?

A

on the dorsal group of respiratory neurons in the medulla

121
Q

how can effects of hypoxia be studied?

A

subject breathe gas mixtures with decreased concentrations of O2

122
Q

what is normocapnia?

A

when levels of CO2 are normal in the blood

123
Q

what can P02 be reduced to before significant changes to minute ventilation occur?

A

60 mm Hg

124
Q

how can an augmented ventilatory response be obtained?

A

through an increase in pCO2 and decrease in PO2

125
Q

what are the 3 types of receptors present in the lungs that respond to mechanical stimuli?

A

pulmonary stretch receptors
irritant receptors
juxta capillaries

126
Q

where can pulmonary stretch receptors be found?

A

in the smooth muscle of the trachea to the terminal bronchiles

127
Q

what innervates pulmonary stretch receptors?

A

large, myelinated fibers

128
Q

how long are the pulmonary stretch receptors active for?

A

as long as the lung is distended

129
Q

what happens to the pulmonary stretch receptors during inspiration?

A

phasically actived due to volume increase of the lungs

130
Q

what is included in the chest wall?

A

rib cage
diaphragm
abdominal wall

131
Q

are the lungs directly attached to the chest wall?

A

no, they are coupled by the visceral and parietal pleura

132
Q

what is the pleural pressure (Ppl)?

A

the pressure that can be measured in the liquid-filled space between lung and chest

133
Q

how is the Ppl at rest? why?

A

negative

due to the opposing forces acting on the lung and chest wall

134
Q

what happens if a hole is punctured through the chest walls?

A

the lungs collapse and the chest springs outwards (pneumothorax)

135
Q

what is measured to evaluate the elastic properties of the respiratory system?

A

measure changes in the recoil pressure of each separate structure for a given change in lung volume

136
Q

what can measure lung volume?

A

spirometry

137
Q

what measures the pressures of the respiratory system?

A

manometers or pressure transducers

138
Q

what is a negative pressure refering to?

A

a pressure below Patm

139
Q

what is the recoil pressure of a structure defined as?

A

he pressure difference between the inside and outside of the structure (transmural pressure)

140
Q

what is the recoil pressure of the chest wall?

A

Pw=Ppl-Pbs

141
Q

how can Ppl be measured?

A

measured using a flexible balloon introduced into the esophagus

142
Q

why can a baloon be placed in the esophagus to determine pressure?

A

Because the esophagus is located between the two pleural spaces, esophageal pressure provides a close approximation of pleural pressure

143
Q

how is transpulmonary pressure (Pl) measured?

A

Pl=Palv-Ppl

144
Q

what is the trans-repsiratory system pressure (Prs)

A

Prs=Palv-Pbs
OR
Prs= Pl+Pw

145
Q

what is compliance

A

refers to the ease with which each of these structures can be distended

146
Q

how is compliance expressed as?

A

the volume change in the lungs for a unitary change in pressure

147
Q

in the pressure-volume curve what does the slope represent?

A

compliance

148
Q

what happens to the slope of the pressure-volume curve if The pressure required to maintain a given volume of gas inside the lungs increases as the volume increases

A

the slope must decrease

149
Q

what happens to compliance in cases of diseases?

A

it can be altered

150
Q

what does the pressure difference between the alveoli (Palv) and the pleural space (Ppl) equal

A

the pressure drop across the lung tissues

151
Q

what does Palv-Ppl represent?

A

is the pressure required to maintain the lungs at a given inflation volume against their tendency to recoil elastically

152
Q

what is elastance

A

1/complance

153
Q

what produces the elastic recoil of the lunfs?

A

by the elastic lung tissue along with the forces of the liquid film lining inside the lungs

154
Q

what is the thoracic compliance defined in terms of?

A

The compliance of the thorax is defined in terms of a change in thoracic volume ∆V and a change in pressure across the chest wal

155
Q

what is the compliance of the respiratory system related to?

A

compliances of the lung and chest wal

156
Q

what is the Prs at FRC?

A

zero because system is at rest

157
Q

what happens to the lungs and chest at FRC?

A

the lungs are above their resting volume and the chest is below its resting volume thus Pl= 5cmH20 and Pcw= -5cmH20

158
Q

what happens to the lungs and chest walll in pneumothroax?

A

lungs collapse to its resting position below RV and the chest wall expands towards its resting position

159
Q

at rest what are the lungs are and what is the Ppl pressure?

A

lungs are at FRC and Ppl is negative

160
Q

what happens to Ppl during inspiration?

A

becomes more negative due to the expansion of the lungs

161
Q

how can air flow into the lungs during inspiration? (pressures)

A

Palv< Patm (negative gradiant)

162
Q

how can air flow out of the lungs during expiration? (pressures)

A

Palv > Patm

163
Q

what happens to the gas in the lungs as the lung volume increases?

A

gas will decompress

164
Q

what happens to alveaolr pressure as the lung volume increaseS?

A

pressure drops

165
Q

what happens to the pressure gradiant and airflow as the lungs fill up during inspiration?

A

both gradually decrease

166
Q

what stops air flow in inspiration

A

Palv=Patm

167
Q

what causes to compress the lungs during expiration?

A

the elastic recoil of the respiratory system

168
Q

what happens to Ppl as the lung volume decreases during inspiration?

A

returns to resting levels

169
Q

at the end of expiration what is the air flow, Palv, and Ppl?

A

air flow= 0
Palv=0 cm H20
Ppl= -5 cmH20

170
Q

what does the time course of changes in pleural pressures during inspiration depend on?

A

diaphragm and air way resistance

171
Q

what must be the Pressure at the airway opening in order for air to flow into the airways?

A

must be different then Palv

172
Q

what is the resitance of the airways to gas flow a ratio of?

A

pressure difference between alveolar and airway opening over the flow

173
Q

what can be carried through a large diameter airway?

A

large flow

174
Q

is the resistance greater in a large or small diameter airway

A

resistance is greater in smaller airways

175
Q

what happens to airway resistance in cases of asthma?

A

resistances becomes vert high

176
Q

what happens to pleural and airway pressures during inspiration

A

they drop

177
Q

what is the airway pressure at the end of inspiration?

A

0

178
Q

what is the airway transmural pressure at the end of inspiration?

A

8 cm h20

179
Q

what happens to intrapleural and alveolar pressures during forced inspirations?

A

pressures increase

180
Q

what happens to the maximim flow rate and volume exhaled in lungs with restrictive diseases?

A

reduced

181
Q

what is the surface tension in the lining of the lungs an important contributior to?

A

to the mechanical properties of the respiratory system

182
Q

how do the molecules in the surface arrange themselves?

A

in their lowest energy conformation, thus more attracted to themselves than to air

183
Q

what happens to the tension on a curved surface?

A

it produces a pressure

184
Q

what equation can be used to approximate the pressure inside the alevoli (small bubble)

A

P=4T/R

185
Q

is the pressure greater inside a small or large bubble?

A

small

186
Q

what happens if a smaller bubble in the proximity of a larger bubble generates a greater pressure?

A

the large bubble will blow up

187
Q

what prevents alveolar collapse?

A

pulmonary surfactant

188
Q

what secretes pulmonary surfactant?

A

type 2 alveolar cells

189
Q

what are the 2 mian roles of pulmonary surfactant

A
  1. making surface tension inside alveoli change with the lung volume
  2. reduing overall tension allowing to breathe
190
Q

what is particular propertie about pulmonary surfactant?

A

decrease surface tension to a greater extend in smaller alveolis

191
Q

what would happen if surface tension inside lining of the lungs was equal to water?

A

lungs would not inflate

192
Q

what happens to tidal volume and breathing frequency when starting to exercise?

A

both increase proportionally

193
Q

what are high ventillatory rates during exercise due to?

A

increase fo frequency due to pleateauing of tidal volume

194
Q

which is more affected by increased breathing frequency inspiration or expiration?

A

expiration

195
Q

what happens to minute ventilation after we pass ~50-65%VO2MAX

A

minute ventilation increases at a rate disproportionately greater than the ventillatory inflection point

196
Q

how much can Ve increase during exercise?

A

35x based on resting volume (5L/min)

197
Q

how much can the CO increase during exercise in a fit individual?

A

5-6 x

198
Q

during exercise what type of response is there in the medullary ecf?

A

ALKALOTIC (increase pH)

199
Q

What is caused by the alkalotic response?

A

decrease of the ventilatory response

200
Q

when is the role of chemoreceptors most important? at rest or during exercise?

A

rest

201
Q

what happen to PaO2 and PaCO2 during exercise?

A

PaO2 stays constant

PaCO2 will decrease

202
Q

what happens to ventialtion origin if PaCO2 decreases?

A

increase in ventilation cannot come from the stimulation of peripheral chemoreceptors by CO2

203
Q

what happens to arterial Ph during exercise?

A

it decreases

204
Q

what is the effect of muscle spindles, golgi tendons and skeletal joint receptors on Ve?

A

small effect during exercise

205
Q

does Ve increase before exercise begain?

A

yes via neural control

206
Q

what type of control is believed to be responsible for the ventilatory response during the exercise events?

A

humoral control

PHGY 210 (11 decks)

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