Respiratory System

Draw and label the structure of the respiratory system:

respiratory system annotated.JPG

Functions of Respiratory System Structure:

Nasal Passage:

Functions as a filter and air conditioner to protect the lower airways. Many particles are efficiently filtered out, and infectious agents are addressed by the nasal immune system.

Pharynx (Throat):
A passageway that extends from the base of the skull to the level of the sixth cervical vertebra. It serves both the respiratory and digestive systems by receiving air from the nasal cavity and air, food, and water from the oral cavity.

Trachea (Windpipe):
A cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air.


Spongy structure which the exchange of gas occurs in.

Carries air that is breathed in through to the functional tissues of the lungs, called alveoli.


To deliver air to a diffuse network of around 300 million alveoli in the lungs.


Increases the surface area of the lung to allow for a more efficient site of gas exchange:

A thin skeletal muscle that sits at the base of the chest and separates the abdomen from the chest and contracts and flattens when inhaling

Pleural Membrane:

It allows for optimal functioning of the lungs during breathing. The pleural cavity contains pleural fluid, which acts as a lubricant and allows the pleurae to slide effortlessly against each other during respiratory movements.

Larynx (Voice Box, Glottis):

The passageway for air between the pharynx above and the trachea below and serves to protect the lower airways, facilitates respiration, and plays a key role in phonation.

Explain the mechanism of ventilation/ State that gases are exchanged by diffusion and outline the process.

Oxygen and carbon dioxide are exchanged in ventilation through diffusion. High concentrations of carbon dioxide in the blood, diffuse to the low concentrations in the alveoli to be exhaled. High concentrations of oxygen in the alveoli diffuse to the low concentration in the blood to be circulated in the body.

Suggest how the alveoli have adapted for gas exchange

The alveoli has a large surface area, making the exchange quicker and more efficient. Walls of the alveoli and capillaries are very thin (one cell thick). Gases can diffuse easily across them. Alveoli are also folded; and increase surface area.