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Flashcards in Physiology Deck (252)
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1

what is the internal respiration equation?

food + oxygen = energy + carbon dioxide (+ water)
consumption of oxygen and production of carbon dioxide

2

what does external respiration refer to?

the exchange of oxygen and carbon dioxide between external environment and the cells of the body

3

how many steps are involved in external respiration?

4

4

what is the 1st step of external respiration?

ventilation

5

what is the 2nd step of external respiration?

gas exchange between alveoli and blood

6

what is the 3rd step of external respiration?

gas transport in the blood

7

what is the 4th step of external respiration?

gas exchange at tissue level

8

what does ventilation (1st step of external respiration) involve?

the mechanical process of gas exchange between the armosphere and the alveoli

9

what does 'gas exchange between alveoli and blood' (2nd step of external respiration) involve?

exchange of oxygen and carbon dioxide between the air in the alveoli and the blood in the pulmonary capillaries

10

what does 'gas transport in the blood' (3rd step of external respiration) involve?

the binding and transport of oxygen and carbon dioxide in the circulating blood

11

what does 'gas exchange at tissue level' (4th step of external respiration) involve?

the exchange of oxygen and carbon dioxide between the blood in the systemic circulation and the body cells

12

what 3 body systems are involved in external respiration?

respiratory system
cardiovascular system
haematology system

13

What is Boyle's Law?

for a given mass of gas -at a certain temperature- as the volume of the gas increases, the pressure exerted by the gas decreases.

14

air flows down a pressure gradient ___ pressure to a region of ___ pressure

high pressure to a region of low pressure

15

when is the intra-alveolar pressure equivalent to the atmospheric pressure?

before inspiration

16

What does expansion of the thorax and lungs do to the intra-alveolar pressure?

makes it fall below atmospheric pressure (Boyle's Law)
this allows air to move from atmosphere into lungs down pressure gradient

17

what 2 forces hold the thoracic wall and the lungs in close opposition?

1. intrapleural fluid cohesiveness
2. the negative intrapleural pressure

18

how does the intrapleural fluid keep thoracic wall and lungs in close opposition?

the water molecules in the intrapleural fluid are attracted to each other and resist being pulled apart, therefore pleural membranes tend to stick together

19

how does the negative intrapleural pressure keep the thoracic wall and lungs in close opposition?

the sub-atmospheric intrapleural pressure creates a transmural pressure gradient across the lung wall and chest wall, therefore lungs are forced to expand outwards while the chest is forced to squeeze inwards

20

what 3 pressures are important in ventilation?

atmospheric pressure
intra-alveolar pressure
intrapleural pressure

21

what is the atmospheric pressure at sea level?

760mmHg

22

what is usually the intrapleural pressure?

756mmHg

23

when the external intercostal muscle contract what do they cause?

elevation of the ribs, causing the sternum to move upwards and forwards- increases AP dimension of thoracic cavity

24

what type of process is inspiration?

active
(brought about by contraction of inspiratory muscles)

25

what type of process is normal expiration?

passive
(brought about by relaxation of inspiratory muscles)

26

what 2 properties allows the lung to recoil to their preinspiratory size during expiration?

elastic connective tissue in the lungs
alveolar surface tension

27

what does the recoil of lungs do to the intra-alveolar pressure?

makes it rise above atmospheric pressure
(Boyle's Law)
this allows air to move from lungs to atmosphere down a pressure gradientq

28

what is a traumatic pneumothorax?

a puncture wound in the chest wall causing a collapsed lung

29

what is a spontaneous pneumothrax?

a hole in the lung itself causing a collapsed lung

30

why do holes in either the chest wall of lung wall cause collapsed lungs?

they permit air to enter the pleural cavity and abolish the transural pressure gradient causing the lung to collapse to its unstretched size