L15- HUBS 2

The lower Respiratory Tract consists of?

• Larynx

• Trachea

• Bronchi

• Bronchioles

• Alveoli

The lungs include what part of the LRT?

bronchi, brochioles and the alveoli

Functions of the LRT?

• Conducts air to and from the site of gas exchange

• Completes cleaning, warming and humidifying the air

• Provides a barrier between the air and blood and a large surface area for gas exchange

What makes up the larynx?

• Epiglottis(flap of cartilidge at the top)

• Hyoid bone

• Laryngeal prominence

• Thyroid cartilage

• Cricoid cartilage

• Tracheal Cartilage

Larynx is what passage ONLY?

Air

What is the larynx anterior to?

esophagus

Larynx is from the what?

Hyoid bone to the trachea

What does the cartilidge do in the larynx?

Protects and maintains an open airway(Patent)

What does the epiglottis do when swallowing?

Closes over the airway

Glottis=?

Voice box

What are the the folds of the larynx?

Vocal(True) and vestibular(false) folds

What does the vocal folds do?

• Pass air causing vibrations= sound waves

• Used for normal phonation

What does testerone affect?

Cartilage and muscle, resulting in longer, thicker folds= deeper voice

What does the vestibular folds do?

• Prevents foreign object entry to the glottis

• Can produce very deep sounds

What is the vestibular folds superior to?

Vocal folds

What does the trachea lie anterior to?

The esophagus

What does the trachea extend between?

The larynx and the primary bronchi

Function of the Trachea?

• Maintains a patent airway

What shape cartilasge rings does the trachea have?

C

What are the ends of the cartiladge conncected by in the trachea?

Connected posteriorly by the trachealis muscle(band of smooth muscle)

What in the trachea contracts for coughing?

Trachealis muscle

What is the trachea supported by?

By many Elastin Fibres in the lamina propria and submucosa.

What is the function of the mucociliary escalator?

Keep the airways patent and clear

What is the mechanism of the mucociliary escalator?

• Mucus from goblet cells and mucus glands coats the surface of the respiratory epithelium

• Debris entering the trachea trapped by the mucus

• Cilia beat upwards to move/push mucus to the pharynx

• Swallowed and digested by stomach acids

Why is the cartilidge of the trachea C shaped?

• The C-shaped cartilage rings keep the airway open.

• The open part of the ring allows the esophagus to expand during swallowing.

• This design balances support and flexibility in a critical shared anatomical space.

How many lobes does the right lung have?

3

How many lobes does the left lung have?

2

What is the root of the lungs?

Collection of structures that enter and exit the lungs(bronchi, blood vessels)

What is the hilium of the lungs?

Region where bronchi and blood vessels enter

What is the apex of the lungs?

Superior region

What is the costal surface of the lungs?

Lateral surface, against ribs

What is the base of the lungs?

Inferior, sits on the diaphragm

What makes up the bronchial Tree?

• Trachea

• Primary bronchi

• Secondary and tetriary bronchi

• Bronchioles< 1mm

• Terminal Bronchioles < 0.5mm

What is the trachea in the bronchial tree?

• Respiratory epithelium

• C-shaped cartilage rings

• The trachealis muscle at the posterior

What is the primary bronchi in the bronchial tree?

• Respiratory epithelium

• Cartilage and smooth muscle rings complete

What is the Secondary and tertiary in the bronchial tree?

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

• Cartilage plates

What is the Bronchioles in the bronchial tree?

• Cuboidal epithelium

• No cartilage but thick smooth muscle for bronchoconstriction/dilation

What is the terminal bronchioles in the bronchial tree?

• Each supplies a pulmonary lobule

What changes occur to the cartilage and epithelial tissue along the LRT?

• Cartilage decreases as you go down the LRT, with it being prominent in the trachea and primary bronchi, and eventually disappearing in the bronchioles.

• The epithelium becomes progressively less specialized for mucus production as you move down, transitioning from pseudostratified ciliated columnar to simple cuboidal by the time you reach the bronchioles.

• This transition reflects the changing functions of these regions: large airways focus on airway support and debris clearance, while smaller airways are more focused on airflow regulation and gas exchange.

Why does the left have 2 lobes and the right have 3?

• The left lung has two lobes because it must make room for the heart, which tilts to the left side.

• The right lung has three lobes because there is no need for space for the heart on that side.

What is the pulmonary lobules made of ?

• Many alveoli(Air sacs) arranegd like a bunch of grapes

How many alveoi per lung?

~150 million alveoli per lung

• most of the lung volume

• Enormous surface area

Alveolar walls are very thin, made up of?

Simple squamous epithelium on a thin basement membrane

The external surface of alveoli is covered by what?

A fine network of pulmonary capillaires

Does the alveolus open at both sides?

No one side- pocket like

What is the alveolus covered by?

By a dense capillary network

What are lung epithelial cells?

Pneumocytes

• Type 1- squamous

• Type 2- Cuboidal

What does type 1 of the Pneumocytes form?

The respiratory membrane/ Blood- air barrier wioth capillary wall and shared basement membrane

What does type 2 of the Pneumocytes form?

• Scattered amongst type 1

• -Secretes surfactant, a complex lipoprotein(phospolid) that reduces the surface tension of the alveolar fluid

What does roaming macrophage do in the alveolus?

Remove debris that makes it to the alveoli

In order what are the layers that oxygen and carbon dioxide pass through?

1. Alveolar Epithelium (Type I pneumocytes)

2. Alveolar-Capillary Membrane (including both alveolar and capillary membranes, and the interstitial space)

3. Capillary Endothelium

4. Interstitial Fluid (if present)

This entire structure is often referred to as the blood-air barrier, and it is extremely thin to ensure efficient gas exchange