RESP- Pulmonary Ventilation

Question 1

what factors are lung volume and capacities dependent on

Answer 1

Age, sex, height

compliance, obstruction / damage

Question 2

what is pulmonary ventilation

Answer 2

movement of air from the atmosphere to the gas exchange surface of within the lung

Question 3

what is pulmonary ventilation used for

Answer 3

maintaining oxygen and carbon dioxide concentration gradients between alveolar air and arterial blood

Question 4

what factors are needed for adequate transport of oxygen from the atmosphere to respiring tissues

Answer 4

alveolar ventilation, gas exchange, cardiac output

Question 5

how are pressure gradients between alveoli and blood maintained

Answer 5

adequate ventilation

Question 6

what is the relationship between partial pressure, ventilation and gas exchange

Answer 6

increase in ventilation = increase in partial pressure gradient between alveoli and the blood = increase in gas exchange

Question 7

what is the relationship between partial pressure of carbon dioxide in the alveoli and an increase in ventilation

Answer 7

as ventilation increases partial pressure of carbon dioxide decreases

Question 8

what is the equation for ventilation

Answer 8

V (minute volume) = Vt (tidal volume, amount of air inhaled in each breath) x f (frequency, number of breaths per minute)

Question 9

where does gas exchange take place

Answer 9

the alveoli

Question 10

how much air remains in the lungs and airways at the end of expiration (residual volume)

Answer 10

150 ml

Question 11

what is the equation for alveolar ventilation

Answer 11

Va = (Vt - Vd) x f

Question 12

what is the ideal gas law

Answer 12

PV=nRT

Question 13

what is boyles law

Answer 13

P= proportional to n/V

pressure, number of moles, volume

Question 14

what causes air to flow into the lungs

Answer 14

the diaphragm contracts and the thoracic cavity expands - this increases lung volume and decreases alveolar pressure

this creates a large pressure gradient between the alveoli and the atmosphere meaning air flows into the lungs

Question 15

what causes air to flow out of the lungs

Answer 15

the diaphragm relaxes, so the lung volume is reduced - thoracic cavity volume decreases

this causes an increase in pressure in the alveoli

meaning pressure in the alveoli is greater than in the atmosphere so air flows out of the lungs

Question 16

what is the pleural cavity

Answer 16

fluid filled space between the membranes (Pleura) that line the chest wall and each lung

Question 17

what is the function of the pleural cavity

Answer 17

helps to reduce the friction between the lungs and the chest

Question 18

what properties does the pleural cavity have and what do these achieve

Answer 18

sealed, fluid filled

means it resists changes in volume

Question 19

outline the process of inspiration

Answer 19

respiratory muscles (diaphragm) contracts

volume of thoracic cavity increases

intrapleural pressure becomes more negative

lungs expand, increasing volume

alveolar pressure decreases below atmospheric pressure

air moves down the pressure gradient through airways into the alveoli equalising pressure difference

Question 20

outline the process of expiration

Answer 20

respiratory muscles (diaphragm) relax, lungs recoil due to elastic fibres

volume of thoracic cavity decreases

intrapleural pressure increases

lungs are compressed

pressure in alveoli increases above atmospheric pressure

air moves down the concentration gradient into the atmosphere, deflating the lungs and equalising the pressure difference

Question 21

what is a pneumothorax

Answer 21

entry of air into the pleural cavity resulting in a loss of intrapleural pressure and collapse of lung tissue

Question 22

what happens to the pressure gradient if either pleural membrane is ruptured

Answer 22

pressure gradient between the pleural cavity and surrounding environment will cause air to enter until intrapleural pressure = atmospheric pressure

entry of air into the pleural cavity increases pleural cavity volume
elastic recoil of lung tissue and the expansion of the chest during inspiration can potentially draw further air into the pleural space