Anatomy of the respiratory system

Question 1

How long is the trachea?

Answer 1

10-12cm in length

Question 2

Describe the anatomical postioning of the trachea and where it divides.

Answer 2

The trachea lies slightly to the right of the midline and divides into the right and left bronchi at the carina (the carina lies beneath the manubrium sterni and the second right costal cartilage).

Question 3

Inhaled material is more likely to get inhaled into which lung and why?

Answer 3

The right as the right bronchus is more vertical than the left.

Question 4

How many lobes does the left and right lungs have?

Answer 4

• Right = three lobes - upper / middle /lower
• Left = …

Question 5

Physical signs on the right side in the front of the chest are due to lesions of which lobes?

Answer 5

The upper and middle as these lie in front of the lower lobe.

Question 6

What is the hilum of the lung?

Answer 6

The hilum of the lung is found on the medial aspect of each lung, and it is the only site of entrance or exit of structures (major bronchi and pulmonary arteries and veins) associated with the lungs.

Question 7

Where do the diaphragm muscle fibres arise, insert and what innervates them?

Answer 7

• Origins - the lower six ribs and their costal cartilages
• Inserts - the central tendon
• Innervation - motor and sensory nerve fibres go seperately to each half of the diaphragm via the phrenic nerves

Question 8

How are the tracheobronchial lymph nodes arranged?

Answer 8

• pulmonary
• bronchopulmonary
• subcarinal
• superior tracheobronchial
• paratracheal

Question 9

Describe the nerve supply to the lung.

Answer 9

• The innervation of the lung remains incompletely understood.
• Parasympathetic and sympathetic fibres (from the vagus and sympathetic chain, respectively) accompany the pulmonary arteries and airways.

Question 10

How is the parietal and visceral pleura innervated?

Answer 10

• The parietal pleura is innervated from intercostal and phrenic nerves
• The visceral pleura has no innervation.

Question 11

Describe the branching of the left and right main bronchi.

Answer 11

• Right - divides into the upper lobe bronchus and the intermediate bronchus, which further subdivides into the middle and lower lobe bronchi.
• Left - divides into upper and lowed lobe bronchi
• (Fun fact: approx. 25 divisions between trachea and the alveoli)

Question 12

Describe the properties of the first seven divisions of bronchi? (4)

Answer 12

• Walls consisting of cartilage and smooth muscle
• An epithelial lining with cilia and goblet cells
• Submucosal mucus-secreating glands
• Endocrine cells - amine precursor and uptake decarboxylation (APUD) cells containing 5-HT

Question 13

Describe the properties of the later 16-18 divisions of the bronchioles. (3)

Answer 13

• No cartilage and a muscular layer that progressively becomes thinner
• A single layer of ciliated cells but very few goblet cells
• Granulated Clara cells that produces a surfactant-like substance

Question 14

The epethial cells consist mainly of which cells?

Answer 14

• Type 1 pneumocytes

Question 15

What limits the movement of fluids in and out of the alveoli?

Answer 15

Tight junctions

Question 16

What allows for communication between alveoli of adjoining lobules?

Answer 16

pores of Kohn

Question 17

Describe type II pneumocytes and their purpose. (4)

Answer 17

• More numerous than type II
• Cover less of the epethial lining
• Contain lamellar vavuoles which are the source of surfactant
• Are the precursors of type I pnemocytes

Question 18

Along with type I and II pneumocytes what other cell is present within the alveoli?

Answer 18

Large alveolar macrophages

Question 20

Describe the path of the visceral pleura. Where is it continuous the parietal pleura?

Answer 20

• Covers the surface of the lung and lines the interlobular fissures
• Continous with the parietal pleura at the hilum. Before joining the parietal pleura the visceral pleura continues alongside the branching bronchial tree for some distance and then reflects back.

Question 21

What serous membranes line the diaphragm?

Answer 21

• Parietal pleura above
• Peritoneum below

Question 22

What are the two blood supplies to the lungs?

Answer 22

• Recieves deoxygenated blood from the right ventricle via the pulmonary artery
• Recieves oxygenated blood via the bronchial circulation

Question 23

Describe the pulmonary circulation.

Answer 23

• Pulmonary artery divides to accompany bronchi
• The pulmonary venules drain laterally to the periphery of the lobules –> pass centrally in the interlobular and intersegmental septa –> join to form the four pulmonary veins

Question 24

Describe the bronchial circulation.

Answer 24

• Arises from the descending aorta –> bronchial arteries supply arteries down to the level of the respiratory bronchiole.
• The bronchial veins drain into the pulmonary veins, forming part of the normal physological shunt.

Question 25

Where do the lymphatic channels lie?

Answer 25

In the interstitial space between the alveolar cells and the cappilary endothelium of the pulmonary arteries.

Question 26

What innervates the airway smooth muscle (3) and what nerotransmitters are used? (6)

Answer 26

• Vagal afferents
• Postganglionic muscarinic vagal efferents
• Vagally derivered non-adrenergic non-cholinergic (NANC) fibres
• Substance P / neurokinins A and B / calcitonin gene related peptide / vasoactive intestinal polypeptide / various adenine and guanine phosphates

Question 27

What muscarinic receptors subtypes have been identified and where are they located? (3)

Answer 27

• M1 - parasympathetic ganglia
• M2 - muscarinic nerve terminals
• M3 - airway smooth muscle