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Kin 200 > respiratory > Flashcards

respiratory Flashcards

1
Q

What are the primary functions of the lungs?

A

○ Provide a gas exchange surface between the blood and the surrounding gaseous environment.
○ Transfer O2 from alveolar air into alveolar capillary blood while moving blood’s CO2 into the alveoli and then into the ambient air.

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2
Q

What are the functions of the conducting zone of the respiratory system?

A

○ Warm inspired air to body temperature.
○ Humidify inspired air by adding water vapor.
○ Filter out foreign material to protect the fragile alveoli.

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3
Q

What is the function of the pleural fluid?

A

○ Creates a moist, slippery surface, enabling the opposing membranes to slide across each other as the lungs move.
○ Keeps the lung adhered to the thoracic wall, maintaining it in a partially inflated state.

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4
Q

How does inspiration occur?

A

The diaphragm contracts downward and respiratory muscles, like the intercostals, contract to expand the thoracic cavity up and out. This expansion lowers intrapulmonary pressure, drawing air into the lungs. The scalene, sternocleidomastoid, and external intercostal muscles also contribute to ribcage lifting and rotation.

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5
Q

How does expiration occur?

A

At rest, expiration is passive due to the relaxation of the diaphragm (upward) and supporting muscles (down and in). This relaxation increases intrapulmonary pressure, expelling air from the lungs. During exercise, internal intercostal and abdominal muscles assist in expiration.

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6
Q

Define pulmonary ventilation.

A

Pulmonary ventilation is the movement of air into and out of the lungs.

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7
Q

What is minute ventilation (VE)?

A

It is the volume of air moved in and out of the lungs each minute. It is calculated by multiplying respiratory frequency (f), the number of breaths per minute, by tidal volume (TV), the volume of air moved per breath.

VE = f (breaths per minute) * TV (L per breath) = L/min.

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8
Q

What is alveolar ventilation (VA)?

A

The volume of air that reaches the alveoli for gas exchange each minute. VA is calculated by subtracting the volume of dead space air (VD) from the total volume of air breathed in each minute (VE).

VA = VE - VD

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9
Q

What is physiological dead space?

A

The portion of the alveoli that is not effectively ventilated or perfused, meaning it is not fully participating in gas exchange

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10
Q

Why is tidal volume important for alveolar ventilation?

A

A larger tidal volume results in a greater proportion of air reaching the alveoli for gas exchange. As tidal volume increases, a larger percentage of the inspired air contributes to alveolar ventilation rather than remaining in the dead space.

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11
Q

What is anatomical dead space (ADS)?

A
  • The volume of air within the conducting zone (nose, trachea, bronchi) that does not participate in gas exchange.
  • In males, it is approximately 0.150 L, and in females, it is approximately 0.100 L.
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12
Q

How does ventilation change during graded exercise?

A

Minute ventilation (VE) increases due to increases in both tidal volume (TV) and breathing frequency (f). This increase in both depth and rate of breathing enhances the delivery of oxygen to working muscles and the removal of carbon dioxide. Tidal volume plateaus at about 60% of vital capacity (VC) during exercise. Further increases in VE are achieved by increasing breathing frequency.

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13
Q

What are static lung volumes used to assess?

A

Whether the lung is a normal size and if its subdivisions are normal. They are used to diagnose potential respiratory diseases that can affect lung size.

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14
Q

What is the purpose of assessing airway function?

A

To determine the ability to generate airflow and identify any evidence of obstruction or restriction in the airways, which can be indicative of lung disease.

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15
Q

What is a spirometer?

A

A device used to measure the volume of air inspired and expired, which is used to assess lung volumes and airflow.

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16
Q

What do forced expiratory maneuvers measure?

A

Dynamic lung volumes, specifically the forced expiratory volume in 1 second (FEV1) and the ratio of FEV1 to forced vital capacity (FVC), expressed as a percentage.

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17
Q

What does the FEV1.0/FVC ratio indicate?

A

Expiratory ability and general resistance to expiration. A normal FEV1.0/FVC ratio is approximately 80%, indicating healthy lung function.

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18
Q

What information can be obtained from flow volume loops?

A

Flow volume loops provide a visual representation of airflow during inspiration and expiration, helping to identify patterns characteristic of different lung conditions, such as obstructive or restrictive lung diseases.

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19
Q

How does aging impact pulmonary function?

A

Significant declines in pulmonary function, particularly in measures of elastic recoil, don’t typically occur until 65-75 years of age.
* Elastic recoil refers to the lungs’ ability to return to its resting state after being stretched during inhalation.

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20
Q

What is Dalton’s Law?

A

The total pressure of a mixture of gases is the sum of the pressures of the individual gases.

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21
Q

What gases make up the atmosphere?

A

Nitrogen, oxygen, and carbon dioxide.

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22
Q

What is the partial pressure of a gas?

A

The pressure of a single gas in a mixture.

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23
Q

How do you calculate the partial pressure of a gas?

A

Multiply the total pressure of the gas mixture by the fractional concentration of the gas. For example, the partial pressure of oxygen (PO2) in the air at sea level can be calculated as follows:
○ PO2 = Total pressure (760 mmHg) * Fractional concentration of O2 (0.2093) = 159 mmHg.

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24
Q

What is Fick’s Law of Diffusion?

A

the rate of diffusion is proportional to the surface area, concentration gradient, and membrane permeability, and inversely proportional to the membrane thickness. This law describes how gases move across membranes, such as the alveolar-capillary membrane in the lungs.

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25
Q

Why is the partial pressure of oxygen lower in the alveoli than in the inspired air?

A

○ Addition of water vapor to the inspired air.
○ Mixing of gases in the alveolar ducts.
○ Continual mixing of CO2 (higher partial pressure) and O2 (lower partial pressure) from blood entering pulmonary capillaries

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26
Q

What are the two ways oxygen is transported in the blood?

A

○ Dissolved in plasma. While only a small amount of oxygen is transported this way, it is important because it determines the partial pressure of oxygen in the blood, which drives diffusion.
○ Bound to hemoglobin (Hb) molecules within red blood cells. The majority of oxygen transport occurs this way

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27
Q

What is the oxygen carrying capacity of hemoglobin?

A

Approximately 1.34 ml of O2 per gram of Hb.

28
Q

Why does the partial pressure of oxygen drop to 40 mmHg in the capillaries?

A

As oxygen diffuses from the alveoli into the capillaries, it binds to hemoglobin in the red blood cells. This binding reduces the partial pressure of oxygen in the capillaries, creating a concentration gradient that continues to drive the diffusion of oxygen from the alveoli into the blood.

29
Q

What are the three ways carbon dioxide is transported in the blood?

A

○ Dissolved in plasma (7-10%) which determines the partial pressure of carbon dioxide (PCO2).
○ Combined with Hb (20%).
○ Combined with H2O to form bicarbonate (70%). This is the primary way CO2 is transported in the blood.

30
Q

Is there sufficient time for gas exchange at rest and during exercise?

A

Yes. The transit time of blood in the pulmonary capillaries is about 0.75 seconds at rest and can decrease to 0.30-0.40 seconds during maximal exercise. Complete gas exchange takes approximately 0.30 to 0.35 seconds. Therefore, even during intense exercise, there appears to be enough time for oxygen and carbon dioxide to be exchanged between the blood and alveoli.

31
Q

What is the oxyhemoglobin dissociation curve?

A

It is a graphical representation of the relationship between the percent saturation of hemoglobin with oxygen (%SaO2) at a given partial pressure of oxygen (PO2). This curve illustrates how readily hemoglobin binds and releases oxygen.

32
Q

What is the arterial-venous oxygen difference (a-v O2 diff)?

A
  • It represents the amount of oxygen extracted by the tissues from each 100 ml of blood.
  • It is calculated as the difference between the oxygen content in arterial blood and venous blood.
  • Normal values are approximately 5 ml/100 ml of blood at rest and 15 ml/100 ml of blood during maximal exercise.
33
Q

What is the Bohr effect?

A

It describes the downward and rightward shift of the oxyhemoglobin dissociation curve during exercise due to:
○ Decreased pH
○ Increased temperature
○ Increased partial pressure of carbon dioxide (PCO2).

34
Q

What is the effect of the Bohr effect on oxygen extraction?

A

The Bohr effect favors oxygen unloading at the muscle level, enhancing oxygen extraction by the tissues and increasing the a-v O2 diff.

35
Q

What are the effects of supplemental oxygen on total oxygen content?

A
  • Breathing pure oxygen only improves the amount of oxygen dissolved in the plasma.
  • Since oxygen has low solubility in solution, this increase does not significantly impact the total oxygen content of the blood.
  • The majority of oxygen is transported bound to hemoglobin, and this binding is already near maximum at normal arterial PO2 levels.
36
Q

What is the effect of hemoglobin concentration on oxygen content?

A

Oxygen carrying capacity is directly proportional to hemoglobin concentration. A decrease in hemoglobin levels will result in a decrease in the blood’s ability to carry oxygen.

37
Q

What is the primary respiratory control center?

A

The pons is the main respiratory control center.

38
Q

What do the sensors in our blood vessels sense and where do they communicate these changes?

A

They sense oxygen, carbon dioxide content, and acid-base status. These changes are communicated to the respiratory center in the pons.

39
Q

What is the main nerve that innervates the diaphragm, and what happens if it is damaged?

A

the phrenic nerve

If damaged, you lose the ability to breathe normally.

40
Q

What two things are we regulating with our breathing?

A

Blood PO2 (partial pressure of oxygen) and PCO2 (partial pressure of carbon dioxide).

41
Q

How can arterial PO2 and PCO2 be estimated?

A

They can be estimated from the PO2 and PCO2 in expired air, also known as end-tidal PO2 and PCO2.

42
Q

What primarily dictates how much we need to breathe?

A

Our CO2 levels dictate how much we need to breathe.

43
Q

Where is the control of breathing located in the brain?

A

In the brainstem, specifically in the medulla oblongata and pons

44
Q

What is the function of the pontine respiratory group in breathing?

A

It contains both inspiratory and expiratory neurons. It may facilitate the transition between inspiration and expiration and fine-tune respiration.

45
Q

What is the function of the dorsal respiratory group in breathing?

A

It contains mostly inspiratory neurons that control the diaphragm.

46
Q

What is the function of the ventral respiratory group in breathing?

A

It contains both inspiratory and expiratory neurons. One area, known as the pre-Botzinger complex, contains spontaneously firing neurons that may act as the basic respiratory pacemaker.

47
Q

What is the primary stimulus for changes in ventilation?

A

Carbon dioxide (CO2)

48
Q

What is the role of central chemoreceptors in breathing?

A
  • They are located in the medulla oblongata and respond to changes in CO2 and H+ concentration in the cerebrospinal fluid.
  • When CO2 levels increase, it crosses the blood-brain barrier, leading to the production of H+ ions, which stimulate the central chemoreceptors to increase ventilation
49
Q

What do peripheral chemoreceptors respond to?

A

○ Decreased partial pressure of oxygen in arterial blood (PaO2).
○ Increased PaCO2.
○ Increased hydrogen ion concentration in arterial blood ([H+]a).
○ Increased potassium ion concentration in arterial blood ([K+]a).

50
Q

Where are peripheral chemoreceptors located?

A

They are located in the bifurcation of the common carotid arteries and the aortic arch.

51
Q

What is the PO2 threshold for stimulating peripheral chemoreceptors?

A

PO2 must fall below 60 mmHg to stimulate the peripheral chemoreceptors

52
Q

What causes the disproportionate increase in ventilation before exercise?

A

Stimulation from the cerebral cortex to the ventilatory response (VE). This is part of the anticipatory response.

53
Q

Why can there be a slight “overshoot” in VE at the onset of exercise?

A

The adjustment to workload may not precisely match metabolic demand, likely due to the effects of several stimuli on VE.

54
Q

How does VE change during progressive submaximal exercise?

A

It increases proportionally at first, then disproportionately, reaching its highest point at maximum exercise intensity.

55
Q

What does the anaerobic threshold indicate?

A

The phase during graded exercise where a greater rate of energy production is required than what can be totally met by aerobic metabolism. Therefore, additional energy from anaerobic glycolysis is required.

56
Q

How is the anaerobic threshold (AT) identified?

A

By a disproportionate increase in lactate accumulation in the blood and/or ventilatory parameters during exercise of increasing intensity.

57
Q

What are the two ways to measure anaerobic threshold?

A

Lactate measures (Lactate Threshold - LT) and ventilation measures (Ventilatory Threshold - VT).

58
Q

What causes lactate threshold (LT)?

A

○ Increased epinephrine release that stimulates glycogenolysis.
○ Blood shunt mechanism causing vasoconstriction in non-working tissue and increased blood flow to working muscle, resulting in an enhanced accumulation of lactate in the blood and decreased removal by other tissues.
○ Increased requirement for anaerobic glycolytic energy supply to contribute to total exercise energy needs.
○ Increased recruitment of fast-twitch (FT) motor units which have a greater capacity for glycolysis

59
Q

What causes ventilatory threshold (VT)?

A

○Increased perception of energy demand (exercise intensity) by the “respiratory centre” in the brain, resulting in increased VE.
○ Increased afferent neural activity from muscle and joint receptors.
○ Increased H+ and CO2 levels that stimulate chemoreceptors (central and peripheral) and stimulate an increase in VE

60
Q

What is the primary link between LT and VT?

A

The stimulation of VE by chemoreceptors due to increased [H+] and CO2 levels through the bicarbonate buffering of H+ ions produced anaerobically during graded exercise.

61
Q

Does LT cause VT, or is it coincidental?

A

They are linked through the stimulation of VE by chemoreceptors, suggesting that LT causes VT and slightly precedes it during graded exercise. This is likely the case under normal circumstances. However, other factors can cause VT independent of LT.

62
Q

What is McArdle’s Disease, and what does it demonstrate about the relationship between LT and VT?

A
  • It is a genetic disease where patients lack the muscle enzyme phosphorylase, preventing them from producing much lactate during graded exercise.
  • However, they still display a VT. This demonstrates that VT can occur without an LT due to the primary neural factors that stimulate ventilation, which are not directly dependent on anaerobic stimulation of chemoreceptors
63
Q

Does anaerobic threshold respond to training?

A

Yes, there is an increase in speed, power output (PO), and VO2 at AT after training, which enhances endurance performance

64
Q

What are the primary reasons AT responds to training?

A

Several factors contribute to the increase in AT after training:
○ Increase in oxidative capacity of skeletal muscle.
○ Increase in lactate & H+ removal rate.
○ Delay in onset of anaerobic glycolysis.
○ Delay in glycogen utilization & increase in fat oxidation.
○ Increased O2 delivery and extraction.
○ Delay in FT motor unit recruitment.
○ Delay in epinephrine release.

65
Q

How does endurance training affect ventilation?

A

VE is somewhat lower at rest and during submaximal exercise after endurance training due to:
○ Greater “efficiency” of the cardiorespiratory and nervous systems in general.
○ Lower afferent neural activity, lower CNS drive.
○ Greater aerobic capacity of ventilatory muscles (diaphragm, other support muscles).

● However, VEmax is increased with endurance training partly due to higher overall cardiorespiratory fitness.

Kin 200 (7 decks)

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