Physiology 1

Question 1

What is Internal Respiration?

Answer 1

Internal respiration refers to the intracellular mechanisms which consumes O2 and produces CO2 (at cell level)

Question 2

What is External Respiration?

Answer 2

The sequence of events leading to exchange of O2 and CO2 between external environment and body cells

Question 3

How many steps does external respiration involve?

Answer 3

4 steps

Question 4

Step 1 of external respiration

Answer 4

Ventilation - gas exchange between atmosphere and alveoli in the lungs

Question 5

Step 2 of external respiration

Answer 5

Exchange of O2 and CO2 between air in alveoli and blood in the lungs

Question 6

Step 3 of external respiration

Answer 6

Transport of O2 and CO2 between lungs and tissue via the blood stream

Question 7

Step 4 of external respiration

Answer 7

Exchange of O2 and CO2 between blood and tissue

Leads to internal respiration occurring at cellular level

Question 8

Route of oxygen through external and internal respiration

Answer 8

Atmosphere > alveoli of lungs > heart > bloodstream > tissue > cells

Question 9

Route of CO2 through internal and external respiration

Answer 9

Cells > tissue > bloodstream > heart > alveoli of lungs > atmosphere

Question 10

What 4 body systems are involved in external respiration?

Answer 10

Respiratory system
Cardiovascular system
Haematology system
Nervous system

Question 11

What does Boyle’s Law state?

Answer 11

Pressure exerted by a gas varies inversely (opposite manner) with the volume of the gas at any constant temperature

Question 12

According to Boyle’s Law, what happens to the gas pressure when the volume of gas is increased?

Answer 12

As gas volume increases, the pressure exerted by gas decreases

Question 13

What causes the thorax and lungs to expand?

Answer 13

Contraction of inspiration muscles

Question 14

What two forces hold the thoracic wall and the lungs in close opposition?

Answer 14

(1) intrapleural fluid cohesiveness - water molecules attached together
(2) negative (relative to atmosphere) intrapleural pressure - sub-atmospheric intrapleural pressure creates pressure gradient across lung and chest wall

Question 15

The intrapleural cavity has a _______ (_______) pressure relative to the atmosphere and lung/alveoli (760 mm Hg)

Answer 15

Lower (756 mmHg)

Question 16

The three pressures important in ventilation

Answer 16

Atmospheric pressure
Intra-alveolar (intrapulmonary) pressure
Intrapleural (intrathoracic) pressure

Question 17

Atmospheric pressure is pressure caused by…

Answer 17

weight of gas in the atmosphere (760mmHg)

Question 18

Intrapleural-alveolar pressure is pressure…

Answer 18

within lung alveoli (760mmHg) when in equilibrium with atmospheric pressure

Question 19

Intrapleural (intrathoracic) pressure is pressure exerted …

Answer 19

outside lungs within pleural cavity (756mmHg) always less than atmosphere pressure

Question 20

Inspiration is an _______ process depending on ___________

Answer 20

Inspiration is an active process depending on muscle contraction (diaphragm and intercostal muscles)

Question 21

What effect does the increased size of the lungs have on intra-alveolar pressure?

Answer 21

Intra-alveolar pressure falls (759mmHg) - (air molecules less condensed - Boyle’s law), allows air to enter lungs down pressure gradient

Question 22

Expiration is a ________ process brought about by ___________

Answer 22

Expiration is a passive process brought about by relaxation of inspiration muscles

Question 23

Recoil of lungs causes…

Answer 23

Intra-alveolar pressure to rise (761mmHg) - (air molecules condensed) air then exists down its pressure gradient

Question 24

What is pneumothorax and what does it indicate?

Answer 24

When there’s air in the pleural space (abnormal), indicates hole in lung and leads to lungs collapsing

Question 25

Signs and symptoms of pneumothorax

Answer 25

Shortness of breath
Chest pain
Hyper-resonant percussion note
Decreased/absent breath sounds

Question 26

What causes recoil of lungs during expiration?

Answer 26

(1) Elastic connective tissue - structure bounces back into shape
(2) alveolar surface tension

Question 27

What is alveolar surface tension?

Answer 27

Lining of water molecules (liquid and air) produce force which resist stretching of lungs

Question 28

What is a surfactant and what is it’s function?

Answer 28

Lipid and protein mixture (secreted by type II alveoli) which prevents smaller alveoli from collapsing by reduces surface tension

Question 29

Developing foetal lungs are able to produce surfactant (true/false)

Answer 29

False
They are unable until late in pregnancy
(Premature babies - lack of surfactant = respiratory distress syndrome)

Question 30

Another factor which keeps alveoli open (other than transmittal pressure gradient and pulmonary surfactant)

Answer 30

Alveolar interdependence - surrounding alveolus stretch and recoil to force collapsing alveolus to open

Question 31

Summary card

List forces keeping alveoli open vs forces promoting alveolar collapse

Answer 31

Open (inspiration)
Transmittal pressure gradient
Pulmonary surfactant
Alveolar interdependence

Collapse (expiration)
Elasticity
Alveolar surface tension