Ventilatory System: Structures and Functions

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Questions and Answers

Which of the following sequences correctly traces the path of air from the nose to the alveoli?

  • Nose, trachea, larynx, pharynx, bronchi, bronchioles, alveoli
  • Nose, pharynx, larynx, trachea, bronchi, bronchioles, alveoli (correct)
  • Nose, larynx, pharynx, trachea, bronchioles, bronchi, alveoli
  • Nose, pharynx, trachea, larynx, bronchioles, bronchi, alveoli

Which function is NOT a primary role of the conducting airways?

  • Facilitating gas exchange (correct)
  • Warming incoming air
  • Moistening incoming air
  • Providing a low resistance pathway for airflow

Tidal volume (TV) typically represents about 60% of the total lung capacity.

False (B)

Explain the relationship between the diaphragm and intercostal muscles during inhalation, and how this affects lung volume and air pressure.

<p>During inhalation, the diaphragm contracts and lowers, while the external intercostal muscles contract, lifting the rib cage upwards and outwards. This action increases the volume of the chest cavity, causing the pressure inside the lungs to drop below atmospheric pressure, which allows air to rush into the lungs.</p>
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Ventilation increases as a direct result of increases in blood acidity levels due to increased ______ content of the blood, which is detected by the respiratory center.

<p>carbon dioxide</p>
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Match each lung volume or capacity with its correct description:

<p>Total Lung Capacity (TLC) = The amount of air in the lungs after a maximal inspiration. Residual Volume (RV) = The amount of air remaining in the lungs after a maximal exhalation. Tidal Volume (TV) = The amount of air inhaled or exhaled during normal quiet breathing. Vital Capacity (VC) = The amount of air that can be exhaled after a maximal inhalation.</p>
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Which of the following muscles are primarily involved in exhalation during quiet breathing?

<p>Primarily, no muscles are actively involved (B)</p>
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The primary role of hemoglobin is to transport carbon dioxide in the blood.

<p>False (B)</p>
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Describe how the structure of alveoli facilitates efficient gaseous exchange.

<p>The alveoli have thin walls that are one cell thick, providing a short diffusion distance for gases. They are also folded, increasing the surface area for gas exchange, and are surrounded by capillaries, ensuring a good blood supply.</p>
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During exhalation, the pressure inside the lungs ______ atmospheric pressure, forcing air out of the lungs.

<p>increases above</p>
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Which of these accurately describes the role of the larynx in the respiratory system?

<p>Voice box and protection of the trachea (B)</p>
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Expiratory reserve volume (ERV) is the amount of air a person can inhale beyond normal tidal inspiration.

<p>False (B)</p>
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Describe the role of chemoreceptors in the control of ventilation.

<p>Chemoreceptors detect changes in blood acidity (pH) due to increased carbon dioxide content. When blood acidity increases, chemoreceptors stimulate the respiratory center in the medulla oblongata to increase the rate and depth of ventilation, helping to remove excess carbon dioxide and restore blood pH balance.</p>
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Most oxygen in the blood (98.5%) is transported by ______ inside red blood cells.

<p>hemoglobin</p>
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During strenuous exercise, which of the following contributes MOST to increased ventilation?

<p>Decreased blood pH (C)</p>
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The diaphragm relaxes and moves downward to facilitate inhalation.

<p>False (B)</p>
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Explain how oxygen moves from the alveoli into the blood.

<p>Oxygen from inhaled air diffuses through the thin walls of the alveoli and the adjacent capillary walls into the bloodstream. This movement is driven by the concentration gradient, where the concentration of oxygen in the alveoli is higher than in the blood.</p>
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The respiratory center, which controls ventilation, is located in the ______.

<p>medulla oblongata</p>
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What adaptation of the alveoli makes gaseous exchange more efficient?

<p>Walls that are one cell thick (C)</p>
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Inhalation is typically an active process, requiring muscle contraction, while exhalation is always a passive process relying on the relaxation of muscles.

<p>False (B)</p>
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Flashcards

Ventilatory System Structures

Nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, lungs, and alveoli.

Conducting Airways Functions

Low resistance pathway for airflow, defense against harmful substances, warming, and moistening the air.

Pulmonary Ventilation

Movement of air in/out of lungs.

Total Lung Capacity (TLC)

Air in lungs after max. inspiration.

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Vital Capacity (VC)

Air exhaled after max. inhalation.

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Tidal Volume (TV)

Volume of one normal breath.

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Expiratory Reserve Volume (ERV)

Air exhaled beyond normal exhale.

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Inspiratory Reserve Volume (IRV)

Air inhaled beyond normal inhale.

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Residual Volume (RV)

Air remaining after max. exhalation.

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Mechanics of Ventilation

Diaphragm & intercostal muscles change volume & pressure.

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Control of Ventilation During Exercise

Increased blood acidity boosts ventilation rate/depth via respiratory center in medulla oblongata, lung stretch receptors, muscle proprioceptors and chemoreceptors.

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Hemoglobin in Oxygen Transport

Hemoglobin transports ~98.5% of oxygen.

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Gaseous Exchange

O2 to blood, CO2 to lungs at alveoli

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Study Notes

  • The principal structures of the ventilatory system are the nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, lungs, and alveoli

Functions of Conducting airways

  • They are a low resistance pathway for airflow
  • They defend against inhaled chemicals and other harmful substances
  • They warm and moisten the air

Nose

  • Humidifies the air
  • Filters particles

Pharynx

  • Offers a low resistance pathway for airflow

Larynx

  • Functions as the 'voice box'
  • Protects the trachea from invasion of foods and fluids

Pulmonary Ventilation

  • Movement of air in and out of the lungs

Total Lung Capacity (TLC)

  • Amount of air in the lungs after a maximal inspiration

Vital Capacity (VC)

  • Amount of air that can be exhaled after a maximal inhalation

Tidal Volume (TV)

  • Amount of air an individual can inhale or exhale during normal quiet breathing
  • It is 7-8% of total lung capacity

Expiratory Reserve Volume (ERV)

  • Amount of air an individual can exhale beyond a tidal expiration
  • It is 20% of total lung capacity

Inspiratory Reserve Volume (IRV)

  • Amount of air that an individual can inhale above a tidal inspiration
  • It is 60% of the total lung capacity

Residual Volume (RV)

  • Amount of air remaining in the lungs after a maximal exhalation
  • It makes up 20% of the total capacity

Inhalation (passive)

  • Diaphragm contracts and lowers
  • External intercostal muscles contract
  • Rib cage moves upwards and outwards
  • Volume of the chest cavity increases
  • Pressure inside the lungs drops below atmospheric pressure
  • Air rushes into the lungs

Exhalation (active)

  • Diaphragm relaxes and turns to a dome shape
  • Internal intercostal muscles contract
  • Rib cage moves downwards and inwards
  • Volume of the chest cavity decreases
  • Pressure inside the lungs increases above atmospheric pressure
  • Air is forced out of the lungs and into the atmosphere

Nervous and Chemical Control of Ventilation During Exercise

  • Ventilation increases as a direct result of increases in blood acidity levels due to increases in carbon dioxide content in the blood, which is detected by the respiratory center
    • This results in an increase in the rate and depth of ventilation
  • Respiratory center is in the medulla oblongata, sending messages to the ventilatory muscles
  • Neural control of ventilation includes lung stretch receptors, muscle proprioceptors and chemoreceptors
  • Most (98.5%) of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within red blood cells

Gaseous exchange at the alveoli

  • Gaseous Exchange is the delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs. It occurs in the lungs between the alveoli and the capillaries which are located around the walls of the alveoli.
  • Oxygen from the inhaled air diffuses through the walls of the alveoli and into the capillaries to the red blood cells
  • The red blood cells carry the oxygen to the body.
  • Adapting to the Alveoli includes:
    • Walls of the alveoli are one cell thick.
    • They are folded, providing a larger surface area.
    • They are each surrounded by capillary which allows the good blood supply.

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