Breathing and Gas Exchange Concepts

Questions and Answers

What primary effect does the contraction of external inter-costal muscles have during inspiration?

It lifts the sternum without affecting the rib movement.

It relaxes the diaphragm while increasing abdominal pressure.

It increases the thoracic volume and decreases intrapulmonary pressure. (correct)

It decreases the thoracic volume and increases intrapulmonary pressure.

Which of the following best describes Tidal Volume (TV)?

The volume of air inspired or expired during normal respiration. (correct)

The minimum volume of air exchanged during forced expiration.

The total lung capacity minus the expiratory reserve volume.

The maximum amount of air inhaled after a normal inspiration.

What role do additional abdominal muscles play in breathing?

They can enhance both inspiration and expiration strength. (correct)

They are only involved during passive expiration.

They exclusively assist in increasing tidal volume.

They reduce the overall rate of respiration.

What happens to the intrapulmonary pressure during expiration?

It rises above atmospheric pressure. Signup and view all the answers

What is the average range of breaths taken by a healthy human per minute?

12-16 breaths. Signup and view all the answers

What is the primary function of residual volume (RV) in the lungs?

To maintain a reserve of air to prevent lung collapse Signup and view all the answers

Which pulmonary capacity includes both tidal volume and inspiratory reserve volume?

Inspiratory Capacity (IC) Signup and view all the answers

How is functional residual capacity (FRC) calculated?

By combining expiratory reserve volume and residual volume Signup and view all the answers

In the context of gas exchange, what is the primary mechanism by which O2 and CO2 are exchanged?

Simple diffusion based on pressure/concentration gradient Signup and view all the answers

Which of the following represents the maximum volume of air a person can breathe in after a forced expiration?

Inspiratory Capacity (IC) Signup and view all the answers

What percentage of CO2 is transported by red blood cells (RBCs)?

20-25 percent Signup and view all the answers

What is the maximum number of oxygen molecules that one hemoglobin molecule can carry?

Four Signup and view all the answers

What primarily regulates the binding of oxygen with hemoglobin?

Partial pressure of O2 Signup and view all the answers

Which of the following factors does NOT affect the binding of oxygen to hemoglobin?

Plasma viscosity Signup and view all the answers

What percentage of CO2 is carried in a dissolved state through plasma?

7 percent Signup and view all the answers

What is the primary factor that increases the formation of oxyhaemoglobin in the alveoli?

Low temperature Signup and view all the answers

Which factor is influential in promoting the release of oxygen from oxyhaemoglobin in the tissues?

High temperature Signup and view all the answers

How does increased pCO2 affect the dissociation of oxygen from oxyhaemoglobin?

It creates a more acidic environment Signup and view all the answers

Which condition is NOT favorable for the formation of oxyhaemoglobin in the alveoli?

High H+ concentration Signup and view all the answers

What effect does low pO2 have on the binding of oxygen to haemoglobin?

It decreases the likelihood of binding Signup and view all the answers

What is the major reason that diffusion of gases occurs only in the alveolar region and not in other parts of the respiratory system?

Alveoli possess a larger surface area for gas exchange. Signup and view all the answers

Which transport mechanism for CO2 is predominant in the human body?

Conversion to bicarbonate Signup and view all the answers

How does the pCO2 in atmospheric air compare to that of alveolar air?

pCO2 in atmospheric air is lower than in alveolar air. Signup and view all the answers

What is the effect of increased pCO2 on oxygen transport in the body?

Decreases oxygen affinity to hemoglobin. Signup and view all the answers

Which of the following correctly distinguishes between inspiratory reserve volume (IRV) and expiratory reserve volume (ERV)?

IRV is the volume of air inhaled after normal inhalation; ERV is the volume of air exhaled after normal exhalation. Signup and view all the answers

Study Notes

Mechanics of Breathing

External intercostal muscle contraction elevates the ribs and sternum, expanding the thoracic and pulmonary volumes.
This increase in volume decreases intra-pulmonary pressure, drawing air into the lungs during inspiration.
Diaphragm and intercostal muscles relaxation causes diaphragm and sternum to return to normal, reducing thoracic and pulmonary volumes, leading to an increase in intra-pulmonary pressure and expulsion of air during expiration.
Inspiration and expiration strength can be enhanced using abdominal muscles.
Average respiratory rate in a healthy adult is 12-16 breaths per minute.
Breathing volume can be measured with a spirometer, which is essential for pulmonary function assessment.

Respiratory Volumes and Capacities

Tidal Volume (TV): Approximately 500 mL of air is moved during normal respiration; a healthy adult can breathe in or out roughly 6000-8000 mL per minute.
Inspiratory Reserve Volume (IRV): Additional air volume that can be inhaled forcefully, averaging 2500-3000 mL.
Expiratory Reserve Volume (ERV): Extra air volume that can be exhaled forcefully, averaging 1000-1100 mL.
Residual Volume (RV): Air that remains in the lungs post-forced expiration, averaging 1100-1200 mL.
Inspiratory Capacity (IC): Total air a person can inhale after normal expiration (TV + IRV).
Expiratory Capacity (EC): Total air a person can exhale after normal inspiration (TV + ERV).
Functional Residual Capacity (FRC): Volume remaining in the lungs after normal expiration (ERV + RV).
Vital Capacity (VC): Maximum air volume exhaled after forced expiration (ERV + TV + IRV).
Total Lung Capacity: Maximum air volume in lungs after forced inspiration (RV + ERV + TV + IRV).

Gas Exchange

Alveoli function as primary sites for gas exchange; oxygen (O2) and carbon dioxide (CO2) are exchanged through simple diffusion based on concentration gradients.
Approximately 20-25% of CO2 is transported by red blood cells; 70% is carried in the form of bicarbonate, and 7% dissolved in plasma.

Transport of Oxygen

Hemoglobin in red blood cells binds O2, forming oxyhemoglobin in a reversible reaction; each hemoglobin can carry up to four O2 molecules.
O2 binding with hemoglobin is influenced by factors such as partial pressure of O2, partial pressure of CO2, hydrogen ion concentration, and temperature.
The oxygen dissociation curve depicts the relationship between hemoglobin saturation and O2 partial pressure, showcasing how varying environmental conditions affect O2 binding:
- In alveoli (high pO2, low pCO2, low H+, lower temperature), conditions favor oxyhemoglobin formation.
- In tissues (low pO2, high pCO2, high H+, higher temperature), conditions favor O2 release from hemoglobin.

Key Terms and Concepts

Vital Capacity: Vital for assessing respiratory health; it is the maximum amount of air that can be inhaled or exhaled.
Diffusion of Gases: Occurs primarily in the alveoli as they are designed for efficient gas exchange due to their high surface area.
Effects of pCO2: Increased pCO2 can lead to a decreased ability of hemoglobin to bind O2, affecting oxygen transport efficiency.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers fundamental concepts related to breathing and the exchange of gases, focusing on the mechanics of intercostal muscle contractions and their effects on thoracic and pulmonary volumes. Test your understanding of the respiratory system and the physiological processes involved in breathing.