Lecture 15: LRT

Question 1

What are the functions of the lower respiratory system?

Answer 1

• Conducts air to/from the site of gas exchange
• Completes cleaning, warming and humidifying of air
• Provides a barrier between the air and blood, and a large surface area for gas exchange

Question 2

What and where is the larynx and what structure for swallowing can be found there?

Answer 2

• Passage of air only
• Anterior to esophagus, From the hyoid bone to the trachea.
• Cartilages protect and maintain an open airway (patent)
• Structure = Epiglottis which closes over the airway when swallowing

Question 3

What folds can be found in the larynx?

Answer 3

Vocal folds
* ‘True’ vocal cords
* Passing air causes vibrations = sound waves
* Used for normal phonation
* Testosterone affects cartilage and muscle, resulting in longer, thicker folds = deeper voice

Vestibular folds
* ’False’ vocal cords
* Superior to vocal folds
* Prevent foreign object entry to the glottis
* Can produce very deep sounds

Question 4

What are the anatomical structures of the larynx? (Superior to inferior)

Answer 4

The epiglottis which is attached to the hyoid bone

Thyroid cartilage including the Laryngeal prominence (Adam’s apple)

The Cricoid cartilage (complete ring of cartilage)

Finally the Tracheal cartilage (bands of cartilage that create a horseshoe shape around the trachea)

All these cartilages ensure the airway remains patent

Question 4

What is the glottis?

Answer 4

The voice box

Question 5

What and where is the trachea? What type of epithelium?

Answer 5

Is the wind pipe that leads to the lungs

• Anterior to esophagus ,Between the larynx and primary
  bronchi

Lined with respiratory epithelium

Also has Many elastin fibres in lamina propria & submucosa which allows for some stretch

Question 6

Name the muscle that connects the C shaped cartilage in the Trachea, what type of muscle and its function:

Answer 6

The band of smooth muscle that connects the trachea cartilage is the trachealis

The trachealis contracts for coughing

Question 7

What is the mucociliary escalator?

Answer 7

• Mucus from goblet cells and mucous glands coat surface of epithelium
• Debris becomes trapped
• Cilia move this mucus to pharynx (acting like an escalator up the trachea) allowing the debris to be swallowed and helps maintain a clear airway

Question 8

Where is the base and apex of the lungs? What is the costal surface of the lungs?

Answer 8

A bit different to the heart, the base of the lungs is the more obvious inferior or bottom part of the lung with the apex being the superior or top of the lung near the clavicles

The costal surface of the lungs is the lateral surface that lies against the ribs

Question 9

Do both lungs have 3 lobes?

Answer 9

No
The right lung has 3 lobes
The left lung has 2 lobes (needs to make space for heart)

Question 10

What is the name of where bronchi & blood
vessels enter the lungs?

Answer 10

The Hilum

Question 11

List the bronchial tree:

Answer 11

• Trachea
• Primary bronchi
• Secondary (lobar) bronchi
• Tertiary (segmental) bronchi
• Bronchioles
• Terminal bronchioles

Question 12

Describe the cartilage and epithelial tissue and muscle in the trachea:

Answer 12

• Respiratory epithelium
• C-shaped cartilage rings
• Trachealis muscle at posterior

Question 13

Describe the cartilage, epithelial and muscle tissue in the Primary Bronchi:

Answer 13

• Respiratory epithelium
• Cartilage and smooth muscle rings complete

Question 14

Describe the cartilage and epithelial tissue in the Secondary and Tertiary Bronchi:

Answer 14

• Respiratory epithelium starts to decrease in height, goblet cell numbers reduce
• Cartilage plates

Question 15

Describe the cartilage, epithelial and muscle tissue in the Bronchioles:

Answer 15

• Cuboidal epithelium
• No cartilage but thick smooth muscle for bronchoconstriction/dilation

Question 16

What do terminal bronchioles supply?

Answer 16

Each supplies a pulmonary lobule

Question 17

What are pulmonary lobules?

Answer 17

• Pulmonary lobules made of many alveoli (air sacs)
  arranged like bunches of grapes (pocket like structures, open at one side to allow air into alveoli)
• ~150 million alveoli per lung
• Most of lung volume
• Enormous surface area
• External surface of alveoli covered in fine network of pulmonary capillaries

Question 18

What are the two types of Pneumocytes (lung epithelial cells)? What are there functions?

Answer 18

Type I simple squamous
* Forms the respiratory membrane/blood-air barrier
with capillary wall and shared basement membrane

Type II simple cuboidal
* Scattered amongst Type I
* Secrete surfactant, a complex lipoprotein (phospholipid) that reduces the surface tension of the alveolar fluid, this helps maintain alveolar structure and efficient gas exchange

Question 19

Do the alveoli have defense mechanisms?

Answer 19

It has Roaming macrophages that removes debris
that makes it to alveoli

Question 20

What structures form the respiratory membrane (blood air barrier)?

Answer 20

Alveolar cell layer, fused basement membrane, capillary epithelium

Question 21

Which of these is NOT associated with the respiratory
membrane?
A. Capillary endothelium
B. Simple squamous epithelium
C. Type 2 pneumocytes
D. Fused basement membrane

Answer 21

C

Whilst Type 2 pneumocytes are found in the alveoli, they are not involved in the thin barrier of gas exchange itself.

Question 22

Which cells remove debris from the alveoli?
A. Pseudostratified ciliated columnar epithelium
B. Goblet cells
C. Type 2 pneumocytes
D. Macrophages

Answer 22

D

Roaming macrophages