External Respiration in Cells

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Questions and Answers

What is the calculated minute alveolar ventilation (VA) if tidal volume (TV) is 500 ml, breath rate is 20 breaths/min, and dead space volume (VD) is 150 ml?

22000 ml

12000 ml (correct)

10000 ml

7000 ml

What is the primary mechanism for the transport of carbon dioxide through the membranes of alveoli and capillaries?

Simple diffusion (correct)

Active transport

Convection

Facilitated diffusion

What is the typical partial pressure of oxygen (pO2) in alveolar air?

60 - 70 mm Hg

155 - 159 mm Hg

105 - 110 mm Hg

95 - 110 mm Hg (correct)

What occurs when the partial pressure of a gas over a liquid exceeds its tension in the liquid?

The gas will dissolve in the liquid. Signup and view all the answers

Which of the following describes the value of anatomical dead space?

Volume that doesn’t participate in gas exchange. Signup and view all the answers

What is the primary reason for the absorption of oxygen by an organism?

To improve ATP efficiency Signup and view all the answers

Which organelle primarily consumes O2 in cells?

Mitochondria Signup and view all the answers

What best describes the sequence of respiratory phases?

Ventilation, gas exchange in lungs, gas transport, biological oxidation Signup and view all the answers

What is the typical gas composition of inhaled air?

20.9% O2, 0.03% CO2 Signup and view all the answers

Which zone of the lungs contains alveoli relevant for gas exchange?

Respiratory zone Signup and view all the answers

What mainly contributes to the negative pressure in the pleural gap?

Elastic recoil force Signup and view all the answers

During quiet breathing, the change in thoracic cavity volume is primarily due to the contraction of which muscle?

Diaphragm Signup and view all the answers

What is the typical gas composition of alveolar air?

16.5% O2, 4.5% CO2 Signup and view all the answers

What act of breathing involves external intercostal muscles?

Quiet inspiration Signup and view all the answers

What are respiratory muscles primarily classified as?

Skeletal muscles Signup and view all the answers

During inspiration, the pressure in the lungs is:

Less than atmospheric pressure Signup and view all the answers

What factors contribute to the expiration phase of breathing?

Elastic recoil force, heaviness of the chest Signup and view all the answers

If the transpulmonary pressure is equal to zero, what will happen to the lungs?

The lungs will be deflated Signup and view all the answers

The anatomical dead space in the respiratory system includes which of the following structures?

Nose, mouth, larynx, trachea, bronchi, bronchioles Signup and view all the answers

What is the purpose of surfactant in the respiratory system?

To prevent alveoli deflation during expiration Signup and view all the answers

How is functional residual capacity calculated?

Expiratory reserve volume + residual volume Signup and view all the answers

The volume of air that a person can inhale and exhale comfortably while at rest is called:

Tidal volume Signup and view all the answers

What does minute ventilation (MV) refer to?

The amount of air ventilated per minute Signup and view all the answers

The average value of tidal volume in healthy adults is approximately:

500 ml Signup and view all the answers

What is the vital capacity defined as?

The volume of air that can be maximally expired after a maximal inspiration Signup and view all the answers

Residual volume indicates which of the following?

Air volume remaining in the lungs after maximal expiration Signup and view all the answers

Study Notes

External Respiration: Gas Exchange in the Lungs

Purpose of Oxygen Absorption: The primary function of acquiring oxygen is to improve the efficiency of ATP resynthesis, the process of creating energy for cellular functions.
Cellular Oxygen Consumers: Mitochondria are the primary organelles in cells that consume oxygen.
ATP Energy Use: The energy stored in ATP is pivotal for various cellular activities including complex substance synthesis, active transport, and mechanical work.
Respiratory Phases: The correct sequence of respiratory processes is ventilation, gas exchange in lungs, gas transport by blood, biological oxidation, and gas exchange in tissues.
Inhaled Air Composition: Normal inhaled air contains approximately 20.9% oxygen and 0.03% carbon dioxide.
Alveolar Air Composition: Alveolar air contains roughly 16% oxygen and 4.5% carbon dioxide.
Exhaled Air Composition: Exhaled air has approximately 16% oxygen and 4-5% carbon dioxide.
Gas Exchange Area: The respiratory zone of the lungs, containing alveoli, is the site of gas exchange with the blood.
Lung Diffusion Capacity: The rate of gas exchange depends on the permeability of the alveolar and capillary membranes.
Lung Stretch: Lungs are maintained in a stretched state during inspiration and quiet breathing.
Pleural Pressure: The negative pressure within the pleural cavity (space between the lung and chest wall) is essential for maintaining lung expansion. Elastic recoil force is a major contributor to this.
Inspiration Mechanism: Inspiration is primarily achieved by diaphragm contraction. Other muscles like external intercostal muscles play a critical role in forced inspiration.
Expiration Mechanism: Expiration is a combination of elastic recoil and, in forced expiration, the contraction of expiratory muscles.
Intra-Pulmonary Pressure vs. Atmospheric Pressure: During inspiration, the intrapulmonary pressure is lower than atmospheric pressure. The reverse occurs during expiration.
Transpulmonary Pressure: The difference between intrapulmonary and intrapleural pressure is called transpulmonary pressure. This pressure difference is critical for lung inflation.
Zero Transpulmonary Pressure: If the transpulmonary pressure is zero, the lungs will deflate.
Pleural Cavity Pressure: The reason for the negative intrapleural pressure is the elastic recoil of the lungs and the surface tension of the alveolar fluid.
Anatomic Dead Space: The conducting zone of the respiratory system, including the trachea, bronchi, and bronchioles, forms the anatomical dead space, which doesn't participate in gas exchange.
Airway Functions: Respiratory airways warm, humidify, and filter inhaled air, and act as conduits for airflow.
Surfactant Function: Surfactant reduces surface tension in the alveoli, preventing alveolar collapse during exhalation and facilitating lung expansion.
Alveolar Air Renewal: Approximately one-seventh of the alveolar air is exchanged with each breath during quiet breathing.
Continuous Gas Exchange: Gas exchange between air and blood happens constantly during both inhalation and exhalation.
Effective Ventilation: The most reliable measure of effective ventilation is the assessment of PaO2 and PaCO2, arterial oxygen and carbon dioxide partial pressures.
Tidal Volume (TV): The volume of air inhaled and exhaled in a quiet breath.
Minute Ventilation (MV): The total volume of air moved in and out of the lungs per minute (TV x breaths per minute).
Alveolar Ventilation (VA): The volume of air that reaches the alveoli per minute ((TV - VD) * breaths/min).
Gas Transport: Carbon dioxide is primarily transported through simple diffusion across alveolar and capillary membranes.
Alveolar Gas Partial Pressures: The partial pressure of oxygen (PO2) in alveolar air is typically 105-110 mmHg, and the partial pressure of carbon dioxide (PCO2) is about 38-40 mmHg .
Gas Dissolution: A higher partial pressure of a gas above a liquid than in the liquid will drive the gas into the liquid.

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Description

Explore the intricate process of external respiration and gas exchange in the lungs. This quiz covers the purpose of oxygen absorption, the role of mitochondria, and the compositions of inhaled and exhaled air. Test your knowledge on the respiratory phases and ATP energy use.