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

Question 22

factors that affect the rate of diffusion across a membrane

Answer 22

• surface area; large surface area increases rate of diffusion
• concentration gradient ; the higher the faster
• thickness of the exchange surfaces; the shorter the diffusion distance the faster diffusion takes place

Question 23

what is the principle called, which is used to calculate the rate at which substances of a given size will diffuse at a known temperature?

Answer 23

Fick’s law of diffusion

Question 24

Fick’s law of diffusion

Answer 24

Question 25

what does an effective gas exchange system include?

Answer 25

• large surface area
• thin layers for short diffusion distance
• rich blood supply
• moist surfaces (diffusion takes places with gases in solutions)
• permeable surfaces

Question 26

what function do the hairs and the mucus in the passages of the nasal cavity have?

Answer 26

filter out and remove much of dust, small particles and pathogens such as bacteria that you breath in

Question 27

what is an alveolus made of?

Answer 27

a single layer of flattened epithelial cells

Question 28

what is found between the alveoli and capillaries?

Answer 28

a layer of elastic connective tissue holding everything together

Question 29

elastic recoil of the lungs

Answer 29

elastic tissue helps to force air out of the lungs, which stretch when you breath in

Question 30

what coats the alveoli?

Answer 30

lung surfactant