The Respiratory System (Slides 24-45)

What is the cartilage and adventitia?

C-shaped hyaline cartilages closed

by fibroelastic membrane

posteriorly (includes the trachealis

muscle)

What is the cartilage?

1. Some cartilages anastomose

2. All have perichondrium

3. Some may be replaced by bone tissue

with age

What is the adventitia?

1. Dense CT

2. Surrounds cartilages and trachealis

muscle

3. Binds trachea to adjacent structures

4. Larger blood and lymphatic vessels,

and nerves

What is the branching pattern of the bronchial tree?

Bronchi branch off repeatedly

Resulting bronchi have smaller diameter

Bronchioles diameter is less than 1 mm

What are the bronchioles?

Each enters a

pulmonary lobule.

Each delineated with

CT, pyramidal shape,

and the apex aimed

at the hilum

What is the tertiary bronchi?

Together with its

branches form a

bronchopulmonary

segment, each w/

CT capsule and

blood supply

What is the secondary bronchi?

each supply a pulmonary lobe

What is the primary bronchi?

each supply a lung

What are the five layers of the bronchi?

1. Mucosa

2. Muscularis (smooth muscle)

3. Submucosa (loose CT)

4. Cartilage layer

5. Adventitia

What does the mucosa contain?

1. Respiratory epithelium

2. Bronchioles

3. Epithelium

The main, secondary, and tertiary bronchi have what?

respiratory epithelium

What is the respiratory epithelium?

1. Cellular height decreases gradually

2. Initial thick basement membrane becomes very

discrete in secondary bronchi

3. Lamina propria similar to trachea

What is the epithelium of the mucosa?

gradual changes from larger

bronchioles to terminal bronchioles

What does the epithelium contain?

1. Pseudostratified (with fewer goblet cells)

2. Ciliated simple columnar (much less goblet cells)

3. Ciliated simple cuboidal (no goblet cells)

The mucosa becomes _______ as bronchial diameter ___________.

thinner, decreases

What does the muscularis ( Smooth Muscle) contain?

1. bronchi

2. bronchioles

3. Terminal bronchioles

What is the bronchi of the muscularis

prominent spiral bands of smooth muscle crisscrossing with elastic fibers of deeper lamina

propria

What is the bronchiles of the muscularis?

prominent circular band of smooth muscle

What are the terminal bronchioles of the muscularis?

thinner, incomplete circular layer of smooth muscle

What is the submucosa ( Loose CT)?

1. Glands and adipose tissue in larger bronchi

2. Bronchioles do not have glands

What is the cartilage layer?

1. Main bronchi have circular rings of cartilage

2. Intrapulmonary bronchi have plates instead of rings and they become smaller in smaller bronchi

3. No cartilage at all starting in bronchioles (replaced by a complete smooth muscle layer)

What is the adventitia of the bronchi?

1. Dense connective tissue

2. Continuous with adjacent structure

What are the main changes of the main (extrapulmonary) bronchi?

Same structure as trachea except

cartilage form a circular ring

What are the cartilage changes in the intrapulmonary bronchi?

1. Cartilage rings replaced by cartilage

plates

2. Plates become gradually smaller and less

numerous

3. Bronchioles (≤ 1 mm), no cartilage plates

How is the muscular layer of the bronchi added?

1. Smooth muscle forming a

complete circular layer

2. As bronchi branch off and

become smaller

3. Smooth muscle becomes an

increasingly conspicuous

layer

4. Amount of cartilage

decreases (disappear

completely in bronchioles)

5. Smaller bronchi have

discontinuous muscle layer

Cartilage plates and smooth muscle in intrapulmonary bronchi

What do the bronchioles contain?

1. No mucosal glands nor cartilage

2. Thicker smooth muscle layer

3. Mucociliary escalator

4. Epithelium

What is the epithelium of the bronchioles?

1. gradual changes from larger

bronchioles to terminal bronchioles

2. Pseudostratified (with goblet cells)

3. Ciliated simple columnar (much less goblet

cells)

4. Ciliated simple cuboidal (no goblet cells)

What gives rise to respiratory bronchioles?

the branches of segmental bronchi

What are mid-sized bronchioles?

1. Ciliated columnar epithelium

2. Smooth muscle associated with

abundant elastic fibers

3. Connective tissue

4. Abundant lymphocytes of MALT

5. numerous lymphoid nodules

What are smaller bronchioles?

1. Ciliated simple cuboidal epithelium

2. Prominent layers of smooth muscle

3. Abundant MALT

What are the simple cuboidal epithelium of the terminal bronchioles?

1. Club cells with exocrine functions

2. Apical domain is dome-shaped

3. Abundant secretory granules

What are the functions of bronchial exocrine (club) cells of the simple cuboidal epithelium of the terminal bronchioles?

1. Secretion of surfactant lipoproteins and

mucins

2. Detoxification of inhaled xenobiotic

compounds by enzymes of the SER

3. Secretion of antimicrobial peptides and

cytokines

What are the other epithelial cells of the simple cuboidal epithelium of the terminal bronchioles?

1. Brush cells

2. DNES small granular cells

3. Stem cells

What are is the lamina propria of the simple cuboidal epithelium of the terminal bronchioles?

1. Elastic fibers

2. Smooth muscle

What are the respiratory bronchioles?

1. Alveoli present in their walls

2. First part of respiratory portion

3. Mucosa similar to that of terminal

bronchioles

4. Have few openings to alveoli

5. Epithelium has Club cells and squamous

cells at alveolar openings

6. Club cells become more numerous

distally as ciliated cells number

decreases

7. Lamina propria of loose CT

8. Smooth muscle

9. Elastic CT

What are the alveolar ducts?

1. After distal respiratory bronchioles

2. Lined by the openings of alveoli

3. Squamous epithelium in both the

alveolar ducts and alveoli

4. Thin lamina propria with a strand of

smooth muscle around the opening

of alveoli

5. Elastic and collagen fibers network

supports each ducts and its alveoli

What are the alveolar sacs?

1. End of alveolar ducts

2. Spaces surrounded by alveoli

opening into this space

3. Lined by a thin simple

squamous epithelium

4. Supported by very thin lamina

propria with elastic and

reticular fibers

5. abundant capillaries surround

each alveolus

What is alveoli?

1. Sack-like invaginations

2. About 200 nm diameter

3. About 200 million alveoli in each lung

4. Total internal surface 75 m2

5. Separated by interalveolar septa: Scattered fibroblasts and Sparse ECM of CT

6. Richest capillary network

What is the sparse ECM of CT?

Elastic and reticular fibers

Blood-air barrier (respiratory membrane)

In the alveolar epithelium, what are the type 1 alveolar cells (type 1 pneumocytes)?

1. 95% of alveolar lining

2. Very thin squamous epithelial

cells

3. Perinuclear organelles

4. Cytoplasm committed to blood-air

barrier only 25 nm thick with

pinocytic vesicles

5. Joint by desmosomes

6. Tight junctions prevent leakage of

interstitial fluid into alveolar

lumen

In the alveolar epithelium, what are the type 2 alveolar cells (type 2 pneumocytes) or septal cells?

1. 5% of alveolar lining

2. Cuboidal cells

3. Interspersed among type I pneumocytes

4. Tight junctions and desmosomes

5. Large, euchromatic, round nucleus with

nucleoli

6. Lightly stained cytoplasm with many

vesicles

7. contains Lamellar bodies

8. Release pulmonary surfactant

What are the lamellar bodies?

1. vesicles with stacked

parallel membrane lamellae

2. Lipids, phospholipids, and proteins

How does the type 2 alveolar cells or septal cells release the pulmonary surfactant?

Continuously removed by type I and type II

pneumocytes, and macrophages

What are dust cells?

1. Alveolar macrophages

2. In alveoli and interalveolar

septum

3. Slightly darker than type II

pneumocytes

What does the pleural membrane contain?

1. Serous membranes

2. Visceral pleura

3. Parietal pleura

4. Mesothelium

5. Pleural cavity

6. Loose connective (supporting) tissue

7. Collagen and elastic fibers (continuous

with those of the lung tissue)

What is the visceral pleura of the pleural membrane?

attached to lung tissue

What is the parietal pleura of the pleural membrane?

lines the thoracic wall

What is the mesothelium of the pleural membrane?

special simple squamous epithelium

What is the pleural cavity of the pleural membrane?

space between visceral

and parietal layers