Anatomy of Chest Wall and Mechanics of Breathing

Question 1

What is Boyle’s law?

Answer 1

States that the pressure exerted by a gas is inversely proportional to its volume

Question 2

What is Dalton’s law?

Answer 2

States that the total pressure of a gas mixture is the sum of all the pressures of each individual gases

Question 3

What is Charles law?

Answer 3

States that the volume occupied by a gas is directly related to the absolute temperature

Question 4

What is Henry’s law?

Answer 4

States that the amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid

Question 5

What is pleurisy?

Answer 5

Inflammation of the pleura, characterised by pain while breathing as the pleural membranes grate over each other

Question 6

What causes pneumothorax?

Answer 6

introduction of air into the pleural cavity, causing the uncoupling of the lungs to the chest wall. This leads to an increase in intrapleural pressure

Question 7

What is the pressure of the pleural cavity normally when compared to atmospheric pressure?

Answer 7

-3mmHg

Question 8

What muscles are used during inspiration?

Answer 8

Diaphragm

External intercostals

Question 9

What muscles are used in active expiration?

Answer 9

Internal intercostals
Abdominal muscles
Accessory muscles in severe respiratory distress?

Question 10

What are the accessory muscles of respiration?

Answer 10

The accessory inspiratory muscles are the sternocleidomastoid, the scalenus anterior, medius and posterior, the pectoralis major and minor, the inferior fibres of serratus anterior and latissimus dorsi, the serratus posterior anterior may help in INSPIRATION

Question 11

What movement of the ribcage increases the anterior-posterior dimensions of the ribcage, dependent on the intercostal muscles?

Answer 11

Pump handle movement

Pulls ribcage forward

Question 12

What movements of the ribcage influences the lateral dimensions of the ribcage, dependent on the intercostal muscles?

Answer 12

Bucket handle movement

Increases lung volume at the sides

Question 13

Define asthma

Answer 13

Over reactive constriction of the bronchial smooth muscle, increasing resistance of airflow, and makes expiration difficult

Question 14

Does asthma make inspiration or expiration difficult?

Answer 14

Expiration, which is why wheeze is normally most noticeable on expiration in asthma

Question 15

Describe intrathoracic (alveolar) pressure

Answer 15

Pa

Pressure inside thoracic cavity, can be positive or negative

Question 16

Describe intrapleural cavity

Answer 16

Pip

Pressure inside pleural cavity, always negative

Question 17

Describe transpulmonary pressure

Answer 17

Pt

Difference between Pa and Pip (Pa-Pip)
Always positive in health, as Pip is always more negative than Pa.

Question 18

How much pleural fluid is normally found in the pleural cavity?

Answer 18

3ml

Question 19

What is the function of pleural fluid?

Answer 19

Lubricates membranes to allow them to glide over each other without causing pain
Prevents separation of membranes

Question 20

What are the symptoms of pneumothorax?

Answer 20

Sudden onset sharp pain
Usually one sided pain
Dyspnoea

Question 21

What movement are the internal intercostal muscles responsible for during expiration?

Answer 21

Move ribs and sternum down and inwards

Question 22

What are the abdominal muscles responsible for in expiration?

Answer 22

Reducing volume of the abdominal cavity (oppose diaphragm effects)

Question 23

What are the external intercostal muscles responsible for in inspiration?

Answer 23

Move sternum and ribs forwards and up, as well as outwards

Question 24

What is the diaphragm responsible for in inspiration?

Answer 24

Increasing lung volume

Question 25

What is the diaphragm?

Answer 25

Sheet of internal skeletal muscle, importune in respiration