Respiratory Structure and Function

Paranasal sinuses

Cavities in certain cranial and facial bones. They lighten the skull, act as voice resonators and produce mucous for the nasal cavities.

Alveoli

Collectively provide a large surface area for gas exchange. Lined with simple squamous epithelium to optimise diffusion. A rich supply of blood capillaries surrounds each alveolus.

Laryngopharynx

Common passageway for air and food.

Oropharynx

Common passageway for air and food.

Secondary and tertiary bronchi

Connect the primary bronchi to the bronchioles. Rings of cartilage replaced by strips of cartilage. Secondary supplies each lobe and tertiary to bronchioles.

Bronchioles

Connect the tertiary bronchi to the alveoli. Cartilage is replaced by smooth muscle allowing for bronchoconstriction and bronchodilation of these airways. Cilia are absent in the smallest airways.

Larynx

Connects pharynx to the trachea. Epiglottis prevents food and drink entering the larynx during swallowing. The vocal cords produce sound.

Trachea

Connects the larynx to the bronchi. Incomplete rings of C shaped cartilage prevent the trachea collapsing during inspiration.

Olfactory epithelium

Contain smell receptors for olfaction.

Septum

Divides nasal cavity.

Respiratory system

Functions: External gas exchange, pH regulation, sense of smell and voice production, aids venous and lymph return (the flow of venous blood and lymph back to the heart).

Nasal cavity

High vascular ciliated mucous membrane lining, which warms, moistens and filters inspired air.

Surfactant

In a fluid secreted from some alveolar cells to lower surface tension. Makes breathing easier (increasing compliance) and prevents alveolar collapse.

Nasal conchae

Increase surface area and generate turbulence to help warm, moisten and filter inspired air.

External gas exchange

O2 and CO2 are exchanged between the air in the alveoli and the blood.

pH regulation

Occurs by regulating blood CO2 concentration.

Lungs

Paired cone shaped organs separated by the mediastinum which contains the heart. Right lung has 3 lobes and left has two lobes.

Nasopharynx

Passageway for air, connects to the ear via auditory tube, (equalizes air pressure in the ears).

Pharynx

Passageway for air, food and drink. Divided into nasopharynx, oropharynx, and laryngopharynx.

Alveolar macrophages

Remove particles from the alveoli.

Primary bronchi

Rings of C shaped cartilage prevent the bronchi from collapsing. Carry air to each lung.

Pleura

Serous membrane that secrete serous fluid. Help maintain negative pressure in the pleural cavity, and through cohesion, help the lungs inflate.

Airway

Tubular passages for movement of air in and out of lungs. Contain ciliated mucous membrane to help trap and remove airborne particles from nasal cavity to larger bronchioles.