Gas Exchange in Humans

Question 1

Explain the functions of the human gas exchange system

Answer 1

To allow a large volume of oxygen and carbon dioxide to be exchanged between the blood and the environment. The gases are needed and produced by respiration

Question 2

Explain why mammals have to absorb large volumes of oxygen and release large volumes of carbon dioxide

Answer 2

• They are large and have a large volume of living cells.
• They have a high metabolic rate and respiratory rate

Question 3

Describe the trachea

Answer 3

flexible airway supported by cartilage to prevent collapse
walls contain muscle and are lined with ciliated epithelium and goblet cells

Question 4

Describe the bronchi

Answer 4

two divisions in trachea leading to a lung each
produce mucus to trap dirt particles and cilia to move the mucus

Question 5

Describe bronchioles

Answer 5

branching subdivisions of bronchi
muscle in walls to control air flow in and out of alveoli

Question 6

Describe alveoli

Answer 6

air sacs 200 micrometres in diameter at the end of the bronchioles.
collagen and elastic fibres between alveoli.
alveoli lined with epithelium.
the elastic fibres allow the alveoli to stretch and recoil

Question 7

List (in order) the structures that air passes through on its journey into the lungs

Answer 7

• lungs
• trachea
• bronchi
• bronchioles
• alveoli

Question 8

What happens when the external intercostal muscles contract?

Answer 8

the contraction leads to inspiration, it causes the ribs to move up and outwards

Question 9

Describe the process of inspiration

Answer 9

• External intercostal muscles contract, internal intercostal muscles relax
• the ribs move up and outwards, increasing the volume of the thorax
• the diaphragm contracts and flattens, increasing the volume of the thorax
• the pressure in the lungs is reduced
• atmospheric pressure is greater (than inside the lungs) so air is forced into the lungs

Question 10

Describe the process of expiration

Answer 10

• internal intercostal contract, external intercostal relax
• ribs move down and in
• volume of thorax decreases
• pressure increases
• air moves out, moving down pressure gradient

Question 11

Why do organisms need oxygen?

Answer 11

acts as final electron acceptor in aerobic respiration which allows energy to be released in the form of ATP

Question 12

Give 2 reasons why the lungs are located inside the body

Answer 12

• air is not dense enough to support these structures
• the body would lose a great deal of water and dry out

Question 13

What is the purpose of cartilage in the trachea?

Answer 13

to prevent the tube from collapsing when air pressure falls

Question 14

How do cells lining the trachea protect the alveoli from damage?

Answer 14

• cells produce mucus
• traps dirt, mucus is moved up by cilia
• if dirt/bacteria entered alveoli, could damage them/cause infection

Question 15

Which type of inter-costal muscle CONTRACTS to allow for EXPIRATION?

Answer 15

internal

Question 16

Which type of inter-costal muscle CONTRACTS to allow for EXPIRATION?

Answer 16

internal

Question 17

How do thin walls in the alveoli allow for rapid diffusion?

Answer 17

short diffusion distance/pathway

Question 18

What are 4 features of the alveoli that make them efficient for gas exchange?

Answer 18

• thin walls
• many of them contained within the lungs
• covered in lots of capillaries
• pulmonary capillaries are very narrow

Question 19

What is emphysema?

Answer 19

damage to the walls of alveoli, caused by smoking or air pollution. This reduce the surface area for gas exchange

Question 20

What 3 factors impact the rate of gas exchange in lung conditions?

Answer 20

• decreased surface area
• decrease concentration gradient
• increased diffusion distance

Question 21

What is vital capacity?

Answer 21

maximum amount of air that can be exhaled and inhaled in a single breath

Question 22

What is vital capacity?

Answer 22

maximum volume of air that can be inhaled or exhaled in a single breath

Question 23

What is tidal volume?

Answer 23

the volume of air we breathe in and out at each breath at rest

Question 24

Why would death of alveolar cells lead to impacted gas exchange?

Answer 24

• increased diffusion distance
• reduced surface area
• less gas exchange

Question 25

How would reduced tidal volume impact CO2 in blood?

Answer 25

• less CO2 breathed out
• smaller concentration gradient
• less CO2 moves out of blood