Physiology 1

Question 1

External Respiration Definition

Answer 1

Sequence of events that leads to the exchange of O2 and CO2 between the external environment and cells of the body

Question 2

How many steps in external respiration?

Answer 2

4

Question 3

4 steps of external respiration?

Answer 3

Ventilation
Gas exchange between alveoli
Gas transport in the blood
Gas exchange at tissue level

Question 4

Internal Respiration Definition?

Answer 4

Intra-cellular mechanism which consumes O2 and produces CO2

Question 5

Ventilation

Answer 5

Mechanical process of moving air between the atmosphere and the alveolar sacs

Question 6

Gas exchange between alveoli

Answer 6

The exchange of O2 and CO2 between the air in the alveoli and the blood in the pulmonary capillaries

Question 7

Gas transport in the blood

Answer 7

The binding and transport of O2 and CO2 in the circulating blood

Question 8

Gas exchange at tissue level

Answer 8

The exchange of 02 and CO2 between blood in the systematic capillaries and the body cells

Question 9

4 body systems involved in external respiration

Answer 9

Respiratory
Circulatory
Nervous
Haematology

Question 10

Boyles Law?

Answer 10

At any constant temperature the pressure exerted by a gas varies inversely with the volume of the gas
(As volume of gas increases the pressure exerted by the gas decreases)

Question 11

What must happen to intra-alveolar pressure for air to flow into the lungs during inspiration?

Answer 11

Must become lower than atmospheric pressure

Question 12

Intra-alveolar pressure before inspiration?

Answer 12

Equivalent to atmospheric pressure

Question 13

Why do thorax and lungs expand in Inspiration

Answer 13

Contraction of Inspiratory muscles

Question 14

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

Answer 14

Intrapleural Fluid cohesiveness- water molecules attract each other, pleural membranes stick together
Negative intraplueral pressure- transmural pressure gradient across lung and chest walls

Question 15

3 pressures important in ventilation?

Answer 15

Atmospheric pressure
Intra-alveolar pressure
Intra-pleural pressure

Question 16

Normal atmospheric pressure?

Answer 16

760 mm hg at sea level

Question 17

How is the volume of the thorax increased?

Answer 17

Contraction of the diaphragm, flattening out its dome shape

Question 18

What lifts the ribs and moves out the sternum?

Answer 18

External intercostal muscle contraction

Question 19

Physiology during inspiration?

Answer 19

Elevated Rib cage- Increases side to side dimensions of thoracic cavity
Contraction of diaphragm- increases vertical volume of thoracic cavity

Question 20

Process of Inspiration

Answer 20

Chest walls and lungs are stretched
Increase in size of lungs causes decrease in intra-alveolar pressure
Air then enters the lungs down the concentration gradient, until intra-alveolar pressure becomes equal to atmospheric

Question 21

Normal expiration?

Answer 21

Passive process brought about by relaxation of the inspiratory muscles

Question 22

Pneumothorax

Answer 22

Air in the pleural space

Question 23

What can abolishe the transmeural pressure gradient?

Answer 23

A Pneumothorax

Question 24

Symptoms of pneumothorax

Answer 24

Shortness of breath, Chest pains

Question 25

Physical signs of pneumothorax?

Answer 25

Hyperresonant percusssion

Decreased/absent breath sounds

Question 26

What causes the lungs to recoil during expiration?

Answer 26

Elastic connective tissue

Alveolar surface tension

Question 27

Alveolar surface tension?

Answer 27

Attraction between water molecules at liquid air interface

Question 28

What reduces alveolar surface tension?

Answer 28

Surfactant

Question 29

If alveoli were coated in water alone?

Answer 29

Surface tension too much, aveoli would collapse

Question 30

LaPlace’s Law?

Answer 30

P=2T/r
P=Inward directed collapsing pressure
T= Surface Tension
r=Radius of the bubble

Question 31

What does LaPlace’s law say?

Answer 31

Alveoli with smaller radiuses have a higher tendancy to collapse

Question 32

Pulmonary surfactant?

Answer 32

Complex mixture of lipids and proteins secreted by type 2 alveoli

Question 33

How does pulmonary Surfactant work?

Answer 33

Lowers alveolar surface tension by interspersing between water molecules lining the alveoli

Question 34

What are developing fetal lungs unable to do until late in pregnancy?

Answer 34

Synthesize surfactant = premature babies may not have enough= Respiratory distress syndrome of newborn

Question 35

Factor which helps keep the alveoli open?

Answer 35

The alveolar interdependence

Question 36

Alveolar Interdependence

Answer 36

If an alveolus starts to collapse, the surrounding alveoli are stretched and then recoil exerting expanding forces in the collapsing alveolus to keep it open.

Question 37

Forces keeping alveoli open?

Answer 37

Transmural pressure gradient
Pulmonary surfactant
Alveolar Interdependence

Question 38

Forces promoting alveolar collapse?

Answer 38

Elasticity of stretched lung connective tissue

Alveolar surface tension