6.6 - Structure of the human gas-exchange system

Question 1

why does the body require a constant supply of oxygen and a constant removal of CO2

Answer 1

• requires the oxygen in order to release ATP for respiration
• the CO2 produced from respiration then needs to be removed because a build up can be harmful for the body

Question 2

why is the volume of oxygen and CO2 being absorbed and removed in animals so large

Answer 2

because:
- they are relatively large organisms with a large volume of living cells
- they maintain a high body temp which is related to them having high metabolic and respiratory rates

Question 3

why are the lungs located inside the body

Answer 3

• air isn’t dense enough to support and protect these delicate structures
• the body as a whole would otherwise lose a great deal of water and dry out

Question 4

what is the function of the ribcage

Answer 4

• support and protect the lungs
• the ribs can be moved by muscles between them

Question 5

what allows proper ventilation to the lungs

Answer 5

• lungs are ventilated by a tidal stream of air, thereby ensuring that the air within them is constantly replenished

Question 6

what are the main components of the human gas-exchange system

Answer 6

• lungs
• trachea
• bronchi
• bronchioles
• alveoli

Question 7

what is the structure + function of the lungs

Answer 7

• the lungs are a pair of lobed structures made up of a series of highly branched tubules, called bronchioles, which end in tiny air sacs called alveoli

Question 8

what is the structure + function of trachea

Answer 8

• the trachea is a flexible airway that is supported by rings of cartilage
• the cartilage prevents the trachea collapsing as the air pressure inside falls when breathing in
• the tracheal walls are made up of muscle, lined with ciliated epithelium and goblet cells

Question 9

what is the structure + function of bronchi

Answer 9

• the bronchi are 2 divisions of the trachea, each leading to 1 lung
• they’re similar in structure to the trachea and (like the trachea) also produce mucus to trap dirt particles and have cilia that move the dirt-laden mucus towards the throat
• the larger bronchi are supported by cartilage, although the amount of cartilage is reduced as the bronchi gets smaller

Question 10

what is the structure + function of the bronchioles

Answer 10

• they’re a series of branching subdivisions of the bronchi
• their walls are made of muscle lined with epithelial cells
• this muscle allows them to constrict so that they can control the flow of air in and out of the alveoli

Question 11

what is the structure + function of the alveoli

Answer 11

• they’re minute air-sacs at the end of the bronchioles (with a diameter of between 100 and 300 micrometres)
• between the alveoli there are some collagen and elastic fibres
• the alveoli are lined with epithelium
• the elastic fibres allow the alveoli to stretches they fill with air when breathing in
• they then spring back during breathing out in order to expel the carbon dioxide-rich air
• the alveolar membrane is the gas-exchange surface

Question 12

where in the respiratory system are the cilia

Answer 12

the bronchi

Question 13

cilia move mucus produced by goblet cells. What is the function of this

Answer 13

trap pathogens, pollutants, debris –> wafts it out –> less infections

Question 14

where else in the (female) body are there cilia, why?

Answer 14

fallopian tubes –> wafts egg

Question 15

the lungs are surrounded by a thin membrane, what’s it called and what are its functions

Answer 15

• pleural membrane
• secretes pleural fluid
  –> IMPORTANT: so the air spaces can expand during normal periods of breathing

Question 16

describe the fine structure of the bronchioles

Answer 16

• muscular walls are lined with epithelial cells
• constrict/dilate to control air flow

Question 17

describe the fine structure of the alveoli

Answer 17

• thin epithelial tissue
• collagen between them provide structure
• elastin allows expansion and recoil of alveoli