ventilation

Question 1

what is ventilation

Answer 1

• consists of inspiration and expiration
• controlled by movements of diaphragm, intercostal muscles and ribcage

Question 2

inspiration

Answer 2

• energy-using process
• diaphragm contracts- flattens and lowers
• external intercostal muscles contract- moves ribs up and out
• volume of thorax increases
• pressure of thorax reduces so it is lower than atmospheric air
• air is drawn into lungs which equalises the pressure inside and outside the chest

Question 3

expiration

Answer 3

• passive process
• diaphragm muscles relax- moves up to dome shape
• external intercostal muscles relax
• ribs move down and in
• elastic fibres in alveoli return to normal length
• thorax volume decreases
• pressure inside thorax is greater than atmospheric air so air moves out of lungs

exhaling forcibly:
- internal intercostal muscles contract
- ribs down and in
- abdominal muscles contract which forces diaphragm up
- pressure increases in the lungs

Question 4

tidal volume

Answer 4

• the volume of air that moves into and out of the lungs with each resting breath

Question 5

vital capacity

Answer 5

the maximum volume of air that can be breathed in our out

Question 6

inspiratory reserve volume

Answer 6

the maximum volume of air you can breathe in above a normal inhalation

Question 7

expiratory reserve volume

Answer 7

the maximum volume of air you can force out of your lungs over the normal tidal volume of air you breathe out

Question 8

residual volume

Answer 8

the volume of air that is left in your lungs when you have exhaled as hard as possible

Question 9

how does a spirometer work

Answer 9

• has oxygen filled chamber with movable lid
• person breathes through tube connected to oxygen chamber
• the lid of chamber moves up or down
• pen attached to lid of chamber records movements on rotating drum
• makes a spirometer trace

Question 10

what does the soda lime in the spirometer do

Answer 10

• absorbs CO2
• so volume of gas in chamber decreases over time as O2 is used up for respiration
• person must wear nose clip

Question 11

total lung capacity

Answer 11

sum of vital capacity and residual volume

Question 12

breathing rate

Answer 12

number of breaths taken per minute

Question 13

ventilation rate

Answer 13

total volume of air inhaled in 1 minute

ventilation rate= tidal volume x breathing rate