Untitled Flashcards Set

Four Main Functions of the Respiratory System

1. Gas Exchange: The primary function involves the exchange of oxygen and carbon dioxide between the lungs and bloodstream, occurring in the alveoli.

2. Regulation of Blood pH: The respiratory system helps maintain acid-base balance by controlling CO2 levels in the blood.

3. Vocalization: The larynx and vocal cords facilitate sound production.

4. Protection: The respiratory system filters out particles and pathogens through mucous and nasal hairs.

Functions carried out only within the respiratory system: Gas Exchange and Vocalization.

Conducting vs. Respiratory Zones

• Conducting Zone: Includes structures responsible for air passage and conditioning (warming, humidifying, and filtering). It comprises the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles.

• Respiratory Zone: Consists of structures where actual gas exchange occurs, primarily the alveoli and respiratory bronchioles.

Nasal Conchae

• The nasal conchae are bony structures located within the nasal cavity that help increase the surface area available for trapping particles and warming/humidifying the air entering the lungs. They assist in directing airflow and enhancing olfaction (sense of smell).

Coverings of the Lungs

• The lungs are covered by a double-layered membrane known as the pleura. The outer layer is called the parietal pleura, and it adheres to the thoracic cavity; the inner layer is the visceral pleura, which covers the lung surface. The pleural cavity between these layers contains pleural fluid, aiding in lubrication and reducing friction during lung expansion and contraction.

Definitions:

• Patm (Atmospheric Pressure): The pressure exerted by the weight of air in the atmosphere, typically around 760 mmHg at sea level.

• Pip (Intrapleural Pressure): The pressure in the pleural cavity, which is usually negative compared to atmospheric pressure, helping to keep the lungs inflated.

• Ppul (Intrapulmonary Pressure): The pressure within the alveoli of the lungs; it fluctuates with breathing and is equal to atmospheric pressure during normal breath.

Boyle’s Law

Boyle's Law states that at constant temperature, the pressure of a gas is inversely proportional to its volume. This means that if the volume of a gas increases, the pressure decreases and vice versa. This principle is crucial in understanding how breathing works, as changes in thoracic volume during inhalation and exhalation affect lung pressure and airflow.

Lung Compliance

Lung compliance is the measure of the lung's ability to stretch and expand. Factors contributing to it include:

1. Elasticity of Lung Tissue: Affects how easily the lungs expand.

2. Surface Tension of Alveoli: More surfactant reduces surface tension, increasing compliance.

3. Chest Wall Mobility: Flexibility of the rib cage influences lung expansion.

Dalton’s Law

Dalton's Law states that in a mixture of gases, the total pressure exerted is equal to the sum of the partial pressures of individual gases. This law helps explain how oxygen and carbon dioxide diffuse in the lungs based on their partial pressures in the air and in the blood.

Henry’s Law

Henry's Law states that the amount of gas that dissolves in a liquid at a given temperature is proportional to the partial pressure of that gas above the liquid. It helps explain how gases like oxygen and carbon dioxide are transported in the blood.

Depth and Rate of Breathing

The depth and rate of breathing significantly affect levels of CO2 and O2 in the lungs. Increased depth and rate generally lead to:

• Higher Oxygen Levels: More oxygen enters the lungs and subsequently the bloodstream.

• Lower Carbon Dioxide Levels: Increased ventilation allows more CO2 to be expelled. Conversely, shallow or slow breathing can lead to lower O2 levels and higher CO2 levels in the lungs.