Ch 23- Respiration and Pressure & Cycle

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1

External Respiration

exchange of 02 & CO2 btwn interstitial fluids and external environments

2

Internal Respiration

consumption/production of O2 & CO2
cellular respiration

3

Pulmonary Ventilation

movement due to pressure differences
air movement in & out of lungs
maintain alveolar ventilation

4

Gas Diffusion

btw alveoli and blood
btw blood and other tissue

5

Gas Transport

from alveolar capillary beds to capillary beds of other tissues

6

Pressure Difference

Boyle's Law P1V1=P2V2
difference in volumes lead to change in pressure- always fill contain space

7

Pressure Force?

F=P1-P2 / R
Air flows from high pressure to low pressure down gradient

8

Pulmonary Ventilation Mechanisms

Ribs and sternum elevate- increase thoracic volume and decrease pressure

9

Thoracic expansion

expands directional and outward

10

Atmospheric pressure P(atm)

pressure exerted by air at sea level
-760 mmHg = 1 atmosphere

11

Intrapulmonary pressure P(pul)

Intra-alveolar, pressure in alveoli

12

Intrapleural pressure P(ip)

pressure in pleural cavity, negative to
P (atm) & P (pul)

13

Breath Cycle Inhalation

Inhalation:
P ip falls to -6mmHg
P pul falls to -1 mmh
Air flows in

14

Breath Cycle Exhalation

P ip & P pul rise; air flows out

15

Quiet Inspiration

contraction of diaphragm & external intercostal
-decrease P pul due to an increase in volume
-P pul < P atm; air flows in

16

Inspiration sequence

1. Inspiratory muscle contract- diaphragm
descends; rib cage rises
2. Thoracic cavity volume increases
3.Lungs stretched; intrapulmonary volume
increases
4. Intrapulmonary pressure drops -1mmHg
5. Air (gases) flows in lungs down pressure
gradient until intrapulmonary pressure is
0 & equal to atmospheric pressure

17

Expiration sequence

1. Inspiratory muscle relax- diaphragm
rises; rib cage descends to to recoil of
costal cartilage
2. Thoracic cavity volume decreases
3. Elastic lungs recoil passively;
intrapulmonary volume decreases
4. Intrapulmonary pressure rises to
+1mmHg
5. Gases flow out of lungs down its
pressure gradient until intrapulmonary
pressure is 0

18

Lung Compliance

Measure of how easily lungs and thorax expand due to distensibility and alveolar surface tension
- volume change per pressure change

19

Respiratory muscle % @ rest

3-5% of resting energy requirement in healthy, resting individual

20

Thorax and lung expansion decreased

loss of elastic CT fiber
reduction of surfactant
decrease in rib flexibility

21

surfactant

a substance capable of reducing the surface tension of a liquid in which it is dissolved