Ventilation and Compliance 2 Flashcards Preview

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Flashcards in Ventilation and Compliance 2 Deck (65)
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1

What are the 2 kinds of cells that makes up alveolar walls?

Type 1 (gas exhange)

Type 2 (secretes surfactant fluid)

2

What do type 1 cell of alveoli do?

Allows gas exchange

3

What do type 2 cells of alveoli do?

Secretes surfactant fluid

4

What is surfactant?

Detergent like fluid produced by type 2 alveolar cells

5

What does surfactant do?

Reduces surface tension on alveolar surface membranes, reducing tendancy for alveoli to collapse

6

What is surface tension?

Attraction between water molecules, occurs wherever there is an air-water interface

7

What does surfactant do to the compliance of the lung?

Increases it

8

What does surfactant do to the lungs tendency to recoil?

Reduces it

9

Is surfactant more effective in small or large alveoli, and why?

Small because surfactant molecules come closer together and are therefore more concentrated

10

Why does air spread evenly between small and large alveoli although there would be a pressure difference?

Surfactant reduces surface tension better in small alveoli, making the pressure in small and large equal

11

When does surfactant production begin and is completed by?

About 25 weeks gestation and is completed by 36 weeks

12

What is production of surfactant stimulated by?

Thyroid hormones which increase towards the end of pregnancy

13

What do premature babies often suffer from due to surfactant production being complete at week 36?

Infant respiratory distress syndrome

14

What is a saline filled lung similar to?

A lung in utero

15

Why does a lung in utero require a smaller change in pressure to inflate?

Does not need to overcome surface tension (no air-water interface)

16

What is compliance?

Change in volume relative to change in pressure

17

What does compliance of the lung represent?

Stretch ability of the lung (not elasticity)

18

What does a high compliance mean?

Large increase in lung volume for a small increase in ip pressure

19

What does a low compliance mean?

Small increase in lung volume for a large decrease in ip pressure

20

What does compliance change with?

Disease and age

21

Does it require a greater change in pressure from fictional residual capacity to reach a lung volume during inspiration or expiration?

Greater change in pressure is required during inspiration

22

Why is expiration passive?

Work on inspiration is recovered as elastic recoil during expiration

23

What is emphysema?

Loss of elastic tissue means expiration requires effort (image c)

24

What is loss of elastic tissue called?

Emphysema

25

What is fibrosis?

Inert fibrous tissue means effort of inspiration increases (image d)

26

What is inert fibrous tissue called?

Fibrosis

27

What does inert mean?

Lacking the ability or strength to move

28

Does emphysema make inspiration or expiration more difficult?

Expiration (image c)

29

Does fibrosis make inspiration or expiration more difficult?

Inspiration (image d)

30

What does the pressure/volume curve vary between?

The apex and the base of the lung