Anatomy of the Respiratory Tract - Lecture 16

Question 1

What are the functions of the respiratory system?

Answer 1

○ Provides oxygen to all body tissues
○ Removes carbon dioxide
○ Regulates blood pH
○ Defence against pathogens
○ Produces sound
○ Olfaction (smell)

Question 2

How is the respiratory tract organised?

Answer 2

○ Upper respiratory tract
○ Lower respiratory tract

Question 3

What makes up the upper respiratory tract?

Answer 3

○ Nose
○ Pharynx
○ Paranasal sinuses
○ Larynx

Question 4

What makes up the lower respiratory tract?

Answer 4

○ Trachea
○ Bronchi
○ Bronchioles
○ Alveoli

Question 5

What is the function of the upper respiratory tract?

Answer 5

○ Warms and moistens and filters the air
○ Olfaction (smell)
○ Production and resonation of sound

Question 6

What are the functional adaptations of the nose (first three)?

Answer 6

Vibrissae:
○ Hairs at the entrance to the nose which traps large dust particles
Conchae:
○ Shelf-like projections from lateral wall which produce turbulene
○ Covered in mucosa
○ Allows more time to warm and moisten the air
Mucosa:
○ Pseudostratified ciliated columnar epithelium with goblet cells
○ Goblet cells produce mucous to trap particles
○ Cilia waft the trapped particles to pharynx where they can be swallowed

Question 7

What are the functional adaptations of the nose (last four)?

Answer 7

Rich capillary network:
○ Blood warms the air
Seromucous glands:
○ Secretions moisten the air
Olfactory mucosa:
○ Located in the upper aspect of the nose, above the superior conchae
○ Contains receptors for smell
Paranasal sinuses:
○ Air filled spaces in bones around the nose
○ Lighten the skull and resonate sound
○ Secretions for the sinuses drain into nasal cavity

Question 8

What is the pharynx?

Answer 8

○ Fibromuscular tube: a communal passageway for respiratory and gastrointestinal systems
○ The close proximity can lead to swallowing difficulties and aspiration of food and fluid

Question 9

What are the three regions of the pharynx and where are they located?Ma

Answer 9

○ Nasopharynx: posterior to nose
○ Oropharynx: posterior to mouth
○ Laryngopharynx: posterior to larynx

Question 10

What are the main functions of the larynx?

Answer 10

○ Maintains an open airway
○ Prevents food and drinks entering the lower respiratory tract
○ Sound production
○ Involved in coughing and defaecation

Question 11

What does the larynx consist of?

Answer 11

○ A cartilaginous skeleton
○ A lining made of membranes
○ Vocal chords
○ Muscles which move the vocal chords

Question 12

What makes up the cartilaginous skeleton of the larynx?

Answer 12

From top to bottom:
○ Epiglottis
○ Hyoid bone
○ Thyroid cartilage (Adam’s apple)
○ Arytenoid cartilage
○ Cricoid cartilage

Question 13

What is the glottis?

Answer 13

○ Space between vocal chords
○ Usually open to allow air flow
○ Closed during swallowing to prevent aspiration
○ Air vibrated over the vocal chords to produce sound

Question 14

Describe the trachea

Answer 14

○ Tough, flexible tube
○ 4.5cm long, 2.5cm in diameter
○ Extends from larynx to carina
○ Lies anterior to the oesophagus

Question 15

What does the trachea consist of?

Answer 15

○ Contains 15-20 horseshoe shaped cartilages: keep the airway open
○ Posterior ends of cartilage are joined by trachealis muscle: constricts during coughing
○ Trachea lined by pseudostratified columnar epithelium: acts as a mucociliary escalator

Question 16

What are the three levels of bronchi?

Answer 16

○ Primary
○ Secondary
○ Tertiary

Question 17

What are the three levels of bronchioles?

Answer 17

○ Bronchioles
○ Terminal bronchioles
○ Respiratory bronchioles

Question 18

What trends are seen as you move down the bronchial tree?

Answer 18

○ Tubes get smaller in diameter
○ Amount of cartilage decreases
○ Amount of smooth muscle increases
○ Height of epithelial cells decrease

Question 19

Describe the primary bronchi and its function

Answer 19

○ Supply each lung
○ 2-3cm long
○ right is wider and more vertical than left
○ C-shaped cartilages

Question 20

Describe the secondary bronchi (lobar) and its function

Answer 20

○ Supply lobes of the lung:
- 3 on the right
- 2 on the left
○ Plates of cartilage that completely encircle it

Question 21

Describe the tertiary bronchi (segmental) and its function

Answer 21

○ Supply segement of the lung:
- 10 on the right
- 8 on the left
○ Smaller plates of cartilage that completely encircle it

Question 22

Describe the bronchioles and their function

Answer 22

○ No cartilage
○ Simple columnar epithelium with cilia
○ Few goblet cells
○ Smooth muscle: can constrict and dilate
○ Each gives rise to 50-80 terminal bronchioles

Question 23

Describe terminal bronchioles and their function

Answer 23

○ Simple columnar epithelium with cilia
○ No goblet cells or mucous glands
○ Clara cells - produce surfactants to reduce surface tension
○ Each gives rise to 2 or more respiratory bronchioles

Question 24

Describe respiratory bronchioles and their function

Answer 24

○ Simple cuboidal epithelia
○ No cilia
○ Clara cells
○ Alveoli extend from lumen: gas exchange

Question 25

What are the levels to alveoli and describe them

Answer 25

○ Respiratory bronchioles -> alveolar ducts
○ Alveolar ducts: elongated airways with walls made of alveoli -> alveolar sacs
○ Alveolar sacs: spaces surrounded by clusters of alveoli

Question 26

What are the key facts of alveoli?

Answer 26

○ 150-250 million alveoli per lung
○ Surrounded by a network of capillaries
○ Provides an extensive surface area for gas exchange

Question 27

What is the structure of alveolus?

Answer 27

○ Type I alveolar cell: simple squamous epithelium that forms wall of alveolus
○ Type II alveolar cell: secretes surfactant that reduces surface tension so that can re-expand when air is expelled
○ Macrophages: phagocytosis of small inhaled particles and bacteria
○ Thin respiratory membrane

Question 28

What is the respiratory membrane made up of?

Answer 28

○ Epithelium of type I cell
○ Endothelium of capillary
○ Fused basement membranes of type I cell and capillary

Question 29

What is the conductive portion of the respiratory tract and what comes under it?

Answer 29

Concerned with getting air into the lungs:
○ Nasal cavity & paranasal sinuses
○ Pharynx
○ Larynx
○ Trachea
○ Primary bronchi
○ Secondary bronchi
○ Tertiary bronchi
○ Bronchioles
○ Terminal bronchioles

Question 30

What is the respiratory portion of the respiratory tract and what comes under it?

Answer 30

Parts where gas exchange takes place:
○ Respiratory bronchioles
○ Alveolar ducts
○ Alveolar sacs
○ Alveoli