The respiratory system

Question 1

How does the respiratory system develop?

Answer 1

• As a diverticulum from the pharynx

Question 2

What are the functions of the nasal cavity?

Answer 2

• Induce turbulent flow (nasal conchae)
• Warm and moisten inspired air (allows gases to dissolve)
• Recover water from expired air
• Phonation
• Olfaction

Question 3

What do nasal conchae do?

Answer 3

• 3 outgrowths on medial surface of nasal cavity
• Increase surface area for inspired air to be moistened and warmed on way in and cooled down on way out

Question 4

Outline the structure of the nasal cavity

Answer 4

• Enters through nostrils and passes into nasal vestibule (lined by keratinised stratified squamous epithelium)
• Nostrils are lined with nasal hair, which filter dust and other foreign materials
• Epithelium then changes to ciliated pseudostratified columnar epithelium

Question 5

What are ostia?

Answer 5

• Small orifices that connect paranasal sinuses to the nasal cavity
• Can become blocked if inflamed

Question 6

How many paranasal sinuses do we have?

Answer 6

• 4 (frontal, sphenoid, ethmoid, maxillary)

Question 7

What are the 3 sections of the pharynx?

Answer 7

• Nasopharynx
• Oropharynx
• Laryngopharynx

Question 8

What are the conducting airways of the respiratory system?

Answer 8

• Trachea
• Primary bronchi
• Secondary bronchi
• Tertiary bronchi
• Bronchioles
• Terminal bronchioles

Question 9

What make up the walls and floor of the thoracic cavity?

Answer 9

• Ribs and costal cartilages make up walls
• Diaphragm makes up floor

Question 10

Which surfaces articulate with the ribs?

Answer 10

• Vertebrae (articular facets articulate with thoracic vertebrae)
• Sternum

Question 11

Which bones make up the sternum?

Answer 11

• Manubrium
• Body
• Xiphoid process

Question 12

What is the mediastinum?

Answer 12

• Septum between lungs

Question 13

What allows ventilation?

Answer 13

• Movement of joints between ribs and vertebrae

Question 14

What is meant by the bucket handle movement?

Answer 14

• Need to increase volume in thorax for ventilation to occur
• Need to increase lateral aspect of chest
• Bucket handle movement allows this
• Rib = bucket handle

Question 15

What is meant by the pump handle movement?

Answer 15

• Sternum moves upwards and anteriorly
• Increases anteroposterior dimension of chest

Question 16

What happens to the diaphragm on inhalation?

Answer 16

• Diaphragm moves down at least 2 intercostal levels

Question 17

How do movements of the ribs cause movement of air into the lungs?

Answer 17

• Alveolar pressure must be lower than atmospheric pressure of air to enter alveoli

Question 18

Where must drains be inserted into the thoracic cavity?

Answer 18

• Must insert above each rib
• Otherwise nerve damage occurs
• Neurovasculature arranged in major bundle below each rib and minor bundle above each rib

Question 19

What is the innervation of the diaphragm?

Answer 19

• Phrenic nerves
• C3, C4, C5

Question 20

What are the muscles of ventilation?

Answer 20

• External intercostal muscles (fibres run in antero-inferior direction)
• Internal intercostal muscles (fibres run perpendicular to external intercostal muscles)
• Innermost intercostal muscles (bigger role in forced expiration)

Question 21

At what level does the vena cava pass through the diaphragm?

Answer 21

• T8

Question 22

At what level does the oesophagus pass through the diaphragm?

Answer 22

• T10

Question 23

At what level does the aortic hiatus pass through the diaphragm?

Answer 23

• T12

Question 24

What are the accessory muscles of respiration?

Answer 24

• Sternocleidomastoid
• Scalenus anterior, medius, and posterior,
• Pectoralis major and minor
• Inferior fibres of serratus anterior and latissimus dorsi

Question 25

What is the dual blood supply to the thoracic cage?

Answer 25

• Intercostal arteries come from aorta and internal thoracic artery

Question 26

What is the venous drainage of the thoracic cage?

Answer 26

• Venous system drains into azygous system

Question 27

What separates the lobes of the lungs?

Answer 27

• Fissures
• Most of back of lung = lower lobe
• Oblique fissure separates lower lobe from rest of lung
• Transverse fissure separates upper lobe

Question 28

Outline the position of the main bronchi of the lungs

Answer 28

• Right main bronchus sits straight
• Left bronchus sits at an angle
• Foreign objects usually enter right lung

Question 29

Why is the right side of the diaphragm higher than the left?

Answer 29

• Liver

Question 30

What is the mediastinum?

Answer 30

• Central compartment of thoracic cavity
• Located between pleural sacs
• Contains most thoracic organs
• Acts as a conduit for structures traversing thorax on their way into abdomen
• Divided into 2 parts by angle of Louie at T4/T5 intervertebral disc
• Superior mediastinum and inferior mediastinum

Question 31

What are the subdivisions of the inferior mediastinum?

Answer 31

• Anterior - mostly fat
• Middle - heart and pericardium
• Posterior - aorta, oesophagus, azygos vein, thoracic duct

Question 32

What is the pleura?

Answer 32

• Serous membrane enveloping lungs
• Parietal and visceral
• Parietal pleura has rich somatic innervation from thoracic nerves and is sensitive to pain

Question 33

Outline the location of the pleura

Answer 33

• Top of parietal pleura goes into superior clavicular fossa
• Extends into superior thoracic aperture
• Pleura almost go down into costophrenic recess (angle between ribs and diaphragm)
• Extend very close to midline

Question 34

What is the blood supply to the lungs?

Answer 34

• Pulmonary artery
• Pulmonary veins

Question 35

Why do the lungs not completely die in pulmonary embolism?

Answer 35

• Bronchial arteries supply lung with blood
• Branches of aorta