6.6- STRUCTURE OF THE HUMAN GAS-EXCHANGE SYSTEM

Question 1

What do all aerobic organisms require and why?

Answer 1

constant supply of oxygen to release energy in form of ATP during respiration

Question 2

Why does carbon dioxide produced from respiration need to be removed?

Answer 2

its build-up could be harmful to body

Question 3

Why is the volume of oxygen that has to be absorbed + volume of carbon dioxide that must be removed large in mammals? (2)

Answer 3

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

Question 4

What specialised surfaces have mammals evolved?

Answer 4

lungs

Question 5

Why have mammals evolved lungs?

Answer 5

to ensure efficient gas exchange between air + their blood

Question 6

What are the lungs the site of in mammals?

Answer 6

site of gas exchange

Question 7

Why is the lungs located inside the body of mammals? (2)

Answer 7

air not dense enough to support + protect these delicate structures

body as a whole would otherwise lose great deal of water + dry out

Question 8

What are the lungs supported + protected by?

Answer 8

bony box called the ribcage

Question 9

What can the ribs be moved by?

Answer 9

muscles between them

Question 10

What are the lungs ventilated by?

Answer 10

tidal stream of air, thereby ensuring air within them constantly replenished

Question 11

What are the main parts of human gas-exchange system? (5)

Answer 11

lungs 
trachea
bronchi
bronchioles
alveoli

Question 12

What are the lungs?

Answer 12

pair of lobes structures made up of series of highly branched tubed, called bronchioles, which end in tiny air sacs called alveoli

Question 13

What is the trachea?

Answer 13

flexible airway that’s supported by rings of cartilage

Question 14

What does the cartilage do?

Answer 14

prevents trachea collapsing as air pressure inside fall when breathing in

Question 15

What are the tracheal walls made up of?

Answer 15

muscle, lined with ciliated epithelium + goblet cells

Question 16

What are the bronchi?

Answer 16

two divisions of trachea, each leading to one lung

Question 17

What are the bronchi similar in structure to?

Answer 17

trachea

Question 18

What do the bronchi produce like the trachea and why?

Answer 18

produce mucus to trap dirt particles + have cilia that move dirt-laden mucus towards throat

Question 19

What is the larger bronchi supported by?

Answer 19

cartilage

Question 20

What is the amount of cartilage supporting like as the bronchi get smaller?

Answer 20

amount of cartilage reduced as bronchi get smaller

Question 21

What are the bronchioles?

Answer 21

series of branching subdivisions of bronchi

Question 22

What are the walls of bronchioles made of?

Answer 22

muscle lined with epithelial cells

Question 23

What does the muscle that makes the walls of the bronchioles allow?

Answer 23

allow them to constrict so they can control flow of air in + out of alveoli

Question 24

What are the alvelio?

Answer 24

minute air-sacs at end of bronchioles

Question 25

What is the diameter of alveoli like?

Answer 25

between 100μm and 300μm

Question 26

What are there between the alveoli?

Answer 26

some collagen + elastic fibres

Question 27

What are the alveoli lined with?

Answer 27

epithelium

Question 28

What do the elastic fibres between the alveoli allow?

Answer 28

allow alveoli to stretch as they fill with air when breathing in
spring back during breathing out to expel CO2-rich air

Question 29

What is the alveolar membrane used as?

Answer 29

gas-exchange surface