Respiratory cycle and mechanics L20

Question 1

What is every respiratory muscle controlled by?

Answer 1

The nervous system

Question 2

Definitions of respiration

Answer 2

1. To extract oxygen from the air and together with the cardiovascular system transport it to respiring tissues
2. Remove carbon dioxide from respiring tissues (an end product of aerobic metabolism) and exhaust into atmosphere

Question 3

What do unicellular organisms use for respiration?

Answer 3

Diffusion

Question 4

What do multicellular organisms use for respiration?

Answer 4

Spiracles (insects), gills (fish), lungs (reptiles + mammals)

Question 5

Yellow Arrow: “INCREASE in Size, Distance, Metabolic Rate”

Answer 5

This indicates that as organisms evolved, they generally became larger, required oxygen to travel greater distances within their bodies, and had higher metabolic rates. These factors drove the development of more specialized and efficient respiratory systems.

Question 6

Where is the diaphragm located?

Answer 6

At the base of throax and inntervated by a nerve called the phrenic nerve, which comes out of the spinal cord C3-C5.

Question 7

Diaphragm muscle and inspiratory effort

Answer 7

The diaphragm muscle produces 70% of inspiratory effort

Question 8

Phrenic Motor Nucleus

Answer 8

• The phrenic nerve arises from the nerve roots C3 to C5 in the cervical spine.
• It innervates the diaphragm, the primary muscle involved in breathing. When the diaphragm contracts, it flattens and moves downward, increasing the volume of the thoracic cavity and causing inhalation.

Question 9

Intercostal Motor Neurons (T1-L1)

Answer 9

These neurons are responsible for innervating the intercostal muscles located between the ribs.

The intercostal nerves are split into two groups:
Internal intercostal nerves control the internal intercostal muscles that aid in forced expiration by depressing the ribs and decreasing thoracic volume.

External intercostal nerves control the external intercostal muscles that help in quiet and forced inhalation by elevating the ribs and expanding the thoracic cavity.

Question 10

Abdominal Motor Neurons (T7-L1)

Answer 10

These neurons innervate the abdominal muscles, including the rectus abdominis, which is highlighted in the diagram with a pathway to the abdominal nerve.
During forceful expiration, abdominal muscles contract to increase abdominal pressure, which pushes the diaphragm upwards, aiding in rapid expulsion of air.

Question 11

Inspiration (active process)

Answer 11

Question 12

Expiration (passive process at rest)

Answer 12

Question 13

External intercostal muscles =

Answer 13

Inspiration

Question 14

Internal intercostal muscles =

Answer 14

Expiration

Question 15

Main muscles of breathing

Answer 15

Question 16

What happens when you go high up in the mountains?

Answer 16

As you go higher up into the mountains, the atmospheric pressure decreases because there is less air above you. This lower pressure affects the density of the air, meaning that each breath you take contains fewer molecules, including oxygen. While the proportion of oxygen in the air remains constant at about 21%, the total amount of oxygen available in each breath decreases as you ascend. This is why breathing at high altitudes can feel more difficult and why some people experience symptoms of altitude sickness.

Question 17

How do we measure the pressures during a respiratory cycle mechanically?

Answer 17

Using manometers, u–shaped and are put inside the airways (inside the lung and one inside the plural space.

Question 18

Pulmonary (Ppul) Pressure:

Answer 18

The pressure within the lungs (inside the alveoli). This pressure changes as you inhale and exhale.

Question 19

Pleural (Ppl) Pressure:

Answer 19

The pressure is within the pleural space (the space between the visceral and parietal pleura).

Question 20

Graph of Respiratory Volume

Answer 20

Respiratory Volume: This graph shows the change in lung volume during inspiration (inhaling) and expiration (exhaling).
During inspiration, lung volume increases.
During expiration, lung volume decreases.

Question 21

Graph of Pressure Changes

Answer 21

Pressure Changes: This graph illustrates how the pulmonary (Ppul) and pleural (Ppl) pressures change during inspiration and expiration.
Ppul (yellow line):
Starts at 0 during normal breathing.
Decreases slightly during inspiration as the lungs expand, drawing air in.
Increases during expiration as air is expelled, reaching slightly positive pressure.
Ppl (blue line):
Remains negative throughout the respiratory cycle, becoming more negative during inspiration as the lungs expand.
Returns to less negative during expiration as the lungs deflate.

Question 22

What happens during pneumothorax?

Answer 22

Wounded Rib Cage:
The diagram illustrates a puncture wound in the chest wall, which has caused air to leak into the pleural space.

Air Rushes into the Chest:
Normally, the pleural space has a negative pressure relative to the outside atmosphere, which helps keep the lungs inflated by pulling them outward.
In a pneumothorax, the puncture allows air to enter the pleural space, which leads to the loss of this negative pressure.

Loss of Negative Pleural Pressure:
As air enters the pleural cavity, the negative pressure that keeps the lungs expanded is lost, causing the lung on the affected side to collapse.
The collapse occurs because the lung is no longer held against the chest wall due to the equalization of pressure between the pleural space and the atmosphere.

Question 23

Measuring lung volumes with spirometet

Answer 23

Floating drum: This drum floats on water inside the spirometer. As the person breathes into the spirometer through the mouthpiece, the drum moves up and down depending on whether the person is inhaling or exhaling. The movement of the floating drum corresponds to changes in lung volume.

Oxygen chamber: The oxygen chamber contains the air (or a mixture of gases) that the patient breathes in and out during the test. When the individual breathes out, the air goes into this chamber, causing the floating drum to rise.

Water: This provides a sealed, airtight environment that allows the floating drum to move smoothly and respond to changes in lung volume during breathing.

Counterbalancing weight: This weight helps stabilize the floating drum, ensuring accurate measurement of lung volume changes.

Mouthpiece: The patient breathes in and out through the mouthpiece, connected to the spirometer. The air they exhale is measured by the spirometer.

Recording drum: As the floating drum moves, the changes are transmitted to the recording drum, which produces a graphical representation of lung volume changes over time. This recording is used to analyze various lung volumes and capacities.

Question 24

How does a spirometer measure lung volume?

Answer 24

Question 25

Tidal Volume (TV or VT):

Answer 25

The amount of air inhaled or exhaled during a normal breath, represented by the small oscillations in the middle of the graph.

Question 26

Inspiratory Reserve Volume (IRV):

Answer 26

The additional air that can be inhaled after a normal inhalation, which is the large upward peak in the graph beyond the normal tidal volume.

Question 27

Expiratory Reserve Volume (ERV):

Answer 27

The additional air that can be exhaled after a normal exhalation, represented by the large downward dip below the normal tidal exhalation.

Question 28

Residual Volume (RV):

Answer 28

The volume of air that remains in the lungs after maximum exhalation, shown at the bottom of the graph, below the ERV.

Question 29

Inspiratory Capacity (IC):

Answer 29

The total amount of air that can be inhaled after a normal exhalation, which is the sum of the tidal volume (TV) and the inspiratory reserve volume (IRV).

Question 30

Vital Capacity (VC):

Answer 30

The total volume of air that can be exhaled after a maximal inhalation, which includes IRV, TV, and ERV.

Question 31

Functional Residual Capacity (FRC):

Answer 31

The amount of air remaining in the lungs after a normal exhalation, which is the sum of the expiratory reserve volume (ERV) and the residual volume (RV).

Question 32

Total Lung Capacity (TLC):

Answer 32

The maximum amount of air that the lungs can hold, which includes all the lung volumes (IRV, TV, ERV, and RV).

Question 33

Calculation of minute ventilation versus alveolar ventilation

Answer 33

Question 34

Calculation of minute ventilation versus alveolar ventilation IN DETAIL

Answer 34

Question 35

Forced expiratory volume +ital capacity

Answer 35