Respiratory Foundations 2

Question 1

Surfactant Functions

Answer 1

1. decreases surface tension inside the alveoli
   - decreases inward pressure and makes alveoli easier to expand
2. preventing alveoli from collapsing
3. making alveoli easier to expand

Question 2

Law of Laplace Equation

Answer 2

(Collapse Pressure)
P = 2T/r

• sulfactant decreases surface tension (T)
• smaller alveoli have more sulfactant which equalizes pressure between large and small alveoli

Question 3

Intrapleural Pressure: Pip

Answer 3

• pressure in the intrapleural space
  always -4mm hg

Question 4

Intra Alveolar Pressure: Palv

Answer 4

0mm hg when full inspired

Question 5

Transpulmonary Pressure

Answer 5

• the pressure/force that is keeping the lungs inflated
  Palv - Pip = 4mm hg

Question 6

Functional Residual Calacity

Answer 6

volume of air left in lungs after full expiration

Question 7

Pneumothorax

Answer 7

air entering the pleural sac, Pip no longer negative
- lung collapse

Question 8

Tidal Volume

Answer 8

volume of air moved during normal quiet breathing
- 500ml

Question 9

Compliance

Answer 9

ability of the lung to stretch and move outward

Question 10

Elastance

Answer 10

ability of the lungs to snap back after being streched (elastin fibres)

Question 11

Boyle’s Law: Inspiration

Answer 11

lung volume increases, pressure inside lungs decreases
- air is sucked into lungs through BULK FLOW

Question 12

Bulk Flow

Answer 12

pressure moves down gradients from high to low

Question 13

Boyle’s Law: Expiration

Answer 13

lung volume decreases, pressure inside lungs increase
- air is expelled through bulk flow

Question 14

Muscles used for forced ventilation

Answer 14

1. sternoclediomastoids
2. scalenes
3. internal intercostals
4. abdominal muscles

Question 15

Quiet Inspiration Pressures

Answer 15

Palv < Patm, therefor air flows in through bulk flow
- ribs are pulled out, diaphragm contracts down

Question 16

Passive Expiration Pressures

Answer 16

Palv > Patm, therefor air flows out through bulk flow
- ribs are pulled back down, diaphragm relaxes up

Question 17

4 Lung Volumes

Answer 17

1. Tidal Volume (Vt = 500mL)
2. Inspiratory Reserve Volume (IRV = 3000mL)
   - max inhalation
3. Expiratory Reserve Volume (ERV = 1100mL)
   - max exhalation
4. Residual Volume (RV = 1200mL)
   - leftovers you cannot get rid of

Question 18

Ventilation Rate

Answer 18

breaths/min

Question 19

Total Pulmonary Ventilation (minute ventilation)

Answer 19

= ventilation rate x tidal volume

• physiological normal is = 6 L/min

Question 20

Dead Space (Vd)

Answer 20

• conducting airways, like the brionchi are a dead space for air
• better indicator of ventilation efficiency is alveolar ventilation

Vd = 150 mL

Question 21

Alveolar Ventilation

Answer 21

= ventilation rate x (Tidal volume - Dead space)
= 12 x (500-150mL) = 4.2L/min