Physiology 2.2

Question 1

Describe Boyle’s law and its relationship between gas pressure and volume.

Answer 1

Boyle’s law states that the pressure exerted by a gas is inversely proportional to its volume. When the volume increases, the pressure decreases, and vice versa.

Question 2

Define Dalton’s law and its significance in gas mixtures.

Answer 2

Dalton’s law states that the total pressure of a gas mixture is the sum of the pressures of the individual gases. It outlines partial pressure and is important in understanding the behavior of gas mixtures.

Question 3

How does Charles’s law relate the volume of a gas to its absolute temperature?

Answer 3

Charles’s law states that the volume occupied by a gas is directly related to the absolute temperature. As the temperature increases, the volume of the gas also increases.

Question 4

Explain the concept of partial pressure in gas mixtures.

Answer 4

Partial pressure refers to the pressure exerted by each gas in a mixture. According to Dalton’s law, the total pressure of a gas mixture is the sum of the pressures of the individual gases.

Question 5

Describe Henry’s law and its relevance to gas dissolved in a liquid.

Answer 5

Henry’s law states that the amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid. This concept becomes important when examining how gases are carried in the blood.

Question 6

What is the significance of gas laws in understanding the mechanics of breathing?

Answer 6

Gas laws, such as Boyle’s law, Dalton’s law, Charles’s law, and Henry’s law, are fundamental in describing the movement of air during inspiration and expiration. They explain the relationship between gas pressure, volume, and temperature, which is crucial in understanding respiratory physiology.

Question 7

Describe the process of in the respiratory system.

Answer 7

Insp uses the external intercostal muscles and the diaphragm to expand the thoracic cavity, allowing air to enter the lungs.

Question 8

What muscles are primarily responsible for the majority of the muscular effort of inspiration?

Answer 8

The diaphragm and the external intercostal muscles are primarily responsible for the majority of the muscular effort of inspiration.

Question 9

Define expiration in the context of the respiratory system.

Answer 9

Expiration is the process of air leaving the lungs, which is primarily passive at rest but can be aided by the internal intercostal muscles and abdominal muscles during increased respiratory load.

Question 10

How are the scalene muscles and sternocleidomastoid muscles involved in the respiratory process?

Answer 10

Under very heavy respiratory load, the scalene muscles and sternocleidomastoid muscles are recruited to aid the expansion of the chest wall and increase the amount of air entering the thoracic cavity.

Question 11

Describe the role of the internal intercostal muscles in expiration.

Answer 11

The internal intercostal muscles run at a different angle to the external intercostal muscles and aid in the process of expiration by running in the opposite direction underneath the external intercostal muscles.

Question 12

What is the primary muscle responsible for inspiration in the respiratory system?

Answer 12

The diaphragm is the main muscle responsible for inspiration, accounting for about 70 percent of the muscular activity of inspiration, possibly even more during very quiet, relaxed breathing.

Question 13

Describe the action of the intercostal muscles during respiration.

Answer 13

When the external intercostal muscles contract, they lift the ribcage upwards and outwards.

Question 14

What is the role of the abdominal muscles during respiration?

Answer 14

When the abdominal muscles contract, they reduce the volume of the abdominal cavity, pushing the organs against the diaphragm and into the thoracic cavity.

Question 15

How does the diaphragm contribute to inspiration?

Answer 15

When the diaphragm contracts, it flattens down, increasing the volume of the thoracic cavity and decreasing the pressure, allowing air to flow into the lungs.

Question 16

Define forced expiration and the muscles involved in this process.

Answer 16

Forced expiration occurs during coughing or increased respiration rate. It involves the use of internal intercostal and abdominal muscles to decrease the volume of the thoracic cavity.

Question 17

Describe the role of the phrenic nerve in respiration.

Answer 17

The phrenic nerve innervates the diaphragm, causing it to contract during inspiration, increasing the volume of the thoracic cavity and decreasing pressure to allow air to flow into the lungs.

Question 18

What happens during normal expiration?

Answer 18

During normal expiration, the phrenic nerve stops innervating the diaphragm, causing it to relax back to its dome shape, reducing the volume inside the thoracic cavity and increasing pressure.

Question 19

Describe the role of the diaphragm in breathing.

Answer 19

The diaphragm is the main muscle of breathing, aiding in the process of inspiration by contracting and flattening to increase the volume of the thoracic cavity.

Question 20

What is the function of the external intercostal muscles during breathing?

Answer 20

The external intercostal muscles act to raise the rib cage upwards and outward, increasing the anterior-posterior and lateral dimensions of the thoracic cavity during inspiration.

Question 21

How do the external intercostal muscles contribute to increasing the thoracic cavity volume?

Answer 21

The external intercostal muscles increase the volume of the thoracic cavity in both anterior-posterior and lateral dimensions during inspiration.

Question 22

Define the action of the external intercostal muscles.

Answer 22

The external intercostal muscles act to raise the sternum and expand the ribs, increasing the thoracic cavity volume during inspiration.

Question 23

Describe the analogy used to explain the action of the external intercostal muscles.

Answer 23

The action of the external intercostal muscles is likened to different types of handles, such as a pump handle, to illustrate the lifting of the sternum and expansion of the rib cage during inspiration.

Question 24

What is the role of the external intercostal muscles in increasing the thoracic cavity volume?

Answer 24

The external intercostal muscles aid in increasing the volume of the thoracic cavity during inspiration by lifting the sternum and expanding the ribs, contributing to both anterior-posterior and lateral dimensions.

Question 25

Describe the process of inspiration in the respiratory system.

Answer 25

During inspiration, the diaphragm contracts and external intercostal muscles contract, increasing the thoracic volume in three dimensions.

Question 26

What happens during expiration in the respiratory system?

Answer 26

During expiration, the diaphragm relaxes, reducing thoracic volume, and the external intercostal muscles stop contracting, leading to a decrease in volume and an increase in pressure.

Question 27

Define the role of internal intercostal muscles in breathing.

Answer 27

The internal intercostal muscles are involved in expiration, actively pulling the ribcage down and the sternum in, working opposite to the external intercostal muscles.

Question 28

How does the change in thoracic cavity volume and pressure affect airflow in the respiratory system?

Answer 28

The change in volume and pressure affects the airways, with inspiration leading to the opening and increased diameter of airways, making airflow easier, and expiration causing compression of the airways.

Question 29

Describe the impact of asthma on the respiratory system during expiration.

Answer 29

Asthma can cause inappropriate constriction of bronchial smooth muscle, narrowing the airways and increasing resistance, which is aggravated during expiration due to the compression of the airways.

Question 30

Explain the impact of healthy lungs on airflow resistance during expiration.

Answer 30

In individuals with healthy lungs, the compression and increase in resistance during expiration are typically unnoticed and do not cause any trouble, unlike in asthmatic individuals.

Question 31

What are the primary muscles involved in relaxed breathing?

Answer 31

During relaxed breathing, the primary muscles involved are the diaphragm and the external intercostal muscles, while the internal intercostal muscles are not typically utilized.

Question 32

How does the pleural fluid affect the airways during inspiration?

Answer 32

The pleural fluid causes the airways to be pulled open during inspiration, reducing resistance to airflow as the chest wall expands and the lungs are stretched.

Question 33

What physical changes occur in the thoracic cavity during inspiration and expiration?

Answer 33

During inspiration, the thoracic volume increases as the diaphragm contracts and the external intercostal muscles contract, while during expiration, the thoracic volume decreases as the diaphragm relaxes and the external intercostal muscles stop contracting.

Question 34

Define alveolar pressure and its relation to atmospheric pressure.

Answer 34

Alveolar pressure is the pressure inside the thoracic cavity, which may be positive or negative relative to atmospheric pressure. In respiratory physiology, pressures are typically related to atmospheric pressure, with greater pressure being called positive and lower pressure being called negative.

Question 35

How does intrapleural pressure typically compare to atmospheric pressure in healthy lungs?

Answer 35

In healthy lungs, intrapleural pressure is typically negative compared to atmospheric pressure.

Question 36

Describe transpulmonary pressure and its expected nature.

Answer 36

Transpulmonary pressure is the difference between alveolar pressure and intrapleural pressure. It should always be positive because intrapleural pressure is always negative.

Question 37

Do intrapleural pressure and alveolar pressure result in a positive or negative transpulmonary pressure?

Answer 37

Intrapleural pressure is always negative, and when combined with alveolar pressure, which can be negative or positive, the result is a positive transpulmonary pressure.

Question 38

Explain the relationship between intrapleural pressure and transpulmonary pressure during the breathing cycle.

Answer 38

Intrapleural pressure is always more negative than alveolar pressure, resulting in a positive transpulmonary pressure, especially in healthy lungs where intrapleural pressure should be negative.

Question 39

Describe the relationship between alolar pressure and atmospheric pressure during the inspiratory phase.

Answer 39

During the inspiratory phase, alveolar pressure is consistently less than atmospheric pressure, causing air to move into the lungs.

Question 40

Explain the movement of air during expiration in relation to alveolar pressure and atmospheric pressure.

Answer 40

During expiration, alveolar pressure is greater than atmospheric pressure, causing air to move out of the lungs.

Question 41

Define tidal volume and its measurement units.

Answer 41

Tidal volume refers to the volume of air inspired or expired during normal breathing. It is measured in millilitres.

Question 42

How is intrapleural pressure related to atmospheric pressure throughout the breathing cycle?

Answer 42

Intrapleural pressure is consistently less than atmospheric pressure during both inspiration and expiration.

Question 43

Describe the significance of alveolar pressure being the same as atmospheric pressure in relation to air movement.

Answer 43

When alveolar pressure is equal to atmospheric pressure, there is no movement of air due to the absence of a pressure gradient.

Question 44

Explain the change in intrapleural pressure during inspiration and expiration.

Answer 44

During inspiration, intrapleural pressure becomes more negative, while during expiration, it becomes less negative.

Question 45

Describe the pressure within the pleural cavity during the breathing cycle.

Answer 45

The pressure within the pleural cavity is always negative, typically about 3mmHg less than atmospheric pressure, due to the constant effort to increase the volume of the intrapleural cavity.

Question 46

How does the chest wall contribute to the movement of the lungs during inspiration?

Answer 46

During inspiration, the chest wall leads the expansion of the thoracic cavity, pulling the parietal pleura away from the visceral pleura and initiating the movement of the lungs.

Question 47

Define the role of the pleural fluid in the movement of the visceral pleura and lungs.

Answer 47

The cohesive force of the pleural fluid causes the visceral pleura and lungs to follow the movement initiated by the chest wall during breathing.

Question 48

Describe the impact of introducing air into the pleural cavity on the mechanics of breathing.

Answer 48

Introducing air into the pleural cavity detaches the lungs from the rib cage and diaphragm, rendering the lung ineffective in ventilation as it cannot change volume or pressure to participate in inspiration.

Question 49

Do the lungs change volume when the external intercostal muscles and diaphragm contract in the presence of air in the pleural cavity?

Answer 49

No, the lungs do not change volume when the external intercostal muscles and diaphragm contract in the presence of air in the pleural cavity, leading to no change in pressure inside the lungs and rendering the lung ineffective in ventilation.

Question 50

Describe the impact of the elastic recoil of the lungs and the contraction of the chest wall on the pleural cavity volume during the expiratory phase.

Answer 50

The elastic recoil of the lungs and the contraction of the chest wall lead to a slight reduction in pleural cavity volume, resulting in an increase in pressure during the expiratory phase of breathing.