6.6- STRUCTURE OF THE HUMAN GAS-EXCHANGE SYSTEM Flashcards
What do all aerobic organisms require and why?
constant supply of oxygen to release energy in form of ATP during respiration
Why does carbon dioxide produced from respiration need to be removed?
its build-up could be harmful to body
Why is the volume of oxygen that has to be absorbed + volume of carbon dioxide that must be removed large in mammals? (2)
they’re relatively large organisms with large volume of living cells
maintain high body temp which is related to them having high metabolic + respiratory rates
What specialised surfaces have mammals evolved?
lungs
Why have mammals evolved lungs?
to ensure efficient gas exchange between air + their blood
What are the lungs the site of in mammals?
site of gas exchange
Why is the lungs located inside the body of mammals? (2)
air not dense enough to support + protect these delicate structures
body as a whole would otherwise lose great deal of water + dry out
What are the lungs supported + protected by?
bony box called the ribcage
What can the ribs be moved by?
muscles between them
What are the lungs ventilated by?
tidal stream of air, thereby ensuring air within them constantly replenished
What are the main parts of human gas-exchange system? (5)
lungs trachea bronchi bronchioles alveoli
What are the lungs?
pair of lobes structures made up of series of highly branched tubed, called bronchioles, which end in tiny air sacs called alveoli
What is the trachea?
flexible airway that’s supported by rings of cartilage
What does the cartilage do?
prevents trachea collapsing as air pressure inside fall when breathing in
What are the tracheal walls made up of?
muscle, lined with ciliated epithelium + goblet cells
What are the bronchi?
two divisions of trachea, each leading to one lung
What are the bronchi similar in structure to?
trachea
What do the bronchi produce like the trachea and why?
produce mucus to trap dirt particles + have cilia that move dirt-laden mucus towards throat
What is the larger bronchi supported by?
cartilage
What is the amount of cartilage supporting like as the bronchi get smaller?
amount of cartilage reduced as bronchi get smaller
What are the bronchioles?
series of branching subdivisions of bronchi
What are the walls of bronchioles made of?
muscle lined with epithelial cells
What does the muscle that makes the walls of the bronchioles allow?
allow them to constrict so they can control flow of air in + out of alveoli
What are the alvelio?
minute air-sacs at end of bronchioles
What is the diameter of alveoli like?
between 100μm and 300μm
What are there between the alveoli?
some collagen + elastic fibres
What are the alveoli lined with?
epithelium
What do the elastic fibres between the alveoli allow?
allow alveoli to stretch as they fill with air when breathing in
spring back during breathing out to expel CO2-rich air
What is the alveolar membrane used as?
gas-exchange surface
