Pulmonary system 1.2

Question 1

define diffusion

Answer 1

the movement of gas molecules from an area of high concentration or partial pressure to an area of low concentration or partial pressure

Question 2

structures of the alveoli that aid gaseous exchange:

Answer 2

• one cell thick walls (short diffusion pathway)
• huge surface area (millions of alveoli in each lung)
• extensive capillary network (lots of blood supply)
• have moist walls allowing gaseous exchange to occur more easily

Question 3

how does inhalation happen at rest?

Answer 3

• external intercostals contract, lifting and expanding the ribcage
• diaphragm flattens increasing the volume of the chest
• increased volume in chest = lower pressure inside lungs meaning air is sucked into the lungs because the pressure in higher in the atmosphere

Question 4

which intercostal muscles are used for inspiration?

Answer 4

external

Question 5

how does exhalation happen at rest?

Answer 5

• external intercostal muscles relax and ribcage drops inwards and downwards
• the diaphragm relaxes, returning to a cone shape, decreasing the volume in the chest
• decreased volume of chest = increased pressure inside chest meaning air is forced out

Question 6

which intercostal muscles are used for exhalation during exercise?

Answer 6

internal

Question 7

what extra muscles are used for inhalation during exercise?

Answer 7

scalenes, pectorals, sternocleidomastoid

Question 8

which muscles contract during exhalation during exercise?

Answer 8

abdominals, internal intercostals

Question 9

define gaseous exchange

Answer 9

the movement of oxygen from the air into the blood and carbon dioxide from the blood into the air

Question 10

define tidal volume

Answer 10

the volume of air breathed in or out per breath

Question 11

what happens to tidal volume during exercise

Answer 11

it increases in depth and frequency so that the body can take in more oxygen and remove more carbon dioxide

Question 12

define inspiratory reserve volume

Answer 12

the volume of air that can be forcibly inspired after a normal breath

Question 13

what happens to the inspiratory reserve volume and expiratory reserve volume during exercise

Answer 13

it decreases because the tidal volume has increased meaning there is less extra air that can be breathed in or out after a normal breath

Question 14

define expiratory reserve volume

Answer 14

the volume of air that can be forcibly expired after a normal breath

Question 15

define residual volume

Answer 15

the volume of air that remains in the lungs after maximum expiration

Question 16

what happens to residual volume during exercise

Answer 16

it remains the same

Question 17

define minute ventilation

Answer 17

the volume of air breathed in or out per minute

Question 18

what is the equation for minute ventilation?

Answer 18

tidal volume x respiratory rate

Question 19

what is the difference between total lung capacity and vital lung capacity?

Answer 19

TLC is the maximum volume of gas in the lungs after a maximal inhalation.
VC is the volume of gas exhaled during a forced exhalation after a force inhalation

Question 20

define partial pressure

Answer 20

the pressure that one gas exerts within a mixture of other gases

Question 21

how is carbon dioxide transported in the blood?

Answer 21

• can bind to haemoglobin to become carbaminohemoglobin
• can dissolve into the plasma

Question 22

what does a decrease in pH do to breathing rate and how?

Answer 22

chemoreceptors detect a change in blood acidity.
- send impulses to inspiratory centre in medulla oblongata
- down the phrenic nerve to stimulate contraction of the extra inspiratory muscles
- breathing rate and depth increases

Question 23

what is the function of stretch receptors and how do they work?

Answer 23

• prevent over-inflation when deeper inspiration occurs during exercise
• send impulses to the expiratory centre in the medulla oblongata then down the intercostal nerve to stimulate contraction of the expiratory muscles