Respiratory System Study Guide

Primary Function

The respiratory system supplies the body with oxygen and disposes of carbon

dioxide.

The Air-Blood Barrier

Also known as the Respiratory Membrane, it is composed of the alveolar and

capillary walls. This is the specific site where gas exchange occurs.

Visceral Pleura

Covers the external surface of the lungs.

Parietal Pleura

Lines the walls of the thoracic cavity.

Pleural Fluid

Found in the pleural cavity; it reduces friction so the lungs can glide easily during

breathing.

The Bronchial Tree

A network of branching passageways starting with the primary bronchi (branching off the trachea). Bronchioles are the smallest of these conducting passageways.

Conducting Zone Components

Nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles.

Conducting Zone Primary Physiology

Purifies, humidifies, and warms incoming air; acts as a conduit to the lungs.

Respiratory Zone Components

Respiratory bronchioles, alveolar ducts, and alveolar sacs.

Respiratory Zone Primary Physiology

The only site of actual gas exchange.

Alveolar Macrophages (Dust Cells)

"Wander" in the alveoli to pick up bacteria, carbon particles, and debris to protect the lungs.

Surfactant

A lipid molecule that coats alveolar surfaces.

Surfactant Physiological Role

It decreases surface tension to prevent the alveoli from collapsing after you breathe out.

Gas Exchange Mechanism

Movement of gases across the respiratory membrane occurs via Diffusion (moving from high to low concentration).

Conducting Zone

Trachea → Primary Bronchi → Bronchioles

Respiratory Zone

Alveolar Ducts → Alveoli (Site of Diffusion)