LUNGS!!!!!!!!!!!

What is tidal volume?

The volume of air inhaled during a normal breath.

What is inspiratory reserve volume?

The maximum volume of air that can be inhaled forcefully after normal exhalation.

What is expiratory reserve volume?

The maximum volume of air that can be exhaled forcefully after normal exhalation.

What is residual volume?

The volume of air remaining in the lungs after a maximum exhalation, which cannot be exhaled and keeps the alveoli open.

What does total lung capacity represent?

The total volume of air in the lungs after a maximum inhalation, calculated as TLC = TV + IRV + ERV + RV.

What is vital capacity?

The maximum volume of air that can be exhaled after maximum inhalation, calculated as VC = TV + IRV + ERV.

What is inspiratory capacity?

The maximum volume of air that can be inhaled after a normal exhalation, calculated as IC = TV + IRV.

What is functional residual capacity?

The volume of air remaining in the lungs after a normal exhalation, represented as FRC = ERV + RV, and indicates the equilibrium point of the respiratory system.

Summarize the steps involved in inspriation/exhilation

Inspiration –

1.      Diaphragm and external intercostal muscles contract

a.      Diaphragm flattens as it contracts, increasing space in thoracis cavity

b.     External intercostals raise the ribcage, expanding thoracic cavity in anterior-posterior and lateral directions

2.      Expansion of the thoracic cavity leads to interpleural pressure to become more negative, pulling the lungs outward and increasing lung volume.

a.      As this occurs, intrapulmonary pressure in alveoli decreases

3.      Pressure changes in the thoracic cavity lead to airflow in due to gradient between atmospheric pressure and thoracis cavity pressure. Occurs until pressures equalize

Expiration –

1.      Diaphragm and external intercostal muscles relax

a.      Thoracic cavity recoils, decreasing lung volume and increasing intrapulmonary pressure above atmospheric pressure

2.      This gradient of pressures forces air out of the lungs until the pressures equalize.

Type 1 alveolar cells

Thin, squamous cells that cover 95% of the alveolar surface area. Primarily function to facilitate gas exchange between the air in the alveoli and the blood in the surroudnign capillaries.

Type 2 alveolar cells

Cuboidal, interspersed among Type 1 cells. Function to create surfactant, which reduced surface tension at the air-liquid interface within the alveoli, preventing alveolar collapse and making it easier for the lungs to inflate. They calso can proliferate and differentiate into type 1 cells to play a role in repairing damaged alveolar epithelium.

Alveolar macrophages

resident immune cells in the alveoli that are phagocytic, and provide a first line of defense against pathogens.