Physiology 2.3

Question 1

Describe the natural tendency of healthy lungs at the end of a normal expiration.

Answer 1

Healthy lungs have a natural tendency to recoil or contract inwards at the end of a normal expiration due to the elastic fibers.

Question 2

Define type I alveolar cells and type II alveolar cells.

Answer 2

Type I alveolar cells are thin-walled cells responsible for gas exchange, while type II alveolar cells secrete surfactant.

Question 3

How does surfactant reduce surface tension on the alveolar surface membrane?

Answer 3

Surfactant, produced by type II alveolar cells, reduces surface tension on the alveolar surface membrane, preventing alveoli collapse.

Question 4

Describe the role of surface tension in the alveoli.

Answer 4

Surface tension occurs at the air-water interface on the surface of the alveoli, and reducing it prevents alveoli collapse.

Question 5

Define surface tension.

Answer 5

Surface tension refers to the attraction between water molecules at an air-water interface, causing phenomena like zigzagging water droplets on a windowpane.

Question 6

Describe the process of water droplets a windowpane being to each other.

Answer 6

Water droplets on a windowpane are attracted to other, causing them to zig zag backwards and forwards across the surface.

Question 7

What is the role of surfactant in the alveoli?

Answer 7

Surfactant reduces the attraction between water molecules, thus reducing surface tension and preventing the collapse of the alveoli.

Question 8

Define lung compliance.

Answer 8

Lung compliance is a measure of the distensibility of the lung, indicating how easy it is to stretch the lung open.

Question 9

How does surfactant affect lung compliance?

Answer 9

Surfactant increases lung compliance by reducing the lungs’ tendency to recoil, making it easier to get air into the lungs.

Question 10

Describe the impact of surfactant on the work of breathing.

Answer 10

Surfactant makes the work of breathing easier by reducing the opposing force to getting air into the lungs, thus making it easier to breathe.

Question 11

What is the main function of the thin film of fluid surrounding the surface of the alveoli?

Answer 11

The thin film of fluid, mainly water, surrounding the surface of the alveoli is necessary for the air in the alveoli to be in solution before it can cross into the blood.

Question 12

Describe the effect of surfactant on small alveoli compared to large alveoli.

Answer 12

Surfactant is more effective in small alveoli than large alveoli because the surfactant molecules are more concentrated in small alveoli, causing an exaggerated effect due to the closer proximity of the molecules.

Question 13

Define the law of Laplace in the context of surfactant and surface tension.

Answer 13

The law of Laplace states that the pressure required to keep an alveoli open is equal to two times the surface tension divided by the radius.

Question 14

How does the presence of surfactant affect the pressure required to keep small and large alveoli open?

Answer 14

Surfactant reduces the pressure required to keep small alveoli open compared to large alveoli, as demonstrated by the law of Laplace.

Question 15

Do small alveoli require more or less pressure to remain open compared to large alveoli in the absence of surfactant?

Answer 15

Small alveoli require more pressure to remain open compared to large alveoli in the absence of surfactant, as indicated by the law of Laplace.

Question 16

Describe the consequence of having one large alveoli instead of a medium-sized one and a small one.

Answer 16

Having one large alveoli instead of a medium-sized one and a small one results in a reduction in surface area available for gas exchange, which can be detrimental to respiratory function.

Question 17

Explain the significance of maintaining surface area for gas exchange in the alveoli.

Answer 17

Maintaining surface area for gas exchange is crucial for efficient respiratory function, as a reduction in surface area can have a significant detrimental effect, as seen in diseases like emphysema.

Question 18

Why is it less advantageous to have one large alveoli instead of a medium-sized one and a small one, despite having the same volume of air?

Answer 18

Having one large alveoli instead of a medium-sized one and a small one results in a significant reduction in surface area available for gas exchange, which can have a detrimental effect on respiratory function.

Question 19

Describe the role of surfactant in reducing surface tension in the alveoli.

Answer 19

Surfactant, produced by type II alveolar cells, reduces surface tension in the alveoli, thereby aiding in maintaining optimal respiratory function.

Question 20

Describe the role of surfactant in maintaining the surface area available for gas exchange in the alveoli.

Answer 20

Surfactant reduces surface tension, preventing alveolar collapse and maintaining the surface area available for gas exchange.

Question 21

Define infant respiratory distress syndrome and its association with surfactant.

Answer 21

Infant respiratory distress syndrome is a condition in premature babies caused by inadequate surfactant, leading to difficulty in breathing and increased energy required for lung inflation.

Question 22

How does surfactant production in premature babies differ from full-term babies?

Answer 22

Surfactant production in premature babies is inadequate due to incomplete development, leading to respiratory distress, while full-term babies have sufficient surfactant for normal breathing.

Question 23

Describe the impact of surfactant on premature babies’ breathing.

Answer 23

Premature babies with inadequate surfactant experience increased surface tension, requiring significant energy to inflate their alveoli and are at risk of severe respiratory distress and death.

Question 24

Do synthetic surfactant aerosols help in treating premature babies with inadequate surfactant?

Answer 24

Yes, synthetic surfactant aerosols can be given to premature babies to ease their breathing by delivering surfactant directly into their lungs and alveoli.

Question 25

Explain the relationship between thyroid hormones, cortisol, and surfactant production in babies.

Answer 25

Thyroid hormones and cortisol stimulate the activity of type II alveolar cells, leading to surfactant production, which is crucial for normal lung function in babies.

Question 26

Describe the use of synthetic surfactant in managing respiratory distress syndrome in premature babies.

Answer 26

Synthetic surfactant can be given to early babies to manage respiratory distress syndrome, making it much more manageable for premature babies to breathe.

Question 27

Define the difference in pressure required to inflate lungs with air versus saline fluid.

Answer 27

It takes much more pressure to fill the lungs with air compared to filling them with saline fluid.

Question 28

How does the inflation curve differ when filling lungs with air versus saline fluid?

Answer 28

The inflation curve is different when filling lungs with air, compared to filling them with saline fluid.

Question 29

Do babies in utero breathe in uterine fluid, and how does it affect the effort required to fill their lungs?

Answer 29

Babies in utero breathe in uterine fluid, which is effectively saline, requiring much less effort to fill their lungs compared to when they are born and have to breathe air.

Question 30

Describe the breathing cycle of babies in utero and how it compares to babies who have been born.

Answer 30

Babies in utero go through the same breathing cycle as babies who have been born and adults, but they are breathing in uterine fluid, which is effectively saline.

Question 31

Explain the difference in lung inflation pressure required for 200 milliliters of air versus 200 milliliters of saline.

Answer 31

It takes much more pressure to fill the lungs with 200 milliliters of air compared to filling them with 200 milliliters of saline.

Question 32

Define the role of the diaphragm and external intercostal muscles in babies in utero.

Answer 32

The diaphragm and external intercostal muscles in babies in utero contract and relax in the same way as in babies who have been born and in adults.

Question 33

How does the use of synthetic surfactant help premature babies manage respiratory distress syndrome?

Answer 33

The use of synthetic surfactant makes it much more manageable for premature babies to breathe, particularly in managing respiratory distress syndrome.

Question 34

Describe the change in breathing process from in utero to after birth.

Answer 34

In utero, oxygen is obtained from the mother through the placenta, but after birth, breathing air becomes necessary to obtain oxygen and expel carbon dioxide.

Question 35

Define compliance in the context of lung physiology.

Answer 35

Compliance measures the stretchability or distensibility of the lungs, indicating how easy it is to inflate the lungs.

Question 36

How does surfactant affect compliance in the lungs?

Answer 36

Surfactant increases compliance by reducing surface tension, making it easier to inflate the lungs.

Question 37

Do premature babies face challenges in breathing? If so, what are the contributing factors?

Answer 37

Yes, premature babies face challenges in breathing, particularly due to the lack of surfactant, which increases the effort required to breathe.

Question 38

Describe the importance of compliance in relation to lung health.

Answer 38

High compliance in healthy lungs means a relatively large increase in lung volume for a small decrease in intrapleural pressure, requiring less effort to breathe.

Question 39

What is the significance of getting carbon dioxide out of the lungs in the context of breathing?

Answer 39

Getting carbon dioxide out of the lungs is as important as getting oxygen in, as carbon dioxide is toxic and needs to be expelled during the expiratory phase of breathing.

Question 40

Define the term compliance in the context of lung physiology.

Answer 40

Compliance measures the stretchability or distensibility of the lungs, indicating how easy it is to inflate the lungs.

Question 41

How does the need for breathing change from in utero to after birth?

Answer 41

In utero, oxygen is obtained from the mother through the placenta, but after birth, breathing air becomes necessary to obtain oxygen and expel carbon dioxide.

Question 42

What is the role of surfactant in the breathing process, especially for premature babies?

Answer 42

Surfactant reduces surface tension in the lungs, making it easier to breathe, which is particularly crucial for premature babies who may lack adequate surfactant.

Question 43

Describe the importance of getting carbon dioxide out of the lungs in the context of breathing.

Answer 43

Getting carbon dioxide out of the lungs is as important as getting oxygen in, as carbon dioxide is toxic and needs to be expelled during the expiratory phase of breathing.

Question 44

Describe the relationship between compliance and elasticity in the context of lung function.

Answer 44

Compliance refers to the ability of the lungs to expand, while elasticity refers to their ability to recoil. High compliance is beneficial only when accompanied by high elasticity, as seen in healthy lungs.

Question 45

Do people with emphysema have high or low compliance?

Answer 45

People with emphysema have highly compliant lungs, but they lack elasticity, leading to poor lung function.

Question 46

Define fibrosis and its impact on lung compliance.

Answer 46

Fibrosis is a condition that decreases the compliance of the lungs by laying down fibrous tissue alongside elastic tissue, making it difficult to expand the lungs.

Question 47

Describe the impact of aging on lung compliance.

Answer 47

As people age, the elastic function of the lungs reduces, leading to a natural decrease in compliance. This reduction can be exaggerated in conditions like fibrosis.

Question 48

What is the consequence of low compliance in the lungs?

Answer 48

Low compliance means that extra effort is required for breathing in order to get air into the lungs, making it a detrimental condition for lung function.