2A Gas exchange

Question 1

Nasal cavity

Answer 1

this is the main route by which air enters the gas exchange system

Question 2

mouth

Answer 2

air can enter the respiratory system here, but misses out on the cleaning, warming and moistening effects of the nasal rout

Question 3

epiglottis

Answer 3

• a flap of tissue that closes over the glottis in a reflex action when food is swallowed
• this prevents food form entering the gas exchange system

Question 4

larynx

Answer 4

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

Question 5

trachea

Answer 5

• 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 form the lungs

Question 6

incomplete rings of cartilage

Answer 6

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

Question 7

left and right bronchi

Answer 7

• these tubes lead to the lungs and are similar in structure to the trachea but narrower
• they divide to form bronchioles

Question 8

bronchioles

Answer 8

• small tubes that spread through the lungs and end in alveoli
• their main function is still as an airway, but some gas exchange may occur

Question 9

alveoli

Answer 9

the main site of gas exchange in the lungs

Question 10

ribs

Answer 10

protective bony cage around the gas exchange system

Question 11

intercostal muscles

Answer 11

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

Question 12

pleural membranes

Answer 12

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

Question 13

pleural cavity

Answer 13

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

Question 14

diaphragm

Answer 14

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

Question 15

inhalation

Answer 15

breathing in

Question 16

exhalation

Answer 16

breathing out

Question 17

breathing in

Answer 17

inhalation

Question 18

breathing out

Answer 18

exhalation

Question 19

pathogens

Answer 19

microorganisms that cause disease

Question 20

breathing

Answer 20

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

Question 21

lung surfactant

Answer 21

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