Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PT663 > Pulmonary Physiology II > Flashcards

Pulmonary Physiology II Flashcards

1
Q

What is the role of the pulmonary system in carbon dioxide removal?

A

The system transports CO₂, generated by cellular respiration, back to the lungs to be expelled during exhalation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is meant by the matching of ventilation and perfusion?

A

It refers to the coordination between airflow (ventilation) and blood flow (perfusion) in the lungs for optimal gas exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is gas exchange, and where does it occur in the body?

A

Gas exchange is the process of oxygen entering the blood and carbon dioxide leaving the blood, occurring in the lungs and tissues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does gas transport work in the circulatory system?

A

Oxygen and carbon dioxide are carried in the blood through the circulatory system to reach tissues or return to the lungs for removal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main process through which gas exchange occurs in the lungs?

A

Gas exchange in the lungs occurs by diffusion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What drives the diffusion of gases during gas exchange?

A

Diffusion is driven by partial pressure gradients.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the partial pressure of oxygen (PO₂) in dry inspired air at sea level?

A

160 millimeters of mercury.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why does the partial pressure of oxygen decrease to 150 mm Hg in the conducting airways?

A

The air is humidified in the conducting airways, which decreases the partial pressure of oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the partial pressures of oxygen and carbon dioxide in the alveolus?

A

Oxygen: 100 mm Hg, Carbon dioxide: 40 mm Hg.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does mixed venous blood become oxygenated in the lungs?

A

Oxygen from the alveolus diffuses into the blood, increasing the blood’s PO₂ from 40 mm Hg to 100 mm Hg.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What three factors determine the rate of diffusion during gas exchange?

A

The pressure gradient, surface area, and membrane thickness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does an increased membrane thickness, like in fibrosis, affect gas exchange?

A

It slows the rate of diffusion, potentially leading to incomplete oxygenation of blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is it harder to breathe at high altitudes?

A

The barometric pressure is lower, which decreases the pressure gradient for oxygen diffusion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to the alveolar PO₂ at high elevations?

A

It decreases, leading to a smaller pressure gradient for oxygen diffusion (e.g., 50 mm Hg instead of 100 mm Hg).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How quickly does blood equilibrate with alveolar oxygen under normal conditions?

A

It equilibrates within the first third of the pulmonary capillary length.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the effect of a smaller pressure gradient on gas exchange, as seen at high altitudes?

A

It slows the exchange of oxygen between the alveolus and the capillary.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is ventilation, and how does it differ from gas exchange?

A

Ventilation is the bulk flow of air into and out of the lungs, while gas exchange involves the diffusion of gases between the alveoli and blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What condition is likely to limit gas exchange in a healthy person under normal conditions?

A

High altitude or diseases that increase membrane thickness or decrease surface area can limit gas exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the two forms in which oxygen is carried in the blood?

A

Oxygen is carried in the blood bound to hemoglobin and dissolved in plasma.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the equation for blood oxygen content?

A

Blood oxygen content = (constant × hemoglobin concentration × percent saturation) + (partial pressure of oxygen × solubility).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What percentage of oxygen in the blood is bound to hemoglobin?

A

98% of oxygen is bound to hemoglobin, while only 2% is dissolved in plasma.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do we determine the oxygen saturation of hemoglobin?

A

Oxygen saturation is determined through laboratory tests or estimated using a pulse oximeter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the oxyhemoglobin dissociation curve?

A

It describes the relationship between partial pressure of oxygen (PO2) and the saturation of hemoglobin with oxygen, typically in an S-shaped curve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens to hemoglobin saturation as the PO2 decreases in the lungs?

A

Hemoglobin saturation changes only slightly with large changes in PO2 in the lungs due to the flat portion of the curve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why is the shape of the oxyhemoglobin dissociation curve advantageous?

A

It allows for efficient oxygen loading in the lungs and unloading in the tissues, with small changes in PO2 leading to significant changes in saturation at the tissue level.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the P50 value?

A

The P50 value is the partial pressure of oxygen at which hemoglobin is 50% saturated with oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does exercise affect the oxyhemoglobin dissociation curve?

A

Exercise increases temperature, CO2, and decreases pH, shifting the curve to the right, which decreases hemoglobin’s affinity for oxygen and facilitates unloading.

28
Q

What are the three modes of carbon dioxide transport in the blood?

A

Carbon dioxide is transported dissolved in plasma, bound to hemoglobin, and as bicarbonate.

29
Q

What percentage of carbon dioxide is transported as bicarbonate?

A

Approximately 92% of carbon dioxide is transported in the form of bicarbonate.

30
Q

What role does carbonic anhydrase play in carbon dioxide transport?

A

Carbonic anhydrase catalyzes the reaction of carbon dioxide with water to form carbonic acid, which dissociates into bicarbonate and protons.

31
Q

How does the relationship between carbon dioxide and protons relate to acidosis?

A

Increased carbon dioxide levels lead to more protons being produced, contributing to acidosis.

32
Q

What is the relationship between PaO2 and SaO2?

A

The partial pressure of oxygen (PaO2) and the oxygen saturation (SaO2) are related by the oxyhemoglobin dissociation curve.

33
Q

What are the three primary blood gases that regulate ventilation?

A

Oxygen, carbon dioxide, and pH.

34
Q

What is hypoxemia and what is its threshold value?

A

Hypoxemia is low blood oxygen levels, defined as a PaO2 of 80 mmHg or less.

35
Q

What is hypercapnia?

A

Hypercapnia refers to high levels of carbon dioxide in the blood, generally above 45 mmHg.

36
Q

What blood pH value indicates acidosis?

A

A pH of less than 7.35 is considered acidosis.

37
Q

How are low oxygen levels and high carbon dioxide levels sensed in the body?

A

They are sensed by chemoreceptors: central chemoreceptors in the brainstem and peripheral chemoreceptors in the blood vessels around the aorta.

38
Q

What is the role of chemoreceptors in regulating ventilation?

A

Chemoreceptors send signals to the medulla and pons to increase ventilation in response to disturbances in blood gas values, such as hypoxemia or hypercapnia.

39
Q

What happens to ventilation when there is acidosis and hypercapnia?

A

Ventilation increases, which helps exhale more carbon dioxide and return levels to normal, also increasing oxygen levels.

40
Q

What is one cause of hypoxemia related to external factors?

A

Breathing a hypoxic gas, such as at high altitudes.

41
Q

How does hypoventilation lead to hypoxemia?

A

In hypoventilation, insufficient breathing causes both PaO2 and arterial PaO2 to fall while carbon dioxide levels rise.

42
Q

What conditions can cause hypoventilation?

A

Causes include decreased ventilatory drive from brain damage or drug overdose, paralysis or weakness of ventilatory muscles, or chest wall damage.

43
Q

What is diffusion limitation in relation to hypoxemia?

A

Diffusion limitation occurs when conditions like fibrosis slow the diffusion of gases across the alveolar-capillary membrane, leading to hypoxemia.

44
Q

Why is the ventilation-perfusion (V/Q) mismatch important?

A

A mismatch between ventilation and perfusion can lead to hypoxemia and is a significant factor in various disease conditions.

45
Q

What do “v” and “Q” stand for in the context of ventilation and perfusion?

A

“v” stands for ventilation (airflow in liters per minute), and “Q” stands for perfusion (blood flow).

46
Q

What is the normal ventilation-perfusion (V/Q) ratio?

A

The normal V/Q ratio is approximately 0.8.

47
Q

How does gravity affect ventilation and perfusion in the lungs?

A

Gravity impacts both ventilation and perfusion; the bases of the lungs are better ventilated and perfused than the apices.

48
Q

What happens to the V/Q ratio when ventilation is obstructed, such as by a mucus plug?

A

The V/Q ratio becomes 0, resulting in arterial blood gas composition similar to venous blood (e.g., PaO2 ~ 40 mmHg, PaCO2 ~ 46 mmHg).

49
Q

What occurs when there is normal ventilation but obstructed blood flow, such as in a pulmonary embolism?

A

The V/Q ratio becomes infinity, and the alveolar gas composition resembles fresh air rather than equilibrated alveolar air.

50
Q

What is the relationship between V/Q ratio and arterial blood composition?

A

A low V/Q ratio leads to arterial blood resembling venous blood; a high V/Q ratio results in arterial blood resembling atmospheric air.

51
Q

How do ventilation and perfusion differ in the apex versus the base of the lungs?

A

The apex is underperfused and overventilated (high V/Q), while the base is overperfused and underventilated (low V/Q).

52
Q

What is the impact of underperfusion and overventilation on blood gases in the apex of the lung?

A

Arterial blood in the apex has higher PaO2 and lower PaCO2, resembling fresh air.

53
Q

What happens to blood gases in the base of the lung?

A

Arterial blood in the base has lower PaO2 and higher PaCO2, resembling mixed venous blood.

54
Q

How does the V/Q relationship affect blood gas composition in normal lung regions?

A

In the middle of the lung, the V/Q ratio is average (0.8), leading to typical arterial blood gases (PaO2 ~ 100 mmHg, PaCO2 ~ 40 mmHg).

55
Q

What can result from defects in the ventilation-perfusion ratio?

A

Defects in the V/Q ratio are a major cause of hypoxemia in pathological conditions.

56
Q

How much can the pulmonary system adapt to increased metabolic demand during exercise?

A

The pulmonary system can adapt to a 20-fold increase in metabolic demand by increasing minute ventilation, also by about 20-fold.

57
Q

What are the phases of the ventilatory response during moderate intensity exercise?

A

The ventilatory response has two phases: an initial rapid increase (neural origin) followed by an exponential increase that eventually plateaus.

58
Q

How does venous carbon dioxide (CO2) change during exercise?

A

Venous CO2 increases with exercise due to higher metabolic activity, but arterial CO2 remains stable as ventilation matches CO2 production.

59
Q

What happens to ventilation during heavy exercise compared to moderate exercise?

A

In heavy exercise, ventilation continues to increase beyond a plateau, with ventilation rising more than CO2 production and oxygen consumption, indicating a ventilatory threshold.

60
Q

What are the two components of minute ventilation?

A

Minute ventilation is the product of respiratory rate and tidal volume.

61
Q

How does the reliance on tidal volume and respiratory rate change with exercise intensity?

A

At low intensities, there is a greater reliance on increasing tidal volume; at higher intensities, reliance shifts to increasing respiratory rate.

62
Q

What effect does lung compliance have on ventilation at different volumes?

A

At low lung volumes, compliance is high (easy to expand), but at high volumes, compliance is low (more effort required to expand).

63
Q

What occurs to the ventilation-perfusion (V/Q) ratio during exercise?

A

The V/Q ratio approaches 1, indicating better matching of ventilation and perfusion.

64
Q

What can happen to oxygen levels in highly trained athletes during high-intensity exercise?

A

Blood can flow so fast through pulmonary capillaries that diffusion limitations may occur, leading to hypoxemia (decreased blood oxygen levels).

65
Q

What physiological change occurs to the oxyhemoglobin dissociation curve during exercise?

A

There is a rightward shift in the curve, decreasing hemoglobin’s affinity for oxygen, facilitating oxygen delivery to tissues.

66
Q

What is the primary limitation to exercise capacity in healthy individuals?

A

In healthy subjects, the pulmonary system is generally not the limiting factor for exercise capacity; the cardiovascular system is the major limiting factor.

67
Q

What triggers the inflection point known as the ventilatory threshold during heavy exercise?

A

The ventilatory threshold is driven by acidosis resulting from anaerobic glycolysis, leading to increased ventilation beyond CO2 production.

PT663 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions