Anatomy of the Respiratory Tract

Question 1

What are the functions of the respiratory system?

Answer 1

• Provide oxygen to all body tissues
• providing a large surface area for gas exchange
  ventilation (providing air)
• Remove carbon dioxide
• Regulate blood pH
• Defence against pathogens
• protecting respiratory surfaces from dehydration and temperature changes
• Produces sound
• Olfaction (sensation of smell)

Question 2

How can the respiratory tract be organised?

Answer 2

• upper or lower

- conductive or respiratory

Question 3

What makes up the upper respiratory tract?

Answer 3

• Nose
• Pharynx
• Paranasal sinuses
• Larynx

Question 4

What are the functions of the upper respiratory tract?

Answer 4

• Warms and moistens and filters the air
• Olfaction (smell)
• Production and resonation of sound (produces in larynx, resonates as it gets moved up through the passageways)
• (protects lower tract)

Question 5

What are the functional adaptations of the nose?

Answer 5

• vibrissae
• conchae
• mucosa
• rich capillary network under mucosa
• seromucous glands
• olfactory mucosa
• paranasal sinuses

Question 6

What are the vibrissae?

Answer 6

hairs at entrance to nose which trap large dust particles

Question 7

What are the Conchae?

Answer 7

 Projections from lateral wall which produce turbulence
 Allow more time to warm and moisten the air
 Means airborne particles are more likely to come into contact with the mucous
 Creates circular air-currents that bring olfactory stimuli to the olfactory receptors

Question 8

What’s the mucosa and what does it do?

Answer 8

 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 9

What does having a rich capillary network in the nose do?

Answer 9

the blood warms the air

Question 10

What do the seromucous glands do?

Answer 10

secretions moisten the air

Question 11

What are the Olfactory mucosa and what do they do?

Answer 11

 Located in upper aspect of nose, above the superior conchae
 Contains receptors for smell

Question 12

What are the paranasal sinuses and what do they do??

Answer 12

 Air filled spaces in bones around the nose
 Lighten the skull and resonate sound
 Secretions for the sinuses drain into nasal cavity

Question 13

What is the pharynx?

Answer 13

A fibromuscular tube that forms a communal passageway for respiratory and gastrointestinal systems

Question 14

What three regions is the pharynx divided into?

Answer 14

 Nasopharynx – posterior (behind) to nose
 Oropharynx – posterior to mouth
 Laryngopharynx – posterior to larynx

Question 15

What does the close proximity of gastrointestinal and respiratory systems lead to?

Answer 15

swallowing difficulties and aspiration of food and fluid

Question 16

What are the main functions of the Larynx?

Answer 16

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

Question 17

What does the Larynx consist of?

Answer 17

 A cartilaginous skeleton (thyroid cartilage is Adam’s apple) (hyoid bone)
 A lining made of membranes – joins the cartilage inside
 Vocal cords – made of edges of membranes. Important in sounds projection and protecting the airway
 Muscles which move the vocal cords
 Glottis

Question 18

What is the glottis and what does it do?

Answer 18

 When air comes in it passes down through the glottis
 Slit like opening
 Space between the vocal cords
 Usually open to allow air flow
 Closed during swallowing to prevent aspiration
 Air vibrates over the vocal cords to produce sound
 The wider the cords are open the louder the sound

Question 19

What is the lower respiratory tract made up of?

Answer 19

• Trachea
• Primary bronchi
• Secondary bronchi
• Tertiary bronchi
• Bronchioles
• Terminal bronchioles
• Respiratory bronchioles
• Alveolar ducts
• Alveolar sacs
• Alveoli

Question 20

What is the trachea?

Answer 20

• Tough, flexible tube, 4.5cm long, 2.5cm in diameter
• Extends from the larynx to the carina
• Lies anterior to the oesophagus (oesophagus is just behind)
• Contains 15-20 horseshoe shaped cartilages which keep airway open
• Posterior ends of cartilage are joined by trachealis muscle which constricts during coughing. Also is soft for when oesophagus expands
• Lined by pseudostratified ciliated columnar epithelium with goblet cells

Question 21

What do pseudostratified ciliated columnar epithelium with goblet cells do?

Answer 21

• Acts as a mucociliary escalator
• Mucus layer which traps dust particle
• Cilia aft particles up to the larynx where they get swallowed and ingested

Question 22

What is the bronchial tree made up of?

Answer 22

- Bronchi
 Primary 
 Secondary 
 Tertiary 
- Bronchioles
 Bronchioles
 Terminal Bronchioles
 Respiratory bronchioles

Question 23

What are the histological changes displayed as you go down the bronchial tree?

Answer 23

 Amount of cartilage decreases
 Amount of smooth muscle increases
 Height of epithelial cells decrease (columnar -> cuboidal -> flattened)

Question 24

What are the primary bronchi and what do they do?

Answer 24

 Supply each lung
 2-3cm long
 Right is wider and more vertical than left
 Left is more horizontal – means that foreign bodies are less likely to get through
 C-shaped cartilages (similar to trachea) – incomplete behind with muscle at the back

Question 25

What are the secondary bronchi (lobar) and what do they do?

Answer 25

 Supply lobes of the lung (3 on right, 2 on left) |  Plates of cartilage (in small pieces) still cover all of the secondary bronchi though

Question 26

What are the tertiary bronchi and what do they do?

Answer 26

 Supply segments of the lung (10 on right, 8 on left) |  Plates of cartilage (smaller than secondary bronchus). Between cartilage there is connective tissue and smooth muscle.

Question 27

What do the bronchi provide?

Answer 27

A passageway for the air to move through

Question 28

What are features of the bronchioles?

Answer 28

 No cartilage  Simple columnar epithelium with cilia  Few goblet cells  Smooth muscle – allows bronchiole to constrict and dilate  Each gives rise to 50-80 terminal bronchioles

Question 29

What are terminal bronchioles?

Answer 29

 Simple columnar epithelium with cilia  No goblet cells or mucous glands  Clara cells – produce surfactant which reduces surface tension  Each gives rise to 2 or more respiratory bronchioles

Question 30

What are respiratory bronchioles?

Answer 30

 Simple cuboidal epithelia  No cilia  Clara cells – produce surfactant  Alveoli extend from the lumen: gas exchange occurs here

Question 31

Why do goblet cells stop before the cilia in bronchioles?

Answer 31

because the cilia needs to waft all the mucous out

Question 32

What is the alveoli?

Answer 32

The sit of gas exchange?

Question 33

How are alveoli distributed?

Answer 33

- respiratory bronchioles lead to alveolar ducts - alveolar ducts are elongated airways with walls made of alveoli - alveolar ducts lead to alveoli sacs - alveoli sacs are spaces surrounded by clusters of alveoli

Question 34

What are the features of alveoli?

Answer 34

- 150-305 million alveoli per lung - Surrounded by a network of capillaries - Provides an extensive surface area for gas exchange - Rich blood supply

Question 35

How does the blood supply to the alveoli work?

Answer 35

- Entering: Pulmonary artery -> pulmonary arteriole -> capillary network around alveolus - Leaving: capillary bed -> pulmonary venule -> pulmonary veins

Question 36

What is the structure of an alveolus?

Answer 36

- Wall is made up of type 1 alveolar cell: simple squamous epithelium - Type II alveolar cell: secretes surfactant (reduces surface tension and allows expansion of the lungs) - Macrophage: phagocytoses small inhaled particles and bacteria - Air has to pass through respiratory membrane from the alveolus into the capillary - Respiratory membrane is very thin promoting diffusion of gases

Question 37

What is the respiratory membrane made up of?

Answer 37

 epithelium of type I cell  basement membrane of type I cell  Basement membrane of capillary  Endothelium of capillary

Question 38

Why is the respiratory membrane so thin?

Answer 38

Because the two basement membranes are often fused together

Question 39

What happens with the respiratory membrane if you are ill?

Answer 39

fluid can collect between the basement membranes making diffusion harder (pulmonary hypertension)

Question 40

What is the conductive portion of the respiratory tract concerned with?

Answer 40

filtering, warming and moistening the air and conducting the air into the lungs

Question 41

What does the conductive portion of the respiratory tract include?

Answer 41

all parts of the tract where gas exchange takes place

Question 42

What does the conductive portion of the respiratory tract consist of?

Answer 42

```  Nasal cavity and paranasal sinuses  Pharynx  Larynx  Trachea  Primary bronchi  Secondary bronchi  bronchioles  terminal bronchioles ```

Question 43

What does the respiratory portion of the respiratory tract consist of?

Answer 43

 Respiratory bronchioles  Alveolar ducts  Alveolar sacs  Alveoli

Question 44

What is a mucosa?

Answer 44

A mucous membrane

Question 45

What does the respiratory mucosa consist of?

Answer 45

an epithelium and an underlying layer of areolar tissue. The lamina propria is the underlying layer of tissue. In the upper respiratory system the lamina propria contains goblet cells. In the lower system it contains smooth muscle cells

Question 46

When does the rate of mucous production in the nasal cavity and paranasal sinuses speed up?

Answer 46

when exposed to unpleasant stimuli

Question 47

Where contains nose hairs?

Answer 47

epithelium of the nasal vestibule

Question 48

What divides the right and left sides of the nose?

Answer 48

the nasal septum

Question 49

what supports the dorsum and apex of your nose?

Answer 49

the hyaline cartilaginous plate

Question 50

How is the nasopharynx separated from the oral cavity?

Answer 50

It has a soft palate that separates it

Question 51

Where does the oropharynx extend between?

Answer 51

the soft palate and the base of the tongue at the level of the hyroid bone

Question 52

What are the three large unpaired cartilages that form the larynx?

Answer 52

the thyroid cartilage, the cricoid cartilage and the epiglottis

Question 53

what do the the thyroid cartilage and the cricoid cartilage do?

Answer 53

protect the glottis and the entrance to the trachea

Question 54

What does the epiglottis do?

Answer 54

forms a lid over the glottis. It folds back over the glottis during swallowing

Question 55

Why are vocal cords highly elastic?

Answer 55

because the vocal ligaments consist of elastic tissue

Question 56

What muscles is the larynx associated with?

Answer 56

muscles of the neck and pharynx which position and stabilize the larynx and smaller intrinsic muscles that control tension in the glottal vocal folds. When you swallow both sets of muscles work together to prevent food or drink from entering the glottis

Question 57

What is laryngitis?

Answer 57

An infection or inflammation of the larynx

Question 58

What does the normal diameter of the trachea change due to?

Answer 58

- the sympathetic division | - it increases the diameter of the trachea

Question 59

What does the carina do?

Answer 59

separates the openings of the right and left main bronchi at their junction with the trachea

Question 60

What happens in bronchitis?

Answer 60

bronchi and bronchioles become inflamed and constricted, increasing resistance

Question 61

What does sympathetic and parasympathetic activation of the bronchi lead to?

Answer 61

Sympathetic activation leads to bronchodilation and parasympathetic activation leads to bronchoconstriction

Question 62

What does tension in smooth muscles commonly cause?

Answer 62

causes the bronchiole mucosa to form a series of folds that limit airflow. This can be particularly severe in asthma

Question 63

What takes place in the bronchi's during an allergic reaction?

Answer 63

bronchoconstriction

Question 64

What are the squamous epithelial cells in alveoli called?

Answer 64

pneumocytes

Question 65

What does surfactant contain?

Answer 65

phospholipids and proteins