Topic 2A.6 The Mammalian Gas Exchange System

nasal cavity

the main route by which air enters the gas exchange system

mouth

when air enters the respiratory system here, it misses out on cleaning, warming and moistening effects of the nasal route

epiglottis

a flap of tissue that closes over the glottis in a reflex action when food is swallowed preventing food from entering the gas exchange system

larynx

the voice box, which uses the flow of air across it to produce sounds

trachea

the major airway to the bronchi, lined with cells including mucus-secreting goblet cells. Cilia on the surface of the trachea move mucus and any trapped microorganisms and dust away from the lungs

incomplete rings of cartilage

prevent the trachea and bronchi from collapsing but allow food to be swallowed and moved down the oesophagus

bronchi

tubes that lead to the lungs and are similar in structure to the trachea but narrower

bronchioles

small tubes that spread through the lungs and end in alveoli

alveoli

the main site of gas exchange in the lungs

ribs

protective bony cage around the gas exchange system

intercostal muscles

found between the ribs and important in breathing, which moves air into and out of the lungs to maintain a steep concentration gradient for rapid gas exchange

pleural membrane

surround the lungs and line the chest cavity forming a sterile, sealed unit

pleural cavity

space between the pleural membranes, usually filled with a thin layer of lubricating fluid that allows the membranes to slide easily with breathing movements

diaphragm

broad sheet of tissue made of tendon and muscle that forms the floor of the chest cavity, also important in breathing movements

lung surfactant

a special phospholipid that coats the alveoli and prevents them from collapsing

breathing (ventilation)

the process in which physical movements of the chest change the pressure so that air is moved in or out

inhalation

breathing in

exhalation

breathing out

pathogens

microorganisms that cause disease