Lecture 36 - Lower Respiratory Tract

Question 1

Name and understand the function of the muscles involved in respiration

Answer 1

o Function = to supply O2 and remove CO2
o Inspiration caused by
 Contraction of diaphragm
 Contraction of external intercostal muscles
 Changes in volume of thorax cause air to flow in
o Expiration caused by
 Passive recoil of thoracic wall due to relaxation of diaphragm and internal intercostals (forces air out of lungs)
 Forced expiration involves use of accessory respiration

Question 1

Differentiate between upper and lower respiratory tract structures

Answer 1

o Upper = nose, nasal cavity, sinuses, pharynx (throat) and larynx (voice box)
o Lower = trachea, bronchi and lungs

Question 2

Understand the structural and functional difference between the trachea and the oesophagus

Answer 2

o Each is a tube, close proximity
o Trachea exterior layer made of rings of hyaline cartilage
 Passageway for air from larynx to lungs (~12cm long)
o Oesophagus is a muscular tube that transports food from the mouth to the stomach (~25cm long)
o Significant mobility exists in these structures
 Breathing and swallowing
o Trachea is anterior, oesophagus is posterior to laryngopharynx

Question 3

Describe the structure of the pleural cavities

Answer 3

o Lie within the thorax on either side of mediastinum
o Each pleural cavity s the potential space between the parietal and visceral pleura

Question 4

Describe the branching structure of the bronchial tree

Answer 4

o One primary bronchus for each lung
o Divides into secondary bronchi (2 left, 3 right)
o Further divides into tertiary bronchi
o Keeps dividing into smaller and smaller bronchi = bronchioles

Question 5

left lung

Answer 5

 Smaller
 Two lobes (superior and inferior)
 Lobes separated by oblique fissure
 Inferior portion is notched to fit the heart

Question 6

right lung

Answer 6

 Larger
 Three lobes (superior, middle, inferior)
 Lobes separated by oblique and horizontal fissures

Question 7

What does the hilum of left and right lungs contain?

Answer 7

o Pulmonary artery; superior
o Bronchus; posterior
o Pulmonary veins; inferior

Question 8

Understand the clinical significance of bronchopulmonary segments

Answer 8

o 10 tertiary bronchi for each lung
o Smallest functionally independent segment of the lung
o Can be surgically isolated and removed without affecting adjacent regions

Question 9

Describe the features of pulmonary circulation

Answer 9

o Each lung has a pulmonary artery and 2 pulmonary veins
o Each pulmonary aa divides into secondary lobar arteries and then tertiary segmental arteries

Question 10

What do bronchial arteries supply?

Answer 10

Structures in the root of the lung, supporting tissues and visceral pleura

Question 11

What do bronchial veins drain into?

Answer 11

Drain into azygos, hemiazygos, accessory hemi-azygos of superior intercostal veins