Respiratory Anatomy and Mechanism

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Questions and Answers

What role does surfactant play in the alveoli?

  • It aids in the diffusion of oxygen into the bloodstream.
  • It increases surface tension to maintain alveolar structure.
  • It acts as a barrier to prevent pathogens from entering the lungs.
  • It reduces surface tension, preventing alveolar collapse during exhalation. (correct)

Which statement correctly describes the relationship between the lungs and the chest wall during inhalation?

  • The lung volume decreases, leading to an increase in pressure.
  • The chest wall contracts, causing the lungs to collapse.
  • The expansion of the chest wall pulls the lungs, creating a pressure differential. (correct)
  • The intrapleural space closes off to prevent air from entering.

What is the primary action of the diaphragm during exhalation?

  • It creates a negative pressure within the pleural cavity.
  • It contracts to increase lung volume.
  • It relaxes, allowing the lungs to recoil. (correct)
  • It moves upward to compress the thoracic cavity.

How do the external intercostal muscles behave during inhalation?

<p>They contract to elevate the rib cage and expand the thoracic cavity. (B)</p> Signup and view all the answers

What prevents the lungs from collapsing completely upon recoil?

<p>The resilient elastic quality of the lungs and surfactant action. (A)</p> Signup and view all the answers

What is the primary mechanism by which air enters the lungs during inhalation?

<p>Expanding thoracic cavity via diaphragm contraction (C)</p> Signup and view all the answers

What role do internal intercostal muscles play during forced exhalation?

<p>Contract to decrease the thoracic cavity volume (A)</p> Signup and view all the answers

What is the definition of vital capacity (VC)?

<p>Difference between the maximum and minimum volume of air in lungs (C)</p> Signup and view all the answers

How does the body respond to high levels of carbon dioxide in the blood?

<p>Increase respiratory rate (C)</p> Signup and view all the answers

What is the primary function of the pulmonary arteries?

<p>Bring deoxygenated blood to the lungs (A)</p> Signup and view all the answers

What is one way the respiratory system aids in thermoregulation?

<p>Vasodilation and vasoconstriction of capillary beds (A)</p> Signup and view all the answers

What happens to the binding dynamics of hemoglobin at higher altitudes?

<p>Facilitates unloading of oxygen to tissues (D)</p> Signup and view all the answers

Which component of the respiratory system helps filter incoming air?

<p>Vibrissae (D)</p> Signup and view all the answers

What occurs during passive exhalation?

<p>Lungs undergo elastic recoil (A)</p> Signup and view all the answers

How does an increase in H ion concentration affect respiratory rate?

<p>Increases respiratory rate (C)</p> Signup and view all the answers

What defines the residual volume (RV)?

<p>Air remaining after complete exhalation (C)</p> Signup and view all the answers

Which mechanism drives gas exchange in the lungs?

<p>Pressure differentials across membranes (B)</p> Signup and view all the answers

How does the medulla oblongata contribute to breathing regulation?

<p>Overrides conscious control during hyperventilation (C)</p> Signup and view all the answers

What is the purpose of the bicarbonate buffer system related to pH control?

<p>Maintain acid-base balance (B)</p> Signup and view all the answers

Flashcards

Alveoli

Tiny air sacs in the lungs where gas exchange occurs. They are surrounded by capillaries, allowing oxygen to pass into the blood and carbon dioxide to pass out.

Surfactant

A substance that coats the alveoli and reduces surface tension, preventing them from collapsing during exhalation.

Pleurae

Two layers of membrane that surround the lungs: the visceral pleura (adjacent to the lung) and the parietal pleura (lining the chest wall).

What does the diaphragm do during inhalation?

The diaphragm contracts, flattening and expanding the chest cavity, creating lower pressure inside the lungs, drawing air in.

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What does the diaphragm do during exhalation?

The diaphragm relaxes, returning to its dome-like shape, decreasing the space in the chest cavity, forcing air out of the lungs.

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Inhalation

Active process of taking air into the lungs.

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Exhalation

Process of releasing air from the lungs.

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External Intercostal Muscles

Muscles between the ribs that contract during inhalation, expanding the chest cavity.

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Internal Intercostal Muscles

Muscles between the ribs that contract during forced exhalation, shrinking the chest cavity.

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Diaphragm

Large muscle that contracts during inhalation, pulling air into the lungs.

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Intrapleural Pressure

Pressure within the space between the lung and chest wall.

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Negative Pressure Breathing

Air is drawn into the lungs because the intrapleural pressure is lower than atmospheric pressure.

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Total Lung Capacity (TLC)

Maximum volume of air lungs can hold after a complete inhalation.

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Residual Volume (RV)

Amount of air remaining in lungs after a complete exhalation.

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Vital Capacity (VC)

The difference between the maximum volume of air in the lungs after a complete inhalation and the minimum volume of air in the lungs after a complete exhalation.

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Tidal Volume (TV)

Volume of air inhaled or exhaled during normal breathing.

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Expiratory Reserve Volume (ERV)

Extra volume of air that can be forcibly exhaled after a normal exhalation.

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Inspiratory Reserve Volume (IRV)

Extra volume of air that can be forcibly inhaled after a normal inhalation.

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Ventilation Center

Collection of neurons in the medulla oblongata that regulates breathing.

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Chemoreceptors

Sensors that detect changes in CO2 levels in the blood and send signals to increase breathing rate.

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Study Notes

Respiratory Anatomy and Mechanism

  • Airflow Pathway: Nares → Nasal cavity → Pharynx → Vibrissae and mucous membranes → Larynx → Trachea → Bronchi → Bronchioles → Alveoli
  • Alveoli: Gas exchange occurs; Interface with pulmonary capillaries
  • Surfactant: Reduces surface tension in alveoli, preventing collapse during exhalation
  • Pleurae: Cover lungs and line chest wall, reducing friction
    • Visceral pleura: Adjacent to lung
    • Parietal pleura: Lines chest wall
    • Intrapleural space: Contains lubricating fluid; Space between visceral and parietal pleura
  • Lung Elasticity: Lungs are elastic, attached to chest wall; Expansion and recoil drive breathing
  • Inhalation (active): Diaphragm contracts; External intercostal muscles contract; Thoracic cavity volume increases; Intrapleural pressure decreases; Lung expansion; Air drawn in.
  • Exhalation (passive/active):
    • Passive: Diaphragm and external intercostal muscles relax; Elastic recoil of lungs; Intrapleural pressure increases; Air expelled
    • Active: Internal intercostal muscles contract; Abdominal muscles contract; Thoracic cavity volume decreases; Intrapleural pressure increases; Air forcibly expelled

Breathing Control

  • Diaphragm: Contracts during inhalation; Relaxes during exhalation
  • Intercostal Muscles:
    • External: Contract during inhalation; Relax during passive exhalation
    • Internal: Contract during forced exhalation
  • Negative Pressure Breathing: Lower pressure in the intrapleural space compared to the lungs draws air in during inhalation
  • Autonomic Control: Breathing is primarily controlled by the autonomic nervous system
  • Central Chemoreceptors: Sensitive to CO2 levels; Increase respiratory rate to compensate for high CO2

Lung Volumes and Capacities

  • Total Lung Capacity (TLC): Maximum volume of air in lungs
  • Residual Volume (RV): Volume remaining in lungs after forced exhalation
  • Vital Capacity (VC): Difference between maximum and minimum lung volumes
  • Tidal Volume (TV): Volume of air inhaled or exhaled with a normal breath
  • Expiratory Reserve Volume (ERV): Additional air forcibly exhaled after normal exhalation
  • Inspiratory Reserve Volume (IRV): Additional air forcibly inhaled after normal inhalation

Respiratory System Functions

  • Gas Exchange: Oxygen moves from alveoli to blood; Carbon dioxide moves from blood to alveoli; Driven by pressure differences
  • Pulmonary Circulation: Deoxygenated blood enters lungs from right ventricle, then oxygenated blood returns to left atrium.
  • Hemoglobin: Oxygen binds to hemoglobin for transport; Binding dynamics shift at higher altitudes
  • Thermoregulation:
    • Vasodilation/Vasoconstriction: Pulmonary blood vessels dilate or constrict to regulate heat loss
  • Immune Function: Mucociliary escalator, lysozyme, macrophages, and antibodies to filter and defend the respiratory tract.

Respiratory Regulation & pH Control

  • Respiratory Center: Located in the medulla oblongata; Regulates breathing rate
  • Chemoreceptors: Detect changes in CO2 and O2 levels
  • Acid-Base Balance: Respiratory system assists in regulating blood pH by controlling CO2 levels and adjusting breathing rate (increase/decrease of breathing).

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