Physiology 3

Question 1

Equation for pulmonary ventilation

Answer 1

Pulmonary ventilation = tidal volume x respiratory rate

Question 2

pulmonary ventilation

Answer 2

Volume of air breathed in and out per minute

Question 3

Alveolar ventilation

Answer 3

Volume of air exchanged between atmosphere and alveoli per minute

Question 4

What factor makes alveolar ventilation lower than pulmonary ventilation?

Answer 4

Presence of anatomical dead space - where air remains, unavailable for gas exchange

Question 5

Equation for alveolar ventilation

Answer 5

Alveolar ventilation = (tidal volume - dead space volume) x respiratory rate

Question 6

To increased pulmonary ventilation…

Answer 6

Both depth (tidal volume) and rate of breathing (RR) increase

Question 7

Due to dead space, it is more beneficial to increase breathing rate (true/false)

Answer 7

False

It is now useful to increase depth of breathing

Question 8

Transfer of gases between body and atmosphere depends on…

Answer 8

Ventilation and perfusion

Question 9

Ventilation

Answer 9

Rate gas passes through lungs

Question 10

Perfusion

Answer 10

Rate blood passes through lungs

Question 11

Rate of ventilation is equal to rate of perfusion (true/false)

Answer 11

False
Ventilation and perfusion and not perfectly matched
(Blood flow lower at top of lungs c.f. Bottom of lungs)

Question 12

What is considered as alveolar dead space?

Answer 12

Ventilated alveoli not adequately perfumed with blood

Question 13

Physiological dead space

Answer 13

Anatomical dead space + alveolar dead space

Question 14

What structures make up the anatomical dead space?

Answer 14

Nose
Pharynx 
Trachea 
Bronchi
(Where gas exchange does not occur)

Question 15

Greater perfusion than ventilation in areas causes…

Answer 15

CO2 increase > O2 decrease
Local airway dilation > Airflow increase
Local vessel constriction > Decreased blood flow

Question 16

Greater ventilation than perfusion in areas causes…

Answer 16

CO2 decrease > O2 increase
Local airway constriction > increased airflow
Local blood vessel dilation > increased blood flow

Question 17

Four factors affecting rate of gas exchange across alveolar membrane

Answer 17

(1) partial pressure gradient
(2) diffusion coefficient
(3) alveolar membrane surface area
(4) alveolar membrane thickness

Question 18

What is ‘Partial pressure of gas’?

Answer 18

Pressure exerted by gas if it occupied entire volume of mixture

Question 19

What does Dalton’s law of partial pressures state?

Answer 19

Total pressure exerted by gaseous mixture (sum of individual partying pressures)

Question 20

The air respiratory tract is saturated with _______

Answer 20

Water (contributes 47 mmHg to total lung pressure)

Question 21

describe Partial pressure gradient

Answer 21

Movement of gases from high to low pressures

Question 22

Partial pressure gradient for CO2 is ______ than for O2

Answer 22

Smaller [x20] - as CO2 is more membrane soluble than O2 (diffusion coefficient)

Question 23

Diffusion coefficient

Answer 23

Solubility of gas in membranes

Question 24

Small gradient between alveolar PO2 (PAO2) and arterial PO2 (PaO2) is present (true/false)

Answer 24

True

A big gradient would indicate gas exchange problems in lungs or shunt in heart

Question 25

Lungs provide _______ surface area with ______ membranes to facilitate effective gas exchange

Answer 25

Large, thin

Question 26

Ficks law of diffusion

Answer 26

Diffusion of gas across sheet of tissue is proportional to area of sheet but oppositely proportional to its thickness