WEEK XIII (Respiratory System)

Question 1

What is Tidal Volume?

Answer 1

Volume inspired or expired with each normal breath (500ml)

Question 2

What is Inspiratory Reserve Volume?

Answer 2

Maximum volume that can be inspired over the inspiration of a tidal volume/normal breath. Used during exercise. (Male = 3100ml, Female = 1900ml)

Question 3

What is Expiratory Reserve Volume?

Answer 3

Maximal volume that can be expired after the expiration of a tidal volume/normal breath (Male = 1200ml, Female = 700ml)

Question 4

What is Residual Volume?

Answer 4

Volume that remains in the lungs after a maximal expiration

Question 5

What is Inspiratory capacity?

Answer 5

Tidal volume + Inspiratory reserve volume

Question 6

What is Functional residual capacity?

Answer 6

Residual volume + Expiratory reserve volume

Question 7

What is Vital capacity?

Answer 7

Inspiratory reserve volume + Tidal volume + Expiratory reserve volume

Question 8

What is Total Lung Capacity

Answer 8

Vital capacity + Residual volume

Question 9

When does Intrapleural pressure exceed atmospheric pressure?

Answer 9

During forceful expiration

Question 10

Resistance to airflow is influenced by which factors?

Answer 10

• Diameter of the airways
• Airway smooth muscle tone
• Mucus production
• Obstruction/narrowing of airways

Question 11

Describe how Parasympathetic and Sympathetic stimulation alter airway flow

Answer 11

PARASYMPATHETIC: bronchoconstriction -> reduces radius of bronchioles -> increases airway resistance

SYMPATHETIC: bronchodilation -> increases bronchiolar radius -> reduces airway resistance

Question 12

What can be administered as Bronchodilators?

Answer 12

• Epinephrine
• Albuterol

Question 13

What is Chronic Obstructive Pulmonary Disease (COPD)?

Answer 13

A group of lung diseases characterised by increased airway resistance resulting from narrowing of the lumen of the lower airways

Question 14

Which diseases encompass COPD?

Answer 14

• Chronic bronchitis
• Asthma
• Emphysema

Question 15

What is Chronic Bronchitis?

Answer 15

A long-term inflammatory condition of the lower respiratory airways triggered by irritants -> In response to irritation, airways become narrowed by PROLONGED EDAMATOUS thickening of the airway linings occupied by overproduction of thick mucous

Question 16

What are the causes of Asthma?

Answer 16

• Thickening of airway walls
  [by inflammation and histamine-induced oedema]
• Excessive secretion of mucous
• Airway hyper responsiveness -> constriction of smaller airways

Question 17

What are the causes of Emphysema?

Answer 17

• Collapse of the smaller airways
• Breakdown of alveolar walls

Question 18

Describe how irritants can lead to Emphysema

Answer 18

Excessive release of protein-digesting enzymes (e.g trypsin) from ALVEOLAR MACROPHAGES as a response to exposure to irritants -> Lungs are protected from damage by A1-ANTITRYPSIN but excessive secretion overwhelms -> Trypsin destroys foreign materials and lung tissue -> Breakdown of alveolar walls and collapse of small airways

Question 19

What is Pulmonary Surfactant?

Answer 19

A mixture of lipids and proteins secreted by Type II alveolar cells

Question 20

What is the importance of lung surfactant?

Answer 20

• Reduces effort required to inflate the lungs
• Reduces tendency of lungs to recoil -> prevents collapse
• Minimises the tendency of small alveoli to collapse and empty into larger alveoli -> stabilise alveolar sizes

Question 21

What happens when two alveoli of unequal size but the same surface tension are connected?

Answer 21

The smaller alveolus tends to collapse and release air into the larger alveolus

Question 22

Why does Pulmonary surfactant reduce surface tension more in smaller alveoli than in larger ones?

Answer 22

Due to the closer proximity of surfactant molecules in small alveoli

Question 23

What are the forces keeping the alveoli open and the forces promoting alveolar collapse?

Answer 23

FORCES KEEPING THE ALVEOLI OPEN
- Transmural pressure gradient
- Pulmonary surfactant

FORCES PROMOTING ALVEOLAR COLLAPSE
- Elasticity of lung
- Alveolar surface tension

Question 24

What is Newborn Respiratory Distress Syndrome?

Answer 24

When prematurely born infants may not have enough surfactant -> infants must exert significant effort to overcome high surface tension and inflate poorly compliant lungs -> Higher transmural pressure is needed to prevent alveolar collapse

TREATMENT:
- Surfactant replacement
- Drugs to mature surfactant-secreting cells