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MDSC 2401- Respiration > Respiratory Physiology (Combined) > Flashcards

Respiratory Physiology (Combined) Flashcards

1
Q

What is respiratory failure?

A

Inability of the lungs to supply adequate amount of O2 and to remove CO2 from the blood.

This condition is critical for maintaining proper gas exchange in the body.

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2
Q

What is the arterial oxygen pressure threshold for diagnosing respiratory failure?

A

Lower than 60 mm Hg

Normal value is 100 mm Hg.

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3
Q

What is the arterial carbon dioxide pressure threshold for diagnosing respiratory failure?

A

Higher than 50 mm Hg

Normal value is 40 mm Hg.

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4
Q

What is required for the diagnosis of respiratory failure?

A

Measurement of arterial blood gases.

This test assesses the levels of oxygen and carbon dioxide in the blood.

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5
Q

List common clinical findings in respiratory failure.

A
  • Cyanosis
  • Dyspnea (breathlessness)
  • Tachypnea
  • ‘Tripod’ position

These findings indicate varying degrees of respiratory distress.

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6
Q

Explain the autonomic nervous system of the conducting zone of the respiratory system.

A

Parasympathetic- involves the muscarnic receptors and bronchocontriction. It decreases the airway resistance/ diameter and increase resistance to air flow. It is blocked by muscarnic antagonist.

Sympathetic stimulation- involves b2 receptors and bronchodilation (relaxation). It increases airway resistance/ diameter and decrease resistance to airflow.

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7
Q

What blocks/ inhibits bronchocontriction of the smooth muscles in the conducting zone?

A

B2 receptors/ agonist such as epinephrine, isoproternol and albuterol.

Note: These increase airway diameter and decrease resistance to airflow.

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8
Q

What components can not be measured by spirometry?

A

TLC, FRC and RV.

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9
Q

Which components can be measured by Spirometry?

A

IRV, ERV and VC

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10
Q

What is the function of surfactant?

A

Reduces surface tension and increases compliance.

It is synthesized by Type II Pneumocytes and consist of DPPC.

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11
Q

What is the relationship between compliance and FRC for the following:
A) obstructive diseases
B) restrictive diseases

A

Obstructive - increase compliance and FRC
Restrictive - decrease compliance and FRC

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12
Q

What is the relationship between FEV1/FVC and obstructive and restrictive diseases?

A

Obstructive diseases - Decrease in FEV1/FVC
Restrictive diseases - increase in FEV1/ FVC

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13
Q

What is the effects of compliance, FRC and FEV1/ FVC on restrictive diseases?

A

Decrease long compliances
Increase FEV1/FVC
Decrease FRC

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14
Q

What are the characteristics of obstructive diseases as it relates to compliance and FEV1/ FVC?

A

Increase lung compliance
Decrease FEV1/FVC
Increase FRC.

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15
Q

How can FRC be determined?

A

Helium dilution and Body Plethysmograph.

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16
Q

What are your inspiratory muscles and what are their functions?

A

Diaphragm- elevate the ribs, dome descends and increase the volume of the thoracic cavity.
External intercostals- elevate the ribs

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17
Q

What are your expiratory muscles and what are their functions?

A

Internal intercostals- pull the ribs down
Abdominal muscles - pulls the ribs down and compresses the abdominal muscles and pushes the diaphragm up.

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18
Q

Measurement of FRC can be done by which law?

A

Boyle’s Law.

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19
Q

When is surfactant visible in the fetus?

A

Alveolar stage (35 week gestation, 8 months - 8 years)

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20
Q

Name the disease that occurs due to the lack of surfactant in infants?

A

Neonatal respiratory distress syndrome.

Results in infant experiencing atelectasis, difficulty reinflating the lungs, decreases V/Q and right to left shunt and hypoxemia.

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21
Q

Which gas demonstrates perfusion- limited exchange between alveolar air and pulmonary capillary blood?

A

O2 (normal conditions)
N2O
CO2

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22
Q

Which gas demonstrates diffusion- limited exchange between alveolar air and pulmonary capillary blood?

A

O2 (Exercise, emphysema, fibrosis)
CO

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23
Q

Describe the volumes and pressures during the breathing cycle at rest.

A

Lung volume is 0 = FRC
Alveolar pressure is zero and = atmospheric pressure.
Intrapleural pressure is negative.

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24
Q

Describe the volumes and pressures during the breathing cycle at inspiration.

A

Lung volume increases
Alveolar pressure is negative as and < the atmospheric pressure
Intrapleural pressure is negative.

At peak inspiration, lung volume is the FRC + one VT

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25
Q

Describe the volumes and pressures during the breathing cycle at expiration.

A

Lung volume decreases
Alveolar pressure becomes + and > atmospheric pressure
Intrapleural pressure is +

Note: Intrapleural pressure returns back to normal during passive expiration but turns + during forceful expiration.

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26
Q

Which law/ gas equation is used to calculate partial pressures?

A

Dalton’s Law.

27
Q

Which law is responsible for gas diffusion across the alveolar- pulmonary capillary barrier?

A

Fick law.

28
Q

Which hemoglobin is responsible for sickle cell?

A

Hemoglobin S

29
Q

Which state is iron in in Methemoglobin?

A

Fe3+ state

30
Q

List some characteristics of Fetal hemoglobin.

A

Chain- a2y2
It has a higher O2 affinity than the O2 affinity in hemoglobin (left shift occurs)

31
Q

State what changes occurs to the hemoglobin -O2 dissociation curve when it shifts to the right.

A

Increase in P50, PCO2, Temperature, 2,3-DPG, unloading of 02.
Decrease in pH and affinity of O2.

32
Q

State what changes occurs to the hemoglobin -O2 dissociation curve when it shifts to the left.

A

Increase- pH and affinity of O2
Decrease - temperature, P50, unloading of O2, PCO2, 2,3-DPG

33
Q

State the effect of carbon monoxide on the hemoglobin -O2 dissociation curve.

A

CO has a greater for affinity for hemoglobin thus it binds and decreases the O2 content in blood.
Results in a left shift of the dissociation curve.

34
Q

List the forms of CO2 in blood.

A

Dissolved CO2
Carbaminohemoglobin
HCO3-

35
Q

Which form of CO2 is the major form transported in the lungs?

A

HCO3-

36
Q

Describe the transport of CO2.

A

CO2 enters the RBC and combines with H2O to form H2CO3 by carbonic anhydrase.
H2CO3 is then dissociated into H+ and HCO3.
HCO3 leaves the RBC in exchange for Cl (chloride shift) and enters the lungs.
The H+ remaining binds with deoxyhemoglobin.

37
Q

State the differences between the pressures and cardiac output of pulmonary and systemic circulation.

A

Pressures and resistance are much lower in pulmonary circulation compared to systemic.

Cardiac output of the RV is the pulmonary blood flow which is = the cardiac output of LV.

38
Q

Describe the pressure difference of pulmonary blood flow in the following:
A) zone 1
B) zone 2
C) zone 3

A

Zone 1- Alveolar pressure > arterial pressure> venous pressure
Zone 2- Arterial pressure > Alveolar > venous
Zone 3- Arterial pressure> venous > alveolar pressure

39
Q

Which gas law is used to determine the solubility?

A

Henry’s Law

40
Q

Discuss what happens to the V/Q ratio in the lungs when an airway obstruction occurs?

A

V/Q = 0 = right to left shunt

There is no gas exchange
PO2 and PCO2 of pulmonary capillary/ systemic blood will reach that of its values of mixed venous blood (40 and 46 respectively)

41
Q

Discuss what happens to the V/Q ratio in the lungs when a pulmonary embolism occurs.

A

V/Q would be infinite = dead space

No gas exchange
PO2 and PCO2 of alveolar air would approach their values of inspired air (150 and 0 mmhg respectively).

42
Q

Describe the different V/Q characteristics for the Apex of the lung.

A

Blood flow - decrease
Ventilation - decrease
PCO2- decrease
V/Q - increase
PO2- increase

43
Q

Describe the different V/Q characteristics for the Base of the lung.

A

Blood flow - increase
Ventilation - increase
PCO2 - increase
V/Q- increase
PO2- increase

44
Q

An increase or decrease in arterial PO2 stimulates what and causes an increase in the breathing rate?

A

Peripheral chemoreceptors

45
Q

Central chemoreceptors are sensitive to what?

A

PH

An decrease in pH will cause an increase in breathing rate (hyperventilation)

46
Q

Describe the transport of CO2 in the tissues and the lungs.

A
  1. Tissues: CO2 —> RBC —> CO2+ H20 —> H2CO3. H2CO3 dissociates and forms H+ and HCO3-. HCO3- leaves the RBC in exchange for Cl- (Chloride shift) . H+ is buffered with deoxyhemoglobin due to it being a better buffer system.
  2. Lungs: HCO3- —> RBC —> HCO3- + H+ —> H2CO3. The reverse reaction forms CO2 + H20, in which H20 is expired.
47
Q

Review the flow- volume loop.

A
48
Q

State what occurs during hyperventilation when adapting to high altitude.

A

Decreasing PCO2 in arterial blood and increases PO2 and causes an increase in pH ( alkalosis)

49
Q

How does the kidney compensate for respiratory alkalosis (high altitude)?

A

The kidney excretes more HCO3- and reduces secretion of H+, which brings the blood pH back to normal.

Can be treated with carbonic anhydrase inhibitors

50
Q

What is the affect on the following regarding adaptation to high altitude?
A) pulmonary gas exchange
B) transport of O2 and CO2 by the blood.
C) Systemic gas exchange.

A

A) increase surface area and alveolar perfusion = increase gas exchange. Increase cardiac output, increase pulmonary blood flow.
B) increase cardiac output, increases # of RBC. Increases blood pressure.
C) increase O2 extraction from arterial blood by peripheral tissues. (Bohr effect, increase tissue vascularity and increase mitochondria and oxi. enzyme.)

51
Q

List some symptoms of altitude sickness and what is it corrected by?

A
  1. Dizziness, headache, palpitations, insomnia, nausea and fatigue.
  2. It is corrected by supplemental O2.
52
Q

State the effects of the alveolar pressure when breathing during diving.

A

The alveolar pressure increases/ doubles thus causing the partial pressures within the alveolar air to increase as well.

53
Q

State how the partial pressure of CO2 within alveolar air is affected in an individual who is breathing during a dive.

A
  • CO2 doubles from 40 to 80 mmhg. With this increase this increases the amount of CO2 in the arterial blood.
  • The increase in alveolar CO2 > CO2 in venous blood there for the direction of CO2 diffusion is reversed.
  • CO diffusion now takes place in venous blood.
  • Once CO2 in venous blood exceeds the CO2 of arterial blood, the direction of diffusion reverses back to alveoli
54
Q

State how the partial pressure of N2 within alveolar air is affected in an individual who is breathing during a dive.

A

N2 increases during a deep dive.
N2 increases in the pulmonary capillary blood flow and also the tissues.
This reduces ion conductance of membranes and neuron excitability.
Increase in N2 can lead to Nitrogen narcosis.
Mild and deep nitrogen narcosis (lethargy and loss of consciousness).
N2 narcosis is corrected with Helium.

55
Q

State how the partial pressure of O2 within alveolar air is affected when diving.

A
  1. O2 increases in pulmonary capillary blood.
  2. High exposure to O2- no negative effects for several hours.
  3. Chronic exposure causes air epithelium damage, smooth muscle and inflammation causing pulmonary edema
  4. High O2 can cause O2 toxicity. Muscle twitching, disorientation, irritability, seizures and comas.

Occur to O2 free radicals oxidizing the fatty acids in cell membrane and enzymes in cellular metabolism.
Can be corrected by reducing fraction of O2 in the inspired air.

56
Q

What is the cause of decompression sickness?

A

The decrease in alveolar air within the body resulting in decrease in N2.
N2 leaves the tissues and enters blood which results in bubbles being formed.
These bubbles can cause emboli within the vessel.

57
Q

Describe the types of decompression sickness.

A

Type 1- bubbles are formed with muscles and joints.
Type 2- bubbles formed with in myelin sheath. Affects CNS. Pulmonary symptoms involves embolism in pulmonary circulation
Type 3 - arterial embolism which can lead to death

Treatment is hyperbaric chamber.

58
Q

Describe the shallow water blackout.

A

Swimmer hyperventilates
Decrease PaCO2
Decrease resp.
Increase O2 intake due to exercise
Decrease PaCO2 due to hypocapnia
Brains - hypoxic
Blackout occurs.

59
Q

How are blood gases affected in arterial and venous blood during exercise?

A

In the venous blood, O2 decreases and CO2 increases.
In arterial blood, O2 and CO2 remains the same.

60
Q

Discuss ventilation at the apex vs. base of the lungs.

A

At the apex, ventilation is low due to the alveoli being stretched. Low compliance.

At the base, ventilation is high due to alveoli being small and can be stretched during inspiration. High compliance.

Alveoli are pulled down at apex and compressed at base thus causing the resting size of alveoli be greater at the apex

61
Q

Where is alveolar dead space present in normal conditions?

A

Apical region.

Alveolar dead space is known as when some alveoli are ventilation and not perfused. (Note: Gas exchange can not occur)

62
Q

Discuss the mechanisms that compensate for the following defects in ventilation- perfusion relationships.
A) Shunt

A
  1. Shunt = perfusion exceeds ventilation
  2. High levels of alveolar CO2 is seen here.
  3. High levels of CO2 in alveolar air results in bronchodilation, increasing ventilation.
  4. Low O2 levels in pulmonary blood flow results in vasoconstriction, reducing perfusion.
63
Q

Discuss the mechanisms that compensate for the following defects in ventilation- perfusion relationships.
A) Alveolar dead space.

A
  1. Alveolar dead space = ventilation exceeds perfusion.
  2. High levels of O2 seen in pulmonary blood.
  3. Low levels of alveolar CO2 results in bronchocontriction, reducing ventilation.
  4. High levels of pulmonary blood O2 levels results in arteriolar vasodilation, increase perfusion.

MDSC 2401- Respiration (9 decks)

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